CA2034919A1 - Cathode and heater assembly for electron-beam devices - Google Patents
Cathode and heater assembly for electron-beam devicesInfo
- Publication number
- CA2034919A1 CA2034919A1 CA002034919A CA2034919A CA2034919A1 CA 2034919 A1 CA2034919 A1 CA 2034919A1 CA 002034919 A CA002034919 A CA 002034919A CA 2034919 A CA2034919 A CA 2034919A CA 2034919 A1 CA2034919 A1 CA 2034919A1
- Authority
- CA
- Canada
- Prior art keywords
- cathode
- heater
- current
- filamentary
- holders
- 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
- H01J1/00—Details of electrodes, of magnetic control means, of screens, or of the mounting or spacing thereof, common to two or more basic types of discharge tubes or lamps
- H01J1/02—Main electrodes
- H01J1/13—Solid thermionic cathodes
- H01J1/20—Cathodes heated indirectly by an electric current; Cathodes heated by electron or ion bombardment
- H01J1/22—Heaters
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J1/00—Details of electrodes, of magnetic control means, of screens, or of the mounting or spacing thereof, common to two or more basic types of discharge tubes or lamps
- H01J1/02—Main electrodes
- H01J1/13—Solid thermionic cathodes
- H01J1/15—Cathodes heated directly by an electric current
- H01J1/16—Cathodes heated directly by an electric current characterised by the shape
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
- H01J2201/00—Electrodes common to discharge tubes
- H01J2201/28—Heaters for thermionic cathodes
- H01J2201/2803—Characterised by the shape or size
- H01J2201/281—Cage-like construction
Landscapes
- Solid Thermionic Cathode (AREA)
- Electron Sources, Ion Sources (AREA)
- Electrodes For Cathode-Ray Tubes (AREA)
- Electric Connection Of Electric Components To Printed Circuits (AREA)
Abstract
CATHODE AND HEATER ASSEMBLY FOR ELECTRON-BEAM DEVICES
ABSTRACT
The cathode and heater assembly comprises an emitter mounted on the middle parts of at least two filamentary heater elements, the peripheral sections whereof are positioned at an equal acute angle to the longitudinal geometrical axis of the emitter and with the ends thereof are fitted to cu rent-conducting leads.
The ends of the peripheral sections are positioned at the apexes of a polygon with two mutually orthogonal symmetry axes, one of which passes through the axes of the current-conducting leads, with the point of sym-metry axes intersections lying on the emitter axis.
ABSTRACT
The cathode and heater assembly comprises an emitter mounted on the middle parts of at least two filamentary heater elements, the peripheral sections whereof are positioned at an equal acute angle to the longitudinal geometrical axis of the emitter and with the ends thereof are fitted to cu rent-conducting leads.
The ends of the peripheral sections are positioned at the apexes of a polygon with two mutually orthogonal symmetry axes, one of which passes through the axes of the current-conducting leads, with the point of sym-metry axes intersections lying on the emitter axis.
Description
CATH~E AND HhATER A'SEh~LY FOR ELECTRON-BEAM
DEVICES
This invention relates to electronics and more specifically to the cathode and heater assemblies of electron-beam devices.
~ he invention can be success~ully used in the electronics industry in the production o~ TV, oscilloscope, display, and other electron-Geam devices (CR~s), whe-rein high electron beam density has to be provided simultaneously with high resolution, long service li~e, short readiness time and low power consumption.
The cathode and heater assembly is a crucial compo-nent of modern electron-beam tubes, which determines such per~ormance parameters as brightness (luminance), resolution, service life, reliability, power consump-tion, readiness time,etc.
Currently, electron-beam tubes use as the source of electrons cathode and heater assemblies with oxide indirectly heated cathodes, whose emissivity is limited and does not allo~s current densities above units of amperes per square centimetre to be obtained in the CW mode, such a density in certain cases being inadequate provide the required perlormance charac-teristics. ~hus, for instance, to provide the luminance speci~ied for modern kinescopes the oxide cathode has to be provide a current density in the beam o~ a value, impairing the cathode's li~espan and, therefore, that o~ the entire device.
- , ~
, 2034~19 Furthermore, oxide cathodes are inertial, i.e.
a certain warmup time is required to attain the opera-ting temperature, and in certain cases this readiness time i9 a critical per~ormance parameter.
These features of oxide cathodes predetermined the trend of further ca-thode devel~pments towards directly heated thermionic emit-ters based on emissive metals and their alloys. Along vJith short warmup time, such cathodes feature higher electron current density and longer life than oxide cathodes. However, the design of such directly heated cathode and heater assemblies is as yet inade-quately developed due to the contradictory requirements of high reliability and low power consumption. Thus, the problem of creating a cathode and heater assembly meeting the requirements of reliability and efficiency, is at present the most urgent one in electron-beam electro-nics .
Another currently urgent pro~lem is that of simul-taneously obtaining the picture and accompanying sound on turning on a ~V receiver, also solvable by using di-rectly heated cathodes.
Known in the art i9 the simplest design of a cathode and heater assembly (K.M. Tisher. Einige Probleme direct geheizter Eatoden fur Fernseh-Bildrohren. ~unk-Technik, S.F.& E., b.33 No. 1, 1978, pp. 1-6. In German), wherein the heater element is rectilinear section of metal band , . . . .
,. . . .
: - . . .
-~` 2~34~19 fitted by its ends to current-conducti~g buses and moun-ting the thermionic emitter at its middle.
When turned on, the cathode heater current heats this thin metal band, this leading to its warping, buck-ling, reduced elasticity Qnd resulting in the cmitter being uncontrollably shifted from the slectron-optical axis of the device. The overall result is a low reliabi-lity and a low repeatability of the performance parameters.
