US2428609A - High-frequency electric discharge device - Google Patents

Description

s n 9 w e m E uwnuviliuil w 5 2 n e A w m W s T J FH Oct. 7, 1947. J. E. BEGGS- HIGH FREQUENCY ELECTRIC DISCHARGE DEVICE Filed Nov. 9, 1942 Patented Oct. 7, 1947 HIGH-FREQUENCY ELECTRIC DISCHARGE DEVICE James E. Beggs, Scotia, N. Y., assignor to General Electric Company, a corporation of New York Application November 9, 1942, Serial No. 464,998

4 Qlaims. (01. 3156) My invention relates to high frequency electric discharge devices, and more particularly to space resonant systems of the ultrahigh frequency type.

It is an object of my invention to provide new and improved high frequency electric discharge devices.

It is another object of my invention to provide new and improved ultra high frequency electric discharge devices suitable for operation in the ultra high frequency region.

It is another object of my invention to provide new and improved forms of ultra high frequency electric} discharge devices suitable for use in connection with space resonant cavities.

It is a further object of my invention to provide new and improved ultra high frequency electric discharge devices of the space resonant type.

Briefly stated, in accordance with one of the illustrated embodiments of my invention, I provide a new and improved ultra high frequency electric discharge device of the space-resonant type comprising a plurality of enclosed electrodes formed in part by a pair of transversely extending metallic members which provide, respectively, externally accessible high frequency terminals for a grid and the cathode, and in which the anode is maintained in spaced relation with respect to the grid and the cathode by means of a metallic housing of cylindrical configuration having at one end a wall or collar which supports the anode. The device comprises within the enclosure means such as the electrodes for defining boundaries of a pair of space resonant or tuned cavities associated with the anode-grid and the grid-cathode circuits, and one of these cavities, such as the grid-cathode cavity, is connected to an external or utilization circuit through an auxiliary or tuning region or cavity which may be adjusted in its characteristics to establish with the grid-cathode circuita resonance condition, thereby aifording means for controlling or adjusting the frequency of the energy supplied to the utilization circuit.

The electric discharge device, in another modification, is arranged to include as an integral part thereof within the enclosed region including the electrodes of the device, tuned or space resonant regions or cavities, one of which may be formed by the structure which supports the grid. The grid cathode space resonant cavity may be tuned by means of an associated external auxiliary or tuning space-resonant chamber formed in part by conductive or metallic mem- 2 bers connected to the transverse members associated with the grid and cathode, and may be provided with means for tuning the natural frequency of the combined internal or enclosed grid-cathode resonant space and the tuning chamber. Output electrode means of suitable form may be associated with the space resonant cavity or, more particularly, with the tuning chamber to supply energy to a utilization circuit.

In accordance with another feature of my invention, I provide a number of discharge devices of the space-resonant type wherein a pair of transverse members of conductive nature support the anode and cathode in spaced relation and are in turn positioned by means of a cylindrical. insulating spacer, thereby providing a portion of the sealed enclosure for the electrodes of the device. I also provide within the enclosed region defined by the insulating cylinder, means for supporting the grid in spaced relation between the anode and cathode. The grid supporting means may comprise an electrically symmetrical means such as a metallic cylinder connected to the transverse member which supports the cathode, and extends along with the electrode axis to a point intermediate the anode and cathode. or may extend a distance sufficient to surround substantially the entire electrode assembly including the anode, cathode and grid. Alternatively, the coupling circuit for the grid may be of the re-entrant type wherein the grid is maintained in spaced relation between the anode and the cathode by means of a metallic or conductive member supported by a plurality of substantially vertical insulators which are positioned on the transverse member supporting the cathode.

In accordance with a still further aspect of my invention, a discharge device embodying my invention may comprise a conductive member such as a metallic cylinder which supports the grid in spaced relation between the anode and cathode, and which is provided with an externally accessible and adjustable electrode means for establishing a suitable bias potential on the grid where such a condition is expedient from the standpoint of obtaining a desired operation of the discharge device as a whole.

