US3559094A

US3559094A - Low voltage a.c. magnetron

Info

Publication number: US3559094A
Application number: US787660A
Authority: US
Inventors: James E Staats
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1968-12-30
Filing date: 1968-12-30
Publication date: 1971-01-26
Anticipated expiration: 1988-01-26

Abstract

THERE IS DISCLOSED A CROSSED-FILED DISCHARGE DEVICE INCLUDING AN ANNULAR FIRST ANODE MEMBER HAVING ARCUATE FIRST RECESSES ON THE INNER SURFACE THEREOF AND TWO ANNULAR SECOND ANODE MEMBERS, EACH HAVING ON THE OUTER SURFACE THEREOF ARCUATE SECOND RECESSES EQUAL IN NUMBER TO THE FIRST RECESSES AND DISPOSED RESPECTIVELY OPPOSITE THE FIRST RECESSES COOPERATING THEREWITH TO FORM INTERACTION SPACES, TWO AXIALLY SPACED-APART CATHODE MEMBERS EACH CARRYING SECONDARY-EMITTING ELECTRON DISCHARGE MEMBERS RESPECTIVELY DISPOSED IN THE INTERACTION SPACES, MEANS FOR

APPLYING LOW FREQUENCY LOW VOLTAGE A.C. OPERATING POTENTIALS TO THE DEVICE AND STARTING MEANS FOR THE DEVICE, OSCILLATOR, AMPLIFIER AND MODULATOR CIRCUITS INCORPORATING THE DEVICES ARE ALSO DISCLOSED.

Description

Jan. `26 1911 J. E. sTAATs Low VOLTAGE A.c. MAGNETRON V sal 'sheets-sheet 1 Filed Dec'.. 59', 1968 Jan. 26, 1971 J E STAATS 3,559,094

LOW VOLTAGE A. C. MAGNETRON Filed neg. 5o, 196e 9 sheets-sheet s FIGA /93 Jan. 26, J. E STAATSv Low VOLTAGE A.c. MAGN EEEEE Jan. 26, '1971 J. E. STAATS Low VOLTAGE A.c. MAGNETRON 9 Sheets-Sheet 8 Filed Dec.` 3G, 1968 Jan. 26, 1971 `1 E, STAATS 3,559,094

LOW VOLTAGE A.C. MAGNETRON Filed oec. :50, 196e' sa sheets-sheet 9 TUNER TTENUA T R OSC/LLA TOR 37/ United States Patent O Int. Cl. H03b 9/10 U.S. Cl. 331-86 65 Claims ABSTRACT OF THE DISCLOSURE There is disclosed a crossed-field discharge device including an annular first anode member having arcuate first recesses on the inner surface thereof and two annular second anode members, each having on the outer surface thereof arcuate second recesses equal in number to the first recesses and disposed respectively opposite the first recesses cooperating therewith to form interaction spaces, two axially spaced-apart cathode members each carrying secondary-emitting electron discharge members respectively disposed in the interaction spaces, means for applying low frequency low voltage A.C. operating potentials to the device and starting means for the device; oscillator, amplifier and modulator circuits incorporating the devices are also disclosed.

The v present invention relates to improved crossedfield electron discharge device and to microwave circuits incorporating the same including microwave oscillator circuits and microwave amplifier circuits.

Itis the general object of the invention to provide a new improved crossed-field electron discharge device for use at microwave frequencies, which device is of exceedingly Simple and economical construction and arrangement and which device lis vparticularly adapted for operation upon the application of relatively low-voltage `A.C. operating potentials thereto. t

It is `a further object of this invention to provide an improved crossed-field electron dischargedevice of the type set forth which upon application of low-frequency, lowvoltage operating potentials-thereto produces high voltage microwave energy. Y v

Another object of this invention is to provide a crossedfield electron discharge device of the type set forth comprising an inner coaxial transmission line including a hollow outer 4conductor and an inner conductor, a plurality t of peripheral coaxial transmission line sections each including a hollow outer conductor and an inner conductor, the peripheral innerconductors each including electron emissive portions, means coupling the peripheral transmission line sections to the inner transmission line of equiangularly spaced points around the periphery thereof, means for establishing unidirectional magnetic fields extending through the peripheral outer conductors parallel to the axes thereof, and means for establishing unidirectional electrical fields between the inner and outer conductors of each of the peripheral transmission line sections for causing electronemission from the associated peripheral innerconduc'tors, whereby the electrons emitted from the peripheral` inner conductors interact with the magnetic fields and the electrical fields to generate microwave energy within the peripheral transmission line sections.

In connection with the foregoing object, it is another object of this invention to provide an improved crossedfield electron discharge device wherein the means for` eS- tablishing unidirectional electrical fields comprises means for applying a 60-cycle, single-phase alternating voltage between the inner and outer conductors of the peripheral transmission line sections, the alternating voltage having an R.M.S. value in the range from about 220 volts to about 2.50 volts, and each of the peripheral transmission line Patented Jan. 26, 1971 ice sections rectifies the alternating voltage for establishing a unidirectional electrical field therein normal to the axis thereof and for causing electron emission from the associated peripheral inner conductors.

A still further object of this invention is to provide an improved crossed-field electron discharge device of the type set forth comprising an annular anode structure dening therein an inner axially extending storage space extending therethrough and a plurality of outer interaction spaces disposed around the storage space and a radially extending passage interconnecting the interaction space and the storage space at equiangularly spaced points around the periphery thereof, cathode structure disposed within the anode structure and including a plurality of electron discharge members equal in number to the interaction spaces and respectively disposed therein, means for establishing a unidirectional magnetic field extending axially through the interaction spaces, and end structures enclosing both the ends of the anode structure and the axially extending spaces.

In connection with the foregoing object, it is another object of this invention to provide an improved crossedfield electron discharge device wherein the outer interaction spaces extend axially of the anode structure and are disposed equiangularly around the storage space.

`In connection with the foregoing object, still another object of this invention is to provide an improved crossedlield electron discharge device wherein the anode structure includes an annular rst anode member and two annular second anode members disposed within the first anode member, the second anode members cooperating to define the inner axially extending storage space, the first and second anode members cooperating to define therebetween the plurality of outer axially extending interaction spaces and the second anode members being axially spaced apart to provide therebetween the radially extending passage interconnecting the inner axially extending storage space and the interaction spaces.

IIt is another object of this invention to provide an improved crossed-field electron discharge device of the type set forth wherein lthe anode structure includes an annular first anode member defining therein an axially extending space extending therethrough, the first anode member having a plurality of arcuate first recesses on the inner surface thereof disposed equiangularly therearound and extending axially thereof, and a cylindrical second anode member having a plurality of arcuate second recesses on the outer surface thereof disposed equiangularly therearound and extending axially thereof, the number of `the second recesses being equal to the number of the first recesses, and wherein the cathode structure is disposed within the axially extending space and includes a plurality of axially extending electron discharge members, the discharge members being respectively disposed in the interaction spaces, and further including end structure enclosing the ends of the anode members and the electron discharge members.

In connection with the foregoing object, it is another object of this invention to provide an improved crossedfield electron discharge device wherein the anode structure includes two cylindrical second anode members, each of the second anode members having a plurality of arcuate recesses on -the outer surface thereof disposed equiangularly therearound and extending axially thereof, the number of the second recesses on each of the second anode members being equal to the number of the first recesses on the first anode member, the second anode members ibeing respectively disposed in the axially extending space and axially spaced apart with respect lto each other, and wherein the cathode structure includes two cathode members, each of the cathode members including a plurality of axially extending electron discharge members, the

cathode members beingrespectivelyIdisposed in the axially extending space and being axially spaced apart with respect to each other, the electron discharge members being respectively disposed in the interaction spaces along the axes thereof.

In connection with the foregoing objects, it is another object of this invention to provide an improved crossedfield electron discharge device wherein the anode members and the cathode members are disposed symmetrically with respect to a plane normal to the longitudinal axis of the anode structure midway between the ends thereof.

It is another object of this invention `to provide a crossed-field electron discharge device of the type set forth comprising an enclosing anode structure and a cathode structure therein defining therewith an interaction space, the cathode structure including an electron discharge member disposed in the interaction space, means for establishing a unidirectional magnetic field through the interaction space, means for applying a low voltage alternating potential between the anode structure and the cathode structure, wherein the alternating potential has an R.M.S. value no greater than about 250 volts, the cathode structure cooperating with the anode structure upon the application of the alternating potential thereto to rectify the alternating potential and thus to provide a unidirectional electrostatic field in the interaction space, the electron discharge member discharging electrons into the interaction space for interaction with both the magnetic field and the electrostatic field therein to generate microwave energy within the device, and structure for withdrawing the microwave energy from the device.

Yet another object of this invention is to provide a crossed-field electron discharge device of the type set forth comprising an enclosing anode structure and two spaced-apart cathode structures in the anode structure and cooperating therewith to define an interaction space, each of the cathode structures including an electron discharge member disposed in the interaction space, means for establishing a unidirectional magnetic field through the interaction space, energizing means for applying an alternating voltage between the anode structure and the cathode structures, the cathode structures cooperating with the anode structure upon the application of the alternating voltage therebetween to provide full-wave rectification of the alternating voltage and to provide a unidirectional electrostatic field in the interaction space, the electron discharge members discharging electrons into the interaction space for interaction with both the magnetic field `and the electrostatic field therein to generate microwave energy within the device, and output structure for withdrawing the microwave energy from the device.