~ his problem cannot be solved by introducing stretching means to componsate the heater element's thermal expan-sion, becauso of the design complications and the stret-ching elements losing their elasticity with time. Further-more, these stretching elements lead to microphonics, i.e. the heater become,s capable of vibrating under the effect of various mechanical loads on the cathode as sembly.
Known in the art is a directly heated cathode for use as a source o~ electrons (US, A, 4193~13), comprising a thermionic emitter in the form of a bar of lanthanum hexaboride ~itted to the central part of the graphite heater of an arced configuration.
~ his design features high electric power requirements ~about 8W) to heat the heater element due to the latter's considerable cross-section area required to exclude displa-cement of the thermionic emitter from its original position.
: :
- : .
. .
- 203491~
Also widel7 used in the art is a cathode and heater assembly for electron-beam devices (EP, B, 02~7772), comprising a thermionic emitter having a longitudi~al geometrical axis and fitted to the middle sections of at least two filamentary heater elements, the peripheral parts whereof are o~ equal length and are ~itted to current-conducting leads rigidly mounted in the base.
This known in the art cathode and heater assembly uses two heater elements, the peripheral sections whereo~
are parallel to the emitter axis.
Such an embodiment of the cathode and heater as-sembly features a low reliability due to the loss of shapo stability when the filamentary heating elements aro heated, leading to displacement o~ the emitter ~rom the elèctron-optical 3XiS 0~ the device during operation. Thus, the reliability of such an a~sembly is determined by the a-qsembly retaining its original positioning in the device, rather than by the properties o~ the emitter itself.
An objectivo of this in~ention is to provide a cathode and heater assembly for electron-beam devices, having a high reliability.
Another objective i9 to improve the efficiency.
: -, : , - -. - ~ . . .. . -" -~ . . .--.
; ~. : - . .: -: - --, . . - ~ . . .
~3~919 ~ his is achieved by that the cathode and heater as-sembly for electron-beam devices, comprising a thermionic emitter having a lcngitudinal geometrical axis and fitted to the middle sections of at least two filamentary heater elements, the per~pheral sections whereof are of equal length and are fitted by t~eir ends to current-conducting leads rigidly fitted to the base, accordin~ to the invention the peripheral sections of the filamentary heaters are positioned at an acute angle to the longitu-dinal geometrical axis of the thermionic emitter with their ends located at the vertices of a polygon with two orthogonal symmetry axes, with one axis passing through the current-conducting leads axes, and with the symmetry axes' intersect on point lying on the longitudinal axis of the thermionic emitter.
It is expedient to design the cathode and heater assombly for electron-beam devices with two groups of h~ater holders, each such group having a number of hol-ders equal to the number of filamentary heating elements, with one holder end connected to the end of the peripheral section of the filamentary heating element and with the other holder end rigidly fitted to one of the current-conducting leads, with holders of one group positioned symmetrioally relative to holders of the other group and in plane passing through the longitudinal geometrical axis of the thermionic emitter and through the symmetry axis of the polygon orthogonal to the symmetry axis passing through the axes of the current-conducti~g leads.
. .
. -- - .
203~g~9 It is desirable that the holders be of a current-conducting material with an electric resistivity higher than tha-t of the filamentary heating el~ments, and that the ratio of the c~oss-sectional areas o~ each hol~er and the filamentary heater be at least equal to the ratio of their electriv resistivi-ties.
It is reasonable that the length o~ each holder be determined by the relation:
l2 = l1 r(1 ~ ~2/~1) /2 _ 1 ~ , where: 11 is the length of the peripheral section of the filamentary heating element;
12 is the ho~ er length;
T1 is the melting temperature of the filamentary heating element; and T2 is the melting temperature of the holder material.
It is highly advantageous that each holder be of arched configuration.
~ he cathode and heater assembly for electron-beam devices of this invention is characterized hy a high reliability during its entire lifespan. ~he shape stabi-lity of this design arrangement, constituting one of the critical factora affecting assembly reliability, is achie-ved by selecting a proper geometry of positioning the filamentary heater elements.
Holders of high electric resistance also improves the shape stability, at the same time facilitating heat sink via them and thus reducing the temperature gradient - . . . ~ ...... , "' , , :
', ~ . ~ ,'.' , ,. - .
'-: ~ ~ ' ' . '-betweon the "cold" current-conducting leads and the "hot"
heater el~men-ts and reducing heat transfer ~rom the thermionic e~itter to the current-conducting leads.
~ hus, the cathode and heater assembly of the in-vention features, on the one hand high mechanical rigidity and temperature stability, and on the other hand low power consumption and quick warmup to the operating temperature.
~ he invention will now be described in greater detail with referencc to specific embodiments thereof and to the acaompanying drawings, wherein:
Fig. 1 shows the general view of the cathode and heater assembly for electron-beam devices, according to the invention;
Fig. 2 shows the plan view of tne cathode and heater assembly o~ the invention shown in Fig. 1;
Fig. 3 shows the axonometric projection of -the cathode and heater a~sembly of Fig. 1 with four holders of recti-linear shape, accordi~g to the invention;
Fig. 4 shows the axonometric projection of the cathode and heater assembly of ~ig. 3 with three filamentary heating elements and six rectilinear holders, according to the invention;
Fig. 5 shows the plan view of the cathode and heater assembly of Fig. 3 with arched holders, according to the invention;
. .
. .
. ~ . ~ . . . .
~3~9 Fig. 6 shows the te~perature distribution along the holders and filamentary heating element.
The cathode and heater assembly for electron-beam devices comprises thermionic emitter 1 (Fig. 1) having longitudinal geometrical axis 2 and fitted to the middle sections 3 (conventionally shown by dashed lines) of at least two filamentar~ hea-ting elements 4.
In this embodiment two heating elements 4 are used, with peripheral sections 5 of each having an equal length 11 and positioned at equal acute angles ~ relative to the longitudinal geometrical axis 2 of thermionic emitter 1.
