US3233823A

US3233823A - Electron-discharge vacuum apparatus

Info

Publication number: US3233823A
Application number: US238662A
Authority: US
Inventors: Asamaki Tatuo
Original assignee: Nippon Electric Co Ltd
Current assignee: NEC Corp
Priority date: 1961-11-20
Filing date: 1962-11-19
Publication date: 1966-02-08
Anticipated expiration: 1983-02-08

Description

2 Sheets-Sheet 1 TATUO ASAMAKI Feb. 8, 1966 Filed Nov. 19, 1962 lill,

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ELECTRON-'DISCHARGE VACUUM APPARATUS Filed Nov. 19, 1962 2 Sheets-Sheet 2 FI E; E. ,/w

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. residual gas.

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. the envelope.

lwhen emitted, has little getter action.

. emitter device.

3,233,823 ELECTRON-DESCHARGE VACUUM APPARATUS Tatuo Asamaki, Shiba Mita, Minatolni, Tokyo, Japan,

assigner to Nippon Electric Company Limited, Shiliolmmachi, Shiba Mita, Minatckn, Tokyo, Japan, a corporation of Japan Filed Nov. 19, 1962, Ser. No. 238,662 Claims priority, application Japan, Nov. 20, 1961, SiS/42,334 8 Claims. (Cl. 23d-69) This invention relates to an electron-discharge vacuum apparatus and, more particularly, to a getter-ion pump of a magnetron type, a vacuum gauge of the same type, and a getter of the magnetron type. Also, the invention relates to an improvement in a getter-ion pump of the cathodedecomposition type disclosed, for example, in Additional Statement 17 of Japanese Patent Publication No. 16136/ 60 and in a getter-ion pump of the magnetron type disclosed in copending application Serial No. 132,468 entitled, A Magnetron Type Getter-Ion Pump, tiled August 18, 1961, by T. Asamaki, which matured into Patent No. 3,141,605.

Generally, a getter-ion pump comprises an emitter device for emitting into a space within an envelope of the getter-ion pump, particles of a getter material or of a material having large getter action or physical and chemy ical reactivity for the residual gas left unexhausted Within the envelope, and a condensation device such as an anode structure upon which the particles of the getter material deposit for additional getter reaction with the In order to make the emitter device emit the particles of the getter material into the space within the envelope, it is general in a getter-ion pump of cold- Vcathode discharge type as well as in a getter-ion pump of the invention, to bombard the surface of the emitter Such positive ions are produced through ionization of the residual gas which is bombarded either by electrons emitted from the cathode through cold-cathode discharge or by secondary electrons emitted from the cathode through bombardment by the positive ions already produced. The positive ion current acts as an indication of thek degree of vacuum within Use of a getter-ion pump by itself as a vacuum gauge, however, would introduce errors, because high pumping speed of a getter-ion pump results in difierencebetween the vacuum to be measured and the vacuum Which is being actually measured or which is within the envelope of the vacuum gauge. It is, therefore, preferable in using the electron-discharge vacuum apparatus of the invention merely as a vacuum gauge, to form at least a surface portion of the emitter device, either of a material which can scarcely be sputtered or which emits upon bombardment by the positive ions very few particles, if any, or of a material whose particles, In other words, the difference between a getter-ion pump and a vacuum gauge of the same type resides in the diterence between the materials forming at least a surface portion of the In this sense, it is intended in the following description to concurrently mean by a getter-ion pump a vacuum gauge of the same type.

Discharge caused between such an emitter and a condensation device arranged Within an envelope to be maintained at a high vacuum, performs getter or exhausting action upon the residual gas within the envelope. In this sense, it is also intended in the following description to concurrently mean by a getter-ion pump a getter of a magnetron type as Well. In any case, increase in the discharge current, in the intensity of bombardment of the surface of the emitter device by the positive ions, or in the positive ion current of a getter-ion pump at a given United States Patent O 3,233,823 Patented F eb. 8, 1966 lCC vacuum, results in increase in the pumping speed when used as a vacuum pump and in sensitivity when used as a vacuum gauge. Incidentally, the material for the surface of the emitter device may be titanium, zirconium, barium, magnesium, hafnium, or the like for a vacuum pump, while aluminum, molybdenum, stainless steel, copper, or the like for a vacuum gauge.