In connection with the foregoing object, it is anotherv object of the invention to provide an improved crossedfield electron discharge device wherein the means for applying an alternating voltage comprises a source of alternating voltage operating potentials including two line conductors respectively coupled to the cathode structures and a neutral conductor coupled to the anode structure, and wherein the cathode structures cooperate with the anode structure upon the application of the alternating voltage therebetween to provide a unidirectional electrostatic field in the interaction space, the electron discharge members discharging electrons into the interaction space for interaction with both the magnetic field and the electrostatic field to generate microwave energy within the device, whereby upon application of the alternating voltage operating potentials to the device, a microwave energy can be extracted therefrom via the output structure utilizing the one cathode structure as a probe.

In connection with the foregoing object, it is another object of this invention to provide an improved crossedfield electron discharge device wherein the source of operating potentials is a three-wire Edison network in-` Cil terminaLcand means -galvanically-connectin-gthe-terminals of the two line conductors respectively to the two cathode Structures and galvanically connecting the terminal of the neutral conductor to the anode structure, the Edison network providing between the terminals oftheltwo line conductors a 16C-cycle, Vsingle-phase alternating voltage having an R.M.S. value in the rangefrom'l about 220 volts to about 250 volts'.` p

In connection with the foregoing object, it is yet another object of this invention to provide an improved crossedfield electron discharge device wherein the cathode structure includesV electron dischargejmember/y disposed in the interaction'space,`and further including starting means coupledto the energizing means for providing a highy starting voltage pulse-between the anode structure and the cathode structure. V

A further object of the invention is to provide an improved microwave oscillator incorporating thereinv the crossed-field electron discharged device of the present invention, the resonantcircuit for lthe oscillator being in the form of a resonant cavity within the device. v

A still further object of the inventionis to provide an improved microwave amplifier incorporating therein a crossed-field electron discharge device of the present invention.

A still further object of the invention is to provide an improved microwave circuity incorporating therein a crossed-field electron discharge device of the present invention together with means for modulating the output of the device, whereby to provide a microwave oscillator having a modulatedl output and to provide amicrowave amplifier having a modulated output. i

Further features of the invention pertain to the particular arrangement of parts of the crossed-field electron discharge device and to Aconnection thereof in the various microwave circuits, whereby the above outlined and additional operating features thereof are attained.

The invention, both as vto its arrangements and method of operation, together with further objects and advantages thereof will best be understood by reference to the following specification and appended claims when taken'incon-` nection with the accompanyingy drawings, in which:

FIG. 1 is a schematic and diagrammatic illustration of anoscillator circuit incorporating therein a crossed-field electron discharge device of the present invention;

FIG.'v 2 is al graphplotting the wave forms of the input and output voltages ofthe crossed-field electron discharge device' of the present invention;

FIG. 3 is a view in vertical section through theoscillator of FIG. y1 and illustrating vthe circuit connectionsk for the crossed-field electron "discharge device f including the magnetic field coil therefor and the coupler and'filter structure used therewith; f

- FIG. 4 is an enlarged view in vertical section through the crossed-field electron discharge .devicey illustrated in the oscillator of FIG. 3; i

: 5 is a viewin horizontal sectionthrofug'h the device of FIG. 4' along the'line 5 5. thereof;

FIG. 6 is a view in horizontal section through the`4 device of FIG. -4 along the hline l6"-6 thereof;

FIG. 7 is a view in horizontal sectionv through the` device of FIG. 4 along'the line 7-7 thereof;

FIGS. 8 to 13, inclusive, are still further enlarged fragmentary views in horizontal section through the device` of FIG. 4 alongthe line 8-8 thereofand illustrating the various electrical and magnetic fields therein;

FIG. 14 is a schematicyand diagrammatic illustration of an amplifier circuit for amplifying the output from the microwave yoscillator of `FIG.,3, the amplifier circuitV utilizing therein a. crossed-field electron. discharge device made in accordance with and yembodying the. principles of the present invention; and

FIG. 15 is a view in vertical section through the amplifier circuit of FIG. 14 and illustrating the crossed'- eld electron discharge device and the circuit connections therefor including the magnetic field coil and the amplifier input circuits and output circuits.

Referring now to FIG. 1 of the drawings, there is diagrammatically illustrated an oscillator circuit 50 embodying features of the present invention, the oscillator circuit 50 having been illustrated as connected to a threewire Edison network of 236 volts, single-phase, 60 cycles A.C., and including two line conductors L1 and L2 and a neutral conductor N, the three conductors mentioned being terminated at an associated electrical insulating block B.

The oscillator circuit 50 comprises an oscillator 200 incorporating therein a crossed-field electron discharge device 100 made in accordance with and embodying the principles of the present invention, the oscillator 200 having three

input terminals

201, 202 and 203 that are connected respectively to the lines L1, L2 and N of the Edison supply network.

The crossed-tield discharge device 100 is shown schematically in FIG. 1 and includes an anode structure 105, two

cathode structures

170 and 180 and an electromagnetic eld coil 210. The input terminal 201 is connected to the cathode structure 170 through a low-pass filter 215 and the input terminal 202 is connected to the cathode structure 180 through a low-pass filter 230. The field coil 210 has one terminal thereof connected to the input terminal 203 of the oscillator and the other terminal thereof connected to the anode structure 105 as at 2,12. A bypass capacitor 228 is connected in parallel with the field coil 210. The oscillator 200 further includes a starting circuit 250 which includes in series combination a capacitor 251 and a switching means 255, the starting circuit 250 being connected between the cathode structure 170 and the anode structure 105. As illustrated, all of the parts of the oscillator 200 are surrounded by a grounded metallic casing 259.

Connection is made to an output transmission line 65 including an outer tubular conductor 66 and an inner conductor 67 disposed therein, a first capacitive coupling being provided by a coupler 242 between the outer conductor 222 and the outer conductor 66, and a second capacitive coupling being provided byl the coupler 244 between the inner conductor 178 and the inner conductor 67.

The microwave energy supplied from the oscillator 200 to the transmission line 65 may be used for any desired purposes, two typical uses of the microwave energy being illustrated in FIG. 1, the first-use being illustrated in the upper right-hand portion of FIG. 1 and the second use being illustrated in the lower right-hand portion of FIG. l. Referring to the upper right-hand portion of FIG. 1, in the first use of the microwave energy illustrated therein the transmission line -6'5 is coupled to an antenna of the type commonly used in search radar, the outer conductor 66 being connected to outer radiating or antenna elements `68 and the inner conductor 67 being connected to an inner radiating or antenna element 69, the antenna elements `68 and'r69 serving to match the impedance of the transmission line 65 to thev impedance of the atmosphere. Referring to the lower right-hand portion of FIG. l, in the second use of the microwave energy illustrated thereinthe transmission line 65 is coupled to an electronic heating apparatus, such as the electronic range` 70 illustrated that is generally designed for home use. More particularly, the range 70 comprises an upstanding substantially box-like casing 71 formed of steel and housingtherein a metal liner 72 deiining a heating cavity therefor. The metal liner 72 may also be formed of steel, and essentially comprises a boxlike structure provided with a top wall, a bottom wall, a rear wall and a pair of opposed side walls, whereby the liner 72 is provided with an upstanding front opening into the heating cavity defined therein, the casing 71 being provided with a front door 73 arranged in the front opening thus formed and cooperating with the liner 72. More particularly, the front door 73 is mounted adjacent to the lower end thereof upon associated hinge structure 74, and is provided adjacent to the upper end thereof with a handle 75, whereby the front door 73 is movable between a substantially vertical closed position and a substantially horizontal open position with respect to the front opening provided in the lines 72. Also the front door 73 has an inner metal sheet that is formed of steel and cooperates with the liner 72 entirely to close the heating cavity when the front door 73 occupies its closed position. For safety purposes, the inner liner 72 is connected by a conductor 76 to the outer casing 71 which is in turn grounded by the conductor N. The outer conductor 66 of the transmission line 75 is connected as at 78 to the casing 71 and to the liner 72 of the range 70, and there is provided within the range 70 at the rear thereof a radiating elementl or antenna 77 that is connected as at 79 to the inner conductor -67 of the transmission line 65. Accordingly, the microwave energy within the transmission line 65 is radiated into the cooking cavity of the range 70 to provide the power for cooking materials disposed therein. It further will be understood that in a preferred embodiment of the range 70i and the oscillator 200 together with the transmission line 65 are all preferably disposed within a common housing that also includes the casing 71, the common housing being preferably formed of metal, such as steel, and grounded for safety purposes. Further details of the construction of the oscillator 200 and the crossed-field discharge device forming a part thereof will now be described with particular reference to FIGS. 3 to 7 of the drawings. The device 100 comprises an anode structure including an outer anode member 110 and two

inner anode members

130 and 140, two annular anode storage members 150, two annular pole pieces 155, two cathode structures 170 and 1'80 and twocnd structures 190.