For a better understanding of my invention, reference may be had to the following description taken in connection with the accompanying drawing, and its scope will be pointed out in the appended claims. Fig. 1 diagrammatically illustrates an embodiment of my invention as applied to a space resonant system and wherein the central control device, such as th electric discharge 3 device, is of a construction comprising an inverted cup -shaped metallic housing which supports the anode in spaced relation and also serves as a means for defining the anode-grid resonant region or cavity. Figs, 2-6, inclusive, represent further modifications of my invention as applied to space resonant discharge devices and systems. In the latter mentioned figures, a space resonant region or cavity is associated with either the anode-grid or grid-cathode circuit, or both, of the electric discharge device, thereby providing at least a tuned or resonant system from which I energy may be extracted directly or through an associated space resonant tuning chamber and deliveredto an external utilization circuit.

Referring now to Fig. 1, my invention is there illustrated as applied to an ultrahigh frequency space resonant system comprising as a central or control element thereof an electric discharge device of the space resonant type peculiarly constructed in order to be adaptable for the utilization and production of ultra high frequency energy, and which comprises a substantially cylindrical shaped anode I, a grid 2 and a cylindrical cathode 3 maintained in spaced relation with respect to each other by structure to be described I presently. Cathode 3 is arranged to have its emissive,part.in the form of a flat disk surface 4 facing the grid 3. I provide a pair of transverse conductive or metallic members, such as disks 5 and 6 which respectively serve as supporting means for the grid 2 and the cathode 3, and also serve as externally accessible high frequency terminals for the electrodes. Disk 6 may be formed integral, if desired, with a skirt 1 to which a base assembly, to be described presently, is attached.

Disk 5 is preferably constructed to be of smaller diameter than disk 6, thereby facilitating the connection thereto of high frequency apparatus such as the conductive or mtalboundispace resonant chamber to be discussed presently.

Cathode 3 is provided at its lower extremity with a flange 8 which parallels the under-surface of disk 6 but which is separated therefrom by an insulating spacer 9 which may be a mica washer or the like. With this arrangement, the flange part 8 has a high frequency connection with disk 6 through the capacity existing between this part and the flange 8. Separate direct current connections are made to the cathode by means of lead-in wires Iil 'and I I which may be terminated in contact pins I2 and I 3, respectively. Additional contact pins I4 and I5 are provided for the purpose of supplying heating current to a coiled cathode heating element I 6 through conductors I1 and I8, respectively. Contact pins I 2-I5, inelusive, are sealed in a metallic header (not shown) which is attached to a base I9 and to which skirt 1 of the member 6 is secured. Base [9 is also provided with an orientation or guide pin for the proper alinement of the device as a Whole within an appropriate socket. Transversely extending metallic disks 5 and 6 are maindrical anode I may extend. Housing 22 may be sealed to disk 5 by a suitable seal such as a vitreous seal 22. The anode I may be constructed to have a shoulder which engages the wall 23, thereby supporting the anode l in the desired spaced relation with respect to the grid 2 and anode 3. It is to be understood that the anode I is closely fitted or soldered to the metallic housing 22 in order that a desired low pressure may be maintained within the envelope as a whole.

The metallic housing-22 is constructed to have a diameter less than that of disk 5 so that the discharge device has a stepwise configuration, thereby facilitating the connection, to the electrodes of the device, of suitable high frequency connections, such as coaxial transmission lines or space resonant cavities.

An important aspect of the embodiment of my inventio'n illustrated inFig. 1 comprises a substantially enclosed or well defined anode-grid cavity or region which includes the anode l, housing 22, seal 22 and disk 5. It will. be noted that the diameter of the opening in disk 5 is substantially less than the inside diameter of housing 22 and consequently serves to close partially or restrict the anode-grid region. Furthermore, in

this modification of my invention, the seal 22' serves a triple purpose, namely serves as a sealing means between housing 22 and disk 5, acts as a high frequency bypass, and also serves as a direct'current insulating means between housing 22 and disk 5. By virtue of this construction, the inverted cup-shaped housing 22 may be readily employed for establishing a space resonant region and at the same'time facilitate its employment in a system where it is required to impress a unidirectional voltage on the anode.

