CA2159970A1 - Linear electron beam tube - Google Patents
Linear electron beam tubeInfo
- Publication number
- CA2159970A1 CA2159970A1 CA002159970A CA2159970A CA2159970A1 CA 2159970 A1 CA2159970 A1 CA 2159970A1 CA 002159970 A CA002159970 A CA 002159970A CA 2159970 A CA2159970 A CA 2159970A CA 2159970 A1 CA2159970 A1 CA 2159970A1
- Authority
- CA
- Canada
- Prior art keywords
- body portion
- tube
- extensive
- parts
- outer body
- 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
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J29/00—Details of cathode-ray tubes or of electron-beam tubes of the types covered by group H01J31/00
- H01J29/46—Arrangements of electrodes and associated parts for generating or controlling the ray or beam, e.g. electron-optical arrangement
- H01J29/52—Arrangements for controlling intensity of ray or beam, e.g. for modulation
-
- 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
-
- 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
- H01J23/02—Electrodes; Magnetic control means; Screens
-
- 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
- H01J23/02—Electrodes; Magnetic control means; Screens
- H01J23/06—Electron or ion guns
-
- 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
- H01J23/16—Circuit elements, having distributed capacitance and inductance, structurally associated with the tube and interacting with the discharge
-
- 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
-
- 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
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J25/00—Transit-time tubes, e.g. klystrons, travelling-wave tubes, magnetrons
- H01J25/34—Travelling-wave tubes; Tubes in which a travelling wave is simulated at spaced gaps
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J2223/00—Details of transit-time tubes of the types covered by group H01J2225/00
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J2225/00—Transit-time tubes, e.g. Klystrons, travelling-wave tubes, magnetrons
Landscapes
- Vessels, Lead-In Wires, Accessory Apparatuses For Cathode-Ray Tubes (AREA)
Abstract
A linear electron beam tube such as an IOT includes an input cavity 6 formed from an inner body portion 12 and an outer body portion 13 which are joined together by a generally cylindrical electrical insulator 14. The input cavity 6 surrounds an electron gun 1 and permits electrical connection to be made to the cathode 2 and grid 3 via parts of the inner body portion 20 and 21. The construction enables high voltage parts of the arrangement to be insulated from the low voltage outer body portion whilst presenting a low leakage path for r.f. energy within the cavity 6.
Description
~A 2 159970 - .
Electron E~eam Tubes This invention relates to electron beam tubes and more particularly to input resonator cavities of such tubes at which high frequency energy is applied.
The present inYention is particularly applicable to inductive output tetrode devices (hereinafter referred to as "IOT's") such as those referred to by the trade name Klystrode (Registered Trade Mark. Varian Associates Inc.) An IOT device includes an electron gun arranged to produce a linear electron beam and an input resonant cavity at which an r.f. signal to be amplified is applied to ptoduce modulation of the beam at a grid of the electron gun. The resultant interaction berveen the r.f. eneroy and the electton bearn causes amplification of the high frequency sional which is then extracted from an output resonant cavity.
During operation of the tube, electrodes of the electron gun must be operated at relatively high voltages, of the order of tens of kilovolts, and this may cause problems.
especially as the input cavity may form an external pa~t of the IOT and therefore be handled during normal usage of the device. The present invention arose from an attempt to provide an improved IOT input cavit arrangement but is also applicable to other types of linear elecuron bea~n devices having input resonant cavities.
CA2 ~ 59970 According to a first aspect of the invention, there is provided a linear electron beam tube comprising:
an input cavity which is sl~hctr~nri~lly cylindncal about a ~ axis and arranged to receive, in use, a high frequency signal to be amplified;
an electron gun arranged to produce an electron beam in a ' 'ly Inn~itlltlin~
direction; and an output cavity from which r- e amplified high frequency signal is extracted; wherein the input cavity ~ lly surrounds the electron gun and comprises an inner body portion cl~tfi~dlly connected to part of the electron gun and an outer body portion electrically insulated from the inner body portion. the inner body portion being maintained at a relatively high voltage compared to that of the outer body portion, and wherein the inner and outer body portions each include an axially extensive flange ~ lly CCh~A~ in an axially direction and e~ectrically insulating material being located between the flanges.
By "high voltage" it is meant of the order of tens of kilovolts.
The use of the invention enables parts of a linear electron beam tube which operate at relatively high voltages to be located such that they are not readily accessible during normal operation of thé tube. In addition, the ~ .,..c,...,...1 of the flanges of the inner and outer body portions enables the two portions to be separated to achieve the desired electrical isolation bet~ n them whilst permitting the input cavity to be such that there is low r.f. Ieakage from it, th~reby affording efficient operation. Also, the flanges extend in ~ lly the same direction and hence are sllhst~nti~lly parallel to each other. This is particularly advantageous as it reduces electrical stresses and therefore the tendency of voltage breakdown ~o occur between the inner and outer body portions, even al high voltages. ru~ llvlcn the ,n ~ of the inner and outer body portions and axially extensive flanges is relatively easy, and therefore il~.,A~.I.~iV~, to fabricate and assemble.
It is preferred that the flanges are ~ ~ 'ly cylindrical, as this is a ~yllull.,~
fnnfi~ ion which is usually desirable in linear electron beam tubes as it gives good electrical .1.,., . r. . ;~ and results in a 'ly robus ,~
Preferably, each of the inner and outer body portions includes two flanges extensive in an axial direction outwardly from the input cavity, there thus being two pairs of co-extensive flanges. Such an ~ minirnizes r. losses in the region berween the inner and outer body portions. Although the input cavity could ~It~ ti~,ly comprise only one pair of flanges, this would tend to result in an r.f. leakage path being present between other parts of the cavity.
It is preferred that the inner body portion comprises two sections which are electrically separate from one another. Ag~un, this facilitates l~u~r~lL.~ and assembly and ~Iv~6~)u~1y also permits diferent voltages to be applied to different parts of the electron gun via the inrler body portion. In one preferred ~ d;lll.,l.. of the invention, the inner body portion is electrically connected to a cathode and a grid of ~he electron gun. Where two sections are included, one of them may be physically and electrically connected to the cathode and Ihe other to the 6rid.
Advantageously, the electrically insulating material is generally cylindrical in form This perrnits insulation to be dish ibuted in a ~yllul~ l manner around the 1~ axis of Ihe tube and also may provide mechanical support and rigidity. Where two pairs of flanges are included in the r -~ t~ the elech ically insulating material may be present as two separate rings, for example, one ring being interposed between one pair of flan~es and the other between the other pair. AIL~ i V~IY~ and preferably, the elec_ically insulating material is a unitaty member which is extensive between both pairs of flanges.
Adv ~ l~" the inner and outer body portions are physically joined together by the elechically insulating material which may, for example, be moulded into a particular shape.
Preferably, the outer body portion is at ground potential.
