CA2180491A1 - Inductive output tube arrangements - Google Patents
Inductive output tube arrangementsInfo
- Publication number
- CA2180491A1 CA2180491A1 CA 2180491 CA2180491A CA2180491A1 CA 2180491 A1 CA2180491 A1 CA 2180491A1 CA 2180491 CA2180491 CA 2180491 CA 2180491 A CA2180491 A CA 2180491A CA 2180491 A1 CA2180491 A1 CA 2180491A1
- Authority
- CA
- Canada
- Prior art keywords
- channel
- arrangement
- high frequency
- electron gun
- cavity
- 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.)
- Abandoned
Links
- 230000001939 inductive effect Effects 0.000 title claims abstract description 8
- 239000011358 absorbing material Substances 0.000 claims abstract description 23
- 239000000463 material Substances 0.000 claims abstract description 22
- 229920002379 silicone rubber Polymers 0.000 claims abstract description 10
- 239000004945 silicone rubber Substances 0.000 claims abstract description 10
- 229910000859 α-Fe Inorganic materials 0.000 claims abstract description 8
- 238000010894 electron beam technology Methods 0.000 claims description 18
- 239000003989 dielectric material Substances 0.000 claims description 8
- 238000001465 metallisation Methods 0.000 claims description 2
- 229910010293 ceramic material Inorganic materials 0.000 claims 1
- 230000010355 oscillation Effects 0.000 abstract description 6
- 239000000919 ceramic Substances 0.000 description 6
- 230000008878 coupling Effects 0.000 description 5
- 238000010168 coupling process Methods 0.000 description 5
- 238000005859 coupling reaction Methods 0.000 description 5
- PXHVJJICTQNCMI-UHFFFAOYSA-N Nickel Chemical compound [Ni] PXHVJJICTQNCMI-UHFFFAOYSA-N 0.000 description 2
- 241000937413 Axia Species 0.000 description 1
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 description 1
- RYGMFSIKBFXOCR-UHFFFAOYSA-N Copper Chemical compound [Cu] RYGMFSIKBFXOCR-UHFFFAOYSA-N 0.000 description 1
- 230000002411 adverse Effects 0.000 description 1
- 101150063578 ald1 gene Proteins 0.000 description 1
- 230000004323 axial length Effects 0.000 description 1
- 229910052802 copper Inorganic materials 0.000 description 1
- 239000010949 copper Substances 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 229920001971 elastomer Polymers 0.000 description 1
- 238000010292 electrical insulation Methods 0.000 description 1
- 230000002708 enhancing effect Effects 0.000 description 1
- 229910002804 graphite Inorganic materials 0.000 description 1
- 239000010439 graphite Substances 0.000 description 1
- 238000011065 in-situ storage Methods 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 229910052759 nickel Inorganic materials 0.000 description 1
- 239000002245 particle Substances 0.000 description 1
- 239000000843 powder Substances 0.000 description 1
- 239000012256 powdered iron Substances 0.000 description 1
- 239000011347 resin Substances 0.000 description 1
- 229920005989 resin Polymers 0.000 description 1
- HBMJWWWQQXIZIP-UHFFFAOYSA-N silicon carbide Chemical compound [Si+]#[C-] HBMJWWWQQXIZIP-UHFFFAOYSA-N 0.000 description 1
- 229910010271 silicon carbide Inorganic materials 0.000 description 1
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J25/00—Transit-time tubes, e.g. klystrons, travelling-wave tubes, magnetrons
- H01J25/02—Tubes with electron stream modulated in velocity or density in a modulator zone and thereafter giving up energy in an inducing zone, the zones being associated with one or more resonators
- H01J25/04—Tubes having one or more resonators, without reflection of the electron stream, and in which the modulation produced in the modulator zone is mainly density modulation, e.g. Heaff tube
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J23/00—Details of transit-time tubes of the types covered by group H01J25/00
- H01J23/14—Leading-in arrangements; Seals therefor
- H01J23/15—Means for preventing wave energy leakage structurally associated with tube leading-in arrangements, e.g. filters, chokes, attenuating devices
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J23/00—Details of transit-time tubes of the types covered by group H01J25/00
- H01J23/36—Coupling devices having distributed capacitance and inductance, structurally associated with the tube, for introducing or removing wave energy
- H01J23/54—Filtering devices preventing unwanted frequencies or modes to be coupled to, or out of, the interaction circuit; Prevention of high frequency leakage in the environment
Landscapes
- Microwave Tubes (AREA)
Abstract
An inductive output tube, such as an IOT has a generally cylindrical input cavity within which an annular channel 32 is defined by part of the cavity wall 30 and other walls 33 and 34 to give a U-shaped cross-section. The channel 32 is substantially wholly filled with high frequency energy absorbing material such as ferrite loaded silicone rubber 35. This prevents unwanted oscillations and because of the large surface area of the channel in contact with the material 35 it is particularly efficient. Other configurations and locations of the channel are also possible and the absorbing material may occupy only part of the channel providing that it is in contact with the surfaces of the channel walls.