The discharge device shown in Fig. 1 comprises two tuned resonant cavities or regions, one of which is the anode-grid cavity which is defined between the longitudinal surface of the cylindrical anode I and. the interior surface of the metal housing 22, and the other of which is the gridcathode cavity or region defined by the longitudinal surface ofthe cathode 3 and the inner surface of an external conductive member to be described presently. The anode-grid cavity is preferably designed to be resonant to a predetermined frequency, or substantially tuned or resonant to a range of frequencies, throughout which the space-resonant system as a whole is intended to operate, and in like manner the gridcathode cavity is also resonant, or substantially tuned or resonant, to the operating frequency. In the latter case involving the grid-cathode cavity, it is of course, understood that the resultant or overall natural frequency of the grid-cathode cavity is determined by the auxiliary or tuning cavity to be described presently.

I provide an auxiliary or tuning space resonant cavity which may be partially defined by a con ductive or metallic member, or members, such as a pair'of coaxial metallic cylinders 24 and 25 which are connected, respectively, to disks 5 and 6 and are therefore electrically connected to grid 2 and cathode 3. I also provide in connection with the space resonant system means for tuning or controlling the natural resonance frequency of the system including the grid-cathode cavity and the external cavity formed by cylinders 24 and 25, and this means may take the form of an annular plunger 26 which is positionable or slidable along the inner surface of cylinder 25 and the outer surface of cylinder 24, being in close engagement With these surfaces in order to prevent the establishment of any discontinuity in' the conductive medium which defines the'cavity.

The plunger 26 may be positioned by any suitable mechanical expedient, such as a rod 21, and energy may be extracted from the space resonent region by any suitable output electrode means, one

form of which may be a loop 28 forming a part of a coaxial transmission line comprising an outer conductor 29 and an inner conductor 33.

Upon impressing a, suitable unidirectional voltage across the anode l and cathode 2, high frequency electromagnetic energy may be derived from the space resonant system through the transmission line comprising conductors 29 and 30. From the standpoint of elementary analysis of the operation of thesystem as a whole, it may be considered that the coupling between the anode-grid and the grid-cathode cavities or regions is obtained by virtue of the mutual capacitanc between the opposing surfaces of anode l and cathode 3 so that energy may be fed back from the anode-grid cavity to the grid-cathode cavity, maintaining the system in a state of oscillation. Output energy may be derived from the anode-grid cavity or, more particularly, from the. resonant region defined by cylinders 24 and 25 by virtue of the connection of these cylinders to the transverse disks 5 and '6, the insulating spacer or seal 22' between housing 22 and disk 5 constituting a high frequency by-pass capacitance.

The elements of the space resonant system which define the region within which the high frequency current or field of the grid-cathode cavity, or cavities, may be considered as being confined, include the grid 2, disk 5, the interior surfaces of cylinders 24 and 25, plunger 28, disk 6 and cathode 3. Of course, within the vicinity of disk 6 some of the high frequency current will fiow in a parallel path by virtue of the capacitance between the surface of disk 6 and flanged part8 to the cathode 3.

Operation or adjustment of plunger 26 controls the intensity or magnitude of the high frequency electromagnetic oscillations within the space resonant system. The frequency of the energy derived from the space resonant system may also be controlled by adjustment of plunger 26 which determines the natural resonance frequency of the region defined between cylinders 24 and 25 and the grid-cathode cavity of the discharge device considered together.