According to a second aspect of the invention. there is provided a linear elechron beam tube ~oll~
an input cavity which is ' "y cylindrical about a ! on E~h~ axis and arranged to receive, in use, a high frequency signal to be amplified;
an elechron gun arranged to produce an elechron beam in a "~J longitudinal direction; and an output cavity from which the amplified high frequency signal is extracted; wherein the input cavity sllhslr~ lly surrounds the electron gun and comprises an inner body portion elech-ically connected to part of the electron gun and an outer body portion electncally insulated from the inner body portion, the inner body portion being maintained at a relatively high voltage compared to that of the outer body portion. and wherein the inner and outer body portions have respective parts which are co-extensiYe to present a choke impedance to high frequency energy within the input cavity and wherein an edge of one or more of the parts clllul.~lPil.g in a region where a patt of the other body portion is extensive is curved.
Use of this aspect of the invention, enables increased Yoltage hold-off to be obtained between the co-extensive parts. The curved edge of the part or parts reduces electrical stresses compared to an v in which no such curvature is employed when electrical field lines tend to be c~ .. I at the end of a part. Thus, by employing the invention, greater design freedom is offered in selecting spacing between the co-extensive parts. This may result in a more efficient choke impedance being feasible and may also lead to a more compact ~l~lv~
Only one of the parts may have a curved edge but it would generaUy be desirable for both or all parts to have curved edges where these terminate in regions of high electrical field.
In one preferred I ...1~.1;..,- ,1 of the invention, the parts. including their edges, are "y planar and the edge is curved out of the plane. The parts may be flat plates or may be planar and curved, that is, cylindrical. In the latter case, the edge is the end of the cylinder and may be curved inwardly or outwardly depending on the particular d" ,.. v.. ,.. 1 In an alternative . ..,I.o~ the curved edge is a solid rim of, say, circular cross-section similar to a beading along the end of the part. For example, it may be a region of increased thickness around the inner ~U~UIUC~I~;IIC~ of a flat annular plate.
Preferably, the edge is curved such that its end is 5~hcr:/nti~11y adjacent a region of the CA21 5qq7~
patt remote from the edge. The edge may be curved sufficiently so that its end actually touches the surface of the part or may be spaced a little way from it It a preferred . .1.1l.~.1;.,.. -: the edge is curved with a s~lhst:~"r~ ly constant radius of curvature. However, the edge could be folded over to ptesent a more oval cross-section.
In aliother ....I,o.l;.... -: of the invention, the said respective parts are extensive in planes s ~ 'Iy transverse to the l.~ I axis. In one particular e,.l~od;~ L. one of the body portions mcludes two patts extensive in a ,~ ly transverse direction and theotherincludesonepartlocatedbetween triem. Insuchan- ,. ~"..,. 1 adv ~ ly, the two outermost parts have edges which curve in a direction away from the said one part.
The said one part may be located closer to one of the two parts than the other. In this case, it is preferred tha~ it has an edge which is curved away from the part which is closer to it.
In a !J~uL;I ul~uly adv~ulL.O_vua u ~llbo~ of the invention. the parts are annular plates, giving a cylindrically ~yllllll~ll~l ~I~UIO~ IIL
In another ~ . ,.I .o.li .... - ~ of the invention, the parts are axially extensive flanges which are ~ lly co-extensive in an axial direction. Preferably, the flanges are s~hsr~nri:~,liy cylindrical.
In many dll O , electrically insulating material' is adv~ulLo~vualy included between the said co-extensive parts. This enables good voltage hold-off to be achieved and may also improve ,....1,,..,: Al stability of the all~10~ . A(1V~IL~UO~VU~IY~ at least one of the said parts is at least pattially embedded in the electrically insulating matenal. In some ~1l..,.~.". .~1~ it may be desirable to wholly encase the parts in the matenal for optimum CA2 1 ~997~
breakdown characteristics.
.
Preferably, the inner and outer body portions include two pairs of co-extenSive respective parts. Such an ~ minimi~es r.f. Iosses in the region between the inner and outer body portions.
It is preferred that the inner body portion comprises two sections which are electtically separate from one another. In one preferred ~ L ' of the invention, the inner body portion is electrically connected to a cathode and a grid of the electron gun. Where two sections are included, one of them may be physically and electrically connected to the cathode and the other to the grid.
Ad~ U5IY1 electrically insulating material located between the co-extensive parts is generally cylindrical in form.
According to a third aspect of the invention, there is proYided a linear elecrron beam tube~
an input caYity which is 5~h~rqnri q l l y cylindrical about a i ~ n~irllf~ axis and arrqnged to receive, in use, a high frequency signal to be amplified;
an electron gun a}ranged to produce an electron beam ih a direction; and an output cavity from whuch the amplified high freo,uency signal is extracted; wherein the input cavit,Y sllh~tqnriqily surrounds the electron gun and compnses an inner body ponion electrically connected to part of the eiectron gun and an outer body portion electncally CA2~ 59970 insulated from the inner body portion, the inner body portion being maintained at a relatiYely high voltage compared to that of the outer body portion, and wherein the inner and outer body portions have respective parts which are substantially co extensive and resiliently deformable electricaUy insulating material is located between the said parts.
An electron beam tubc in accordance with the tnvention may suffer from ~
shocks and stresses during use of the tube and during shipping and handling. for example, for servicing Ic~ ta. In a ~_UII~ iU-lal tube. shocks may cause cracks or other defects to appear between parts of the device. This may lead to severe problems wherc these parts are at widely differing electrical potentials when a crack form a path for electrical breakdown to occur. By using the invention, the integrity of the electrically insulating material itself and also its interface with other parts of the tube may be maintained as the material tends to deform under mt~rhlnirql shrck~ returning to its original state afterwards. Thus, although there is a loss in the rigidity of the tube in the input region. the ~ c~ UI~JIU~
in electrical hold-off eh~T~rtrricrirc under adverse conditions is highly ~1~ ~ The resilient nature of the insulating material reduces the tendency for voids to be formed between the material and adjacent rigid members. Thus a, ~ urliform dielectric constant may be maintained throughout the electrically irlsulating material which is important in avoiding electrical breakdown through it.
In a preferred ~ ..I.o.l;.. . "~ of the invention, the electrically insulating material is of silicone rubber. This is a relatively easy material to conform to a required shape without any air bubbles or the like being included and is also able to withstand larger electrical stresses across it.
Preferably, the silicone rubber is moulded to give the required CU~.f ~ L;UII although other fabrication techniques could be used.
Adv ~ Iy, at least one of the said parts is at least partially embedded in the electrically insulating material. In some - . c,. .. ~ it may be desirable to wholly encase the parts i~ the material for optimum breakdown ~
In one ~ ...I,o.l;,. of the invention, the said respective parts are members which are extensive in planes s ' "y transverse to the l~ axis. Preferably, one of the inner and outer body portions includes two members extensive in a ~ ''S, transverse direction and the other of the body portions includes one member extensive in a aubat~lu~llly transverse direction and interleaved between the two members of the other portion. Such an - ,...~;...,...~ is l~fi~.ul~ly good at preventing leakage of rf energy from the input cavity.