Description
`-- 2180491 INDUCTIVE OUTPUT TUBE ARRAN( r~ENTS
This invention relates to inductive output tube arrangements and more particularly to input resonator cavities for such tubes at which high frequency energy is applied.
The present invenbon is particularly applicable to inductive output bube devices ( l1er~ d~L~I referred to as 'lOT'sa). An IOT device includes a tube having an electron gun arranged to produce a linear electron beam and a resonant input cavity at which an r.f. signal to be amplified is applied to produce modulation of the beam at a grid of the electron gun. The resultant interaction between the r.f. energy and the electron beam produces a" 1 of the high frequency signal which is then extracted from an output resonant cavity.
One known IOT device is S- llellldliCdlly illustrated in longitudinal secbon in Figure 1. The IOT includes an electron gun 1 which comprises a cathode 2, an anode 3 and a grid 4 located between them. The electron gun is arranged to produce an electron beam directed along the longitudinal axis X-X of the ar,dl1g~",e"~. The IOT also includes drift tubes 5 and 6 via which the electron beam passes before being collected by a collector (not shown). A cylindrical annular input cavity 7 is arranged coaxially about the electron gun 1 and includes an input coupling 8 at which an r.f. signal to be amplified is applied. An output cavity 9 surrounds the gap between the drift tubes 5 and 6 and includes a coupling loop 10 ~ 2 1 8049 1 via which an amplified r.f. signal is extracted and coupled into a secondary output cavity 11 from which the output signal is taken via an output coupling 12.
The IOT includes two transversely arranged annular plates 13 and 14 which each form part of respective rf chokes. The first plate 13 is connected via conductive spring fingers (not shown) to a tubular member 15 which ",e~l,ani~
supports the cathode 2 and is " Idil Itdil ~ed at cathode potentiai. The other transverse plate 14 is connected via spring fingers to a support 16 of the grid 4 and is at the grid potential. An outer portion is ele,;l,i~al ~ separate from the inner portion and comprises transverse annular plates 17 and 18 connected by a cylindrical axially extensive wall 19 and arranged coextensively with part of the plate 13. The outer body portion also includes further transverse plates 20 and 21 cul " ,eL:t~d by a cylindrical wall 22 which are partially coextensive with the plate 14 which is ele- l,i~lly connected to the grid 4. The two rf chokes formed by the interleaved structures reduce leakage of the applied high frequency energy from the cavity 7.
The cavitv 7 further includes an axially extensive portion 23 having a movable tuning door 24 to permit the frequency of operation to be altered. It also includes a cylindrical wall 25 coaxial with the axis X-X and extensive in the region between the grid support 16 and anode support 26.
Dielectric material 27 is located between the interleaved transverse plates of the rf chokes to provide structural support and electrical insulation.
2 1 804q 1 Ceramic cylinders 28 and 29 surround the electron gun assembly and define part of the vacuum envelope.
In use, a d.c. voltage, typically of the order of 30-40kV is established between the cabhode 2 and bhe anode 3 and an r.f. input signal is applied between the cathode 2 and the grid 4. The r.f. choke defined by plates 14, 20 and 21 reduces coupling between the cathode/grid region and the anode 3. However, in some circumstances this may be insufficient to completely prevent leakage of r.f. energy and coupling between bhe two regions and, as a result, unwanted oscillation of the electron beam may occur. Such oscillation may not only decrease the operating efficiency of the tube but may also cause arcing within the tube sufficient to damage or disable it.
Our earlier ~ , published under serial number GB -A-2 279 496, discloses some ways in which oscillab'on may be reduced. The present invention arose from consideri"g whether unwanted oscillation may be reduced even more effectively or su~tldl ," ''y eliminated. The invention is parb'cularly applicable to lOTs but may also be advantageously cmployed in other types of electron beam tube a,Idl1g~",~
According to the invention there is provided an inducbve output tube a~dllge,~,e~lcu,,,~u,i~,illganelectrongunassemblyincludingacathodeandagridfor generab'ng an electron beam; a s~b tldl ," "y annular high frequency resonant input cavity arranged coaxially about the assembly; means for applying high frequency ~ 2180491 energy to the resonant cavity to modulate the electron beam; and wherein a wall of the cavity includes a channel within which is located material capable of absorbing high frequency energy.
By employing the invention, unwanted oscillation may be reduced or eliminated as the lossy material within the wall may be arranged so that it tends to absorb energy which might otherwise be coupled between different parts of the tube, in particular between the cathode/grid region and the anode. The channel provides a large surface area in contact with the absorbing material and this is a siyl, ~ I;ly more effective configuration than would be the case if the material were simply carried on a surface as the high frequency energy travels around the channel walls.
The invention thus provides a compact dlldn9~r~ with better energy abs~",lic"~
than would be achievable in a device where the channel is not used. As suitable absorbing material is expensive, use of the invention may also lead to cost benefits, as a reduced amount may be used to achieve the same effect as absorbing material merely attached to a wall. A suitable absorbing material for use in the invention is a ferrite loaded dielectric material and preferably the dielectric material is silicone rubber. One suitable material loaded with dielectric particles is that designated as Eccosorb CF-S~180 obtainable from Emerson and Cuming. This ferrite loaded silicone rubber material is a high loss material in the UHF and microwave ranges and is also capable of holding off high dc voltages of the order of several tens of kilovolts. Other absorbing materials may be used.