Fig. 2 diagrammatically illustrates another embodiment of my invention as applied to a space resonant system wherein an electric discharge device constitutes a central or principal element of the system. The electric discharge device may be of the space-resonant type peculiarly constructed for use in the ultra high frequency field and which is provided with terminals or connections to facilitate its use in high frequency systems. More particularly, I employ in the arrangement of Fig. 2 an electric discharge device comprising a metallic cylindrical anode 3i and a cathode 32 similar in construction and arrangement to anode l and cathode 3 shown in Fig. 1. Anode 3| and cathode 32 are arranged to have opposing surfaces of appreciable area, thereby constituting a substantial capacitive coupling through which energy may be fed back from the anode-grid circuit to the grid-cathode circuit to maintain the device in oscillation. Anode 3| is maintained in position and supported by a transverse disk 33 preferably constructed at least in part of a metal such as copper, and cathode 32 is supported by a member 34 having a disk-like end part 35 and a 6 skirt 36. Cathode 32 is also provided with a flanged part 31 which parallels the undersurface of disk 35 and is spaced therefrom by means of an insulating spacer 38 which serves a dual purpose, that is serves as a high frequency connection btween cathode 32 and external means to be described presently, and as an insulating means for unidirectional current. Part 31 may be provided with direct current cathode conductors 39 and 40 which are made externally accessible through contact pins 4| and 42, respectively. Terminals for supplying heating current to a cathode heating element 43 may comprise conductors 44 and 45 which are connected, respectively, to contact pins 43 and 41. It will be appreciated that conductors 39, 40 and 44, 45 are supported by and sealed to a suitable header such as a metallic header (not shown) and which may be positioned immediately above base 48, the latter being attached to the header by suitable means such as crimped locks (not shown).

I provide means for maintaining disk 33 and member 34 in spaced relation, and this means may comprise a vitreous insulating cylinder 49 which is sealed to disk 33 and member 34, particularly the disk or flat part 35 and constitutes, in part, a portion of the sealing envelope for the discharge 2 device.

As a means for establishing a space resonant grid-cathode region or cavity within the enclosure provided by insulating cylinder 49, I employ an electrically symmetrical and conductive member, such as a metallic tubular member or cylinder 59; that is, the grid-cathode resonant cavity constitutes the region between cathode 32 and the inner surface of cylinder 5!]. Cylinder 50 may also be employed as a means for supporting the grid 5! in spaced relation between anode 3| and cathode 32.

A space resonant anode-grid cavity is provided and includes the region defined between the longitudinal surface of cylindrical anode 3! and the opposing or facing interior surface of a cylindrical member constituting a part of an external tuning chamber to be described presently. This region, of course, is tuned, or substantially tuned, to the operating frequency, or range of operating frequencies, at which the system as a whole is intended to operate and the effective natural frequency thereof may be controlled or adjusted by means of the aum'liary or tuning space resonant cavity described immediately hereinafter.

, As a means for deriving energy from the discharge device, I provide an auxiliary or tuning space resonant cavity or region defined by a conductive member, or members, connected respectively to the disk 33 and member 34. For example, I may employ a pair of substantially concentric metallic cylinders 52 and 53 which are held in good contact with disk 33 and member 34, respectively. It will be noted that the region defined by cylinders 52 and 53 may be considered as a space resonant cavity energized in response to or from the anode-grid circuit of the discharge device.

' The frequency of oscillation of the space resonant system as an entirety may be controlled by any suitable tuning means and I provide means for controlling the natural resonance frequency of the region defined between cylinders 52 and 53. This means may constitute an adjustable plunger 54, having an actuating rod 55, and which is in close contact with and slidable along the inner surface of outer cylinder 52 and the outer surface of the inner cylinder 53. Energy may be r "7 extracted from the space resonant cavity by any suitable electrode means which may take the form of a loop 56 which is connected to a concentric transmission line comprising an outer conductor 51 and an inner conductor 58.

The system shown in Fig. 2 operates to supply ultra high frequency energy to a utilization circuit which may be connected to the transmission line comprising conductors 51 and 58. Upon the impression of a suitable unidirectional voltage across anode 3| and cathode 32, the system as a whole will oscillate at a,frequency determined by the adjustment of plunger 54 which, in turn, controls the natural frequency of the cavity, or cavities, connected, to the anode-grid circuit of the discharge device.