The anode structure 105 is essentially annular in shape and comprises an outer annular member surrounding two inner

annular members

130 and 140, which in turn respectively surround

annular storage members

150 and 155. The outer member 110 is generally tubular in shape and symmetrical with respect to a plane normal to the longitudinal axis thereof midway between the ends thereof, which plane will hereinafter be referred to as the midplane of the anode member 110. The anode member 110 has concentric cylindrical outer and inner surfaces 111 and 112, the inner surface 112 having adjacent each end thereof a recess defining upper andy lower annular side wall surfaces 113 and 114 asviewed in FIG. 4 having diameters equal to each other and slightly less than the diameter of the inner surface 112 and being concentric with the outer surface 111 of the anode member 110. The side wall surfaces- 113 and 114 are member 110. Each of the annular side wall surfaces 113 and 114 is further recessed at the outer end thereof to respectively form steps or notches 117 and 1'18 at the upper and lower ends of the anode member 110 asviewed in FIG. 4. The inner surface 112 of the anode member 110 between the end walls 115 and 11-6 has a plurality of arcuate recesses 125 therein, each of the recesses 125 extending axially of the anode member 110 from the lend.

wall to the end wall 116, the recesses 125 being equiangularly spaced around the innersurface 112 of the anode member 110 as shown in FIGS. Sand 6.- Each ,0f the recesses has an arcuate wall 126` the outermost `portion of which is coplanar with the annular side walls 11-3 and 114, each of the walls 126v being preferably part circular in shape normal to the longitudinal axis of the anode member 110. Adjacent ones of the recesses 125 are separated by unrecessed portions 127 of the inner surface 112, all of the portions 127 having the same circumferential extent which varies with the number and radius of curvature of the recesses 125.

Disposed within the outer anode member 110 and also forming a part of the anode structure 105 are the two

identical anode members

130 and 140 symmetrical with respect to the midplane of the anode member 110 and each having an outer diameter less than the inner diameter of the member 110 so as to be radially spaced inwardly therefrom. The anode member 130 is generally annular in shape and is disposed within the anode member 110 concentric therewith and adjacent to the upper end thereof as viewed in FIG. 4. The anode memebr 130 has a cylindrical inner surface 131 and a substantially cylindrical outer surface 132, the inner and

outer surfaces

131 and 132 being connected at the upper and lower ends thereof as viewed in FIG. 4 respectively by an annular outer end surface 133 and an annular inner end surface 134, the end surfaces 133 and 134 being substantially parallel to each other and disposed substantially normal to the longitudinal axis of the anode member 110. The axial extent of the inner and

outer surfaces

131 and 132 is preferably substantially less than the axial extent of the inner surface 112 of the anode mem-ber 1'10 between the end walls 115 and 116 thereof. -In particular, the outer end surface 133 of the anode member '130 is coplanar with the end wall 115 of the anode member 110 and the inner surface 134 of the anode member 130 is disposed a predetermined distance above the midplane of the anode member 110 as viewed in CFIG. 4. The outer surface 132' of the anode member 130 has a plurality of arcuate recesses 135 therein, each of the recesses 135 extending axially between the end surfaces 133 and 134 and being equiangularly spaced around the outer periphery of the anode member 130. Each of the arcuate recesses '135 has an arcuate wall 136, each of the walls 136 being part circular in shape normal to the longitudinal axis if the device 100. As can be seen from FIGS. 5 and 6- the number of recesses 135 in the anode member 130 is equal to the number of recesses 125 in the anode member 110. Further, the recesses 135 are respectively disposed opposite the recesses 125, the angular spacing between the recesses 135 being the same as the angular spacing between the recesses 125. Each of the recesses 135 preferably has the same radius and the same center of curvature as its corresponding recess 125. Adjacent ones of the recesses 135 are separated by unrecessed portions 137 of the outer surface 132, all of the portions 137 having the same circumferential extent which varies with the number and radius of curvature of the recesses 135.

Disposed Within the anode member 110 adjacent to the lower end thereof as viewed in FIG. 4 and concentric therewith is the anode member 140. The anode member 140 has a cylindrical inner surface 141 and a substantially cylindrical outer surface 142, the inner and

outer surfaces

141 and 142 being connected at the lower and upper ends thereof as viewed in FIG. 4 respectively by an outer end surface 143 and an inner end surface 144, the end surfaces 143 and 144 being substantially parallel to each other and being disposed substantially normal to the longitudinal axis of the device 100. The axial extent of the anode member 1'40 is preferably substantially less than the axial extent of the inner surface 112 of the anode member 110 between the end walls 115 and 116 thereof. More particularly, the outer end surface 143 of the anode member 140l is coplanar with the end wall 115 of the anode member 110 and the inner end surface 144 of the anode member 140 is disposed a predetermined distance below the midplane of the anode member 110 as viewed in FIG. 4. The outer surface 142 of the anode member 140 has a plurality of arcuate recesses 145 therein, each of the recesses 145 extending axially between the end surfaces 143 and 144 and having an arcuate wall 146 which is part circular in shape normal to the longitudinal axis of the anode member 140. The recesses 145 are equiangularly spaced around the outer periphery of the anode member 140 and are equal in number to the recesses 125 of the anode member and are respectively disposed opposite thereto, the angular spacing between the recesses 145 being the same as the angular spacing between the recesses 125. Furthermore, each of the recesses 145 in the anode member 140 has the same radius and the same center of curvature as its corresponding recess on the anode member 110. Adjacent ones of the recesses 145 are separated by unrecessed portions 147 of the outer surface 142, all of the unrecessed portions 1'47 having the same circumferential extent which varies with the number and radius of curvature of the recesses 14'5.

The recesses and 145 in the anode members 130 and respectively cooperate with the corresponding recesses 125 in the anode member 110` to form a plurality of axially extending interaction spaces 120` therebetween, each of the interaction spaces 120` having an upper portion 121 and a lower portion 122. More particularly, the recesses 135 in the anode member 130 respectively cooperate with their corresponding recesses 125 in the anode member 110 to form the upper portions 121 of the interaction spaces 120 and the recesses 145 in the anode member 14|]y respectively cooperate with their corresponding recesses 125 in the anode member 110 to form the lower portions 122 of the interaction spaces 120. Each of the interaction spaces 120 is circumferentially connected to the adjacent ones of the interaction spaces 120 by circumferentially extending connecting passages 123 as can be seen in FIGS. 5 and 6, the passages 123 being respectively dened by the unrecessed portions 137 and 147 of the outer surfaces 132 and 1-42 of the

anode members

130 and 140 and the oppositely arrayed unrecessed portions 127 of the inner surfaces 112 of the anode member 110. More particularly, the unrecessed portions 137 and 147 of the

outer surfaces

132 and 142 cooperate to respectively define the inner walls of the passages 123 and the unrecessed portions 127 0f surface 112 respectively define the outer walls of the passages 123.

Respectively disposed within the

inner anode members

130 and 140 are the two annular anode storage members 150 symmetrical Iwith respect to the midplane of the anode member 110. The members 150 are identical in construction and, therefore, like reference numerals will be used for like parts of the two members 150. The upper member 150 as viewed in FIG. 4 will be described in detail, the construction and disposition of the lower member 115 being identical to that of the upper member 150. The upper anode member 150 is tubular in shape, being circular in transverse cross section at all points therei along and being disposed concentrically With the inner anode member 130. The anode member .150 has a cylindrical inner side wall surface 151 and a cylindrical outer side Wall surface 152, the outer surface 152 having a diameter only slightly less than the diameter of the inner surface 131 of the inner anode member `130, whereby the anode member 150 can fit within the anode member 130 and ultimately is connected thereto as by brazing. The inner and outer surfaces .151 and 152 of the anode member 150 are connected at the upper and lower ends thereof as viewed in FIG. 4 respectively by an outer annular end surface 153 and an inner annular end surface 154, the end surfaces 153 and 154 being parallel to each other and disposed substantially normal to the longitudinal axis of the device 100. The axial extent of the anode member 150 is substantially greater than the axial extent of the anode member 130. More particularly, the inner end surface 154of the anode member 150 is coterminous with the inner end surface .134 of the anode member 130, while the upper end of the anode member 150 as viewed in FIG. 4 extends outwardly a substantial distance beyond the upper end of the outer anode member 110. The disposition of the lower anode member 150'as viewed in FIG. 4 with respect to the anode member 140 is the same as the disposition of the upper anode member 150 with respect to the anode member 130.