The silicone rubber for the absorbing material could be replaced by other 21 8049~
P/60667/VPoW
types of rubber or a resin, and could be loaded with one, or a combination of, the following: powdered iron, powdered nickel, silicon carbide, dispersed graphite or ferrite. Other materials having similar ul ,ald1~e,i~ti~s may also be suitable, and the dispersed material could be present in powder or particulate form, for example.
The channel may have one of a number of different cross-secUonal configurations. In one preferred embodiment, it is su~ld~ y annular and has three sides in cross-section. The substantially U- or C-shaped channel thus provides a large surface area for contact with the absorbing material such that currents in the cavity wall may be absorbed to reduce unwanted oscillation. The absorbing material may wholly occupy the interior defined by the channel. In an allt:" Idti~/C ~",bodi",e"l, the surfaces of the channel are in contact with the absorbing material but an inner volume within the channel is free from such material.
This volume could be occupied by a non-lossy material such as silicone rubber or it could be an air space.
It has been found that only one channel is required to give good pel ~ul " ,allce but in some electron beam tubes, two or more may be required.
Where the channel has three sides, facing sides may extend in the direcUon of the longitudinal axis along which the electron beam is directed or in a radial direction either inwardly into the cavity or outwardly from it. In one arrangement, the channel is partially radially orientated and partially extensive in an axial direction.
21 8049~
6 P/60667/VPoW
The channel may have other cross-sectional shapes, for example it could have a rounded wall to give a Gshaped section or could have more than three sides.
In one particularly advantageous embodiment of the invention, one wall of the channel also defines part of an rf choke means. This gives a compact arrangement and as the interior surfaces of the channel are those which are in contact with the absorbing material, the inclusion of the channel wall in the choke a"dng~" ,e, should not suL~ld, .';..!:y adversely affect the effectiveness of the choke.
Preferably, the channel is located sub~ldll.;~lly in the region between supports for the grid and an anode of the electron gun assembly. It is particularly effective in this region in reducing the unwanted ~ s or substantially u';."i, IdLil ,g them.
Advantageously, the electron gun assembly is located within a vacuum envelope and the material is located outside the envelope.
According to a feature of the invention, a cavity a, Idl 19~ for use with an inductive output tube comprises a wall which includes a channel within which is located material capable of absorbing high frequency energy.
As the material is located within a channel included in a wall defining the cavity, it can be arranged to be readily accessible for replacement, if necessary, or for upgrading an existing tube. The main body of the tube, including sections under ~ 21 8~491 7 P/60667/VPOW .
vacuum, may be kept in situ as set up for operation and the cavity wall removed for servicing elsewhere, if desired. During servicing, a ~,ulac~ L cavity wall can be fitted to the tube to enable operation to continue Sl,lb::~Ldl 1';.~11,/ uninterrupted whilst the servicing work is carried out separately. Thus, the positioning of the material on the cavity wall gives significant benefits in Illdil ILdil lil ,g the tube in a serviceable condition whilst also enhancing its performance.
Some ways in which the invenbon may be performed are now described by way of example with reference to bhe accompanying drawings in which:
Figures 2 to g s.;l ,el"dlic~'ly illustrate parts of lOTs in dcc~ a~ce with bhe invenbon which include respective different configurations of bhe channel and absorbing material, with like ,~ ces being used for like parts. Other portions of the lOTs are as shown in Figure 1.
With reference to Figure 2, an IOT has an electron gun assembly 1 with a cathode 2, grid 4 and anode 3. The IOT 7ncludes an annular input resonant cavity 7 arranged to receive high frequency energy to cause modulaUon of the electron beam. The cavity 7 includes a cylindrical cavity wall 30 which extends from a choke al,d"g~",~"l 31 to the anode support 26 in a longitudinal axial direction X-X along which an electron beam is generated during use. An annular channel 32 is defined by part of the cavity wall 30 and two other walls 33 and 34. The channel has a substantially U-shaped cross-sectional shape in which the facing surfaces are extensive in the longitudinal direction X-X and in which the wall which joins them is ~ 2 1 8049 1 located at their ends nearest the rf choke 31. The channel 32 is substantially wholly filled with ferrite loaded silicone rubber 35. The wall 33 which joins the two facing walls 30 and 34 of the channel is also included as part of the rf choke 31 in Co~ illdtiUll with plates 14 and 20. The region between the interleaved sections of the choke 31 is filled with dielectric material such as silicone rubber. Although in this dlldllg6lll~lll the channel is completely filled with the absorbing material, in other anrangements it may extend only part way between the end wall 33 and the open end of the channel. However, such an a~ ~d~ ~yt~ e~ ~l is not as efficient. The channel 32 is located in the region between a grid support 16 and the anode support 26.