The transfer of energy from the anode-grid circuit to the grid-cathode circuit of the discharge device is obtained principally by virtue of the capacitance coupling due to the opposing surfaces of anode 3| and cathode 32. Cyclic variation in the grid voltage produced by the capacitive coupling establishes oscillation of thegrid-cathOde cavity defined by cathode 32 and cylinder 50.

Cylinder 59, by virtue of its position between cathode 32 and insulating cylinder 49, serves to localize the field incident to the grid-cathode electromagnetic oscillations and consequently localizes the field and reduces the losses which would otherwise be present if the incident electromagnetic field were allowed to extend to an insulating or dielectric defining means, such as cylinder 49. The elements which define the region of the high frequency electromagnetic field of the anodegrid cavity and the associated auxiliary or tuning cavity may be considered as comprising disk 33, the opposing surfaces of cylinders 52 and 53 lying above disk 33, plunger 54, the opposing surfaces of cylinder 59 and cylinder 53 joined by the associated annular space of disk 35 and the opposing surfaces of anode 3| and cylinder 53.

Fig. 3 shows an alternative arrangement of a space resonant system applicable to ultra high frequencies and which embodies further features of my invention. The discharge device shown in Fig. 3 is similar in many respects to that shown in Fig. 2 and corresponding elements have been assigned like reference numerals. In the arrangement of Fig. 3, I provide a re-entrant type grid structure associated with anode 3| and cathode 32, whereby energy may be derived from the anode-grid circuit of the discharge device and supplied to the grid-cathode circuit. This re-entrant construction may be completely enclosed and surrounded by the insulating and spacing cylinder 49 and may comprise a conductive or metallic cylinder 59 supported on disk 35 by means of a plurality of insulating pins 6!]. Cylinder 59 may also be employed as a, means for supporting a grid 6| in spaced relation between the opposing surfaces of anode 3| and cathode 32.

In the arrangement of Fig. 3, the inner membar which defines one boundary of the space resonant cavity'may comprise a cylinder 62 which is connected directly to the enlarged portion of the anode 3|. This modification is optional and, if desired, the cylinder 62 could be connected to the disk 33.

Inasmuch as the cylinder 59 is insulated from the part 35, the grid 6| may be considered as floating, that s y be considered as free to assume the biasing potential established in part by the standing electromagnetic waves along the interior surface thereof facing the anode 3| and cathode 32 and in part by the electronic current drawn by grid 6 Cylinder 59 is,of course, preferably designed to havealength correlated to the a voltage impressed. on grid 6| is of the proper phase to maintain the discharge device in oscillation. That is, viewing the various electrode voltages from'the grid 6|, the anode and cathode voltages may be considered as varying intime phase with respect to each other, which relation, when viewed from the cathode, is the conventional one usuallyemployed, where the grid and the anode Voltages with respect to the cathode may be considered substantially electrical-degrees out of phase. I Furthermore, the discharge device shown in Fig, 3 comprises two enclosed space resonant cavities or regions, one of which is the anode-grid cavity defined between the surface of anode 3| and the opposing surface of cylinder 53, and the grid-cathode resonant space or cavity maybe considered as defined by the surface of cathode 32 and the interior or opposing surface of cylinder 59. V

The elements which define the high frequency current region or field to obtain energization of the auxiliary or tuning chamber defined by cylinders 53 and 62, and hence to effect energization of the output electrode means, may be con sidered as including disk 33, opposing surfaces of cylinders 53 and 62, opposing surfaces of cylinders 53 and 59, part 35, or part 35 and'the flanged portion of cathode 32. The cylinder 59 and anode 3| and cathode 32 may be considered as a tuned concentric electric transmission line,. energy being propagated through the region defined by opposing surfaces of anode 3|, cathode 32 and cylinder 53 to obtain the desired coupling between the anode-grid and grid-cathode circuits or cavities.