In another adv ~ .. 1.~1;,.. ; of the invention, the said parts are axially extensive flanges which are ' 'Iy co-extensive in an axial direction, The flanges extend in ~ ~Iy the same direction and hence are ~ ly parallel to one another.
Thus electrical âtresses are reduced to a minimum.
The .. ~,.. ,.. ,~ of the inner and outer body portions and axially extensive flanges is relatively easy, and therefûre inexpensiYe, to &bricate and assemble.
CA215~970 It is preferred that the flanges are sl~str~ntir~lly cylindrical.
Preferably, the inner and outer body portions include two paus of co-extensive repective parts.
Some ways in which the invention may be performed are now described by way of example with the reference to the r I ,~' ,, drawings in which:
Figure 1 is a schematic sectional view of an IOT in accordance with the present invention, some parts of which have been omitted for sake of clarity; and Figure 2 to 7 s-' "~, illustrate respective different lOTs in accordance with the invention.
With reference to Figure 1, an IOT comprises an electron gun 1 which includes a cathode ~ and grid 3 arranged to produce an electron beam along the lon~itll-linrl axis X-X
of the ~"~ The IOT includes drift tubes 4 and 5 via which the electron beam passes before being collected by a collector (not shown). A cylindrical input resonant cavity 6 is arranged coaxially about the electron gun 1 and includes an input coupling 7 at which an r.f.
signal to be amplified is applied. An output cavity 8 surrounds the drift tubes 4 and 5 and includes a coupling loop 9 via which an arnplified r.f. signal is extracted and coupled into a secondary output cavity 10 and an output coupling 11.
During operation of this device, the cathode ~ and grid 3 are maintained al potenuals ~ CA21 59970 of the order of 30kV, the grid 3 being m~lin~inrd at a dc bias voltage at about 100 volts less than the cathode potential. The input high frequency signal applied at 7 results in an r.f.
voltage of a few hundred volts being produced between the cathode 2 and the grid 3.
The input cavity 6 is defined by an inner body por~ion 12 and an outer body portion 13 with a 5~hctl~nti~11y cylindrical moulded insulating member 14 between them, the inner body portion 12 being electrically insulated from the outer body portion 13 by the intervening dielectric material 14. The outer body portion 13 is maintained at substantially ground potential, thus facilitating safe handling of device, whilst the inner body portion 12 is mamtained at much higher voltages.
The outer body portion consists of two annular plates 15 and 16 arranged parallel to one another and transverse to the 1....~,;1...l; -~l axis X-X with a cylindrical outer wall 17 deflning the outer extent of the cavity 6. The inner part of the outer body pottion 13 includes two cylindrical flanges 18 and 19 extending outwardly from the cavity volume and arranged cylindrically about the axis X-X.
The inner body portion 12 comprises two sections. The first section 20 is ,.~1.,.,.;.,~lly and electrically connected to the cathode 2 and the second section 21 is mrrl~ ~nir~llly and electrically connected to the grid 3. In the,: ~ ~ ' shown, a ceramic cylinder 22 is located between the sections 20 and 21 to give additional mechanical support to the assembly.
The inner body portion 12 also includes cylindrical llanges 23 and 24 which extend l2 outwardly away from the input cavi~y 6 and are arranged coaxially about the axis X-X and within the flanges 18 and 19 of the outer body portion 13. The two pairs of flanges 18 and 23, and 19 and 24 are arranged to extend ~ ct~nt~ y parallel to one another and are ~ub~..i~ily co-extensive in the axial direction. The outer flanges 18 and 19 are located in shallow channels irl the outer surfaoe of the dielectric member 14. The inner flange 23 which is connected to the cathode 2 is partialiy embedded within the member 14 and the other inner flange 24 is s~ st~ lly wholly embedded within it.
J
The inner surface of the member 14 includes ~ f~ l grooves 25 around the cathode 2 and grid 3 regions to improYe voltage hold off ability. However, in other c.~odi~ t~, this surface may be smooth.
A power lead 26 is routed via an aperture in the flange 19 and through the dielectric material 14 to supply the grid 3 with the appropriate bias voltage whilst " the elecmcal insulation of the exterior body portion 13, the connection being made via the lead 26 to the section 21.
Another IOT is shown in Flgure 2 and is similar to the Flgure I .- 1,.~,~,...,.:
However. in ttus device, the input cavity 27 includes an axially extensive portion 28 which forms part of the outer body portion.
With referenoe to Figure 3, an rOT is similar to that shown in Figure 2, with like references being used for like parts, but includes a different interface between the inner and outer body portions.
.
The inner hody portion 12 compnses two sections. The first section 20 is m~-nh~ni~lly and electrically connected IO the cathode 2 and the second section 21 is ",. .1,~.,;. ~lly and electrically connected to the grid 3. In the ~ mhotiinn~nt shown, a ceramic cylinder 22 is located between the sections 20 and 21.
The inner body portion 12 also includes cylindtical flanges 23 and 24 which extend outwardly away from the input cavity 6 and are arranged coaxially about the axis X-X and within the flanges 18 and 19 of the outer body portion 13. The two pairs of flanges 18 and 23, and 19 and 24 are arranged to extend sllhs~nri~lly parallel to one another and are ~ub~ Li~ll.r co-extensive in the axial direction. They define r.f. choke ;"'1~ and are substantially wholly embedded within the insulating material 14, which in this ~ I,o.lillu,...
is of silicone rubber.
The two flanges 18 and 23 have edges 29 and 30 which are curved away from each other such that each end of the flange is shielded from the other body portion by the axially extensive part of that flange. The parts of flanges 18 and 23 which are fixed to the outer and inner body portions deftned by plates 15 and 20 are arranged to join in a smooth curve to reduce electrical stresses between the two body portions.
The other pair of co-extensive cylindrical flanges 19 and`24 are similarly curved where they join plates 16 and 21. The inner flange 24 extends in axial direction for ~ u,.i~ ~ly half the distance of the outer flange 19. Thus, the inner flamge 24 terminates in a region where it is co-extensive with the outer flange 19 whereas the outer flange 19 terminates at a location remote from the inner flange 24. The inner flange 24 has a curved edge 31 which is curved away from the outer flange 19.
-In this ~ 1,...~,, .... 2 of co-extensive parts the end 28 of the outer flange 19 is not curved out of the plane of the flange 19.
Another IOT is shown in Figure 4 and is sirnilar in many aspects to the Figure 3 ~.. .;~.,..: Theinputcavityincludespa~tswhichareextensiveina 511hc2sln~ y transverse directiontothe Irn~i22lr2i~~l axisandwhichareinterleavedtoprovidetherec,uireddcisolation between the inner body portion 32 and the outer body portion 33 and providing an r.f. choke The inner body portion 32 comprises two annular plates 34 and 35. One of the plates 34 is connected electrically to the cathode and is interleaved between two annular plates 36 and 37 forming part of the outer body portion 33. The annular plate 35 is cor2nected to the electrode gun grid and is interleaved with annular plates 38 and 39 which between thern define an annular channel into which the plate 35 is extensive. The regions belween the interleaved transverse parts are occupied by resiliently deformable electrically insulating material 40 which is of silicone rubber.