With reference to Figure 3, in another ar,di~g~",~"l in aucoldd"ce with the invention, a channel 36 is again defined by part of the cavity wall 30 between the choke 31 and anode support member 26 but in this case the two other sides of the U-shaped channel are formed by part 37 of the support plate 26 and a wall 38 extending from the plate 26 towards the choke 31. Again, the channel 36 is wholly filled with absorbing material.
With reference to Figure 4, an a" dl~9~ 1 ll is shown which is similar to that of Figure 2 but in this embodiment, the absorbing material 39 does not wholly flll the channel 40 defined by walls 30, 41 and 42. The interior part of the channel is occupied by an air space 43 and the absorbing material 39 covers the interior walls of the channel 40.
Inanotherembodimentshown in Figure5which issimilartothed~,d,~ ,e"l 2 1 80~9 ~
g P/60667/VPOW
of Figure 2 the channel 44 is orientated in the same way but in this arrangement the choke 31 is separate from the channel 44 and does not share a common component.
With reference to Figure 6 another ar~dnge~"~l in accu,da"ce with the invention includes an rf choke 31 and a cylindrical cavity wall 30 which adjoins the support 26 of the anode. A channel 45 is again of U-shaped cross-sectional area but in this case the facing wall 46 and 47 are extensive in a radial direction with respect to the longitudinal axis X-X of the dl,d"g~",e"l. A wall 48 joins them to define the channel 45. In this embodiment the channel is adjacent the rf choke 31 but does not form part of it. Absorbing material 49 fills the channel. The channel 45 extends outwards away from the centre of the tube and thus increases the volume occupied by the IOT. In other ~ Jo~i~"e~ (not shown) a radially extensive channel extends inwardly.
With reference to Figure 7 in another d"d"~",~"1, the channel is of a more ru", - structure having a transversely extending part 50 similar to that shown in Figure 6 in C~ il ldliol1 with an axial extending part 51 similar to that of the Figure 2 arrangement. This provides a large surface area over which the absorbing material 52 is in contact the material filling the channel.
With reference to Figure 8 a channel 53 is defined by a part of the cylindrical cavity wall 30 the end plate 26 which supports the anode 3 part 54 of the rf choke 55 and a wall 56 extensive in a direction towards the rf choke 55 from the support ~ 21804ql 26. In this arrangement, therefore, the channel is sub~ldl, ~y four sided, therebeing a gap between the part 54 and that the free end of the wall 56. Absorbing material 57 is enclosed within the channel.
In the arrangement shown in Figures 2 to 8, bhe rf chokes are shown as being made up of interleaved plates which are in a plane normal to the longitudinal axis X-X. However, in other arrangements, these may be replaced by axia~ rf chokes which, say, two cylinders are located one within the obher to form a choke between them and are coaxial with axis X-X.
Wibh reference to Figure 9, in another IOT in accolddl1ce with the invention, an electron gun 1 is again surrounded by an annular resonant input cavity 7. In this ~",bodi",t:"L, the input cavity 7 comprises an outer body portion 58 and an inner body portion 60 maintained at a different potential to the first body porbon. Two rf chokes 61 and 62 are included between the inner and outer body portions 58 and 60. Each of the chokes 61 and 62 is extensive in the direction of the longitudinal axis X-X along which in use an electron beam is generated. A ceramic tube 63 is arranged coaxiaily around axis X-X and forms part of chokes 61 and 62. Choke 61 includes copper metallised regions 64 and 65 on the outer and inner surfaces of ceramic cylinder 63. Choke 62 includes a ", " , layer 66 on the inner surface of ceramic tube 63 and a second m~' " 'i~ 1 layer 67 on its outer surface. The m~' " , 67 extends over a greater axial length bhan the inner m~ " " 1 region 66. An anode support 68 has a secbon 69 which is ~ e~ d to an annular plate 70 fomming part of the outer body portion 58 of resonant cavity 7.
~ 2 1 8049 1 The wall 69, the inner part 70a of plate 70 and the outer metallisation layer 67 together define a channel within which is located ferrite loaded silicone rubber 71 or some other suitable rf absorbing material.
In another ~lllbodi~ l of the invenbon, a non-lossy dielectric material such as silicone rubber is located over part of the inner surface of ceramic cylinder 63 and over the " ,~ layer 66 as shown by the broken line at 72.
In other Cl"d"~b",e,lts similar to bhat shown in Figure 9, materials other than ceramic may form part one or bobh rf chokes. The dielectric material need not be conUnuous between both chokes. Also, the l~ layers shown in Figure 9 may be replaced by metallic members affixed to the i~ ",osed dielectric material.
This invention relates to inductive output tube arrangements and more particularly to input resonator cavities for such tubes at which high frequency energy is applied.
The present invenbon is particularly applicable to inductive output bube devices ( l1er~ d~L~I referred to as 'lOT'sa). An IOT device includes a tube having an electron gun arranged to produce a linear electron beam and a resonant input cavity at which an r.f. signal to be amplified is applied to produce modulation of the beam at a grid of the electron gun. The resultant interaction between the r.f. energy and the electron beam produces a" 1 of the high frequency signal which is then extracted from an output resonant cavity.