The system of Fig. 3 operates as an ultra high frequency oscillator upon the impression of a suitable unidirectional voltage across anode 3| and cathode 32, and energy may be derived from the anode-grid cavity circuit of the discharge device through the space resonant region defined by cylinders 53 and 62. The natural frequency of oscillation of the system is determined by the adjustment of plunger 54 and energy may be extracted through a suitable probe or electrode means, such as loop 56' associated with the space resonant cavity or region.

As to the explanation of the mechanism by virtue of which the requisite amount of. energy is transferred from the anode-grid circuit to the grid-cathode circuit to maintain the system in oscillation, cylinder 59 may be considered as a,

tuned transmission line coupling'means to support standing electromagnetic waves, the dimension of the cylinder 59 with respect to the spacing of the anode 3| and grid 6| and cathode 32 and the wave length of the electromagnetic oscillations being such'thatthe phase of the grid voltage is proper to maintain the discharge device in oscillation.

A further modification of my invention is illustrated in Fig. 4 wherein a solid anode 63, preferably of cylindrical configuration, and a cylindrical shaped cathode 64 are supported'by a pair of transverse conductive members or disks 65 and a part 66. Disk 65 and part 66 are provided being joined to a metallic cylinder 69 which is provided with a transverse wall 10 supporting a grid H in spaced relation between the anode and the cathode. Of course, cylinder 69 is sealed, constituting in part a sealed enclosure for the electrodes of the discharge device. The flanged part 12 of cathode 64 is spaced from the undersurface of member 66 by an insulating spacer 13 which constitutes a high frequency coupling between the cathode and. member 66 and which also serves as a direct current insulating mean for the cathode 64. Direct current conductors l4 and 15 for cathode 66 are provided and may be terminated in contact pins 16 and 11; and terminals for a cathode heating element 18 may comprise conductors l9 and 86 terminated in contact pins 8| and 82. As a means for sealing and supporting the conductors 14, 15 and 19, 86, I may employ a metallic header 83 having a plurality of extruded parts 84 and a plurality of insulating beads 85 which serve as a means for sealing the conductors to the header. The entire system, including the discharge device, may be supported by an insulating base 86 to which the skirt or part 66 and the header 83 are attached or secured.

In the arrangement of Fig. 4, the electric discharge device also includes a pair of internal space resonant cavities or regions, one Of which is defined by the interior surface of a metallic tuning chamber and the anode 63, and the other of which is defined by the cathode 64 and the interior surface of cylinder 69 lying below wall 18. The space resonant or auxiliary tuning cavity to be described presently may be associated with and serve to tune the overall effect of the anodegrid cavity defined by anode 63 and the interior surface of member defining an exteriorboundary of the space-resonant system.

The system of Fig. 4 may include an auxiliary or space resonant cavity or region defined by a plurality of conductive or metalic cylinders 81 and 88 which are connected, respectively, to

. disk 65 and part 66 so that high frequency energy may be derived from the anode-cathode circuit of the discharge device. As in the arrangements disclosed hereinbefore, the space resonant cavity defined by cylinders 81 and 88 may be tuned by any suitable means, such as a plunger 89, and energy may be extracted from the region by means of a concentric transmission line 96 and a loop 9| which constitut an extension of one conductor of the line.

Due to the fact that the supporting structure for wall 16 and grid H, thatis cylinder 69, is insulated from disk 65 and member 66, in the absence of additional means for controlling the potential of grid ll, grid H will assume a predetermined biasing potential, that is will be self-biasing and the magnitude of th potential which it assumes will, of course, depend upon the magnitude and phase of the excitations of the anode-grid and grid-cathode cavities. Accordingly, in accordance with the teachings of one aspect of my invention, I provide means for impressing on grid 1| an adjustable or controllable unidirectional biasing potential such as a negativ biasing potential which may be effected by impressing a suitable voltage along the exterior surface of cylinder 69.