~he ends of peripheral sections 5 are fitted, i.e. welded by resistance spot welding, to current-conducting leads 6 rigidly fitted to base 7 of an electrically insulating material, e.g. ceramics.
Such a con~iguration of heating elemen~s 4 as if constitutes the cage of a tetrahedral, pyramid which i9 a rigid structure, providin~ shape stability and constancy o~ emitter 1 positioning when heated during service.
~ he amount of thermal displacement of emitter 1 along axis 2 is constant and can easily be defined for ea¢h speci~ic con~iguration and, consequently, taken into account during precise emitter 1 positioning in the electron-beam device. The ends of peripheral sec-tions 5 are in a plane normal to geometrical axis 2 and inoluding the vortices on the polygon (in this embodiment -the rectangl~) with two orthogonal symmetry axes 8 (Fig. 2), .' ~ .
~f~3~ 9 _9~
one such axis passing through the axes of current-conduc--ting lea~s 6, ànd VJith the point of axes 8 intersection lying on geometrical axis 2 (Fig. 1).
Increasing the number of heating elements improves the shape stability, and consequently - the reliability, but results in a more complex structure1 so that it proves practically expedient to restrict the number of heating elements to two or three.
Heating elements 4 are of a refractory metal, e.g.
of tungsten wire, and thermionis emitter 1 is of rare earth borides, e.g. LaB6.
~ o ~urther improve the structure rigidity and the efficiency of the cathode and heater assembly, it is complemented with holders 10 (Fig. 3) supporting heating elements 4. Xolders 10 are of a high resistivity current--conducting material, higher than that of heater ele-ments 4, e.g. of chromic alloys, such as nickel-chrome, nickel-tungsten-zirconium alloys etc.
Holders 10 are combined into two groups, each group having a n-~mber of holders 10 equal to that of heating elements 4, with one end of each holder 10 connected to the end of a peripheral section 5 of heater element 4 and with the other end o~ each holder 10 rigidly fitted to one of the current-conducting leads 6. Holders 10 of one group are positioned symmetrically relative to those of the other group and ~o the plane passing through ... . , ~. ..
., ., ,. . ~, . i .. . .
: ~ : . . .
.~ ; . .
. . . -geometric axis 2 of emitter 1 and that of polygon sym-metry axes 8, 9 (in this embodiment - axis 8) normal to axis 9, 8 passing through the axes of current-conducting leads 6 In this embodiment holders 1~ are rectilinear sec-tions of conductors connecting the ends of peripheral se¢tions 4 o~ heatin~ elements 4 to current-conducting leads 6.
In the embodiment shown in ~ig. 4 there are three heater elements 4 and, respectively, six holders 1 positioned radially relative to current-conducting leads 6. ~his structure of the cathode and heater as-sembly is si~ilar to the cage o~ a hexagonal pyramid with peripheral sections 5 of heat.er elements 4 consti-tuting the pyramid edges.
An embodiment, wherein holders 1J are arched, rather than rectilinear is shown in Fig. 5, this shape further enhancing emitter 1 positioring stability durin, heating by that the thermal expansion (elongation) of holders 10 is reduced to their displacement along the directrix o~ a cone enclosing the pyramid, rather than being trans-ferred to e~itter 1 via the edges of the pyramid cage, and this, as is well known, does not cause displacement of the pyramid apex, wherein emitter 1 is positioned.
The use of holders 1~, independent of their con~igu-ration and positioning, allows utilizing heater elements 4 ' ~
- - .
DEVICES
This invention relates to electronics and more specifically to the cathode and heater assemblies of electron-beam devices.
~ he invention can be success~ully used in the electronics industry in the production o~ TV, oscilloscope, display, and other electron-Geam devices (CR~s), whe-rein high electron beam density has to be provided simultaneously with high resolution, long service li~e, short readiness time and low power consumption.
The cathode and heater assembly is a crucial compo-nent of modern electron-beam tubes, which determines such per~ormance parameters as brightness (luminance), resolution, service life, reliability, power consump-tion, readiness time,etc.
Currently, electron-beam tubes use as the source of electrons cathode and heater assemblies with oxide indirectly heated cathodes, whose emissivity is limited and does not allo~s current densities above units of amperes per square centimetre to be obtained in the CW mode, such a density in certain cases being inadequate provide the required perlormance charac-teristics. ~hus, for instance, to provide the luminance speci~ied for modern kinescopes the oxide cathode has to be provide a current density in the beam o~ a value, impairing the cathode's li~espan and, therefore, that o~ the entire device.
- , ~
, 2034~19 Furthermore, oxide cathodes are inertial, i.e.
a certain warmup time is required to attain the opera-ting temperature, and in certain cases this readiness time i9 a critical per~ormance parameter.
These features of oxide cathodes predetermined the trend of further ca-thode devel~pments towards directly heated thermionic emit-ters based on emissive metals and their alloys. Along vJith short warmup time, such cathodes feature higher electron current density and longer life than oxide cathodes. However, the design of such directly heated cathode and heater assemblies is as yet inade-quately developed due to the contradictory requirements of high reliability and low power consumption. Thus, the problem of creating a cathode and heater assembly meeting the requirements of reliability and efficiency, is at present the most urgent one in electron-beam electro-nics .
Another currently urgent pro~lem is that of simul-taneously obtaining the picture and accompanying sound on turning on a ~V receiver, also solvable by using di-rectly heated cathodes.
Known in the art i9 the simplest design of a cathode and heater assembly (K.M. Tisher. Einige Probleme direct geheizter Eatoden fur Fernseh-Bildrohren. ~unk-Technik, S.F.& E., b.33 No. 1, 1978, pp. 1-6. In German), wherein the heater element is rectilinear section of metal band , . . . .