One known IOT device is S- llellldliCdlly illustrated in longitudinal secbon in Figure 1. The IOT includes an electron gun 1 which comprises a cathode 2, an anode 3 and a grid 4 located between them. The electron gun is arranged to produce an electron beam directed along the longitudinal axis X-X of the ar,dl1g~",e"~. The IOT also includes drift tubes 5 and 6 via which the electron beam passes before being collected by a collector (not shown). A cylindrical annular input cavity 7 is arranged coaxially about the electron gun 1 and includes an input coupling 8 at which an r.f. signal to be amplified is applied. An output cavity 9 surrounds the gap between the drift tubes 5 and 6 and includes a coupling loop 10 ~ 2 1 8049 1 via which an amplified r.f. signal is extracted and coupled into a secondary output cavity 11 from which the output signal is taken via an output coupling 12.
The IOT includes two transversely arranged annular plates 13 and 14 which each form part of respective rf chokes. The first plate 13 is connected via conductive spring fingers (not shown) to a tubular member 15 which ",e~l,ani~
supports the cathode 2 and is " Idil Itdil ~ed at cathode potentiai. The other transverse plate 14 is connected via spring fingers to a support 16 of the grid 4 and is at the grid potential. An outer portion is ele,;l,i~al ~ separate from the inner portion and comprises transverse annular plates 17 and 18 connected by a cylindrical axially extensive wall 19 and arranged coextensively with part of the plate 13. The outer body portion also includes further transverse plates 20 and 21 cul " ,eL:t~d by a cylindrical wall 22 which are partially coextensive with the plate 14 which is ele- l,i~lly connected to the grid 4. The two rf chokes formed by the interleaved structures reduce leakage of the applied high frequency energy from the cavity 7.
The cavitv 7 further includes an axially extensive portion 23 having a movable tuning door 24 to permit the frequency of operation to be altered. It also includes a cylindrical wall 25 coaxial with the axis X-X and extensive in the region between the grid support 16 and anode support 26.
Dielectric material 27 is located between the interleaved transverse plates of the rf chokes to provide structural support and electrical insulation.
2 1 804q 1 Ceramic cylinders 28 and 29 surround the electron gun assembly and define part of the vacuum envelope.
In use, a d.c. voltage, typically of the order of 30-40kV is established between the cabhode 2 and bhe anode 3 and an r.f. input signal is applied between the cathode 2 and the grid 4. The r.f. choke defined by plates 14, 20 and 21 reduces coupling between the cathode/grid region and the anode 3. However, in some circumstances this may be insufficient to completely prevent leakage of r.f. energy and coupling between bhe two regions and, as a result, unwanted oscillation of the electron beam may occur. Such oscillation may not only decrease the operating efficiency of the tube but may also cause arcing within the tube sufficient to damage or disable it.
Our earlier ~ , published under serial number GB -A-2 279 496, discloses some ways in which oscillab'on may be reduced. The present invention arose from consideri"g whether unwanted oscillation may be reduced even more effectively or su~tldl ," ''y eliminated. The invention is parb'cularly applicable to lOTs but may also be advantageously cmployed in other types of electron beam tube a,Idl1g~",~
According to the invention there is provided an inducbve output tube a~dllge,~,e~lcu,,,~u,i~,illganelectrongunassemblyincludingacathodeandagridfor generab'ng an electron beam; a s~b tldl ," "y annular high frequency resonant input cavity arranged coaxially about the assembly; means for applying high frequency ~ 2180491 energy to the resonant cavity to modulate the electron beam; and wherein a wall of the cavity includes a channel within which is located material capable of absorbing high frequency energy.
By employing the invention, unwanted oscillation may be reduced or eliminated as the lossy material within the wall may be arranged so that it tends to absorb energy which might otherwise be coupled between different parts of the tube, in particular between the cathode/grid region and the anode. The channel provides a large surface area in contact with the absorbing material and this is a siyl, ~ I;ly more effective configuration than would be the case if the material were simply carried on a surface as the high frequency energy travels around the channel walls.
The invention thus provides a compact dlldn9~r~ with better energy abs~",lic"~
than would be achievable in a device where the channel is not used. As suitable absorbing material is expensive, use of the invention may also lead to cost benefits, as a reduced amount may be used to achieve the same effect as absorbing material merely attached to a wall. A suitable absorbing material for use in the invention is a ferrite loaded dielectric material and preferably the dielectric material is silicone rubber. One suitable material loaded with dielectric particles is that designated as Eccosorb CF-S~180 obtainable from Emerson and Cuming. This ferrite loaded silicone rubber material is a high loss material in the UHF and microwave ranges and is also capable of holding off high dc voltages of the order of several tens of kilovolts. Other absorbing materials may be used.
The silicone rubber for the absorbing material could be replaced by other 21 8049~
P/60667/VPoW
types of rubber or a resin, and could be loaded with one, or a combination of, the following: powdered iron, powdered nickel, silicon carbide, dispersed graphite or ferrite. Other materials having similar ul ,ald1~e,i~ti~s may also be suitable, and the dispersed material could be present in powder or particulate form, for example.