According to the invention, there is provided a getterion pump of a magnetron type in which electrons emitted in a magnetic ield by the cold-cathode discharge from an emitter device or a cathode towards a condensation device or an anode are accelerated so that such electrons 'may have velocity components in the direction of the magnetic iield or, in other words, in which the electric eld has components in the direction of the magnetic field in the neighborhood of the cathode surface. The necessary electric field components are obtained by providing cathode and anode elements whose geometric configurations and/or relationships generate the necessary electric tield components.

According to the invention, there is also provided a getter of a magnetron type for use in a vacuum envelope of an electron discharge device operated in a magnetic ield, wherein an emitter and a condensation device are installed within the envelope.

One object of the invention is to provide an electrondischarge vacuum apparatus which has a large pumping speed for exhaustion purposes or as a getter-ion pump in a narrow sense and as a getter of a magnetron type and has a large sensitivity as a vacuum gauge and which is operable in a wide-range of vacuums, has long life, and is very simple in construction.

Another object of this invention is to provide an electron-discharge vacuum apparatus having an anode configuration designed to produce electric field components in the direction of the magnetic iield in the immediate region of the cathode surface.

Still another object of this invention is to provide a cathode structure having a conguration which is designed to provide electric iield components in alignment with the magnetic field in the immediate region of the cathode surface.

Another object of this invention is to provide an electron-discharge vacuum apparatus having anode and cathode electrodes which are so designed and positioned as to provide electric iield components in the direction of the magnetic iield in the immediate region of the cathode surface.

These and other objects of the invention will become apparent when reading the accompanying description and drawings in which:

FIGUREI 1 is a diagrammatic cross-sectional View of a magnetron for illustrating the principles of the invention,

FIGURE 2 is a cross-sectional View of an embodiment of the invention,

FIGURE 3 shows a longitudinal section of the embodiment of FIGURE 2 taken along line 3 3 together with line 2-2 along which the section shown in FIG- URE 2 is taken,

FIGURE 4 is a similar longitudinal sectional View of a modiiication of the embodiment of FIGURES 2 and 3,

FIGURE 5 diagrammatically shows an exhausting equipment in which an electron-discharge Vacuum apparatus of the invention serves mainly as a getter-ion pump and at the same time as a vacuum gauge,

FIGURE 6 is a cross-sectional View of a second alternative embodiment of the invention,

FIGURE 7 shows a longitudinal section of the second alternative embodiment taken along line 77 of FIG- URE 6, together with line 6--6 along which the section shown in FIGURE 6 is taken,

FIGURE 8 is a cross-sectional view of a third embodiment of the invention,

FIGURE 9 shows a longitudinal section of the third embodiment taken along line 9-9 of, FIGURE 8, together with line 8-8 along which the section shown in FIGURE 8 is taken,

FIGURE l is a similar longitudinal sectional View of modification of the third embodiment,

FIGURE ll is a cross-sectional view of a fourth embodiment of the invention,

FIGURE l2 shows a longitudinal section of the fourth embodiment taken along line 12-12 of FIGURE ll, together with line 1li-11 along which the section shown in FIGURE l1 is taken,

FIGURE 13 is a similar longitudinal sectional view of a modification of the fourth embodiment.

FIGURE 14 is a cross-sectional view of a fifth embodiment of the invention, and

FIGURE l shows a longitudinal section of the fth embodiment taken along line 15-15 of FIGURE 14, together with line 14--14 along which the section shown in FIGURE 14 is taken.