There is provided adjacent to the ends of the outer anode member 110 two anular pole pieces 155. The pole pieces .155 being identical in construction and symmetrically disposed with respect to the longitudinal midplane of the device 100 and, therefore, like reference numerals will be used for like parts of the pole pieces 155. Referring to the upper pole piece 155 as yviewed in FIG. 4, the pole piece 155 has a cylindrical inner Surface 156 and a cylindrical outer surface 157, the

surfaces

156 and 157 being coaxial with each other and with the inner and outer surfaces 151 and .152 of the anode member 150. The inner surface 156 of the pole piece 155 has a diameter only slightly greater than the diameter of the outer side wall surface 152 of the anode member 150, whereby the pole piece 155 lits snugly around the anode member 150 in surrounding relationship therewith and ultimately is connected thereto as by brazing. The inner and

outer surfaces

156 and 157 of the pole piece 155 are connected at the upper and lower ends thereof as viewed in FIG. 4 respectively by an annular outer surface 158 and an annular inner surface 159, the

surfaces

158 and 159 being parallel to each other and disposed substantially normal to the longitudinal axis of the device 100. The outer surface 157 of the pole piece 155 has a diameter only slightly less than the diameter of the recessed or notched portion 1.17 of the outer anode member 110, whereby the pole piece 155 fits snugly into the notch `117 and is ultimately connected to the anode member 110 as by brazing. Similarly, the lower one of the pole pieces 155 fits into the notch 118 at the opposite end of the anode member 110.

Disposed within the anode structure 105 adjacent to the inner ends of the anode storage members 150 are two annular insulating spacers 163 symmetrical with respect to the midplane of the anode member 110. The insulating spacers 163 are identical -in construction and, therefore, like reference numerals will be used for like parts thereof. The upper one of the insulating spacers 163 as viewed in FIG. 4 is annular in shape having a recessed portion 164 in the outer side Wall thereof, the spacer 163 fitting within the lower end of its corresponding anode member .150 so that the recessed portion 174 ts snugly against the inner ends of the side wall 151 and the inner end wall 154. The insulating spacer 163 has a circular opening 165 extending therethrough along the longitudinal axis thereof. The lower one of the insulating spacers 163 as viewed in FIG. 4 is similarly disposed with respect to the lower one of the anode members 150.

The

cathode structures

170 and 180 are disposed within the anode structure 105 and are symmetrical with respect to the midplane of the anode member .110. The cathode structure 170 is disposed adjacent to the upper end of the anode structure 105 as viewed in FIG. 4 and the cathode structure `180 is disposed adjacent to the lower end of the anode structure 105. The cathode structure 170 includes an annular plate member 171 being essentially disc-like in shape and having a at inner surface 172 and a iiat outer surface 173, the surfaces 172 and .173 being parallel to each other and disposed substantially normal to the longitudinal axis of the device 100. The plate member 171 is disposed within the outer anode member 110 and has a diameter slightly less than the diameter of the inner surface 112 thereof so as to be spaced radially inwardly a small distance therefrom. The inner surface 172 of the plate member 17.1 is disposed above the midplane of the anode member 110 as viewed in FIG. 4 and is spaced a predetermined small distance therefrom. Disposed centrally of the plate member `171 is a relatively small circular opening .174 extending axially therethrough. Disposed around the periphery of the plate member 171, integral therewith and extending axially outwardly therefrom is a plurality of electron discharge members 175, each of the discharge members 175 being cylindrical in shape and having a cylindrical external surface 176 and an end surface 177 at the outer end thereof. The electron discharge members 175 are equal in number to the interaction spaces 120 and are respectively disposed in the upper portions 121 thereof. More particularly, each of the electron discharge members 175 has its longitudinal axis disposed along the longitudinal axis of its corresponding interaction space 120, the axial extent of the electron discharge members 175 being such that their outer ends 177 are coterminous with the outer end surface 133 of the anode member 130 and with the upper end wall 115 of the anode member 110. Disposed in the central opening 17-4 of the plate member 171 and attached thereto is an input-output lead 178 being cylindrical in shape and extending outwardly from the plate member 171 along the longitudinal axis of the device to a point beyond the outer end of the anode structure 105, the lead 178 serving to convey electrical energy to and from the device 100.

The cathode structure 180 includes an annular plate member 181 being essentially disc-like in shape and having a flat inner surface 182 and a flat outer surface 183, the

surfaces

182 and 183 being parallel to each other and disposed substantially normal to the longitudinal axis of the device 100. The plate member 181 is disposed within the outer anode member and has a diameter slightly less than the diameter of the inner surface 112 thereof so as to be spaced radially inwardly a small ditsance therefrom. The inner surface 182 of the plate member 181 is disposed below the midplane of the anode member 110 as viewed in FIG. 4 and is spaced a predetermined small distance therefrom. Disposed centrally of the plate member 181 is a relatively small circular opening 184 extending axially therethrough. Disposed around the periphery of the plate member 181, integral therewith and extending axially outwardly therefrom is a plurality of electron discharge members 185, each of the discharge members 185 being cylindrical in shape and having a cylindrical external surface 186 and an end surface 187 at the outer end thereof. The electron discharge members 185 are equal in number to the interaction spaces and are respectively disposed in the lower portions 122 thereof. More particularly, each of the electron discharge members 185 has its longitudinal axis disposed along the longitudinal axis of its corresponding interaction space 120, the axial extent of the electron discharge members 185 being such that their outer ends 187 are coterminous with the outer end surface 143 of the anode member and with the lower end wall 116 of the anode member 110. Disposed in the center opening 184 of the plate member 181 and attached thereto is an input-output lead 188 being cylindrical in shape and extending outwardly from the plate member 181 along the longitudinal axis of the device 100 to a point beyond the outer end of the anode structure 105, the lead 188 serving to convey electrical energy to and from the device 100.

'Each of the

electron discharge members

175 and 185 is provided on the external surface 176 thereof with a coating of a suitable electron emissive oxide material, whereby upon application of a high starting voltage pulse between the anode structure 105 and the

cathode structures

170 and 180 the resulting electrical eld will cause the electron emissive coating to begin to emit electrons from the outer surface thereof, which emission, once started, will be self-sustaining in the presence of the A.C. operating potentials applied to the device 100.

The

anode members

110, 130, 140 and 150 are formed of a metal having good thermal conductivity, the preferred material being copper. These anode members must also have good electrical conductivity as well as the good thermal conductivity. The pole pieces are formed of a material having high magnetic permeability, the preferred material being a low carbon steel. The pole pieces 155 are preferably copper plated to render the outer surfaces thereof high conductive to R.F. energy and to provide a good electrical connection between the anode member 110 and the anode members 150. The

cathode structures

170 and 180 are formed of a metal having a good electrical conductivity, the preferred metal being copper. The insulating spacers 164 are formed from an electrically insulating dielectric material, the preferred material being a synthetic organic plastic resin, the preferred resin being a tetrafluoroethylene resin sold under the trademark Teflon The anode structure 105 and the pole pieces 155 and the

cathode structures

170 and 180 are all symmetrical with respect to the midplane of the anode member 110 and they cooperate to define a group of interconnected spaces which are also symmetrical with respect to the same midplane. In particular, the tubular anode storage members 150 cooperate to deiine an inner axially extending storage space 160 extending through the device 100, the storage space 160 having an upper portion 161 dened by the upper one of the anode members 150 and a lower portion 162 defined by the lower one of the anode members 150 as viewed in lFIG. 4. IFurthermore,

- as has been described above, the

inner anode members

130 and 140 cooperate with the outer anode member 110 to define therebetween a plurality of outer axially extending interaction spaces 120. The inner surfaces 158 of the pole pieces 155 are respectively spaced outwardly from the outer end surfaces 133 and 143 of the

anode members

130 and 140 and from the end walls 115 and 116 of the anode member 110, thereby defining upper and lower end spaces 166 and 167 as viewed in FIG. 4, the end spaces 166 and 167 being closed respectively by the outer side wall surfaces 156 of the anode storage members 155 and communicating with and forming extensions of the interaction spaces 120 at the upper and lower ends thereof. The facing

inner surfaces

172 and 182 of the

cathode members

170 and 180 are spaced apart a predetermined distance and deiine therebetween a radially extending gap or passage 190 which communicates the interaction spaces 120 at the mid-regions thereof with the inner axially extending storage space 160 at the midregion thereof.

Upper and lower end structures 195 are provided respectively at the upper and lower ends of the device 100, the end structures 195 serving ot provide a hermetic seal between the associated anode storage members 150 and the associated cathode leads 178 and 188. The end structures 195 are identical in construction and symmetrical with respect the midplane of the anode member 110` and, therefore, like reference numerals Will be used for like parts thereof. Referring now to the upper one of the end structures 195 as viewed in FIG. 4, there is provided an annular insulator 191, the lower end of which is received within the upper end of the anode storage member 150, the insulator 191 being formed, for example, of a good electrically insulating ceramic. The annular insulator 191 has an axially extending opening therein receiving therethrough the cathode lead 178. Surrounding the upper end of the insulator 191 and the adjacent portion of the cathode lead 178 is an end cap 192, the cap 192 being generally annular in shape and including an annular ange 193 surrounding an outer periphery of the upper end of the insulator 191 and being hermetically sealed thereto. Integral with the upper edge of the outer flange 193 is an inwardly directed flange 194 carrying on the inneredge thereof an outwardly directed annular inner flange 193 surrounding the adjacent portion of the lead 178 and hermetically sealed thereto as by brazing. At the upper end of the anode member 150y there is provided in surrounding relationship with the insulator 191 an annular seal member 197. The seal member 197 includes a mounting flange 198 lixedly secured as by brazing to the outer end surface 153 of the anode member 150, the mounting ange 198 having integral therewith an annular flange 199 folded inwardly upon itself so as to define an attachment flange which is substantially U-shaped in vertical cross section, the inner fold of the flange 199 surrounding and being secured to the outer wall of the insulator 191. It is pointed out that the cap 192 and the ,seal member 197 are both formed of a material that can be readily secured both to a metal surface and to a ceramic surface, the preferred material being Fernico alloy, a typical composition being 54% iron, 28% nickel and 18% cobalt. It will be seen that the end structure 195 forms a good hermetic seal that also provides electrical insulation between the anode member 150 and the cathode lead 178, the end structure 195 likewise providing the necessary mechanical support of the cathode structure 120 to position it within the anode structure 105'. The lower one of the end structures 195 is similarly disposed with respect to the lower one of the anode members 150 and the cathode lead 188 of the cathode structure 180 to provide a hermetic seal at the lower end of the device and to mechanically support the cathode structure 180 within the anode structure 105, the end structures 195 being the only seals necessary for the device 100.