The channel may have one of a number of different cross-secUonal configurations. In one preferred embodiment, it is su~ld~ y annular and has three sides in cross-section. The substantially U- or C-shaped channel thus provides a large surface area for contact with the absorbing material such that currents in the cavity wall may be absorbed to reduce unwanted oscillation. The absorbing material may wholly occupy the interior defined by the channel. In an allt:" Idti~/C ~",bodi",e"l, the surfaces of the channel are in contact with the absorbing material but an inner volume within the channel is free from such material.
This volume could be occupied by a non-lossy material such as silicone rubber or it could be an air space.
It has been found that only one channel is required to give good pel ~ul " ,allce but in some electron beam tubes, two or more may be required.
Where the channel has three sides, facing sides may extend in the direcUon of the longitudinal axis along which the electron beam is directed or in a radial direction either inwardly into the cavity or outwardly from it. In one arrangement, the channel is partially radially orientated and partially extensive in an axial direction.
21 8049~
6 P/60667/VPoW
The channel may have other cross-sectional shapes, for example it could have a rounded wall to give a Gshaped section or could have more than three sides.
In one particularly advantageous embodiment of the invention, one wall of the channel also defines part of an rf choke means. This gives a compact arrangement and as the interior surfaces of the channel are those which are in contact with the absorbing material, the inclusion of the channel wall in the choke a"dng~" ,e, should not suL~ld, .';..!:y adversely affect the effectiveness of the choke.
Preferably, the channel is located sub~ldll.;~lly in the region between supports for the grid and an anode of the electron gun assembly. It is particularly effective in this region in reducing the unwanted ~ s or substantially u';."i, IdLil ,g them.
Advantageously, the electron gun assembly is located within a vacuum envelope and the material is located outside the envelope.
According to a feature of the invention, a cavity a, Idl 19~ for use with an inductive output tube comprises a wall which includes a channel within which is located material capable of absorbing high frequency energy.
As the material is located within a channel included in a wall defining the cavity, it can be arranged to be readily accessible for replacement, if necessary, or for upgrading an existing tube. The main body of the tube, including sections under ~ 21 8~491 7 P/60667/VPOW .
vacuum, may be kept in situ as set up for operation and the cavity wall removed for servicing elsewhere, if desired. During servicing, a ~,ulac~ L cavity wall can be fitted to the tube to enable operation to continue Sl,lb::~Ldl 1';.~11,/ uninterrupted whilst the servicing work is carried out separately. Thus, the positioning of the material on the cavity wall gives significant benefits in Illdil ILdil lil ,g the tube in a serviceable condition whilst also enhancing its performance.
Some ways in which the invenbon may be performed are now described by way of example with reference to bhe accompanying drawings in which:
Figures 2 to g s.;l ,el"dlic~'ly illustrate parts of lOTs in dcc~ a~ce with bhe invenbon which include respective different configurations of bhe channel and absorbing material, with like ,~ ces being used for like parts. Other portions of the lOTs are as shown in Figure 1.
With reference to Figure 2, an IOT has an electron gun assembly 1 with a cathode 2, grid 4 and anode 3. The IOT 7ncludes an annular input resonant cavity 7 arranged to receive high frequency energy to cause modulaUon of the electron beam. The cavity 7 includes a cylindrical cavity wall 30 which extends from a choke al,d"g~",~"l 31 to the anode support 26 in a longitudinal axial direction X-X along which an electron beam is generated during use. An annular channel 32 is defined by part of the cavity wall 30 and two other walls 33 and 34. The channel has a substantially U-shaped cross-sectional shape in which the facing surfaces are extensive in the longitudinal direction X-X and in which the wall which joins them is ~ 2 1 8049 1 located at their ends nearest the rf choke 31. The channel 32 is substantially wholly filled with ferrite loaded silicone rubber 35. The wall 33 which joins the two facing walls 30 and 34 of the channel is also included as part of the rf choke 31 in Co~ illdtiUll with plates 14 and 20. The region between the interleaved sections of the choke 31 is filled with dielectric material such as silicone rubber. Although in this dlldllg6lll~lll the channel is completely filled with the absorbing material, in other anrangements it may extend only part way between the end wall 33 and the open end of the channel. However, such an a~ ~d~ ~yt~ e~ ~l is not as efficient. The channel 32 is located in the region between a grid support 16 and the anode support 26.
With reference to Figure 3, in another ar,di~g~",~"l in aucoldd"ce with the invention, a channel 36 is again defined by part of the cavity wall 30 between the choke 31 and anode support member 26 but in this case the two other sides of the U-shaped channel are formed by part 37 of the support plate 26 and a wall 38 extending from the plate 26 towards the choke 31. Again, the channel 36 is wholly filled with absorbing material.
With reference to Figure 4, an a" dl~9~ 1 ll is shown which is similar to that of Figure 2 but in this embodiment, the absorbing material 39 does not wholly flll the channel 40 defined by walls 30, 41 and 42. The interior part of the channel is occupied by an air space 43 and the absorbing material 39 covers the interior walls of the channel 40.