,. . . .
: - . . .
-~` 2~34~19 fitted by its ends to current-conducti~g buses and moun-ting the thermionic emitter at its middle.
When turned on, the cathode heater current heats this thin metal band, this leading to its warping, buck-ling, reduced elasticity Qnd resulting in the cmitter being uncontrollably shifted from the slectron-optical axis of the device. The overall result is a low reliabi-lity and a low repeatability of the performance parameters.
~ his problem cannot be solved by introducing stretching means to componsate the heater element's thermal expan-sion, becauso of the design complications and the stret-ching elements losing their elasticity with time. Further-more, these stretching elements lead to microphonics, i.e. the heater become,s capable of vibrating under the effect of various mechanical loads on the cathode as sembly.
Known in the art is a directly heated cathode for use as a source o~ electrons (US, A, 4193~13), comprising a thermionic emitter in the form of a bar of lanthanum hexaboride ~itted to the central part of the graphite heater of an arced configuration.
~ his design features high electric power requirements ~about 8W) to heat the heater element due to the latter's considerable cross-section area required to exclude displa-cement of the thermionic emitter from its original position.
: :
- : .
. .
- 203491~
Also widel7 used in the art is a cathode and heater assembly for electron-beam devices (EP, B, 02~7772), comprising a thermionic emitter having a longitudi~al geometrical axis and fitted to the middle sections of at least two filamentary heater elements, the peripheral parts whereof are o~ equal length and are ~itted to current-conducting leads rigidly mounted in the base.
This known in the art cathode and heater assembly uses two heater elements, the peripheral sections whereo~
are parallel to the emitter axis.
Such an embodiment of the cathode and heater as-sembly features a low reliability due to the loss of shapo stability when the filamentary heating elements aro heated, leading to displacement o~ the emitter ~rom the elèctron-optical 3XiS 0~ the device during operation. Thus, the reliability of such an a~sembly is determined by the a-qsembly retaining its original positioning in the device, rather than by the properties o~ the emitter itself.
An objectivo of this in~ention is to provide a cathode and heater assembly for electron-beam devices, having a high reliability.
Another objective i9 to improve the efficiency.
: -, : , - -. - ~ . . .. . -" -~ . . .--.
; ~. : - . .: -: - --, . . - ~ . . .
~3~919 ~ his is achieved by that the cathode and heater as-sembly for electron-beam devices, comprising a thermionic emitter having a lcngitudinal geometrical axis and fitted to the middle sections of at least two filamentary heater elements, the per~pheral sections whereof are of equal length and are fitted by t~eir ends to current-conducting leads rigidly fitted to the base, accordin~ to the invention the peripheral sections of the filamentary heaters are positioned at an acute angle to the longitu-dinal geometrical axis of the thermionic emitter with their ends located at the vertices of a polygon with two orthogonal symmetry axes, with one axis passing through the current-conducting leads axes, and with the symmetry axes' intersect on point lying on the longitudinal axis of the thermionic emitter.
It is expedient to design the cathode and heater assombly for electron-beam devices with two groups of h~ater holders, each such group having a number of hol-ders equal to the number of filamentary heating elements, with one holder end connected to the end of the peripheral section of the filamentary heating element and with the other holder end rigidly fitted to one of the current-conducting leads, with holders of one group positioned symmetrioally relative to holders of the other group and in plane passing through the longitudinal geometrical axis of the thermionic emitter and through the symmetry axis of the polygon orthogonal to the symmetry axis passing through the axes of the current-conducti~g leads.
. .
. -- - .
203~g~9 It is desirable that the holders be of a current-conducting material with an electric resistivity higher than tha-t of the filamentary heating el~ments, and that the ratio of the c~oss-sectional areas o~ each hol~er and the filamentary heater be at least equal to the ratio of their electriv resistivi-ties.
It is reasonable that the length o~ each holder be determined by the relation:
l2 = l1 r(1 ~ ~2/~1) /2 _ 1 ~ , where: 11 is the length of the peripheral section of the filamentary heating element;
12 is the ho~ er length;
T1 is the melting temperature of the filamentary heating element; and T2 is the melting temperature of the holder material.
It is highly advantageous that each holder be of arched configuration.
~ he cathode and heater assembly for electron-beam devices of this invention is characterized hy a high reliability during its entire lifespan. ~he shape stabi-lity of this design arrangement, constituting one of the critical factora affecting assembly reliability, is achie-ved by selecting a proper geometry of positioning the filamentary heater elements.
Holders of high electric resistance also improves the shape stability, at the same time facilitating heat sink via them and thus reducing the temperature gradient - . . . ~ ...... , "' , , :
', ~ . ~ ,'.' , ,. - .
'-: ~ ~ ' ' . '-betweon the "cold" current-conducting leads and the "hot"
heater el~men-ts and reducing heat transfer ~rom the thermionic e~itter to the current-conducting leads.
~ hus, the cathode and heater assembly of the in-vention features, on the one hand high mechanical rigidity and temperature stability, and on the other hand low power consumption and quick warmup to the operating temperature.
~ he invention will now be described in greater detail with referencc to specific embodiments thereof and to the acaompanying drawings, wherein:
Fig. 1 shows the general view of the cathode and heater assembly for electron-beam devices, according to the invention;
Fig. 2 shows the plan view of tne cathode and heater assembly o~ the invention shown in Fig. 1;
Fig. 3 shows the axonometric projection of -the cathode and heater a~sembly of Fig. 1 with four holders of recti-linear shape, accordi~g to the invention;
Fig. 4 shows the axonometric projection of the cathode and heater assembly of ~ig. 3 with three filamentary heating elements and six rectilinear holders, according to the invention;
Fig. 5 shows the plan view of the cathode and heater assembly of Fig. 3 with arched holders, according to the invention;
. .
. .