The outer edges of the annular plates 34 and 35 terminate in the annular channels and in the regions of the transverse plates of the outer body portion 33. The edges of the plates 34 and 35 are curved out of the plane of the plates so as to present a smooth surface, the ends of the edges touching the surfaces of the plates 34 and 35.
The annular plates 36. 37 and 38, 39 of the outer body portion are curved ou~wardl,v away from the interleaved part of the inner body portion but do not touch the surfaces of the 1S CA2 1 5qq70 plates.
Figure S illustrates srh~m~hr~lly part of another IOT in accordance with the invention and is a l~-n~n~ section showing some ~ only of the IOT The are cylindrically ~y~ i~l about the axis X-X and only half is shown.
The input cavity 41 of the IOT includes an outer body portion defined by plates 42 and 43 in ~ with an outer cylindrical wall (not shown). A metal cylinder 44 is mounted on one of the plates 4~ via a plurality of screws, one of which is shown. around its ~,iUUU~ . Two annular plates 45 and 46 are fixed at each end of the cylinder 44 and extend radially inwardly from it. The IOT includes a grid electrode 47 which is mounted on an annular plate 48 which surrounds it and is extensive between the plates 45 and 46 forming part of the outer body portion of the input cavity 41. The plates 45, 46 and 48 togethèr define an r.f. choke impedance which prevents loss of r.f. energy from the cavity 41. The plates 45 and 46 have inner edges which are curved outwardly away from the plate 48 located between them. The interleaved plate 48 is located in a plane which is spaced a distance a from the lower plate 46 in an axial direction and a larger distance b from the upper plate 46. HoweYer, the curvature of its end is such that the nearest point of the interleaved plate 48 from the upper plate 46 is also a in the a~ial direction. T'ne region between plates 45, 46 and 48 includes electrically insulating material to improve voltage hold-off between the plates and hence permit relatively large potential dirf~ ~ to be appiied between the inner body portion and the outer body portion.
The plate 43 defining the outer body portion is also electrically connected to two ~A~ 15997~
annular plates 49 and 50 and a generally cylindrical outer member 51 to which they are mounted. A central plate 52 of the inner body portion is connected to the cathode (not shown) of the ~OT electron gun. The spacing of the inner body portion 52 relative to the platQ 49 and 50 is arranged in a sirnilar manner to that of plates 45, 46 and 48.
In this ~ the inner body portion of the input cavity 41 is essentiaUy defined by the platQ 48 and æ which themselvQ are also the parts of the inner body portion which are co-extensive with ~vllQ~ ld.llg parts of the outer body portion.
Figure 6 illush atQs an ~ similar to that shown in Figure 5. ~lowever, in this ~LLI~I~.,III~II~. the platQ 53 and 54 forming part of the inner body portion are spaced eq.li~' -'y between adjacent plates 55, 56, 57 and 58 of the outer body portion. The radial inner edgQ of the outer body portion p~atQ and the outer edge of the inner body platQ are defined by beading of sllhct~nti:~lly circular cross-section to give the required curved edge in accordance with the invention.
Another IOT is shown in Figure 7 and is similar to the Flgure 4 ,.. ~ having an input cavity including parts which are extensive in a s1~hct~nri~1ly transverse direction to the l(ln~ihlAin il axis and which are interleaved to provide the required dc isolation between the inner body portion and the outer body portion whilst affording low r.f. Ieakage between them. However, in this confi~llr~t;-)n, the transverse platQ do not have curved ends. The re~ions ~etween the interleaved transverse parts are occupied by resiliently deformable electrically insulating material which again is of silicone rubber.
, . , . . ... .. .. , . _ . . . ., . . _ , _ . .
Electron E~eam Tubes This invention relates to electron beam tubes and more particularly to input resonator cavities of such tubes at which high frequency energy is applied.
The present inYention is particularly applicable to inductive output tetrode devices (hereinafter referred to as "IOT's") such as those referred to by the trade name Klystrode (Registered Trade Mark. Varian Associates Inc.) An IOT device includes an electron gun arranged to produce a linear electron beam and an input resonant cavity at which an r.f. signal to be amplified is applied to ptoduce modulation of the beam at a grid of the electron gun. The resultant interaction berveen the r.f. eneroy and the electton bearn causes amplification of the high frequency sional which is then extracted from an output resonant cavity.
During operation of the tube, electrodes of the electron gun must be operated at relatively high voltages, of the order of tens of kilovolts, and this may cause problems.
especially as the input cavity may form an external pa~t of the IOT and therefore be handled during normal usage of the device. The present invention arose from an attempt to provide an improved IOT input cavit arrangement but is also applicable to other types of linear elecuron bea~n devices having input resonant cavities.
CA2 ~ 59970 According to a first aspect of the invention, there is provided a linear electron beam tube comprising:
an input cavity which is sl~hctr~nri~lly cylindncal about a ~ axis and arranged to receive, in use, a high frequency signal to be amplified;
an electron gun arranged to produce an electron beam in a ' 'ly Inn~itlltlin~
direction; and an output cavity from which r- e amplified high frequency signal is extracted; wherein the input cavity ~ lly surrounds the electron gun and comprises an inner body portion cl~tfi~dlly connected to part of the electron gun and an outer body portion electrically insulated from the inner body portion. the inner body portion being maintained at a relatively high voltage compared to that of the outer body portion, and wherein the inner and outer body portions each include an axially extensive flange ~ lly CCh~A~ in an axially direction and e~ectrically insulating material being located between the flanges.
By "high voltage" it is meant of the order of tens of kilovolts.
The use of the invention enables parts of a linear electron beam tube which operate at relatively high voltages to be located such that they are not readily accessible during normal operation of thé tube. In addition, the ~ .,..c,...,...1 of the flanges of the inner and outer body portions enables the two portions to be separated to achieve the desired electrical isolation bet~ n them whilst permitting the input cavity to be such that there is low r.f. Ieakage from it, th~reby affording efficient operation. Also, the flanges extend in ~ lly the same direction and hence are sllhst~nti~lly parallel to each other. This is particularly advantageous as it reduces electrical stresses and therefore the tendency of voltage breakdown ~o occur between the inner and outer body portions, even al high voltages. ru~ llvlcn the ,n ~ of the inner and outer body portions and axially extensive flanges is relatively easy, and therefore il~.,A~.I.~iV~, to fabricate and assemble.