Inanotherembodimentshown in Figure5which issimilartothed~,d,~ ,e"l 2 1 80~9 ~
g P/60667/VPOW
of Figure 2 the channel 44 is orientated in the same way but in this arrangement the choke 31 is separate from the channel 44 and does not share a common component.
With reference to Figure 6 another ar~dnge~"~l in accu,da"ce with the invention includes an rf choke 31 and a cylindrical cavity wall 30 which adjoins the support 26 of the anode. A channel 45 is again of U-shaped cross-sectional area but in this case the facing wall 46 and 47 are extensive in a radial direction with respect to the longitudinal axis X-X of the dl,d"g~",e"l. A wall 48 joins them to define the channel 45. In this embodiment the channel is adjacent the rf choke 31 but does not form part of it. Absorbing material 49 fills the channel. The channel 45 extends outwards away from the centre of the tube and thus increases the volume occupied by the IOT. In other ~ Jo~i~"e~ (not shown) a radially extensive channel extends inwardly.
With reference to Figure 7 in another d"d"~",~"1, the channel is of a more ru", - structure having a transversely extending part 50 similar to that shown in Figure 6 in C~ il ldliol1 with an axial extending part 51 similar to that of the Figure 2 arrangement. This provides a large surface area over which the absorbing material 52 is in contact the material filling the channel.
With reference to Figure 8 a channel 53 is defined by a part of the cylindrical cavity wall 30 the end plate 26 which supports the anode 3 part 54 of the rf choke 55 and a wall 56 extensive in a direction towards the rf choke 55 from the support ~ 21804ql 26. In this arrangement, therefore, the channel is sub~ldl, ~y four sided, therebeing a gap between the part 54 and that the free end of the wall 56. Absorbing material 57 is enclosed within the channel.
In the arrangement shown in Figures 2 to 8, bhe rf chokes are shown as being made up of interleaved plates which are in a plane normal to the longitudinal axis X-X. However, in other arrangements, these may be replaced by axia~ rf chokes which, say, two cylinders are located one within the obher to form a choke between them and are coaxial with axis X-X.
Wibh reference to Figure 9, in another IOT in accolddl1ce with the invention, an electron gun 1 is again surrounded by an annular resonant input cavity 7. In this ~",bodi",t:"L, the input cavity 7 comprises an outer body portion 58 and an inner body portion 60 maintained at a different potential to the first body porbon. Two rf chokes 61 and 62 are included between the inner and outer body portions 58 and 60. Each of the chokes 61 and 62 is extensive in the direction of the longitudinal axis X-X along which in use an electron beam is generated. A ceramic tube 63 is arranged coaxiaily around axis X-X and forms part of chokes 61 and 62. Choke 61 includes copper metallised regions 64 and 65 on the outer and inner surfaces of ceramic cylinder 63. Choke 62 includes a ", " , layer 66 on the inner surface of ceramic tube 63 and a second m~' " 'i~ 1 layer 67 on its outer surface. The m~' " , 67 extends over a greater axial length bhan the inner m~ " " 1 region 66. An anode support 68 has a secbon 69 which is ~ e~ d to an annular plate 70 fomming part of the outer body portion 58 of resonant cavity 7.
~ 2 1 8049 1 The wall 69, the inner part 70a of plate 70 and the outer metallisation layer 67 together define a channel within which is located ferrite loaded silicone rubber 71 or some other suitable rf absorbing material.
In another ~lllbodi~ l of the invenbon, a non-lossy dielectric material such as silicone rubber is located over part of the inner surface of ceramic cylinder 63 and over the " ,~ layer 66 as shown by the broken line at 72.
In other Cl"d"~b",e,lts similar to bhat shown in Figure 9, materials other than ceramic may form part one or bobh rf chokes. The dielectric material need not be conUnuous between both chokes. Also, the l~ layers shown in Figure 9 may be replaced by metallic members affixed to the i~ ",osed dielectric material.
Claims (17)
1. An inductive output tube arrangement comprising an electron gun assembly including a cathode and a grid for generating an electron beam; a substantially annular high frequency resonant cavity arranged coaxially about the assembly;
means for applying high frequency energy to the resonant cavity to modulate the electron beam; and wherein a wall of the cavity includes a channel within which is located material capable of absorbing high frequency energy.
means for applying high frequency energy to the resonant cavity to modulate the electron beam; and wherein a wall of the cavity includes a channel within which is located material capable of absorbing high frequency energy.
2. An arrangement as claimed in claim 1 wherein the channel is of U- or C-shaped configuration.
3. An arrangement as claimed in claim 1 or 2 wherein two facing sides of the channel extend in the electron beam direction.
4. An arrangement as claimed in claim 1, 2 or 3 wherein facing sides of the channel extend in a radial direction with respect to the longitudinal axis of the electron gun assembly along which the electron beam is directed.
5. An arrangement as claimed in any preceding claim wherein the channel is substantially annular and coaxial with the electron beam path.
6. An arrangement as claimed in any preceding claim wherein one wall of the channel also defines part of an rf choke means.