. ~ . ~ . . . .
~3~9 Fig. 6 shows the te~perature distribution along the holders and filamentary heating element.
The cathode and heater assembly for electron-beam devices comprises thermionic emitter 1 (Fig. 1) having longitudinal geometrical axis 2 and fitted to the middle sections 3 (conventionally shown by dashed lines) of at least two filamentar~ hea-ting elements 4.
In this embodiment two heating elements 4 are used, with peripheral sections 5 of each having an equal length 11 and positioned at equal acute angles ~ relative to the longitudinal geometrical axis 2 of thermionic emitter 1.
~he ends of peripheral sections 5 are fitted, i.e. welded by resistance spot welding, to current-conducting leads 6 rigidly fitted to base 7 of an electrically insulating material, e.g. ceramics.
Such a con~iguration of heating elemen~s 4 as if constitutes the cage of a tetrahedral, pyramid which i9 a rigid structure, providin~ shape stability and constancy o~ emitter 1 positioning when heated during service.
~ he amount of thermal displacement of emitter 1 along axis 2 is constant and can easily be defined for ea¢h speci~ic con~iguration and, consequently, taken into account during precise emitter 1 positioning in the electron-beam device. The ends of peripheral sec-tions 5 are in a plane normal to geometrical axis 2 and inoluding the vortices on the polygon (in this embodiment -the rectangl~) with two orthogonal symmetry axes 8 (Fig. 2), .' ~ .
~f~3~ 9 _9~
one such axis passing through the axes of current-conduc--ting lea~s 6, ànd VJith the point of axes 8 intersection lying on geometrical axis 2 (Fig. 1).
Increasing the number of heating elements improves the shape stability, and consequently - the reliability, but results in a more complex structure1 so that it proves practically expedient to restrict the number of heating elements to two or three.
Heating elements 4 are of a refractory metal, e.g.
of tungsten wire, and thermionis emitter 1 is of rare earth borides, e.g. LaB6.
~ o ~urther improve the structure rigidity and the efficiency of the cathode and heater assembly, it is complemented with holders 10 (Fig. 3) supporting heating elements 4. Xolders 10 are of a high resistivity current--conducting material, higher than that of heater ele-ments 4, e.g. of chromic alloys, such as nickel-chrome, nickel-tungsten-zirconium alloys etc.
Holders 10 are combined into two groups, each group having a n-~mber of holders 10 equal to that of heating elements 4, with one end of each holder 10 connected to the end of a peripheral section 5 of heater element 4 and with the other end o~ each holder 10 rigidly fitted to one of the current-conducting leads 6. Holders 10 of one group are positioned symmetrically relative to those of the other group and ~o the plane passing through ... . , ~. ..
., ., ,. . ~, . i .. . .
: ~ : . . .
.~ ; . .
. . . -geometric axis 2 of emitter 1 and that of polygon sym-metry axes 8, 9 (in this embodiment - axis 8) normal to axis 9, 8 passing through the axes of current-conducting leads 6 In this embodiment holders 1~ are rectilinear sec-tions of conductors connecting the ends of peripheral se¢tions 4 o~ heatin~ elements 4 to current-conducting leads 6.
In the embodiment shown in ~ig. 4 there are three heater elements 4 and, respectively, six holders 1 positioned radially relative to current-conducting leads 6. ~his structure of the cathode and heater as-sembly is si~ilar to the cage o~ a hexagonal pyramid with peripheral sections 5 of heat.er elements 4 consti-tuting the pyramid edges.
An embodiment, wherein holders 1J are arched, rather than rectilinear is shown in Fig. 5, this shape further enhancing emitter 1 positioring stability durin, heating by that the thermal expansion (elongation) of holders 10 is reduced to their displacement along the directrix o~ a cone enclosing the pyramid, rather than being trans-ferred to e~itter 1 via the edges of the pyramid cage, and this, as is well known, does not cause displacement of the pyramid apex, wherein emitter 1 is positioned.
The use of holders 1~, independent of their con~igu-ration and positioning, allows utilizing heater elements 4 ' ~
- - .
2~3l~
of shorter length and smaller cross-~ection area~ The cross-section are o~ holders 10 and heater elements 4 are selected in accordance with their electric resistivity.
As is well known, least heat transfer from heater element 4 to current-conducting leads ~ ~ill be at a constant power dissipated along the integrated heater co~posed of two holders 10 and the heater element 10 itsel~, ~his condition will be sa-tisfied at a constant electric resistance per unit length of the integrated h~ater, this in the embodiment being described practically meaning an equality between the ratio of cross-sectional areas of holders 10 and heater elements 4 and the ratio o~
-their resistivitles, or slioh-t exceed of this value.
Optimization o~ lengths l1, l2 ~ peripheral sec-tion 5 o~ heater element 4 and holder 1~, respectively, takes into account melting temperatures T1~ T2 of their materials.
Obviously, holder 10 length 12 may be increased till the temperature at its point of contact with heater element 4 does not exceed T2, with the necessity to main-tain a constant electric resistance per unit length o~ the integrated heater (to maintain a constant heat emission) taken into account. Heat losses due to thermal condu¢tivity Ph at any point of the in-tegrated heater depend on the distance from this point to the site o~
holder 10 mounting to the massive current-conducting . - . ,, : .
.:- - . -.. . - . . . .
, - 2~3~919 ~12 leads 6 (the origin x=0 co~responds to one of the leads 6) and can be described as:
Ph = Pi( x t i-x ) = Pi x~1-x) (1) where Pi i5 th~ emitted he~t power and 1 = 2(11 + 12), neglecting -the length of the middle part 3 of heater element 4 as insignicant.
The steady-state ~emperature, ~, in any point of the integrated heater under these conditions is in-versely proportional to the heat lossea, i.e.:
~(x) = k ~ =_~ ~(1 1 x) (2) where k is the proportionality factor.