It is preferred that the flanges are ~ ~ 'ly cylindrical, as this is a ~yllull.,~
fnnfi~ ion which is usually desirable in linear electron beam tubes as it gives good electrical .1.,., . r. . ;~ and results in a 'ly robus ,~
Preferably, each of the inner and outer body portions includes two flanges extensive in an axial direction outwardly from the input cavity, there thus being two pairs of co-extensive flanges. Such an ~ minirnizes r. losses in the region berween the inner and outer body portions. Although the input cavity could ~It~ ti~,ly comprise only one pair of flanges, this would tend to result in an r.f. leakage path being present between other parts of the cavity.
It is preferred that the inner body portion comprises two sections which are electrically separate from one another. Ag~un, this facilitates l~u~r~lL.~ and assembly and ~Iv~6~)u~1y also permits diferent voltages to be applied to different parts of the electron gun via the inrler body portion. In one preferred ~ d;lll.,l.. of the invention, the inner body portion is electrically connected to a cathode and a grid of ~he electron gun. Where two sections are included, one of them may be physically and electrically connected to the cathode and Ihe other to the 6rid.
Advantageously, the electrically insulating material is generally cylindrical in form This perrnits insulation to be dish ibuted in a ~yllul~ l manner around the 1~ axis of Ihe tube and also may provide mechanical support and rigidity. Where two pairs of flanges are included in the r -~ t~ the elech ically insulating material may be present as two separate rings, for example, one ring being interposed between one pair of flan~es and the other between the other pair. AIL~ i V~IY~ and preferably, the elec_ically insulating material is a unitaty member which is extensive between both pairs of flanges.
Adv ~ l~" the inner and outer body portions are physically joined together by the elechically insulating material which may, for example, be moulded into a particular shape.
Preferably, the outer body portion is at ground potential.
According to a second aspect of the invention. there is provided a linear elechron beam tube ~oll~
an input cavity which is ' "y cylindrical about a ! on E~h~ axis and arranged to receive, in use, a high frequency signal to be amplified;
an elechron gun arranged to produce an elechron beam in a "~J longitudinal direction; and an output cavity from which the amplified high frequency signal is extracted; wherein the input cavity sllhslr~ lly surrounds the electron gun and comprises an inner body portion elech-ically connected to part of the electron gun and an outer body portion electncally insulated from the inner body portion, the inner body portion being maintained at a relatively high voltage compared to that of the outer body portion. and wherein the inner and outer body portions have respective parts which are co-extensiYe to present a choke impedance to high frequency energy within the input cavity and wherein an edge of one or more of the parts clllul.~lPil.g in a region where a patt of the other body portion is extensive is curved.
Use of this aspect of the invention, enables increased Yoltage hold-off to be obtained between the co-extensive parts. The curved edge of the part or parts reduces electrical stresses compared to an v in which no such curvature is employed when electrical field lines tend to be c~ .. I at the end of a part. Thus, by employing the invention, greater design freedom is offered in selecting spacing between the co-extensive parts. This may result in a more efficient choke impedance being feasible and may also lead to a more compact ~l~lv~
Only one of the parts may have a curved edge but it would generaUy be desirable for both or all parts to have curved edges where these terminate in regions of high electrical field.
In one preferred I ...1~.1;..,- ,1 of the invention, the parts. including their edges, are "y planar and the edge is curved out of the plane. The parts may be flat plates or may be planar and curved, that is, cylindrical. In the latter case, the edge is the end of the cylinder and may be curved inwardly or outwardly depending on the particular d" ,.. v.. ,.. 1 In an alternative . ..,I.o~ the curved edge is a solid rim of, say, circular cross-section similar to a beading along the end of the part. For example, it may be a region of increased thickness around the inner ~U~UIUC~I~;IIC~ of a flat annular plate.
Preferably, the edge is curved such that its end is 5~hcr:/nti~11y adjacent a region of the CA21 5qq7~
patt remote from the edge. The edge may be curved sufficiently so that its end actually touches the surface of the part or may be spaced a little way from it It a preferred . .1.1l.~.1;.,.. -: the edge is curved with a s~lhst:~"r~ ly constant radius of curvature. However, the edge could be folded over to ptesent a more oval cross-section.
In aliother ....I,o.l;.... -: of the invention, the said respective parts are extensive in planes s ~ 'Iy transverse to the l.~ I axis. In one particular e,.l~od;~ L. one of the body portions mcludes two patts extensive in a ,~ ly transverse direction and theotherincludesonepartlocatedbetween triem. Insuchan- ,. ~"..,. 1 adv ~ ly, the two outermost parts have edges which curve in a direction away from the said one part.
The said one part may be located closer to one of the two parts than the other. In this case, it is preferred tha~ it has an edge which is curved away from the part which is closer to it.
In a !J~uL;I ul~uly adv~ulL.O_vua u ~llbo~ of the invention. the parts are annular plates, giving a cylindrically ~yllllll~ll~l ~I~UIO~ IIL
In another ~ . ,.I .o.li .... - ~ of the invention, the parts are axially extensive flanges which are ~ lly co-extensive in an axial direction. Preferably, the flanges are s~hsr~nri:~,liy cylindrical.
In many dll O , electrically insulating material' is adv~ulLo~vualy included between the said co-extensive parts. This enables good voltage hold-off to be achieved and may also improve ,....1,,..,: Al stability of the all~10~ . A(1V~IL~UO~VU~IY~ at least one of the said parts is at least pattially embedded in the electrically insulating matenal. In some ~1l..,.~.". .~1~ it may be desirable to wholly encase the parts in the matenal for optimum CA2 1 ~997~
breakdown characteristics.
.
Preferably, the inner and outer body portions include two pairs of co-extenSive respective parts. Such an ~ minimi~es r.f. Iosses in the region between the inner and outer body portions.
It is preferred that the inner body portion comprises two sections which are electtically separate from one another. In one preferred ~ L ' of the invention, the inner body portion is electrically connected to a cathode and a grid of the electron gun. Where two sections are included, one of them may be physically and electrically connected to the cathode and the other to the grid.
Ad~ U5IY1 electrically insulating material located between the co-extensive parts is generally cylindrical in form.
According to a third aspect of the invention, there is proYided a linear elecrron beam tube~
an input caYity which is 5~h~rqnri q l l y cylindrical about a i ~ n~irllf~ axis and arrqnged to receive, in use, a high frequency signal to be amplified;
an electron gun a}ranged to produce an electron beam ih a direction; and an output cavity from whuch the amplified high freo,uency signal is extracted; wherein the input cavit,Y sllh~tqnriqily surrounds the electron gun and compnses an inner body ponion electrically connected to part of the eiectron gun and an outer body portion electncally CA2~ 59970 insulated from the inner body portion, the inner body portion being maintained at a relatiYely high voltage compared to that of the outer body portion, and wherein the inner and outer body portions have respective parts which are substantially co extensive and resiliently deformable electricaUy insulating material is located between the said parts.