Disposed around the upper end of the upper anode member 150 in surrounding relationship therewith is a cooling iin package 204, the package 204 comprising a cylindrical heat conductive sleeve 205 attached to the anode member 150 at the outer surface 152 thereof, the sleeve 205 carrying thereon a plurality of axially spacedapart cooling fins disposed substantially normal to the sleeve 205 and extending outwardly therefrom. The sleeve 205 extends axially outwardly beyond the outer end of the anode member 150 thereby forming a cylindrical conductor to be described more fully hereinafter. Similarly, there is disposed about the outer end of the lower anode member 150 in surrounding relationship therewith a second cooling n package 207 comprising a cylindrical heat-conductive sleeve 208 attached to the anode member 150 at the outer surface 152 thereof and carrying a plurality of axially spaced-apart cooling tins 209 disposed substantially normal to the sleeve 208 and extending outwardly therefrom. The sleeve 208 extends outwardly beyond the outer end surface 153 of the lower anode member 150 to form a cylindrical conductor the purpose of which will be more fully described hereinafter. The cooling fine packages i204 and 207 are formed of a good heat-conductive material, the preferred material being copper, for dissipating the heat generated within the device 100. There is preferably lprovided a means such as a fan or blower (not shown) for passing a stream of cooling air over the

iins

206 and 209 for cooling the device 100. It is noted that the

sleeves

205 and 208 are in good electrical connection as well as thermal connection with the anode members 150 thereby providing a good electrically conductive path from the anode structure to the

sleeves

205 and 208.

When the device 100 is incorporated as a crossed-field discharge device in a microwave circuit, the pole pieces 155 arranged adjacent to the opposite ends of the anode member are utilized for establishing a unidirectional magnetic field extending axially through the several interaction spaces within the anode structure 105. To this end a magnet coil 210 has been provided, the magnet coil 210 being disposed about the anode member 110 in surrounding relationship therewith as viewed in FIG. 3. The magnet coil 210 is shaped as a torous and is wound of electrically conductive wire and is supported around the anode member 110 by any annular casing 213, It will be understood that the pole pieces 155 are formed of metals having a high magnetic permeability, such as soft iron or low carbon steel, whereby when the magnet coil 210 is energized a strong and uniform unidirectional magnetic field is established between the pole pieces extending axially through the interaction spaces 120 Within the device 100.

The circuit for energizing the coil 210 can be traced with reference to FIGS. 1 and 3 from the Edison supply network, and specifically the neutral conductor N thereof, to the input terminal 203 of the oscillator 200 to which is 4connected one terminal of the magnet coil 210. The other terminal of the magnet coil 210 is connected by a conductor 211 to one of the cooling tins 209 as at 212, whereby the input terminal 203,is connected via magnet coil 210, the conductor 211, and the cooling lin 209 to the anode member 150 of the device 100. The flow of current through the magnet coil 210 serves toproduce the unidirectional magnetic eld in the interaction spaces 120 of the device 100.

Referring now to fFIG. 3 of the drawings, the manner in which the crossed-field electron discharge device 100 is incorporated in the oscillator 200 will be described in further detail. At the lower end of the device 100 as viewed in FIG. 3 there is provided an R.F. rejection filter 215, the filter 215 comprising an annular cup-like electrically conductive member 216 having a flat annular end wall 214 disposed in a plane substantially normalto the longitudinal axis of the device 100 anda cylindrical side wall 217 integral with the end wall214 at the: outer periphery thereof and extending axially inwardly therefrom. The cup-like member 21=6 is telescopically received within the outer end of the sleeve 208 and is separated therefrom by an annular insulator 218 disposed therebetween, the insulator 218 preferably being formed of a synthetic organic plastic resin, the preferred resin' being a tetralluoroethylene resin sold under the trademark Teom There is also provided a cylindrical inner conductor 219 electrically connecting the outer end of the cathode lead 188 to the end wall 214 of the cup member 216, the inner end of the conductor 219 having a centrally disposed opening therein in which is received the outer end of the cathode lead 188 and the outer end of the flange 195 of the end cap 192, the outer end of the conductor 219 having an internally threaded opening therein in which is received a terminal screw 202 which is passed through an opening in the end wall 214 and which forms the input terminal 202 of the oscillator 200 and which secures the cup 216 to the coupler 219. The terminal 202 is one of the A.C. input terminals for the oscillator 200, the rejection ilter 215 serving to prevent the microwave energy generated lwithin the device 100 from being introduced into the Edison supply network through the terminal 202.

At the opposite end of the device 100.there is provided a coupler and lter structure 220 to accommodate.

the application of the A.C. operating potentials tov the device 100 and the withdrawal of microwave energy-therefrom whilepreventing the introduction of R.F. energy` an electrically conductive T-member 221 comprising an,

axially extending lower arm 222 and two radially outwardly extending

arms

223 and 224. The T-member 221 is hollow, the lower arm 222 being annular in` shape and extending outwardly from and being integral with the outer edge of the sleeve 205. The radial arm 223 is integral with the lower arm 222 and forms a hollow annular conductor extending to the left of the lower arm 222and substantially normal thereto as viewed in FIG. 3. The radial arm 224 is also integral with the lower arm 222 and forms a hollow annular conductor extending to the right of the lower arm 222 substantially normal thereto and coaxial with the arm 223 as viewed in FIG. 3. Coupled to the outer end of the cathode lead 178 is an axially extending cylindrical bullet coupler 225 having in the lower end thereof an opening 226 for receiving therein the outer end of the cathode lead 178 and the surrounding flange 196 of the end cap 192. The upper end ofthe coupler 225 has a reduced diameter portion 227 having a threaded eye 228 therethrough along the longitudinal axis of the

arms

223 and 224. An electrically conductive CTI probe member 229 is disposed in the radial arm 224 of the T-member 221 along the longitudinal axis thereof the left-hand end of the probe 229 as viewed in FIG. 3 being disposed through the eye 228 in the bullet coupler 225, and threadedly engaged therewith and extending slightly beyond the bullet coupler 225 at the left-hand side thereof. l

Coupled to the T-member 221, and in particular to the radial arm 223 thereof, is an RJF. rejection filter 230. The lter 230 includes an annular cup-like conductor 231 having a lat annular end ywall 232 disposed normal to the longitudinal axis of the radial arm 223, the end wall 232 carrying at theperiphery thereof and integral therewith an annular side Iwall 233 extending axially of the arm 223 and telescopically received therein. Surrounding the side wall 233 and separating the side wall 233 from the arm 223 is an annular insulating sleeve 234, the sleeve 234 preferably being formed of a synthetic organic plastic resin, the preferred resin being a tetrafluoroethylene resin sold under the trademark Teonf Electrically coupling the bullet coupler 225 to the end wall 232 of the cup 231 is an inner conductor 235, the conductor 235 being cylindrical in shape with the right-hand end thereof abutting the recessed portion 227 of the bullet coupler 225 and having an internally threaded opening therein in which the left-hand end of the probe member 229 is threadedly engaged. The conductor 235 has a reduced diameter portion 237 at the left-hand end thereof, the portion 237 abutting the end wall 232 of the conductor 231 and having an internally threaded opening therein in which is threadedly engaged a terminal screw 201 which is passed through an opening in the end wall 232 and which forms the input terminal 201 of the oscillator 200 and secures the cup 231 to the coupler 235. The right-hand end of the side wall 233 of the cup 231 abuts the unrecessed portion of the coupler 235 while the left-hand end extends outwardly beyond the end of the arm 223, and the righthand end of the insulating sleeve 234 abuts the unrecessed portion of the bullet coupler 225 while the left-hand end extends outwardly beyond the end of the arm 223 but not as far as the end 232 of the cup 231.