~ he ratio k/Pi ¢an be obtained from the condition o~ equality of temperatures T(x) at the middle of heater element 4, i.e. at x = 1/2, to the operating temperature, To~ of thermionic emitter 1:
~(l/e) = ~0 = ~ ~ = pk whence k = ~ 4 ~ o r Thus, the ~inal equation decribing T(x) will be:
~ (x) = To4x(l2~-x) , (4) desoribing the dynamic equilibrum between heat emission and heat losses due to heat sinking established in the integrated heater.
Fig. 6 shows the temperature distribution along the .
~: .- ; . :. . -~3~9 length of the integrated heater (holder 1~ and heater element 4), with the temperature of current-conducting leads 6 conventionally as~med to be zero.
Coordinates of the point~ of holder 10 ¢onnection to the ends of peripheral sections 5 of heater elements 4 can be deter~ined from the boundary condition that the current temperature T(x) at this poin~ be equal to ~2 and the tempera~ure at the middle of heater element 4 be T1 = To~ With this taken into account, T2 = 4x(1 - x) T1 1 2 (5) Hence x ~ +(1 ~ T2 )1/2~ (6) Thus, the optimal point of heater element 10 joint to holder 10, i.e. the length l1, is symmetrically spaced from the middle o~ heater element 4 by x1 = 2 (1 ~ T1 ) / (7) ~ he optimal ratio of holder 10 length 12 to the length 11 of peripheral se¢tion 5 of heater element 4 will th~re~ore be:
2 X2 ~-- L1 - (1 - T2/~1)1/
(1 - T2/T1)1/2 - 1, ( 1 - T2 /~1 ) /
whence the length, 12, of holder 1~ can be obtained a9:
2 = 11 ~ 2/T1) 1/2 _ 1~ (8) ' - : ''' :- - - .- ' :
. , " :' : , .
-~
2~34~9 -An increase in length 12 above this analytical optimal value can lead to the danger of softening or melting of holders 1~ at the point of fitting to heater elements 4, a shorter than opt~mal length l2 is inexpe-dient because of the lower shape stability and higher heat losses due to shorter holders 1~.
The cathode and heater assembly of the invention functions as follows.
Application of volta~e to current-conducting leads (Figs. 1, 2) causes heating of heater elemen-ts 4, thus heating thermionic emit~er 1 to its operating temperature ~0.
Emitter 1 emits electrons, bunched into an electron beam in the electron-beam device, wherein the cathode and heater assembly is installed.
~ he cathode and heater assembly of the herein above described design configuration fea-tures a short warmup time (o~ about 1 second) due to the short length and thinness of heater elements 4.
Embodiments of the cathode and hea-ter assembly shown in Figs. 3-5 mainly function in a similar manner, di~-fering in that after voltage application to current-conduoting leads 6, the temperature whereof rises to about 100C, the ends of holders 10 at the points of their fitting to heater elements 4 are heated to about 7~0C, whereas the heater elements 4 raise the temperature of emitter 1 to its operating temperature of about 1400C
to provide thermionic emission. Thus, introduction of hol-~, -' . ' . ' .
~3l~9 ders 10 reduces the temperature gradient across the junction between heater elements 4 and leads 6 there-fore reduces heat losses, thus improving the cathode and heater assembly efficiency.
On the whole, the cathode and heater assembly of the invention, due to the herein above described geometry of filamentary heater elements positioning and to the introduction of holders of a specified length and cross-section to constitute a rigid structure, shape-stable under high-temperature operating conditions, is cha-racterized by a high reliability and a high efficiency.
. ~ .
:. `. `` ` ~ ' , ' :
of shorter length and smaller cross-~ection area~ The cross-section are o~ holders 10 and heater elements 4 are selected in accordance with their electric resistivity.
As is well known, least heat transfer from heater element 4 to current-conducting leads ~ ~ill be at a constant power dissipated along the integrated heater co~posed of two holders 10 and the heater element 10 itsel~, ~his condition will be sa-tisfied at a constant electric resistance per unit length of the integrated h~ater, this in the embodiment being described practically meaning an equality between the ratio of cross-sectional areas of holders 10 and heater elements 4 and the ratio o~
-their resistivitles, or slioh-t exceed of this value.
Optimization o~ lengths l1, l2 ~ peripheral sec-tion 5 o~ heater element 4 and holder 1~, respectively, takes into account melting temperatures T1~ T2 of their materials.
Obviously, holder 10 length 12 may be increased till the temperature at its point of contact with heater element 4 does not exceed T2, with the necessity to main-tain a constant electric resistance per unit length o~ the integrated heater (to maintain a constant heat emission) taken into account. Heat losses due to thermal condu¢tivity Ph at any point of the in-tegrated heater depend on the distance from this point to the site o~
holder 10 mounting to the massive current-conducting . - . ,, : .
.:- - . -.. . - . . . .
, - 2~3~919 ~12 leads 6 (the origin x=0 co~responds to one of the leads 6) and can be described as:
Ph = Pi( x t i-x ) = Pi x~1-x) (1) where Pi i5 th~ emitted he~t power and 1 = 2(11 + 12), neglecting -the length of the middle part 3 of heater element 4 as insignicant.
The steady-state ~emperature, ~, in any point of the integrated heater under these conditions is in-versely proportional to the heat lossea, i.e.:
~(x) = k ~ =_~ ~(1 1 x) (2) where k is the proportionality factor.
~ he ratio k/Pi ¢an be obtained from the condition o~ equality of temperatures T(x) at the middle of heater element 4, i.e. at x = 1/2, to the operating temperature, To~ of thermionic emitter 1:
~(l/e) = ~0 = ~ ~ = pk whence k = ~ 4 ~ o r Thus, the ~inal equation decribing T(x) will be:
~ (x) = To4x(l2~-x) , (4) desoribing the dynamic equilibrum between heat emission and heat losses due to heat sinking established in the integrated heater.