An electron beam tubc in accordance with the tnvention may suffer from ~
shocks and stresses during use of the tube and during shipping and handling. for example, for servicing Ic~ ta. In a ~_UII~ iU-lal tube. shocks may cause cracks or other defects to appear between parts of the device. This may lead to severe problems wherc these parts are at widely differing electrical potentials when a crack form a path for electrical breakdown to occur. By using the invention, the integrity of the electrically insulating material itself and also its interface with other parts of the tube may be maintained as the material tends to deform under mt~rhlnirql shrck~ returning to its original state afterwards. Thus, although there is a loss in the rigidity of the tube in the input region. the ~ c~ UI~JIU~
in electrical hold-off eh~T~rtrricrirc under adverse conditions is highly ~1~ ~ The resilient nature of the insulating material reduces the tendency for voids to be formed between the material and adjacent rigid members. Thus a, ~ urliform dielectric constant may be maintained throughout the electrically irlsulating material which is important in avoiding electrical breakdown through it.
In a preferred ~ ..I.o.l;.. . "~ of the invention, the electrically insulating material is of silicone rubber. This is a relatively easy material to conform to a required shape without any air bubbles or the like being included and is also able to withstand larger electrical stresses across it.
Preferably, the silicone rubber is moulded to give the required CU~.f ~ L;UII although other fabrication techniques could be used.
Adv ~ Iy, at least one of the said parts is at least partially embedded in the electrically insulating material. In some - . c,. .. ~ it may be desirable to wholly encase the parts i~ the material for optimum breakdown ~
In one ~ ...I,o.l;,. of the invention, the said respective parts are members which are extensive in planes s ' "y transverse to the l~ axis. Preferably, one of the inner and outer body portions includes two members extensive in a ~ ''S, transverse direction and the other of the body portions includes one member extensive in a aubat~lu~llly transverse direction and interleaved between the two members of the other portion. Such an - ,...~;...,...~ is l~fi~.ul~ly good at preventing leakage of rf energy from the input cavity.
In another adv ~ .. 1.~1;,.. ; of the invention, the said parts are axially extensive flanges which are ' 'Iy co-extensive in an axial direction, The flanges extend in ~ ~Iy the same direction and hence are ~ ly parallel to one another.
Thus electrical âtresses are reduced to a minimum.
The .. ~,.. ,.. ,~ of the inner and outer body portions and axially extensive flanges is relatively easy, and therefûre inexpensiYe, to &bricate and assemble.
CA215~970 It is preferred that the flanges are sl~str~ntir~lly cylindrical.
Preferably, the inner and outer body portions include two paus of co-extensive repective parts.
Some ways in which the invention may be performed are now described by way of example with the reference to the r I ,~' ,, drawings in which:
Figure 1 is a schematic sectional view of an IOT in accordance with the present invention, some parts of which have been omitted for sake of clarity; and Figure 2 to 7 s-' "~, illustrate respective different lOTs in accordance with the invention.
With reference to Figure 1, an IOT comprises an electron gun 1 which includes a cathode ~ and grid 3 arranged to produce an electron beam along the lon~itll-linrl axis X-X
of the ~"~ The IOT includes drift tubes 4 and 5 via which the electron beam passes before being collected by a collector (not shown). A cylindrical input resonant cavity 6 is arranged coaxially about the electron gun 1 and includes an input coupling 7 at which an r.f.
signal to be amplified is applied. An output cavity 8 surrounds the drift tubes 4 and 5 and includes a coupling loop 9 via which an arnplified r.f. signal is extracted and coupled into a secondary output cavity 10 and an output coupling 11.
During operation of this device, the cathode ~ and grid 3 are maintained al potenuals ~ CA21 59970 of the order of 30kV, the grid 3 being m~lin~inrd at a dc bias voltage at about 100 volts less than the cathode potential. The input high frequency signal applied at 7 results in an r.f.
voltage of a few hundred volts being produced between the cathode 2 and the grid 3.
The input cavity 6 is defined by an inner body por~ion 12 and an outer body portion 13 with a 5~hctl~nti~11y cylindrical moulded insulating member 14 between them, the inner body portion 12 being electrically insulated from the outer body portion 13 by the intervening dielectric material 14. The outer body portion 13 is maintained at substantially ground potential, thus facilitating safe handling of device, whilst the inner body portion 12 is mamtained at much higher voltages.
The outer body portion consists of two annular plates 15 and 16 arranged parallel to one another and transverse to the 1....~,;1...l; -~l axis X-X with a cylindrical outer wall 17 deflning the outer extent of the cavity 6. The inner part of the outer body pottion 13 includes two cylindrical flanges 18 and 19 extending outwardly from the cavity volume and arranged cylindrically about the axis X-X.
The inner body portion 12 comprises two sections. The first section 20 is ,.~1.,.,.;.,~lly and electrically connected to the cathode 2 and the second section 21 is mrrl~ ~nir~llly and electrically connected to the grid 3. In the,: ~ ~ ' shown, a ceramic cylinder 22 is located between the sections 20 and 21 to give additional mechanical support to the assembly.
The inner body portion 12 also includes cylindrical llanges 23 and 24 which extend l2 outwardly away from the input cavi~y 6 and are arranged coaxially about the axis X-X and within the flanges 18 and 19 of the outer body portion 13. The two pairs of flanges 18 and 23, and 19 and 24 are arranged to extend ~ ct~nt~ y parallel to one another and are ~ub~..i~ily co-extensive in the axial direction. The outer flanges 18 and 19 are located in shallow channels irl the outer surfaoe of the dielectric member 14. The inner flange 23 which is connected to the cathode 2 is partialiy embedded within the member 14 and the other inner flange 24 is s~ st~ lly wholly embedded within it.
J
The inner surface of the member 14 includes ~ f~ l grooves 25 around the cathode 2 and grid 3 regions to improYe voltage hold off ability. However, in other c.~odi~ t~, this surface may be smooth.
A power lead 26 is routed via an aperture in the flange 19 and through the dielectric material 14 to supply the grid 3 with the appropriate bias voltage whilst " the elecmcal insulation of the exterior body portion 13, the connection being made via the lead 26 to the section 21.
Another IOT is shown in Flgure 2 and is similar to the Flgure I .- 1,.~,~,...,.:
However. in ttus device, the input cavity 27 includes an axially extensive portion 28 which forms part of the outer body portion.
With referenoe to Figure 3, an rOT is similar to that shown in Figure 2, with like references being used for like parts, but includes a different interface between the inner and outer body portions.
.
The inner hody portion 12 compnses two sections. The first section 20 is m~-nh~ni~lly and electrically connected IO the cathode 2 and the second section 21 is ",. .1,~.,;. ~lly and electrically connected to the grid 3. In the ~ mhotiinn~nt shown, a ceramic cylinder 22 is located between the sections 20 and 21.
The inner body portion 12 also includes cylindtical flanges 23 and 24 which extend outwardly away from the input cavity 6 and are arranged coaxially about the axis X-X and within the flanges 18 and 19 of the outer body portion 13. The two pairs of flanges 18 and 23, and 19 and 24 are arranged to extend sllhs~nri~lly parallel to one another and are ~ub~ Li~ll.r co-extensive in the axial direction. They define r.f. choke ;"'1~ and are substantially wholly embedded within the insulating material 14, which in this ~ I,o.lillu,...
is of silicone rubber.