The arm 224 of the T-member 221 cooperates with the probe member 229 to form a coaxial output transmission line for withdrawing microwave energy from the device 100. There is provided for this output transmission line, a capacitive coupler 240, the coupler comprising an insulating sleeve 241 surrounding and firmly embracing the right-hand end of the arm 224 and an insulating sleeve 242 surround and firmly embracing the probe member 229 and extending to the right a short distance beyond the end thereof. The

sleeves

241 and 242 are formed of an electrically insulating dielectric material, the preferred material being a synthetic organic plastic resin, the preferred resin being a tetrafluoroethylene resin sold under the trademark Teonf Overlapping the sleeve 241 is an annular outer conductor 243 and overlapping the right-hand end of the sleeve 242 is an annular inner conductor 244, the

sleeves

241 and 242 serving respectively to provide a capacitive coupling between the

outer conductors

224 and 243 and between the

inner conductors

229 and 244. The outer conductor 243 has at the righthand end thereof and integral therewith a short inwardly tapered section 245 integral at the inner end thereof with a short reduced diameter portion 247. Telescopically received within the reduced diameter portion 247 and connected thereto is an annular outer conductor 248. The inner annular conductor 244 extends outwardly beyond the right-hand end of the sleeve 242 and into the outer conductor 248, the outer conductor 248 and the inner conductor 244 cooperating to form a coaxial output transmission line 249 for the device 100.

In operation, the line conductors L1 and L2 are respectively connected to the cathode structures and 180 to apply an A.C. operating potential thereto. More particularly, the line conductor L1 is connected to the cathode structure 170 via the input terminal screw 201, the inner conductor 235, the bullet coupler 225 and the cathode lead 178 while the line conductor L2 is connected to the cathode structure 180 via the input terminal 202, the inner conductor 219 and the cathode lead 188. The microwave energy generated within the device 100 is coupled to the load via a series of interconnected coaxial transmission lines. The first of these transmission lines has an outer conductor defined by the arm 222 and an inner conductor defined by the cathode lead 178 and the bullet coupler 225. This transmission line is coupled to a second transmission line the outer conductor of which is defined by the arm 224 and the inner conductor of which is defined by the probe member 229, which second transmission line is capacitively coupled via the coupling structure 240 to a third transmission line having an outer conductor defined by the

outer conductors

243 and 248 and an inner conductor 244. Introduction of the microwave energy into the Edison supply network is prevented by the R.F. rejection filters 215 and 230. The length of each of the cup-

like members

216 and 231 is substantially one-fourth of the wavelength of the operating frequency of the device 100 whereby the cup-like members define quarter-wave cavities which operate as rejection filters at the microwave frequency of the device 100.

Since the

electron discharge members

175 and 185 of the

cathode structures

170 and 180 are of the cold cathode type, to initiate the emission of electrons therefrom it is necessary to provide a starting circuit. The starting circuit 240 is shown schematically in FIG. 1 and includes a capacitor 251 and a two-terminal switching device 255. One terminal of the capacitor 251 is connected to the cathode structure 170 as at 252, the other terminal of the capacitor 251 being connected to a movable contact 254 of the switch 255. The switch means 255 has a fixed contact 256 which is connected to the anode structure 105. Suitable actuating means (not shown) are provided to momentarily close the switch means 255 when the capacitor 251 has become charged thereby discharging the capacitor 281 through the anode structure 105 and the magnet coil 210 thereby providing an initial magnetic field and a transient pulse of high voltage for establishing an initial electrical field for starting electron emission in the device 100. Once started, the electron emission from the

discharge members

175 and 185 is sustained by the A.C. operating potentials applied between the anode structure 105 and the

cathode structures

170 and 180.

During the operation of the crossed-field discharge device 100 in the oscillator 200, the

anode members

110, 130 and 140 and the

cathode structures

170 and 180` cooperate to provide a plurality of coaxial transmission lines Within the device 100, the coaxial transmission lines thus formed accommodating axially extending R.F. Waves therein and providing a frequency determining resonant cavity for the device 100 and for the oscillator 200. The coaxial transmission lines more specifically include an inner coaxial transmission line defined by the inner annular surfaces 151 on the anode members 150 and the cathode leads 178 and 188 of the

cathode structures

170 and 180; the surfaces 151 cooperate to provide a hollow outer conductor for the inner transmission line and the cathode leads 178 and 188 cooperate to form an inner conductor for the inner transmission line. The

anode members

110, 130 and 140 and the

electron discharge members

135 and 145 cooperate to define a plurality of outer axially extending transmission line sections, in particular, the

arcuate recess walls

126, 136 and 146 cooperating to define a plurality of outer conductors for the outer transmission line sections and each of the electron discharge members 135 cooperating with its corresponding electron discharge member 145 to form an inner conductor for the associated one of the outer transmission lige sections. The radial passage 190 serves to couple the outer transmission line-sections to-the inner transmission line thereby coupling microwave energy generated in the outer transmission line sections from these sections to the inner transmission line.

In the operation of the device 100, the outer transmission line sections provide a resonant cavity which can be excited to cause oscillations therein at a frequency equal substantially to twice the length thereof, i.e., twice the axial distance between the inner surfaces 158 of the pole pieces 155, whereby to provide an axially extending wave in the interaction spaces which is reflected by the inner surfaces 158 at the ends of the transmission line sections to produce a standing R.F. wave. The standing R.F. waves of microwave energy are communicated to the inner transmission line by the radial passage 190 which acts as a wave guide for this purpose, the

cathode lead

178 or 188 being utilized as a probe for extracting the microwave energy from the inner transmission line.

In the operation of the oscillator 200, it is necessary to produce within the crossed-field discharge device 100 a pattern of electrical and magnetic fields. More particularly, there must be established in the interaction spaces 120 an axially extending unidirectional magnetic field and a unidirectional electrical field normal to the axes of the interaction spaces. It is noted that the operating potentials applied to the input terminals 201-203 of the oscillator 200 are alternating, having a frequency of 60 cycles per second. In order to establish unidirectional magnetic and electrical fields within the device 100, it is necessary that the alternating component of the operating potentials be substantially eliminated. This function is accomplished in the device 100 by the two

cathode structures

170 and 180 which cooperate with the anode structure 105 to provide a full-wave rectification of the alternating potentials within the device 100. Referring to FIG. 2' there is shown a waveform diagram illustrating the operating potentials applied to the device 100 and their rectication thereby. The 60-cycle, single-phase alternating voltage which is applied to the input terminals of the oscillator 200 from the Edison supply network is represented by the sine wave shown in broken lines, only one cycle of the sine wave being shown for purposes of convenience. The

cathode structures

170 and 180 serve to full-wave rectify the input voltage wave 80, thereby producing the rectified voltage waveform 82. The device 100 conducts for only a portion of each half cycle of the input voltage waveform, the conducting portion of each one-half cycle preferably being about 20% thereof, this conductive portion being indicated vby the solid line at the peak of each half cycle of rectified input voltage. Thus, the device has a somewhat intermittent, but unidirectional operation. g g i Thedescription of the electrical fields and magnetic fields within the device 100 during the operation thereof as an oscillator and the method of creating those fields will now be given. The operating potentials for device 100 are derived directly from the Edison supply network, as is indicated above, the conductors L1, L2 and N being respectively galvanically connected to the

input terminals

201, 202 and 203 of the oscillator 200. The input termimal 201 is connected through the filter 2 30 and kthe coupler 225 to the cathode structure 170 which is in turn connected to the output of the device 100 via the coupler 225', the probe 219` and the coupler 3240;' the input terminal 202 is connected through the filter 215 to the cathode structure 180; the input terminal 203 is connected to one terminal of the magnet coil 210, the other terminal of the magnet coil 210 being connected to the anode structure and thence tothe output conductor 222 at the output ofthe device .100."Upon the application of the operating potentials to the device 200 the capacitor 251 of the starting circuit 250 becomes charged to a predetermined potential. Upon operation of the switch means 255 of the startingcircuit 250, the capacitor 251 becomes discharged, thereby providing a 17 high voltage starting pulse between the cathodestructure 180 and the anode structure 105 for initiating electron emission in the device 100. The capacitor 251 also cooperates with the field coil 210 to provide an initial magnetic field within the device 100.

The application of the above-described alternating potentials to the device 100 and their rectification thereby serves to establish a unidirectional electrical field 260 (see FIG. 8), that extends between the electron discharge members 175 (for example) and the anode members 110 and 130 (for example). In particular, the electrical field extends between the electron discharge members 175 and the

Walls

126 and 136 of'the

arcuate recesses

125 and and 135. The electrical eld 250 extends substantially normal to the longitudinal axes of the interaction spaces 120, the field lines entering walls 126 and 1'36 normal thereto and entering the surfaces 176 of the discharge members 175 normal thereto, whereby the field 250 takes the shape illustrated in FIG. 8. It will be understood that a like-shaped unidirectional electrical field is provided between the electron discharge members 185 and the

anode segments

110 and 140 in the lower portion of the device 100.