Fig. 6 shows the temperature distribution along the .
~: .- ; . :. . -~3~9 length of the integrated heater (holder 1~ and heater element 4), with the temperature of current-conducting leads 6 conventionally as~med to be zero.
Coordinates of the point~ of holder 10 ¢onnection to the ends of peripheral sections 5 of heater elements 4 can be deter~ined from the boundary condition that the current temperature T(x) at this poin~ be equal to ~2 and the tempera~ure at the middle of heater element 4 be T1 = To~ With this taken into account, T2 = 4x(1 - x) T1 1 2 (5) Hence x ~ +(1 ~ T2 )1/2~ (6) Thus, the optimal point of heater element 10 joint to holder 10, i.e. the length l1, is symmetrically spaced from the middle o~ heater element 4 by x1 = 2 (1 ~ T1 ) / (7) ~ he optimal ratio of holder 10 length 12 to the length 11 of peripheral se¢tion 5 of heater element 4 will th~re~ore be:
2 X2 ~-- L1 - (1 - T2/~1)1/
(1 - T2/T1)1/2 - 1, ( 1 - T2 /~1 ) /
whence the length, 12, of holder 1~ can be obtained a9:
2 = 11 ~ 2/T1) 1/2 _ 1~ (8) ' - : ''' :- - - .- ' :
. , " :' : , .
-~
2~34~9 -An increase in length 12 above this analytical optimal value can lead to the danger of softening or melting of holders 1~ at the point of fitting to heater elements 4, a shorter than opt~mal length l2 is inexpe-dient because of the lower shape stability and higher heat losses due to shorter holders 1~.
The cathode and heater assembly of the invention functions as follows.
Application of volta~e to current-conducting leads (Figs. 1, 2) causes heating of heater elemen-ts 4, thus heating thermionic emit~er 1 to its operating temperature ~0.
Emitter 1 emits electrons, bunched into an electron beam in the electron-beam device, wherein the cathode and heater assembly is installed.
~ he cathode and heater assembly of the herein above described design configuration fea-tures a short warmup time (o~ about 1 second) due to the short length and thinness of heater elements 4.
Embodiments of the cathode and hea-ter assembly shown in Figs. 3-5 mainly function in a similar manner, di~-fering in that after voltage application to current-conduoting leads 6, the temperature whereof rises to about 100C, the ends of holders 10 at the points of their fitting to heater elements 4 are heated to about 7~0C, whereas the heater elements 4 raise the temperature of emitter 1 to its operating temperature of about 1400C
to provide thermionic emission. Thus, introduction of hol-~, -' . ' . ' .
~3l~9 ders 10 reduces the temperature gradient across the junction between heater elements 4 and leads 6 there-fore reduces heat losses, thus improving the cathode and heater assembly efficiency.
On the whole, the cathode and heater assembly of the invention, due to the herein above described geometry of filamentary heater elements positioning and to the introduction of holders of a specified length and cross-section to constitute a rigid structure, shape-stable under high-temperature operating conditions, is cha-racterized by a high reliability and a high efficiency.
. ~ .
:. `. `` ` ~ ' , ' :
Claims (5)
1. A cathode and heater assembly for electron-beam devices, comprising:
- a thermionic emitter having a longitudinal geometric axis;
- a group of filamentary heater elements, the number whereof is at least two, with each said filamentary heater element having a middle part, whereon the said thermionic emitter is mounted, a first peripheral section having an end, and a second peripheral section of a length equal to that of said first peripheral section and having an end, wherein said first and said second peripheral sections are positioned at an equal acute angle to the longitudinal geometrical axis of said ther-mionic emitter, and their said ends are positioned at the apexes of a polygon with two mutually orthogonal axes of symmetry, the intersection point whereof is positioned on the geometrical axis of said thermionic emitter;
- a first current-conducting lead having an axis and connected to said ends of said first peripheral sections of said filamentary heater elements;
- a second current-conducting lead having an axis and connected to said ends of said second peripheral sec-tions of said filamentary heater elements, wherein one of the axes of symmetry of the polygon passes through said axes of said first and said second current-conducting leads;
- a base rigidly mounting said first and said second current-conducting leads.
- a thermionic emitter having a longitudinal geometric axis;
- a group of filamentary heater elements, the number whereof is at least two, with each said filamentary heater element having a middle part, whereon the said thermionic emitter is mounted, a first peripheral section having an end, and a second peripheral section of a length equal to that of said first peripheral section and having an end, wherein said first and said second peripheral sections are positioned at an equal acute angle to the longitudinal geometrical axis of said ther-mionic emitter, and their said ends are positioned at the apexes of a polygon with two mutually orthogonal axes of symmetry, the intersection point whereof is positioned on the geometrical axis of said thermionic emitter;
- a first current-conducting lead having an axis and connected to said ends of said first peripheral sections of said filamentary heater elements;
- a second current-conducting lead having an axis and connected to said ends of said second peripheral sec-tions of said filamentary heater elements, wherein one of the axes of symmetry of the polygon passes through said axes of said first and said second current-conducting leads;
- a base rigidly mounting said first and said second current-conducting leads.
2. A cathode and heater assembly as claimed in Claim 1, comprising:
- a first group of holders, the number whereof is equal to that of said filamentary heater elements with said holders having first ends wherewith they are con-nected to said ends of said first peripheral sections of said filamentary heater elements, and second ends rigidly fitted to said first current-conducting lead;
- a second group of holders, the number whereof is equal to that of said filamentary heater elements, with said holders having first ends wherewith they are connected to said ends of said second peripheral sections of said filamentary heater elements, and second ends rigidly fitted to said second current-conducting lead, with said holders of said first group positioned sym-metrically to said holders of said second group relative to a plane passing through the longitudinal geometric axis of said thermionic emitter and through the symmetry axis of the polygon normal to the axis passing through the axes said first and said second current-conducting leads.