The two flanges 18 and 23 have edges 29 and 30 which are curved away from each other such that each end of the flange is shielded from the other body portion by the axially extensive part of that flange. The parts of flanges 18 and 23 which are fixed to the outer and inner body portions deftned by plates 15 and 20 are arranged to join in a smooth curve to reduce electrical stresses between the two body portions.
The other pair of co-extensive cylindrical flanges 19 and`24 are similarly curved where they join plates 16 and 21. The inner flange 24 extends in axial direction for ~ u,.i~ ~ly half the distance of the outer flange 19. Thus, the inner flamge 24 terminates in a region where it is co-extensive with the outer flange 19 whereas the outer flange 19 terminates at a location remote from the inner flange 24. The inner flange 24 has a curved edge 31 which is curved away from the outer flange 19.
-In this ~ 1,...~,, .... 2 of co-extensive parts the end 28 of the outer flange 19 is not curved out of the plane of the flange 19.
Another IOT is shown in Figure 4 and is sirnilar in many aspects to the Figure 3 ~.. .;~.,..: Theinputcavityincludespa~tswhichareextensiveina 511hc2sln~ y transverse directiontothe Irn~i22lr2i~~l axisandwhichareinterleavedtoprovidetherec,uireddcisolation between the inner body portion 32 and the outer body portion 33 and providing an r.f. choke The inner body portion 32 comprises two annular plates 34 and 35. One of the plates 34 is connected electrically to the cathode and is interleaved between two annular plates 36 and 37 forming part of the outer body portion 33. The annular plate 35 is cor2nected to the electrode gun grid and is interleaved with annular plates 38 and 39 which between thern define an annular channel into which the plate 35 is extensive. The regions belween the interleaved transverse parts are occupied by resiliently deformable electrically insulating material 40 which is of silicone rubber.
The outer edges of the annular plates 34 and 35 terminate in the annular channels and in the regions of the transverse plates of the outer body portion 33. The edges of the plates 34 and 35 are curved out of the plane of the plates so as to present a smooth surface, the ends of the edges touching the surfaces of the plates 34 and 35.
The annular plates 36. 37 and 38, 39 of the outer body portion are curved ou~wardl,v away from the interleaved part of the inner body portion but do not touch the surfaces of the 1S CA2 1 5qq70 plates.
Figure S illustrates srh~m~hr~lly part of another IOT in accordance with the invention and is a l~-n~n~ section showing some ~ only of the IOT The are cylindrically ~y~ i~l about the axis X-X and only half is shown.
The input cavity 41 of the IOT includes an outer body portion defined by plates 42 and 43 in ~ with an outer cylindrical wall (not shown). A metal cylinder 44 is mounted on one of the plates 4~ via a plurality of screws, one of which is shown. around its ~,iUUU~ . Two annular plates 45 and 46 are fixed at each end of the cylinder 44 and extend radially inwardly from it. The IOT includes a grid electrode 47 which is mounted on an annular plate 48 which surrounds it and is extensive between the plates 45 and 46 forming part of the outer body portion of the input cavity 41. The plates 45, 46 and 48 togethèr define an r.f. choke impedance which prevents loss of r.f. energy from the cavity 41. The plates 45 and 46 have inner edges which are curved outwardly away from the plate 48 located between them. The interleaved plate 48 is located in a plane which is spaced a distance a from the lower plate 46 in an axial direction and a larger distance b from the upper plate 46. HoweYer, the curvature of its end is such that the nearest point of the interleaved plate 48 from the upper plate 46 is also a in the a~ial direction. T'ne region between plates 45, 46 and 48 includes electrically insulating material to improve voltage hold-off between the plates and hence permit relatively large potential dirf~ ~ to be appiied between the inner body portion and the outer body portion.
The plate 43 defining the outer body portion is also electrically connected to two ~A~ 15997~
annular plates 49 and 50 and a generally cylindrical outer member 51 to which they are mounted. A central plate 52 of the inner body portion is connected to the cathode (not shown) of the ~OT electron gun. The spacing of the inner body portion 52 relative to the platQ 49 and 50 is arranged in a sirnilar manner to that of plates 45, 46 and 48.
In this ~ the inner body portion of the input cavity 41 is essentiaUy defined by the platQ 48 and æ which themselvQ are also the parts of the inner body portion which are co-extensive with ~vllQ~ ld.llg parts of the outer body portion.
Figure 6 illush atQs an ~ similar to that shown in Figure 5. ~lowever, in this ~LLI~I~.,III~II~. the platQ 53 and 54 forming part of the inner body portion are spaced eq.li~' -'y between adjacent plates 55, 56, 57 and 58 of the outer body portion. The radial inner edgQ of the outer body portion p~atQ and the outer edge of the inner body platQ are defined by beading of sllhct~nti:~lly circular cross-section to give the required curved edge in accordance with the invention.
Another IOT is shown in Figure 7 and is similar to the Flgure 4 ,.. ~ having an input cavity including parts which are extensive in a s1~hct~nri~1ly transverse direction to the l(ln~ihlAin il axis and which are interleaved to provide the required dc isolation between the inner body portion and the outer body portion whilst affording low r.f. Ieakage between them. However, in this confi~llr~t;-)n, the transverse platQ do not have curved ends. The re~ions ~etween the interleaved transverse parts are occupied by resiliently deformable electrically insulating material which again is of silicone rubber.
, . , . . ... .. .. , . _ . . . ., . . _ , _ . .
Claims (34)
1. A linear electron beam tube comprising:
an input cavity which is substantially cylindrical about a longitudinal axis and arranged to receive, in use, a high frequency signal to be amplified;
an electron gun arranged to produce an electron beam in a substantially longitudinal direction; and an output cavity from which the amplified high frequency signal is extracted; wherein the input cavity substantially surrounds the electron gun and comprises an inner body portion electrically connected to part of the electron gun and an outer body portion electrically insulated from the inner body portion, the inner body portion being maintained at a relatively high voltage compared to that of the outer body portion, and wherein the inner and outer body portions each includes an axially extensive flange substantially co-extensive in an axial direction and electrically insulating material being located between the flanges.
an input cavity which is substantially cylindrical about a longitudinal axis and arranged to receive, in use, a high frequency signal to be amplified;
an electron gun arranged to produce an electron beam in a substantially longitudinal direction; and an output cavity from which the amplified high frequency signal is extracted; wherein the input cavity substantially surrounds the electron gun and comprises an inner body portion electrically connected to part of the electron gun and an outer body portion electrically insulated from the inner body portion, the inner body portion being maintained at a relatively high voltage compared to that of the outer body portion, and wherein the inner and outer body portions each includes an axially extensive flange substantially co-extensive in an axial direction and electrically insulating material being located between the flanges.