Where it is desired to bias the grid H to a suitable potential, such as a negative potential, to obtain the desired operation of the discharge device, I provide adjustable electrode means such as a conductor 92 which extendsthrough an opening 93 in cylinder 88 and engages cylinder 69, thereby serving as, a means for controlling the bias on grid 1|. 7 r

. 10 An important feature of the embodiment of my invention shown in Fig. 4 is the arrangement including electrode or conductor 92 which permits a wide degree of freedom in adjusting the point along cylinder 69 at which a unidirectional or negativebiasing potential may be impressed, thereby controlling the biasing potential of grid H. By this arrangement, it is possible to adjust or establish the position of conductor 92 to a point which causes a minimum disturbance of the high frequency electromagnetic field within the region defined by cylinders 81 and 83. In other words, the conductor 92 may be positioned along cylinder 69 at a point where the magnetic intensity of the standing wave due to the electromagnetic field is a minimum.

The manner in which the adjustable conductor 92 controls the biasing potential of grid ll involves a joint consideration not only of the biasing potential provided or impressed on this conductor, but also consideration of the excitation or voltage which is impressed on grid ll due to the tuned grid-cathode cavity. That is, the voltage which is impressed on conductor 92 either increases or decreases the magnitude of a self-excited biasing potential which would be produced by the internally derived excitation.

The arrangement of Fig. 4 for exciting the grid 7| may also be considered as comprising two space resonant cavities. One of these cavities, the anode-grid cavity, may be considered as defined by the surface of anode 63, disk 65, the opposing surfaces of cylinders 81 and 88 and that part of the internal surface of cylinder 88 opposite anode 63. The grid-cathode cavity may be considered as defined by cathode 64 and the inner surface of cylinder 69 opposite the cathode surface and lying below wall 10. The energy for exciting the grid H at the operating frequency may be considered as being derived through the capacitive coupling incident to the opposed surfaces of anode 63 and cathode 64, and the direct coupling between the two cavities or regions.

The natural frequency of the anode-grid cavity is controllable by means of plunger 89, thereby affording a means for controlling the operating frequency of the space resonant system in its entirety.

Figs. 5 and 6 represent an alternative arrangement of the embodiment of my invention shown in Fig. 2, and corresponding elements have been assigned like reference numerals. A grid 94 is positioned in spaced relation between anode 3| and cathode 32 by means of a structure comprising a plurality of substantially vertical and symmetrically arranged 'metallic conductors 95 which are connected to an annular ring 96 which supports grid 94. This construction comprises a means for obtaining loose coupling between the anode-grid and grid-cathode circuits of the discharge device.

The modification of my invention shown in Fig. 5 may be employed in a space resonant system, such as illustrated in Fig. 2, wherein energy may be derived from the anode-grid circuit and supplied to a utilization circuit through employment of turnable space resonant cavities which may be connected to the disk 33 and member 34 in the manner illustrated in Fig. 2.

I Claims to certain of the inventive features in the embodiments in the Figures 2 through 6 are presented in my co-pending application for Highfrequency electric discharge devices, Serial No.

7 734,082, filed March 12, 1947.

ode, and a grid, a pair of aligned substantially parallel annular shaped conductive members having central opening and constituting externally accessible high frequency terminals for said cathode and said grid, one of said conductive members having a substantially smaller outer diameter than the other, an annular spacer of insulating material sealed between and positioning said conductive members in insulated spaced relation, a cylindrical metallic housing supported at one end by said one of said conductive members and closed at the other end by a transverse wall portion constituting a support for said anode, said housing substantially enclosing and supporting said anode and constituting therewith means defining an anode-grid cavity resonator, a dielectric hermetic seal between said housing and said one of said conductive members, said housing, seal, and said one of said conductive members constituting a grid-anode by-pass capacitor, said grid constituting a conductive extension across the opening in said one of said conductive members, a cathode extending through the opening in the other of said conductive members and having a transverse flange parallel thereto, a dielectric hermetic seal between said flange and the other of said conductive members, said flange,

seal, and said other of said conductive members constituting a cathode-grid by-pass capacitor, and a pair of co-axial conductive cylinders having cylindrical walls directly abutting on said conductive members externally of said device and constituting with said cathode a grid-cathode resonant cavity.

JAMES E'. BEGGS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS

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