In order to provide the necessary unidirectional magnetic field normal to or crossed with respect to the electrical field 260, a current is established in the magnet coil 210. More particularly, electrons fiow from the anode structure 105 through the cooling fins 209, the conductor 211, the magnet coil 210 and the conductor N to the Edison supply network output terminal. With such a flow of electrons through the magnet coil 210, a strong unidirectional magnetic flux is established through a path including the upper magnetic pole piece 155, the interaction spaces 120 and the lower magnetic pole piece 155. Referring to FIG. 9 of the drawings, the unidirectional magnetic iiux lines extending through the interaction spaces 120 are designated by the numeral 265, the flux lines 265 extending axially through the spaces 120 and, therefore, normal to the plane of the sheet of drawing in FIG. 9. Due to the provision of the pole pieces 155 having a high magnetic permeability there vis a unidirectional distribution of the unidirectional vtiux lines 265 throughout'the spaces 120. It is further pointed out that the unidirectional magnetic iiux lines 265 are disposed normal to the unidirectional electrical field 260 illustrated in FIG. 8, whereby the unidirectional electrical field 260 and the unidirectional magnetic field 265 provide the necessary crossed fields for the operation of the crossedfield discharge device 100V. i l

As has been pointed out above, the axially extending interaction spaces 120 provide coaxial transmission line sections extending axially of the device 100, each having a length equaltoone-half the wave length of the op'eratingfrequency of the device.` The transmission line thus provided 'forms a tuned cavity for thejoscillator 200, the tuned cavity being readily excited at a frequencyhaving a wave length corresponding to twice the axial distance between the inner surfaces 158 of the pole pieces 155. When the tuned resonant cavity thus formed is excited by the establishment therein of the unidirectional electrical field 260 of FIG. 8 and the unidirectional magnetic field 265 of FIG. 9, the tuned cavity resonates at a frequency having the wave length mentioned, i.e., a standing RF. wave is established within the tuned cavity and extends axially thereof and axially of the device 100.

There is believed to be associated with the standing RF. wave thus established an RF. electrical field disposed normal to lthe axis of the device 100, a diagrarnf matic representation of the field ,being illustrated in FIG. l0. In FIG. 10 the instantaneous R.F.`electrical field has been designated by the numeral 270, the field 270 having a first portion 271l disposed between the unrecessed portions 127 of the inner surface 112 ofthe anode member 110 and the corresponding unrecessed portions 137 of the outer surfaceV 132 of the anode member 130 (for example). The field 270 also includes a second portion 272 disposedbetween the electron discharge members 175 and their associated recess walls 126 and 136 (for example). The field 270 also includes a third portion 273 extending between the recess walls 126 and their corresponding recess walls 136 (for example). |Each of the flux lines 270 is so disposed that it enters the anode and cathode surfaces normal thereto. It will be understood that a like R.F. electrical field 270 is disposed in the lower end of the device between the unrecessed surfaces 127 and 147 and between the electron discharge members 185 and their

corresponding recess walls

126 and 146 and between the recess walls 126 and their corresponding recess walls 146.

Associated with the R.F. electrical field 270 of the standing R.F. wave is a RF. magnetic field 275 shown is believed to have the form illustrated in FIG. 11. The R.F. magnetic field 275 is also disposed normal to the axis of the device 100 and is concentric about and surrounds the electron discharge members 175 (and 185). The major portion of the RF. magnetic field 275 is disposed within the interaction spaces 120 and is designated by the numeral 276, but a portion of the magnetic field 275 extends into the spaces 123 interconnecting adjacent ones of the interaction spaces 120, this portion of the magnetic field 275 being designated by the numeral 277. It will be understood that the 'R.F. magnetic field 275 is symmetrically disposed in both the upper and lower portions of the device 100.

After the application of the operating potentials to the device 100 and after the starting circuit 250 has been actuated to establish a high voltage pulse between the anode structure and the cathode structure 180 for starting the device 100, electrons are emitted from the emissive coating of the

electron discharge members

175 and 185, the electrons being emitted into the interaction spaces where they are subjected to the action of the unidirectional fields and the R.F. fields described hereinabove. There is illustrated in FIG. 12 of the drawings a diagrammatic representation of what are believed to be typical paths of electrons emitted from the

electron discharge members

175 and 185, the electron paths being designated by the numeral 280. As illustrated, the electrons follow an arcuate path, the initial direction of fiow being in a clockwise direction, this being due to the inliuence of the unidirectional magnetic field 265 described above. The arcuate paths 280 of the electrons carry them into contact with the anode members 110 or 130 (for example), whereby to complete an electrical circuit through the device 100. During the time that the electrons are in the arcuate paths 280, they impart a portion of the energy contained therein to the vR.F. standing wave within the device 100 to add power thereto and to reinforce the standing wave. It will be understood that like electron paths 280 are found between the electron discharge members 185 and the anode members 110 and in the lower portion of the device 100.

There is illustrated in FIG. 13 a composite representation of all of the fields that are believed to be present in the device 100 and in the interaction spaces 120 thereof when the device 100 is operating as part of the oscillator 200. From FIG. 13 it is apparent that the electrons in the paths 280 clearly interact with the unidirectional fields and the R.F. fields within the interaction spaces 120, whereby to give up a portion of the energy of the electrons to the RF. fields within the interaction spaces 120. More specifically, when the R.F. electrical field 270 is established in the interaction spaces 120 it tends to bunch electrons that rotate around the electron discharge members and 185 in the presence of the D.C. electrical field 260 and the D.C. magnetic field 265. These electrons tend to rotate in synchronization with a slow wave component of the axial fast wave and to extract energy from the D.C. fields while giving up energy to the R.F. fields. In this manner the R.F. standing wave within the device is maintained and the energy contained thereof increased and replenished due to the operation of the oscillator 200.

As is best seen from FIGS. 3 and 13, the cathode 170 is coupled to the R.F. standing wave within the interaction spaces and, therefore, serves a probe for the removal of a portion of the R.F. energy from the tuned cavity for the supplying thereof to the coupler and filter structure 220 and thence to the output transmission line 65. In the structure illustrated, the cathode lead 178 is directly connected to the bullet coupler 225 and the anode member 150 is directly connected to the sleeve 205 which is integral with and forms a part of arm 222 of the T-structure 221, whereby an output R.F. potential appears between the conductor 222 and the coupler 225. The coupler and filter structure 220, including the capacitive coupling 240, serves to connect the R.F. energy between the coupler 225 and the conductor 222 to the output transmission line 65, and also to apply to the cathode 170l via the

couplers

235 and 225 an A C. operating potential, all without the introduction of R.F. energy into the Edison supply network via the terminal 201. As has been explained above, the R.'F. wave within the oscillator 200 extends axially with respect to the device 100, there being no radial R.F. waves within the device 100, i.e., no R.F. waves extending normal to the axis of the device 100. Furthermore, the radial distance between the axis of the device 100 and the outer wall 126 of the arcuate recesses is less than that required to accommodate a radial standing wave at the operating frequency of the oscillator 200. Likewise, the radial distance between the outermost point of the recess wall 126 and the innermost point of the corresponding recess wall 136 is less than that required to accommodate a radial standing wave at the operating frequency of the device 100 as defined above.

In a constructional example of the crossed-field discharge device 100 the various parts thereof preferably have the following dimensions. The

electron discharge members

175 and 185 each has a diameter of 10 mils; each of the interaction spaces 120 has a diameter of 32 mils; the axial extent of the interaction spaces 120, i.e., the axial distance between the inner surfaces 158 of the pole pieces 155 is effectively one half wave length at 915 mHz.

From the above description it will be seen that the physical dimensions of the device 100 are relatively small compared to the wave length of the microwave energy to be generated thereby and the power output therefrom. The thermal characteristics of the device 100 are excellent, kthe effects of thermal expansion of the parts being minimized resulting in improved thermal suitability. It will be understood that cooling may be provided by means of clamp-on radiators or cooling coils in lieu of the stacked array of cooling

fins

206 and 209 illustrated. The

anode members

110, 130, and 150 are all constructed from a good heat conducting material and the thick radial extending portions thereof offer a very low thermal resistance thus permitting high power operation.

In a test version of the device 100, with the dimensions indicated above, and with a peak value of volts applied between the anode and either one of the cathode structures or 180, the associated electron discharge members operated at a current density of 1.35 amperes per square centimeter, the magnetic field for this operating condition being about 2,000 gauss. Each of the electron discharge members and 185 cooperates with its corresponding

arcuate recess walls

126, 136 and 146 to operate as a dipole, each dipole producing a peak pulse power output of 14 watts at 915 mHz., the duty cycle being 20% and the average output power per dipole being 2.8 watts at 50% efiiciency. For the 16 sections or dipoles illustrated, the power output would be 45 watts total. The duty cycle may be increased by reducing the magnetic field slightly to obtain a higher power output at a lower efficiency. A power output of 55 watts may be obtained in this manner. Higher power Output may be obtained by adding more sections, the mode characteristics of the anode being such that a very large number of sections can be used. Operation at higher power output may also be obtained with smaller interaction spaces and cathode diameters with resulting higher magnetic field and current density.

Referring to FIG. 14 of the drawings, there is diagrammatically illustrated the manner in which the output from the oscillator circuit 50 can be connected to the input of an amplier circuit 300 which embodies therein certain additional features of the present invention. Inasmuch as the construction and operation of the oscillator 200 in the circuit of FIG. 14 is identical to those described above, like reference numerals have been applied to like parts throughout and the description thereof will not here be repeated. It will be understood that the output of the oscillator 200 is applied to a coaxial transmission line 310 which has the outer conductor 311 thereof connected to the capacitive coupler 242, and the outer conductor 311 is in turn connected by capacitive couplers 325 to a cavity connected to one end of a crossed-field discharge device 100 of the type set forth above. The transmission line 310 also comprises an inner conductor 312 which terminates in a radiating probe 313 that radiates into a cavity formed by a coaxial transmission line 320 connected to the lower end of the device 100 (see FIG. 15 also). The amplifying circuit 300 also includes three

input terminals

301, 302 and 303 that are connected respectively to the conductors L1, L2 and N of the Edison supply network.