2. A tube as claimed in claim 1 wherein the flanges are substantially cylindrical.
3. A tube as claimed in claim 1 or 2 wherein each of the inner and outer body portions includes two flanges extensive in an axial direction outwardly from the input cavity.
4. A tube as claimed in claim 3 wherein the insulating material is in the form of a single member which is extensive between both pairs of flanges.
5. A tube as claimed in claim 1, 2. 3 or 4 wherein the inner body portion comprises two sections which are electrically separate from one another.
6. A tube as claimed in any preceding claim wherein the inner body portion is electrically connected to a cathode and a grid of the electron gun.
7. A tube as claimed in any preceding claim wherein the electrically insulating material is generally cylindrical in form.
8. An arrangement as claimed in any preceding claim wherein the inner and outer body portions are physically joined together by the electrically insulating material.
9. A tube as claimed in any preceding claim wherein the outer body portion is at ground potential.
10. A tube as claimed in any preceding claim wherein electrical connection is provided between the outside of the input cavity and the inner body portion through the insulating material.
11. An arrangement as claimed in any preceding claim wherein at least one of the flanges is embedded in the electrically insulating material.
12. An arrangement as claimed in any preceding claim wherein a surface of the electrically insulating material includes at least one circumferential groove.
13. A linear electron beam tube comprising:
an input cavity which is substantially cylindrical about a longitudinal axis and arranged to receive, in use, a high frequency signal to be amplified;
an electron gun arranged to produce an electron beam in a substantially longitudinal direction; and an output cavity from which the amplified high frequency signal is extracted; wherein the input cavity substantially surrounds the electron gun and comprises an inner body portion electrically connected to part of the electron gun and an outer body portion electrically insulated from the inner body portion, the inner body portion being maintained at a relatively high voltage compared to that of the outer body portion, and wherein the inner and outer body portions have respective parts which are co-extensive to present a choke impedance to high frequency energy within the input cavity and wherein an edge of one or more of the parts terminating in a region where a part of the other body portion is extensive is curved.
an input cavity which is substantially cylindrical about a longitudinal axis and arranged to receive, in use, a high frequency signal to be amplified;
an electron gun arranged to produce an electron beam in a substantially longitudinal direction; and an output cavity from which the amplified high frequency signal is extracted; wherein the input cavity substantially surrounds the electron gun and comprises an inner body portion electrically connected to part of the electron gun and an outer body portion electrically insulated from the inner body portion, the inner body portion being maintained at a relatively high voltage compared to that of the outer body portion, and wherein the inner and outer body portions have respective parts which are co-extensive to present a choke impedance to high frequency energy within the input cavity and wherein an edge of one or more of the parts terminating in a region where a part of the other body portion is extensive is curved.
14. A tube as claimed in claim 13 wherein the parts substantially planar and the edge is curved out of the plane.
15. A tube as claimed in claim 14 wherein the edge is curved to an extent such that its end is substantially adjacent a region of the part remote from the edge.
16. A tube as claimed in claim 14 or 15 wherein the edge has a substantially constant radius of curvature.
17. A tube as claimed in any of claims 13 to 16 wherein the said respective parts are extensive in planes substantially transverse to the longitudinal axis.
18. A tube as claimed in claim 17 wherein one of the body portions includes two parts extensive in a substantially transverse direction and the other of the body portions includes one part extensive in substantially transverse direction and interleaved between the two parts of the other portion.
19. A tube as claimed in claim 18 wherein the said two parts have edges which curve in a direction away from the said one part.
20. A tube as claimed in claim 19 wherein the said one part is located nearer one of the said two parts than the other and has an edge which is curved away from the closer pari.
21. A tube as claimed in claim 17, 18, 19 or 20 wherein the parts are annular plates.
22. A tube as claimed in claim 13, 14, 15 or 16 wherein the said parts are axially extensive flanges which are substantially co-extensive in an axial direction.
23. A tube as claimed in claim 22 wherein the flanges are substantially cylindrical.
24. A tube as claimed in any of claims 13 to 23 wherein the inner and outer body portions include two pairs of co-extensive respective parts.
25. A tube as claimed in any of claims 13 to 24 and including electrically insulating material located between the said co-extensive parts
26. A linear electron beam tube comprising:
art input cavity which is substantially cylindrical about a longitudinal axis and arranged to receive, in use, a high frequency signal to be amplified;
an electron gun arranged to produce an electron beam in a substantially longitudinal direction; and an output cavity from which the amplified high frequency signal is extracted; wherein the input cavity substantially surrounds the electron gun and comprises an inner body portion electrically connected to part of the electron gun and an outer body portion electrically insulated from the inner body portion, the inner body portion being maintained at a relatively high voltage compared to that of the outer body portion, and wherein the inner and outer body portions have respective parts which are substantially co-extensive and resiliently deformable electrically insulating material is located between the said parts.
art input cavity which is substantially cylindrical about a longitudinal axis and arranged to receive, in use, a high frequency signal to be amplified;
an electron gun arranged to produce an electron beam in a substantially longitudinal direction; and an output cavity from which the amplified high frequency signal is extracted; wherein the input cavity substantially surrounds the electron gun and comprises an inner body portion electrically connected to part of the electron gun and an outer body portion electrically insulated from the inner body portion, the inner body portion being maintained at a relatively high voltage compared to that of the outer body portion, and wherein the inner and outer body portions have respective parts which are substantially co-extensive and resiliently deformable electrically insulating material is located between the said parts.
27. A tube as claimed in claim 25 or 26 wherein the resiliently deformable electrically insulating material is silicone rubber.
28. A tube as claimed in claim 27 wherein the electrically insulating material is moulded into the required configuration.
29. A tube as claimed in claim 25, 26, 27 or 28 wherein at least one of the said parts is at least partially embedded in the electrically insulating material
30. A tube as claimed in any of claims 13 to 39 wherein the electrically insulating material is substantially cylindrical in form.
31. An arrangement as claimed in any of claims 13 to 30 wherein the inner and outer body portions are physically joined together by the electrically insulating material.
32. A tube as claimed in any of claims 13 to 31 wherein the inner body portion comprises two sections which are electrically separate from one another.
33. A tube as claimed in an of claims 13 to 32 wherein the inner body portion is electrically connected to a cathode and a grid of the electron gun.
34. A tube as claimed in any preceding claim wherein the outer body portion is at ground potential.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002159970A CA2159970A1 (en) | 1995-10-05 | 1995-10-05 | Linear electron beam tube |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA002159970A CA2159970A1 (en) | 1995-10-05 | 1995-10-05 | Linear electron beam tube |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2159970A1 true CA2159970A1 (en) | 1997-04-06 |
Family
ID=4156713
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002159970A Abandoned CA2159970A1 (en) | 1995-10-05 | 1995-10-05 | Linear electron beam tube |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2159970A1 (en) |
-
1995
- 1995-10-05 CA CA002159970A patent/CA2159970A1/en not_active Abandoned
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |
Effective date: 20060317 |