7. An arrangement as claimed in claim 6 wherein the rf choke means includes electrically conductive members extensive in a direction normal to the longitudinal axis of the electron gun assembly.
8. An arrangement as claimed in claim 6 wherein the rf choke means includes electrically conductive members extensive in a direction parallel to the longitudinal axis of the electron gun assembly.
9. An arrangement as claimed in claim 8 wherein ceramic material is located between axially co-extensive conductive members of the rf choke means.
10. An arrangement as claimed in claim 8 or 9 wherein at least one of the electrically conductive members comprises a metallisation layer.
11. An arrangement as claimed in any preceding claim wherein the channel is located substantially in the region between a support for the grid and a support for the anode of the electron gun assembly.
12. An arrangement as claimed in any preceding claim wherein the channel is substantially filled with material capable of absorbing high frequency energy.
13. An arrangement as claimed in any of claims 1 to 11 wherein the inner surfaces of the channel are in contact with the material which is absent from an inner volume defined by the channel.
14 14. An arrangement as claimed in any preceding claim wherein the absorbing material is a ferrite loaded dielectric material.
15. An arrangement as claimed in claim 14 wherein the absorbing material is ferrite loaded silicone rubber.
16. An arrangement as claimed in any preceding claim wherein the electron gun assembly is located within a vacuum envelope and the material is located outside the envelope.
17. A cavity arrangement for use with an inductive output tube wherein a wall of the cavity includes a channel within which is located material capable of absorbing high frequency energy.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB9514005.9 | 1995-07-10 | ||
| GBGB9514005.9A GB9514005D0 (en) | 1995-07-10 | 1995-07-10 | Electron beam tubes |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2180491A1 true CA2180491A1 (en) | 1997-01-11 |
Family
ID=10777385
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA 2180491 Abandoned CA2180491A1 (en) | 1995-07-10 | 1996-07-04 | Inductive output tube arrangements |
Country Status (4)
| Country | Link |
|---|---|
| EP (1) | EP0753879A2 (en) |
| CN (1) | CN1149194A (en) |
| CA (1) | CA2180491A1 (en) |
| GB (2) | GB9514005D0 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5914067A (en) * | 1997-08-30 | 1999-06-22 | Daewoo Electronics Co., Ltd. | Microwave oven equipped with a structurally simple microwave generating apparatus |
| GB2346257A (en) * | 1999-01-26 | 2000-08-02 | Eev Ltd | Electron beam tubes |
| US20050230387A1 (en) * | 2004-04-14 | 2005-10-20 | Michael Regan | Insulated RF suppressor for industrial magnetrons |
| CN104201080A (en) * | 2014-07-22 | 2014-12-10 | 中国科学院电子学研究所 | Double frequency induction output pipe |
Family Cites Families (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3748513A (en) * | 1969-06-16 | 1973-07-24 | Varian Associates | High frequency beam tube having an r.f. shielded and insulated collector |
| US4163175A (en) * | 1977-01-21 | 1979-07-31 | Tokyo Shibaura Electric Co., Ltd. | Magnetron for which leakage of H.F. noise is minimized |
| DE3134034A1 (en) * | 1981-08-28 | 1983-03-10 | Gesellschaft für Schwerionenforschung mbH, 6100 Darmstadt | "ABSORBER" |
| US5130206A (en) * | 1991-07-29 | 1992-07-14 | Hughes Aircraft Company | Surface coated RF circuit element and method |
| GB2259708B (en) * | 1991-09-18 | 1995-05-10 | Eev Ltd | RF radiation absorbing material |
| US5572092A (en) * | 1993-06-01 | 1996-11-05 | Communications And Power Industries, Inc. | High frequency vacuum tube with closely spaced cathode and non-emissive grid |
| GB9313265D0 (en) * | 1993-06-28 | 1993-08-11 | Eev Ltd | Electron beam tubes |
| GB9322934D0 (en) * | 1993-11-08 | 1994-01-26 | Eev Ltd | Linear electron beam tube arrangements |
| US5477107A (en) * | 1993-12-21 | 1995-12-19 | Hughes Aircraft Company | Linear-beam cavity circuits with non-resonant RF loss slabs |
-
1995
- 1995-07-10 GB GBGB9514005.9A patent/GB9514005D0/en active Pending
-
1996
- 1996-07-03 GB GB9613896A patent/GB2303244A/en not_active Withdrawn
- 1996-07-04 EP EP96304941A patent/EP0753879A2/en not_active Withdrawn
- 1996-07-04 CA CA 2180491 patent/CA2180491A1/en not_active Abandoned
- 1996-07-10 CN CN 96110946 patent/CN1149194A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| CN1149194A (en) | 1997-05-07 |
| EP0753879A3 (en) | 1997-01-29 |
| GB9514005D0 (en) | 1995-09-06 |
| GB9613896D0 (en) | 1996-09-04 |
| EP0753879A2 (en) | 1997-01-15 |
| GB2303244A (en) | 1997-02-12 |
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| Date | Code | Title | Description |
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| FZDE | Dead |
Effective date: 19990705 |