The output of the amplifier circuit 300 is applied to a cavity including an outer conductor 347 that is capacitively coupled by the coupler 345 to an output transmission line 340 which connects with the transmission line 65. More specifically, the outer conductor of the transmission line 340 is directly connected to the outer conductor 66 of the transmission line 65 and a coupling probe 352 is provided within the transmission line 340 and is connected to the inner conductor 67 of the output transmission line 65. The capacitive coupling provided by the coupler 345 is desirable and necessary since the output terminal 347 is at a relatively high D.C. potential, whereby it is necessary electrically to isolate the output terminals 347 from the outer conductor 66 so that the outer conductor 66 can be grounded.

The microwave energy supplied from the amplifier circuit 300 to the transmission line 65 can be used for any desired purpose, two typical uses of the microwave energy being illustrated in FIG. 14, the first use being illustrated in the upper right-hand portion of FIG. 14, and the second use being illustrated in the lower right-hand portion of FIG. 14. Referring to the first use illustrated in the upper right-hand portion of FIG. 14, the transmission line 65 is shown coupled to an antenna of the type commonly used in Search radar, the outer conductor 66 being connected to outer radiating or antenna elements 68, and the inner conductor 67 being connected to an inner radiating or antenna element 69, the

antenna elements

68 and 69 serving to match the impedance of the transmission line 65 to the impedance of the atmosphere. Referring to the second use of the microwave energy illustrated in the lower right-hand portion of FIG. 14, the transmission line 65 is shown coupled to an electronic heating apparatus, such as the electronic range 70 illustrated that is especially designed for home use. The electronic range 70 in FIG.`

14, is identical to the electronic range 70 described above with respect to FIG. 1 of the drawings, and accordingly, like reference numerals have been applied to like parts throughout. The microwave energy within the transmission line 65 is radiated into the internal cavity of the electronic range 70 to provide the power for heating materials disposed therein. It further will be understood that in a preferred embodiment of the range 70, the oscillator 200 and the amplifier circuit 300 together with the transmission line 65 are all preferably disposed within a common housing that also includes the casing 71, the common housing preferably being formed of an electri- 21 cally conductive metal of high magnetic permeability and grounded for safety purposes.

Further details of the construction of the amplifier circuit 300 and the connections thereof to the crossedfield discharge device 100 incorporated therein will noW be described with reference to FIG. 15 of the drawings." The construction of the crossed-field discharge device 100- incorporated in the amplifier circuit 300 of FIG. 15 is identical to the construction of the crossed-field discharge device 100 described above with reference to the oscillator 200 and illustrated in detail in FIGS. 37 of the drawings, rwhereby like reference numerals have been applied to like parts throughout including the magnet coil 210 and the associated mechanical and electrical connections. As illustrated, the input coaxial transmission line 310 includes the annular outer conductor 311 within which is disposed the inner conductor 312, the left-hand end of the outer conductor 311 communicating with the outer coaxial transmission line 320 that is connected to the lower end of the device 100. More specifically, the coaxial transmission line 320 includes an outer annular conductor 321 within which is disposed an annular inner conductor 322, the lower and outer ends thereof being interconnected and the space therebetween closed by an end wall 323. An opening is formed adjacent to the lower `end of the outer conductor 321 and the outer conductor 311 is mechanically and electrically connected thereto in surrounding relationship with the opening therein. Connected between the input

transmission line conductors

311 and 312 is the radiating probe 313 that serves to radiate the microwave energy within the input transmission line 310 into the coaxial transmission line 320. The outer conductor 321 extends upwardly toward the sleeve 208 of the lower cooling n package 207 and is capacitively coupled thereto by the coupler 325; more particularly, the sleeve 208 surrounds the adjacent portion of the outer conductor 321, an insulating dielectric sleeve 326 being disposed in and substantially filling the annular space between the

concentric conductors

321 and 208, the sleeve 326 being formed of a synthetic organic plastic resin, the preferred resin being a tetrafiuoroethylene resin sold under the trademark Tefion. The inner conductor 322 extends upwardly toward the lower end of thecathode lead 188 and is capacitively coupled thereto by a coupler 330; more particularly, an outer terminal 302 is connected at the upper end thereof to the conductor 219 that is in turn connected to the cathode lead 208 and is capacitively coupled thereto at the lower end thereof, the terminal 303 extending downwardly beyond the end wall 323 and being disposed within and surrounded by the inner conductor 322, an insulating and dielectric sleeve 331 being disposed in and substantially filling the annular space between the terminal 303 and the conductor 322, the sleeve 331 being formed of a synthetic organic plastic resin, the preferred resin being a tetrafiuoroethylene resin sold under the trademark Tefion.

The output from the amplifier circuit 300 is taken from the upper end of the crossed-field discharge device 100, the output being taken from the coaxial transmission line 340 connected to the upper end of the device 100. More specifically, the coaxial transmission line 340 includes an outer annular conductor 341 within which is disposed an annular inner conductor 342, the upper ends thereof being interconnected and the space threbetween closed by an end wall 343. An opening is formed adjacent to the upper end of the outer conductor 341 and the outer conductor 66 of the output transmission line 65 is mechanically and electrically connected thereto in surrounding relationship with the opening therein. Connected between the output

transmission line conductors

66 and 67 is the probe 352 that serves to pick up the microwave energy within the output transmission line 340 and to apply the microwave energyv to the output transmission line 65. The outer conductor 341 extends downwardly toward the sleeve 205 of the upper cooling fin package 204 and is capacitively coupled thereto by the coupler 345. More particularly, the sleeve 205 surrounds the adjacent portion of the outer conductor 341, an insulating dielectric sleeve 346 being disposed in and substantially filling the annular space between the

concentric conductors

341 and 205, the sleeve 346 being formed of a synthetic organic plastic resin, the preferred resin being a tetrafluoroethylene resin sold under the trademark Teflon. The inner conductor 342 extends downwardly t0- ward the upper end of the cathode lead 178 and is capacitively coupled thereto by a coupler 350. More particularly, the output terminal 301 is provided having the lower end thereof attached to the bullet coupler 225 that is in direct electrical connection with the upper end of the cathode lead 178 and extends upwardly therefrom and outwardly beyond the end wall 343, the inner annular conductor 342 surrounding the adjacent portion of the terminal 302, and an insulating dielectric sleeve 351 being disposed in and substantially filling the annular space between the terminal 302 and the conductor 342, the sleeve 351 being formed of a synthetic organic plastic resin, the preferred resin being a tetrauoroethylene resin sold under the trademark Teflon The conductor N of the Edison supply network is connected as at 303 to one terminal of the magnet coil 210, whereby to apply the operating potential to the anode structure 105 of the device 100 through the upper magnet coil 210, the conductor 211 and the cooling fin 209 that is electrically connected to the anode member 150. The conductor L2 of the Edison supply network is attached to the terminal 302 that is in turn directly connected to the cathode 180 through the cathode lead 188. Finally, the other terminal L1 of the Edison supply network is connected to the terminal 301 that is in turn connected to the other cathode 170 through the cathode lead 178.

The microwave energy to be amplified in the amplifier circuit 300 is applied thereto through the input transmission line 310, and more particularly, the probe 313 radiates into the coaxial transmission line 320 that is capacitively coupled both to the anode structure 105 and the cathode 180, thereby to apply the input energy between the anode structure 105 and the cathode 180. In order to provide a suitable match between the impedance of the transmission line 310 and the impedance of the amplifier circuit 300, the transmission line 320 preferably has a length equivalent to 5%; of the wave-length of the energy to be amplied, i.e., the distance between the inner surface of the end wall 323 and a plane normal to the axis of the device and disposed midway between the ends of the anode structure is equivalent to 5ML of the wavelength of the microwave energy to be amplified. It would also be permissible to connect the transmission line 310 to the transmission line 320 at points spaced A or of the wavelength of the microwave energy to be amplified from the midplane of the device 100, but for most frequencies to be amplified it is not possible to make the necessary electrical connections at this point as illustrated in FIG. 15.

In order to provide a suitable match between the impedance of the amplifier circuit 300 and the impedance of the output transmission line 65, the transmission line 340 preferably has a length equivalent to 5%; of the wavelength of the microwave energy to be amplified, i.e., the distance between the inner surface of the end wall 343 and a plane normal to the axis of the device 100 and disposed midway between the ends of the anode structure `105 is equivalent to 5A of the wavelength of the microwave 4energy to be amplified. It would also be permissible to connect the transmission line -65 at points spaced 1A or 3A of the wavelength of the microwave energy being amplified from the midplane of the device 100, but for most frequencies it is not possible to make the necessary electrical connections at this point as illustrated in FIG. l5.

The microwave energy thus injected into the lower end of the amplifier circuit 300 passes into the crossed-field