- a first group of holders, the number whereof is equal to that of said filamentary heater elements with said holders having first ends wherewith they are con-nected to said ends of said first peripheral sections of said filamentary heater elements, and second ends rigidly fitted to said first current-conducting lead;
- a second group of holders, the number whereof is equal to that of said filamentary heater elements, with said holders having first ends wherewith they are connected to said ends of said second peripheral sections of said filamentary heater elements, and second ends rigidly fitted to said second current-conducting lead, with said holders of said first group positioned sym-metrically to said holders of said second group relative to a plane passing through the longitudinal geometric axis of said thermionic emitter and through the symmetry axis of the polygon normal to the axis passing through the axes said first and said second current-conducting leads.
3. A cathode and heater assembly as claimed in Claim 2, wherein each said holder of said first and said second groups is of a current-conducting material with a resistivity higher than that of said filamentary heater elements, wherein the ratio of cross-section areas of said holder and said filamentary heater element is at least equal to the ratio of their resistivities.
4. A cathode and heater assembly as claimed in Claim 2, wherein the length of each said holder of said first and said second groups is defined by the relation:
, where l1 is the length of said first or said second periphe-ral section of said filamentary heater element;
l2 is the length of said holder;
T1 is the melting temperature of said filamentary element material; and T2 is the melting temperature of said holder material.
, where l1 is the length of said first or said second periphe-ral section of said filamentary heater element;
l2 is the length of said holder;
T1 is the melting temperature of said filamentary element material; and T2 is the melting temperature of said holder material.
5. A cathode and heater assembly as claimed in Claim 2, wherein each said holder of said first and said second groups is of an arched configuration.
Priority Applications (4)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PCT/SU1989/000229 WO1991003831A1 (en) | 1989-08-29 | 1989-08-29 | Cathode-heating device for electron-ray tube |
| CA002034919A CA2034919A1 (en) | 1989-08-29 | 1991-01-25 | Cathode and heater assembly for electron-beam devices |
| FR9100985A FR2672156A1 (en) | 1989-08-29 | 1991-01-29 | Thermoelectronic (thermionic) cathode assembly for electron beam devices |
| CN91101081.5A CN1064564A (en) | 1989-08-29 | 1991-02-21 | The cathode and heater assembly of electron beam devices |
Applications Claiming Priority (3)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| PCT/SU1989/000229 WO1991003831A1 (en) | 1989-08-29 | 1989-08-29 | Cathode-heating device for electron-ray tube |
| CA002034919A CA2034919A1 (en) | 1989-08-29 | 1991-01-25 | Cathode and heater assembly for electron-beam devices |
| CN91101081.5A CN1064564A (en) | 1989-08-29 | 1991-02-21 | The cathode and heater assembly of electron beam devices |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2034919A1 true CA2034919A1 (en) | 1992-07-26 |
Family
ID=32329374
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002034919A Abandoned CA2034919A1 (en) | 1989-08-29 | 1991-01-25 | Cathode and heater assembly for electron-beam devices |
Country Status (4)
| Country | Link |
|---|---|
| CN (1) | CN1064564A (en) |
| CA (1) | CA2034919A1 (en) |
| FR (1) | FR2672156A1 (en) |
| WO (1) | WO1991003831A1 (en) |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1991003831A1 (en) * | 1989-08-29 | 1991-03-21 | Olgerd Ivanovich Babich | Cathode-heating device for electron-ray tube |
| UA28130C2 (en) * | 1998-11-09 | 2000-10-16 | Товариство З Обмеженою Відповідальністю "Нікос-Еко" | Straight filament cathode pack for electron-beam tubes |
| EP1705684A1 (en) * | 2005-03-22 | 2006-09-27 | ICT Integrated Circuit Testing Gesellschaft für Halbleiterprüftechnik mbH | Stabilized emitter and method for stabilizing same |
| PT3500792T (en) * | 2017-01-05 | 2020-05-14 | Signify Holding Bv | Ssl lamp |
Family Cites Families (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3461338A (en) * | 1967-01-16 | 1969-08-12 | Ibm | Non-inductive filament configuration |
| NL7003279A (en) * | 1970-03-07 | 1971-09-09 | ||
| JPS53128971A (en) * | 1977-04-18 | 1978-11-10 | Hitachi Ltd | Manufacture of electron radiation cathode |
| JPS55109343A (en) * | 1979-02-16 | 1980-08-22 | Chiyou Lsi Gijutsu Kenkyu Kumiai | Cathode for electron gun |
| SU873302A1 (en) * | 1979-12-28 | 1981-10-15 | Предприятие П/Я В-2058 | Directly heated cathode |
| GB2178229A (en) * | 1985-07-02 | 1987-02-04 | Dr Wilhelm Heinrich Brunger | Electron source of lanthanum hexaboride |
| WO1991003831A1 (en) * | 1989-08-29 | 1991-03-21 | Olgerd Ivanovich Babich | Cathode-heating device for electron-ray tube |
-
1989
- 1989-08-29 WO PCT/SU1989/000229 patent/WO1991003831A1/en unknown
-
1991
- 1991-01-25 CA CA002034919A patent/CA2034919A1/en not_active Abandoned
- 1991-01-29 FR FR9100985A patent/FR2672156A1/en active Pending
- 1991-02-21 CN CN91101081.5A patent/CN1064564A/en active Pending
Also Published As
| Publication number | Publication date |
|---|---|
| WO1991003831A1 (en) | 1991-03-21 |
| CN1064564A (en) | 1992-09-16 |
| FR2672156A1 (en) | 1992-07-31 |
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| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |