US3297901A - Dispenser cathode for use in high power magnetron devices - Google Patents

Dispenser cathode for use in high power magnetron devices Download PDF

Info

Publication number
US3297901A
US3297901A US372804A US37280464A US3297901A US 3297901 A US3297901 A US 3297901A US 372804 A US372804 A US 372804A US 37280464 A US37280464 A US 37280464A US 3297901 A US3297901 A US 3297901A
Authority
US
United States
Prior art keywords
cathode
alkaline earth
surface region
earth metal
cylindrical
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US372804A
Inventor
Kenneth A Macdonald
Joseph A Smith
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Litton Industries Inc
Original Assignee
Litton Industries Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Litton Industries Inc filed Critical Litton Industries Inc
Priority to US372804A priority Critical patent/US3297901A/en
Priority to GB24261/65A priority patent/GB1083833A/en
Application granted granted Critical
Publication of US3297901A publication Critical patent/US3297901A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • HELECTRICITY
    • H01ELECTRIC ELEMENTS
    • H01JELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J23/00Details of transit-time tubes of the types covered by group H01J25/00
    • H01J23/02Electrodes; Magnetic control means; Screens
    • H01J23/04Cathodes
    • H01J23/05Cathodes having a cylindrical emissive surface, e.g. cathodes for magnetrons

Definitions

  • the alkaline earth composition chosen is normally one which will be slowly reduced by the refractory metal at the operating temperature of the cathode to provide free alkaline earth metal at the emissive surface of the cathode, thereby enhancing the electron emitting capabilities of the surface and producing a copious supply of primary electrons.
  • the plentiful supply of primary electrons from a dispenser type cathode depends on the availability of an adequate quantity of free alkaline earth metal at the emissive surface of the cathode.
  • the quantity of free alkaline earth metal produced by cathodes most commonly used in magnetrons is more than sufficient for this purpose, and some of the excess material evaporates from the surface of the cathode and deposits on adjacent elements of the magnetron structure, such as the cathode and shields, the magnet pole pieces, and the anode vane tips.
  • the free alkaline earth metal causes spurious electron emission from these elements which interferes with the proper oscillating mode of the magnetron.
  • the conventional impregnated tungsten cathode may be operated at a lower temperature, or special cathodes may be fabricated employing materials which have good secondary emission capabilities but a low rate of evaporation of alkaline earth metal, and consequently low primary emission.
  • high power magnetrons employing cathodes of these types frequently have poor starting stability. That is, the mag netron may not start to oscillate immediately upon the application of the full pulsed voltage. The poor starting characteristics'of these devices appear to be due to the fact that the cathode produces little or no free alkaline earth metal at the operating temperature, and therefore the cathode surface is susceptible to deactivation by poisoning.
  • a cathode according to the invention comprises a major surface region of a material capable of emitting secondary electrons and a minor surface region of a material which provides a source of primary electrons.
  • the minor surface region of the cathode may be constituted of a material which in itself is a good primary emitter of electrons or it may be of a reducing material which reduces non-emitting compounds diffusing from the major surface region to form a low work function material, thereby creating a region of high primary emission at the interface between the reducing material and the major surface region.
  • FIG. 1 is a cross-sectional view in elevation of a portion of a magnetron having mounted therein a cathode according to one embodiment of the invention.
  • FIG. 2 is a cross-sectional view illustrating a cathode according to another embodiment of the invention.
  • FIG. 1 A magnetron incorporating the first embodiment of the invention is illustrated in FIG. 1.
  • the magnetron includes a cylindrical anode block 10 having a plurality of vanes 11 extending radially inward therefrom to provide a plurality of cavity resonators lying in a circular array about the central axis of the anode.
  • the anode is strapped with pairs of concentric metal rings 12 located in recesses in each end of the vanes. Each strapping ring is connected only to alternate vanes in the manner well known in the art in order to insure operation of the magnetron in the 11' mode.
  • Upper and lower magnet pole pieces 13 and 14 are sealed to the anode block and are arranged to direct a magnetic field from permanent magnets (not shown) through the magnetron interaction space.
  • Electromagnetic energy is coupled from the device by an output coupler 15 communicating with one of the cavity resonators.
  • An electron emissive cathode 20 is positioned centrally of the anode and spaced from the tips of the vanes.
  • the cathode is brazed to a cathode support 21 and passes through a bore 22 in the lower pole piece 14.
  • the cathode support 21, and pole piece 14 are attached together by a suitable arrangement of insulating hermetic seals (not shown).
  • the cathode 20 includes a hollow cylindrical sleeve 25 of molybdenum which is sealed at its lower end to the cathode support 21 and which extends centrally of the anode up into a recess 26 in the upper magnet pole piece.
  • Non-emissive end shields 27 and 28 are staked to steps on the molybdenum sleeve so as to confine the electrons and prevent their movement into the end spaces above and below the ends of the anode vanes.
  • the end shields are separated from the electron emissive surface 30 of the cathode by molybdenum spacers 31 and 32.
  • a coiled heater element 33 of tungsten wound on a ceramic mandrel 34 is positioned centrally of the molybdenum sleeve 25.
  • One end of the heater element is electrically connected to the cylindrical sleeve 25.
  • the lower end of the heater element extends through a spacer in the bottom of the sleeve and passes externally of the magnetron through a suitable arrangement (not shown) to provide a terminal for supplying heater current to the heater element.
  • the active surface of the cathode includes a first or major surface region having a material at the surface which is capable of emitting secondary electrons and has a low rate of evaporating of emission enhancing material. Adjoining the ends of this region are two minor surface regions 41 and 42, each of which provides a source of primary electrons. The area of the minor surface regions is small relative to the area of the major surface region.
  • the major surface region 40 is formed of a cylinder of material which is a good secondary emitter of electrons but which has a 'low rate of evaporation of free alkaline earth metal.
  • the cylinder may be a matrix of refractory metal having dispersed therein a series of compounds of an alkaline earth metal of the nature of, for example, tungstates and molybdates which are not readily reduced to the free alkaline earth metal by the refractory metal.
  • the cylinder may be formed by compacting a mixture of barium carbonate and one or more refractory metals such as tungsten and molybdenum and sintering at a high temperature in an inert atmosphere. Under such conditions tungstates and/or molybdates of barium are formed.
  • the cylinder may be of porous tungsten, molybdenum, or rhenium impregnated with tungstates or molybdates of an alkaline earth metal such as barium.
  • the minor surface regions 41 and 42 are formed of cylinders coaxial with the cylinder forming the major surface region and adjoining each end of the major surface region.
  • Each cylinder may be a matrix of refractory metal having dispersed therein an alkaline earth metal composition capable of furnishing alkaline earth metal to the surface of the cylinder. More specifically, the cylinders may be annular members or washers of porous tungsten impregnated with a barimum calcium aluminate of relatively low barium content.
  • the minor surface regions 41 and 42 may be formed of a material which is of strongly reducing nature such that non-emitting compounds diffusing from the adjoining secondary emitting region are reduced and a low work function material is formed, thereby creating a region of high primary emission at the interface between the major and minor surface regions. More specificially, rings or washers of tantalum, zirconium, titanium. or niobium may be employed, tantalum being preferred.
  • the total surface area of the minor surface regions 41 and 42 desirably should be of the order of 20% or less of the total emission surface area of the cathode.
  • cathodes have been fabricated in which the major surface region 40 was provided by a cylinder .100 inch high of a compacted mixture of 10% by weight barium carbonate, 45% by weight tungsten, and 45% by weight molybdenum, sintered at 1700 C. in pure dry nitrogen.
  • This cylinder was employed with two washers 41 and 42 each .010 inch thick of porous tungsten impregnated with barium calcium aluminate of the composition BaO-2CaO-2Al O Alternatively, tantalum washers .010 inch thick have been employed in place of the impregnated tungsten washers.
  • FIG. 2. illustrates a second embodiment of a cathode according to the invention which may be mounted in the magnetron of FIG. 1.
  • the cylindrical surface of secondary electron emitting material is provided by two cylinders 51 and 52. Intermediate the two cylinders and adjoining an end of each is a narrow cylindrical region 53 of material providing a source of primary electrons.
  • the materials employed for producing primary and secondary electron emission may be the same materials as those employed in the first embodiment of the invention.
  • Cathodes according to the invention have been utilized in high power magnetrons with excellent results. Starting stability has been satisfactory indicating that sufficient free alkaline earth metal is available at the surface of the minor surface regions to keep the surface active and not susceptible to deactivation by poisoning. Interference with the proper operating mode of the device has been eliminated indicating that there is no significant excess of free alkaline earth metal available to establish sources of spurious electrons on elements of the device adjacent the cathode.
  • a cathode comprising a first surface region of material capable of emitting secondary electrons and having a low rate of evaporation of emission enhancing material
  • a cathode comprising a first surface region of material having a high secondary electron emission yield and a low rate of evaporation of free alkaline earth metal
  • the surface area of the second surface region being small relative to the surface area of the first surface region.
  • a cathode comprising a first surface region of material having a high secondary electron emission yield and a low rate of evaporation of free alkaline earth metal
  • a second surface region of material capable of reduc ing non-emitting compounds diffusing from the first surface region to create a region of primary electron emission at the interface of the first and second surface regions.
  • the surface area of the second surface region being small relative to the surface area of the first surface region.
  • said first surface region comprises a matrix of refractory metal selected from the group consisting of tungsten, molybdenum, and rhenium having dispersed therein a material selected from the group consisting of tungstates and molybdates of an alkaline earth metal.
  • a cathode according to claim 6 in which of both the first and second materials.
  • said second material comprises a porous tungsten body impregnated with barium calcium aluminate of com position BaO ZCaO- 2Al O 14.
  • a cylindrical cathode comprising a first material comprising a matrix of refractory metal said first surface region comprises a material produced 5 having dispersed therein compounds of an alkaline by compacting and 'sintering a mixture of an alkaearth metal which are not readily reduced to the free line earth metal carbonate and a refractory metal alkaline earth metal by the refractory metal, selected from the group consisting of tungsten and a second material capable of red i g non-emitting molybdenum, 10 compounds diffusing from the first material to create 10.
  • a cathode according to claim 6 in which said a region of primary electron emission at interfaces second surface region comprises a refractory metal sebetween the first and second materials, lected from the group consisting of tantalum, niobium, a fi st cy ndrical body constituted of one of said mazirconium and titanium. terials,
  • a cylindrical cathode comprising a second cylindrical body constituted of the other of a first material comprising a matrix of refractory metal id m e ia s coa al With the first cylindrical body having dispersed therein compounds of an alkaline and adjoining first ylin i al y t ne nd earth metal which are not readily reduced to the free thereof, alkaline earth metal by the refractory metal, a third cylindrical body constituted of the other Of a second material comprising a matrix of refractory aid ma erials oaxial With the first and second metal having dispersed therein an alkaline earth cylindrical bodies and adjoining the first cylindrical metal composition capable of furnishing primary body at the other end thereof, electron emission at the surface, the cylindrical surface area of the second material a first cylindrical body constituted of one of said mabeing less than 20% of the cylindrical surface area terials, of both the first and second materials.
  • first and said second material comprises a washer of tantalum.
  • cylindrical bodies and adJommg the first cylindrical A Cathode according to claim 14 in which body.at h other end thereof said first material comprises a porous tungsten matrix the cylindrical surface area of the second material im re mated with mnostates of barium being less than 20% of the cylindrical surface area p g said second material comprises a washer of tantalum.
  • said second material comprises a porous tungsten body 2,957,100 10/1960 ESPCFSBII et a1 313346 impregnated with barium calcium aluminate of com- 3,027,489 3/1962 Tulnlla 313346 X position BaO 2Ca0 2Al O 13.

Description

Jan. 10, 1967 K. MACDONALD ETAL DISPENSER GATHODE FOR USE IN HIGH POWER MAGNETRON DEVICES Filed June 5, 1964 IFI,G.2
IN VENTORS. KENNETH A. MACDONALD and JOSEPH A SMITH EM 774 M4 AGENT.
United States Patent 3,297,901 DKSPENSER CATHQDE FOR USE IN HIGH PUWER MAGNETRON DEVICES Kenneth A. Macdonald and Joseph A. Smith, Williamsport, Pa, assignors, by mesne assignments, to Litton Industries, Inc, Beverly Hills, Calif, a corporation of Delaware Filed June 5, 1964, Ser. No. 372,804 16 Claims. (Cl. 313-346) This invention relates to emissive cathodes, particufearth compound with one or more refractory metals.
The alkaline earth composition chosen is normally one which will be slowly reduced by the refractory metal at the operating temperature of the cathode to provide free alkaline earth metal at the emissive surface of the cathode, thereby enhancing the electron emitting capabilities of the surface and producing a copious supply of primary electrons.
As is well known in the operation of pulsed magnetrons, electrons from the=cathode which are not in proper phase to contribute energy to the oscillating mode of the magnetron return to the cathode. Since the returning electrons strike the cathode with considerable energy, secondary electrons are expelled and the cathode is heated. After oscillation has been started, the cathode heater current is reduced and the necessary energy for heating the cathode is largely obtained from the back bombardment by the electrons returning to the cathode. In high power magnetrons, secondary electrons are the principal constituent of the cathode current; therefore, dispenser type cathodes for use in high power magnetrons commonly employ materials which have good secondary emission capabilities in addition to their primary electron emission capabilities. A frequently used exam ple of such a cathode is a porous tungsten body impregnated with barium calcium aluminate.
As mentioned above, the plentiful supply of primary electrons from a dispenser type cathode depends on the availability of an adequate quantity of free alkaline earth metal at the emissive surface of the cathode. However, the quantity of free alkaline earth metal produced by cathodes most commonly used in magnetrons is more than sufficient for this purpose, and some of the excess material evaporates from the surface of the cathode and deposits on adjacent elements of the magnetron structure, such as the cathode and shields, the magnet pole pieces, and the anode vane tips. The free alkaline earth metal causes spurious electron emission from these elements which interferes with the proper oscillating mode of the magnetron.
Various techniques have been employed in attempting to avoid the excessive production of freealkaline earth metal. For example, the conventional impregnated tungsten cathode may be operated at a lower temperature, or special cathodes may be fabricated employing materials which have good secondary emission capabilities but a low rate of evaporation of alkaline earth metal, and consequently low primary emission. However, high power magnetrons employing cathodes of these types frequently have poor starting stability. That is, the mag netron may not start to oscillate immediately upon the application of the full pulsed voltage. The poor starting characteristics'of these devices appear to be due to the fact that the cathode produces little or no free alkaline earth metal at the operating temperature, and therefore the cathode surface is susceptible to deactivation by poisoning.
It is an object of the present invention, therefore, to provide an improved cathode.
It is a more specific object of the invention to provide a dispenser type cathode which is capable of producing sufficient primary electrons to provide immediate starting of a high power magnetron but which does not evaporate an excessive quantity of emission enhancing material.
Briefly, in accordance with the foregoing objects, a cathode according to the invention comprises a major surface region of a material capable of emitting secondary electrons and a minor surface region of a material which provides a source of primary electrons. The minor surface region of the cathode may be constituted of a material which in itself is a good primary emitter of electrons or it may be of a reducing material which reduces non-emitting compounds diffusing from the major surface region to form a low work function material, thereby creating a region of high primary emission at the interface between the reducing material and the major surface region.
Additional objects, features, and advantages of cathodes according to the invention will be apparent from the following detailed discussion and the accompanying drawings wherein:
FIG. 1 is a cross-sectional view in elevation of a portion of a magnetron having mounted therein a cathode according to one embodiment of the invention, and
FIG. 2 is a cross-sectional view illustrating a cathode according to another embodiment of the invention.
A magnetron incorporating the first embodiment of the invention is illustrated in FIG. 1. The magnetron includes a cylindrical anode block 10 having a plurality of vanes 11 extending radially inward therefrom to provide a plurality of cavity resonators lying in a circular array about the central axis of the anode. The anode is strapped with pairs of concentric metal rings 12 located in recesses in each end of the vanes. Each strapping ring is connected only to alternate vanes in the manner well known in the art in order to insure operation of the magnetron in the 11' mode. Upper and lower magnet pole pieces 13 and 14 are sealed to the anode block and are arranged to direct a magnetic field from permanent magnets (not shown) through the magnetron interaction space. Electromagnetic energy is coupled from the device by an output coupler 15 communicating with one of the cavity resonators.
An electron emissive cathode 20 according to the invention is positioned centrally of the anode and spaced from the tips of the vanes. The cathode is brazed to a cathode support 21 and passes through a bore 22 in the lower pole piece 14. The cathode support 21, and pole piece 14 are attached together by a suitable arrangement of insulating hermetic seals (not shown).
The cathode 20 includes a hollow cylindrical sleeve 25 of molybdenum which is sealed at its lower end to the cathode support 21 and which extends centrally of the anode up into a recess 26 in the upper magnet pole piece. Non-emissive end shields 27 and 28 are staked to steps on the molybdenum sleeve so as to confine the electrons and prevent their movement into the end spaces above and below the ends of the anode vanes. The end shields are separated from the electron emissive surface 30 of the cathode by molybdenum spacers 31 and 32. A coiled heater element 33 of tungsten wound on a ceramic mandrel 34 is positioned centrally of the molybdenum sleeve 25. One end of the heater element is electrically connected to the cylindrical sleeve 25. The lower end of the heater element extends through a spacer in the bottom of the sleeve and passes externally of the magnetron through a suitable arrangement (not shown) to provide a terminal for supplying heater current to the heater element.
In the cathode according to the invention as illustrated in FIG. 1 the active surface of the cathode includes a first or major surface region having a material at the surface which is capable of emitting secondary electrons and has a low rate of evaporating of emission enhancing material. Adjoining the ends of this region are two minor surface regions 41 and 42, each of which provides a source of primary electrons. The area of the minor surface regions is small relative to the area of the major surface region.
The major surface region 40 is formed of a cylinder of material which is a good secondary emitter of electrons but which has a 'low rate of evaporation of free alkaline earth metal. The cylinder may be a matrix of refractory metal having dispersed therein a series of compounds of an alkaline earth metal of the nature of, for example, tungstates and molybdates which are not readily reduced to the free alkaline earth metal by the refractory metal.
More specifically, the cylinder may be formed by compacting a mixture of barium carbonate and one or more refractory metals such as tungsten and molybdenum and sintering at a high temperature in an inert atmosphere. Under such conditions tungstates and/or molybdates of barium are formed. Alternatively, the cylinder may be of porous tungsten, molybdenum, or rhenium impregnated with tungstates or molybdates of an alkaline earth metal such as barium.
The minor surface regions 41 and 42 are formed of cylinders coaxial with the cylinder forming the major surface region and adjoining each end of the major surface region. Each cylinder may be a matrix of refractory metal having dispersed therein an alkaline earth metal composition capable of furnishing alkaline earth metal to the surface of the cylinder. More specifically, the cylinders may be annular members or washers of porous tungsten impregnated with a barimum calcium aluminate of relatively low barium content.
Alternatively, the minor surface regions 41 and 42 may be formed of a material which is of strongly reducing nature such that non-emitting compounds diffusing from the adjoining secondary emitting region are reduced and a low work function material is formed, thereby creating a region of high primary emission at the interface between the major and minor surface regions. More specificially, rings or washers of tantalum, zirconium, titanium. or niobium may be employed, tantalum being preferred.
The total surface area of the minor surface regions 41 and 42 desirably should be of the order of 20% or less of the total emission surface area of the cathode. Specifically, cathodes have been fabricated in which the major surface region 40 was provided by a cylinder .100 inch high of a compacted mixture of 10% by weight barium carbonate, 45% by weight tungsten, and 45% by weight molybdenum, sintered at 1700 C. in pure dry nitrogen. This cylinder was employed with two washers 41 and 42 each .010 inch thick of porous tungsten impregnated with barium calcium aluminate of the composition BaO-2CaO-2Al O Alternatively, tantalum washers .010 inch thick have been employed in place of the impregnated tungsten washers.
FIG. 2. illustrates a second embodiment of a cathode according to the invention which may be mounted in the magnetron of FIG. 1. In this embodiment the cylindrical surface of secondary electron emitting material is provided by two cylinders 51 and 52. Intermediate the two cylinders and adjoining an end of each is a narrow cylindrical region 53 of material providing a source of primary electrons. The materials employed for producing primary and secondary electron emission may be the same materials as those employed in the first embodiment of the invention.
Cathodes according to the invention have been utilized in high power magnetrons with excellent results. Starting stability has been satisfactory indicating that sufficient free alkaline earth metal is available at the surface of the minor surface regions to keep the surface active and not susceptible to deactivation by poisoning. Interference with the proper operating mode of the device has been eliminated indicating that there is no significant excess of free alkaline earth metal available to establish sources of spurious electrons on elements of the device adjacent the cathode.
What is claimed is:
1. A cathode comprising a first surface region of material capable of emitting secondary electrons and having a low rate of evaporation of emission enhancing material, and
a second surface region of material providing a source of primary electrons.
2. A cathode comprising a first surface region of material having a high secondary electron emission yield and a low rate of evaporation of free alkaline earth metal, and
a second surface region of a refractory metal having dispersed therein an alkaline earth compound capable of furnishing primary electron emission at the surface adjoining the first surface region,
the surface area of the second surface region being small relative to the surface area of the first surface region.
3. A cathode according to claim 2 in which said first surface region comprises a matrix of refractory metal having dispersed therein compounds of an alkaline earth metal which are not readily reduced to free alkaline earth metal by the refractory metal of the matrix.
4. A cathode according to claim 2 in which said first surface region comprises a matrix of refractory metal selected from the group consisting of tungsten, molybdenum, and rhenium having dispersed therein a material selected from the group consisting of tungstates and molybdates of an alkaline earth metal.
5. A cathode according to claim 2 in which said first surface region comprises a material produced by compacting and sintering a mixture of an alkaline earth metal carbonate and a refractory metal selected from the group consisting of tungsten and molybdenum.
6. A cathode comprising a first surface region of material having a high secondary electron emission yield and a low rate of evaporation of free alkaline earth metal, and
a second surface region of material capable of reduc ing non-emitting compounds diffusing from the first surface region to create a region of primary electron emission at the interface of the first and second surface regions.
the surface area of the second surface region being small relative to the surface area of the first surface region.
7. A cathode according to claim 6 in which said first surface region comprises a matrix of refractory metal having dispersed therein compounds of an alkaline earth metal which are not readily reduced to free alkaline earth metal by the refractory metal of the matrix.
8. A cathode according to claim 6 in which said first surface region comprises a matrix of refractory metal selected from the group consisting of tungsten, molybdenum, and rhenium having dispersed therein a material selected from the group consisting of tungstates and molybdates of an alkaline earth metal.
9. A cathode according to claim 6 in which of both the first and second materials.
12. A cathode according to claim 11 in which said first material comprises a material produced by compacting and sintering a mixture including by weight about barium carbonate, 45% tungsten, 40
said second material comprises a porous tungsten body impregnated with barium calcium aluminate of com position BaO ZCaO- 2Al O 14. a cylindrical cathode comprising a first material comprising a matrix of refractory metal said first surface region comprises a material produced 5 having dispersed therein compounds of an alkaline by compacting and 'sintering a mixture of an alkaearth metal which are not readily reduced to the free line earth metal carbonate and a refractory metal alkaline earth metal by the refractory metal, selected from the group consisting of tungsten and a second material capable of red i g non-emitting molybdenum, 10 compounds diffusing from the first material to create 10. A cathode according to claim 6 in which said a region of primary electron emission at interfaces second surface region comprises a refractory metal sebetween the first and second materials, lected from the group consisting of tantalum, niobium, a fi st cy ndrical body constituted of one of said mazirconium and titanium. terials,
11. A cylindrical cathode comprising a second cylindrical body constituted of the other of a first material comprising a matrix of refractory metal id m e ia s coa al With the first cylindrical body having dispersed therein compounds of an alkaline and adjoining first ylin i al y t ne nd earth metal which are not readily reduced to the free thereof, alkaline earth metal by the refractory metal, a third cylindrical body constituted of the other Of a second material comprising a matrix of refractory aid ma erials oaxial With the first and second metal having dispersed therein an alkaline earth cylindrical bodies and adjoining the first cylindrical metal composition capable of furnishing primary body at the other end thereof, electron emission at the surface, the cylindrical surface area of the second material a first cylindrical body constituted of one of said mabeing less than 20% of the cylindrical surface area terials, of both the first and second materials. a second cylindrical body constituted of the other of 15. A cathode according to claim 14 in which said materials coaxial with the first cylindrical body id fi t i l cemprises a i l produced by and adjoining the first Cylindrical y at 0116 end compacting and sintering a mixture including by thereof, and weight about 10% barium carbonate, 45 tungsten, a-th rd cylindrical body constituted of the other of and molybdenum, and
mammals ,Coaxlal the first and said second material comprises a washer of tantalum. cylindrical bodies and adJommg the first cylindrical A Cathode according to claim 14 in which body.at h other end thereof said first material comprises a porous tungsten matrix the cylindrical surface area of the second material im re mated with mnostates of barium being less than 20% of the cylindrical surface area p g said second material comprises a washer of tantalum.
References Cited by the Examiner UNITED STATES PATENTS and molybdenum, and 2,698,913 1/1955 Espersen 313-446 said second material comprises a porous tungsten body 2,957,100 10/1960 ESPCFSBII et a1 313346 impregnated with barium calcium aluminate of com- 3,027,489 3/1962 Tulnlla 313346 X position BaO 2Ca0 2Al O 13. A cathode according to claim 11 in which said first material comprises a porous tungsten matrix impregnated with tungstates of barium,
45 JOHN W. HUCKERT, Primary Examiner.
A J. JAMES, Assistant Examiner.

Claims (1)

1. A CATHODE COMPRISING A FIRST SURFACE REGION OF MATERIAL CAPABLE OF EMITTING SECONDARY ELECTRONS AND HAVING A LOW RATE OF EVAPORATION OF EMISSION ENHANCING MATERIAL, AND A SECOND SURFACE REGION OF MATERIAL PROVIDING A SOURCE OF PRIMARY ELECTRONS.
US372804A 1964-06-05 1964-06-05 Dispenser cathode for use in high power magnetron devices Expired - Lifetime US3297901A (en)

Priority Applications (2)

Application Number Priority Date Filing Date Title
US372804A US3297901A (en) 1964-06-05 1964-06-05 Dispenser cathode for use in high power magnetron devices
GB24261/65A GB1083833A (en) 1964-06-05 1965-06-08 Cathode

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US372804A US3297901A (en) 1964-06-05 1964-06-05 Dispenser cathode for use in high power magnetron devices

Publications (1)

Publication Number Publication Date
US3297901A true US3297901A (en) 1967-01-10

Family

ID=23469701

Family Applications (1)

Application Number Title Priority Date Filing Date
US372804A Expired - Lifetime US3297901A (en) 1964-06-05 1964-06-05 Dispenser cathode for use in high power magnetron devices

Country Status (2)

Country Link
US (1) US3297901A (en)
GB (1) GB1083833A (en)

Cited By (11)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3459986A (en) * 1967-01-27 1969-08-05 Otto G Koppius Secondary emission cathode or dynode of a porous matrix of tungsten or molybdenum impregnated with secondary emission material such as a tungstate or an alkali halide of calcium
US3899714A (en) * 1972-12-21 1975-08-12 English Electric Valve Co Ltd Quick starting magnetron with shielded cathode
US5172030A (en) * 1988-01-20 1992-12-15 Eev Limited Magnetron
WO1993021648A1 (en) * 1992-04-15 1993-10-28 Gosudarstvennoe Proizvodstvennoe Obiedinenie 'pluton' Magnetron
FR2699325A1 (en) * 1992-12-11 1994-06-17 Litton Systems Inc Elimination of instability in a cross-field amplifier using a field emitter.
US5874806A (en) * 1996-10-02 1999-02-23 Litton Systems, Inc. Passive jitter reduction in crossed-field amplifier with secondary emission material on anode vanes
US6329753B1 (en) 1998-01-08 2001-12-11 Litton Systems, Inc. M-type microwave device with slanted field emitter
US6388379B1 (en) 1998-01-08 2002-05-14 Northrop Grumman Corporation Magnetron having a secondary electron emitter isolated from an end shield
US6485346B1 (en) 2000-05-26 2002-11-26 Litton Systems, Inc. Field emitter for microwave devices and the method of its production
FR3007192A1 (en) * 2013-06-14 2014-12-19 Thales Sa IMPROVED OPTICAL ELECTRONIC CANON
WO2014134595A3 (en) * 2013-03-01 2015-02-19 Soo Yong Park Magnetron

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3578218A (en) * 1969-03-06 1971-05-11 Harold Thomas Atwood Vacuum seal for dough dividers
GB8611967D0 (en) * 1986-05-16 1986-10-29 English Electric Valve Co Ltd Directly heated cathodes
GB2317741B (en) * 1995-12-12 1999-02-17 Lg Electronics Inc Magnetron

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2698913A (en) * 1951-11-29 1955-01-04 Philips Corp Cathode structure
US2957100A (en) * 1957-08-27 1960-10-18 Philips Corp Magnetron cathode structure
US3027489A (en) * 1956-03-29 1962-03-27 Auto Test Inc Timing light circuit

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2698913A (en) * 1951-11-29 1955-01-04 Philips Corp Cathode structure
US3027489A (en) * 1956-03-29 1962-03-27 Auto Test Inc Timing light circuit
US2957100A (en) * 1957-08-27 1960-10-18 Philips Corp Magnetron cathode structure

Cited By (15)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3459986A (en) * 1967-01-27 1969-08-05 Otto G Koppius Secondary emission cathode or dynode of a porous matrix of tungsten or molybdenum impregnated with secondary emission material such as a tungstate or an alkali halide of calcium
US3899714A (en) * 1972-12-21 1975-08-12 English Electric Valve Co Ltd Quick starting magnetron with shielded cathode
US5172030A (en) * 1988-01-20 1992-12-15 Eev Limited Magnetron
WO1993021648A1 (en) * 1992-04-15 1993-10-28 Gosudarstvennoe Proizvodstvennoe Obiedinenie 'pluton' Magnetron
FR2699325A1 (en) * 1992-12-11 1994-06-17 Litton Systems Inc Elimination of instability in a cross-field amplifier using a field emitter.
US5874806A (en) * 1996-10-02 1999-02-23 Litton Systems, Inc. Passive jitter reduction in crossed-field amplifier with secondary emission material on anode vanes
US6329753B1 (en) 1998-01-08 2001-12-11 Litton Systems, Inc. M-type microwave device with slanted field emitter
US6388379B1 (en) 1998-01-08 2002-05-14 Northrop Grumman Corporation Magnetron having a secondary electron emitter isolated from an end shield
US6485346B1 (en) 2000-05-26 2002-11-26 Litton Systems, Inc. Field emitter for microwave devices and the method of its production
US6646367B2 (en) 2000-05-26 2003-11-11 L-3 Communications Corporation Field emitter for microwave devices and the method of its production
WO2014134595A3 (en) * 2013-03-01 2015-02-19 Soo Yong Park Magnetron
CN105190822A (en) * 2013-03-01 2015-12-23 朴秀用 Magnetron
CN108962704A (en) * 2013-03-01 2018-12-07 朴秀用 Magnetron
US11011339B2 (en) 2013-03-01 2021-05-18 Soo Yong Park Magnetron
FR3007192A1 (en) * 2013-06-14 2014-12-19 Thales Sa IMPROVED OPTICAL ELECTRONIC CANON

Also Published As

Publication number Publication date
GB1083833A (en) 1967-09-20

Similar Documents

Publication Publication Date Title
US3297901A (en) Dispenser cathode for use in high power magnetron devices
US2543728A (en) Incandescible cathode
EP1505627B1 (en) Magnetron
US4165473A (en) Electron tube with dispenser cathode
US2121589A (en) Emissive incandescent cathode
US3558966A (en) Directly heated dispenser cathode
US2488731A (en) Electron-emitting electrode for electric discharge tubes
EP0448133A2 (en) A directly heated cathode assembly
US2647216A (en) Dispenser cathode
US2957100A (en) Magnetron cathode structure
US4097762A (en) Xenon arc discharge lamp having a particular electrode composition and wherein the arc discharge is obtained without heating the electrode
US3160780A (en) Indirectly heated cathode
US2518879A (en) Hydrogen thyratron
US2975320A (en) Low-temperature plasma source
US2848644A (en) Thermionic cathode
US3029359A (en) Thermionic electrode for discharge lamps
US4302701A (en) Directly heated cathode for an electron tube with coaxial electrode design
US3555334A (en) Cathode with graphite end shields
US3263118A (en) Magnetron having concentric annular tunable resonator utilizing axial plunger and vacuum sealing bellows mounted inside principal envelope wall
US2810089A (en) Cathodes for electron discharge devices
US3174063A (en) Compatible electrode system in vacuum thermionic apparatus
US3441781A (en) Microwave tube cathode of the bariumcalcium aluminate type
US4954745A (en) Cathode structure
US2995674A (en) Impregnated cathodes
US2877355A (en) Bistable phototube