Referring to FIGURE 1, a cold-cathode magnetron Z0 which is diagrammatically shown therein in cross-section is comprised of an anode 21 and a cathode 22 and is provided with a potential difference V between such electrodes 21 and 22 from a directcurrent power source 23 and with a uniform magnetic field B aligned perpendicularly to the plane of FIGURE 1 and whose direction is extending into the plane of FIGURE l, as shown by the cross-hatched circle, which field is provided by a magnetic field applying means (not shown). If the potential difference V and magnetic eld B are so adjusted that the anode current may becut off when there is no high-frequency electric field between the anode 21 and cathode 22, the orbit of an electron emitted from the cathode 22 with a zero initial velocity will be as shown by a full-line and 'dotted-line epicycloid curve 24. More particularly, such an electron will reach a point 25 which is spaced from the surface of the cathode 22 by a distance v determined by the potential difference V and magnetic field B, and then will turn back to the cathode Z2 to be in most cases absorbed by the cathode 22 Vand not to continue its orbital motion along the next epicycloid portion which is shown in the drawing with the dotted line. The fact is, however, that inasmuch as the electrons emitted from the cathode 22 have such arbitrary initial velocities that extend outwardly of the tangential plane at the emitted points, the actual orbit of an electron will be as shown by a full-line and dotted-line epitrochoid curve 26 when there is no high-frequency electric field.- and when the anode current is cut-off. More particularly, the electron would continue its movement, when it returns back to the surface yof the cathode Z2 and if there were no cathode 22, to a point 27 which is inwardly spaced from the surface of the cathode 22 by a distance v1 determined by the potential difference V, magnetic field B, and direction and magnitude of the initial velocity. Thus, the electrons will move completely along such epitrochoidal orbits if the effect of space charge is neglected. Therefore, the probability of absorption of an electron by the cathode 22 soon after the emission from the cathode 22 is very large. Inasmuch as such electrons that have epitrochoidal orbits 26 are mainly used in a conventional getter-ion pump of the magnetron type, emitted eiectrons immediately disappear from the space between the anode 21 and cathode 22, with the result that neither sufficient ionization of the residual gas within the space nor intensive positive ion bombardment can be expected. In contrast, the orbit of an electron emitted from the cathode 22 is made, in a getter-ion pump of the instant invention, to be, even when the effect of space charge is neglected, as shown by a curve 28 or, more particularly, such that an electron will reach, as it turns back to the cathode 22, a

point 29 which is outwardly spaced from the surface of the cathode 212 by a distance v2 and then departs again away from the surface of the cathode 22, Such an orbit of the electron can be realized by so accelerating the electron emitted from the cathode 22 that it may have velocity component in the direction of the longitudinal axis of the magnetron 2t) or in the direction of the magnetic field. The distance v2 yis determined by the potential diterence V, magnetic field B, direction and magnitude of the initial velocity of the electron, and direction and magnitude of thevelocity which is given to the electron and which has a component in the direction of the magnetic field. Incidentally, the distances v, v1, and v2 are designated by a letter v which corresponds to the potential difference V, because such distances can be calculated in terms of electric potential.

Each of the electrons which are so accelerated as soon as they are emitted from the cathode Z2 of the magnetron 20 that they may have velocity components in the direction of the magnetic field, will continue its orbital motion shown in FIGURE l by the curve 28 without being caught by the cathode 22. Therefore, there are many electrons positioned between the anode Z1 and cathode 22 of the getter-ion pump of the invention. The probability of ionization of a gas particle by an electron is generally maximum when the energy of the electron is 100430 eV (electronwolts). Consequently, the distance between the surface of the cathode 22 and such a point along the orbit Z8 of the electron emitted from the cathode 22 that is remotest from the cathode surface is preferably made, as calculated in terms of potential difference, to be 1GO-130 V in the getter-ion pump of the invention by selection of the potential difference V, magnetic field B, and direction and magnitude of the velocity having a component in the direction of the magnetic field. Thus, it will be appreciated that inasmuch as there are many electrons and the probability of ionization `of the residual gas by such electrons is large in getter-ion pump of the invention, the residual gas is effectively ionized to produce a number of positive ions, with the result that the thus produced large positive ion current provid-es the getter-ion pump of the invention with high pumping speed as an exhausting device and with high sensitivity as a vacuum gauge.

Large positive ion current of the getter-ion pump of the invention results in a widening of the operating range. t is to be noted here that the material deposited after being emitted from the emitter device by the positive ion bombardment, on the surface of the condensation device, will be re-emitted from the condensation device upon reception of the bomabdrnent by electrons or other negative charge particles and will set the residual gas once caught thereby free, with resulting adverse effects on the efficiency as Well as on the operable range of the getter-ion pump. Such adverse effects are substantially eliminated in the getter-ion Vpump of Vthe invention, because the energy of the electron emitted from the emitter device is as small as eV. Furthermore, the life of the getter-ion pump of the invention is much lengthened, because deposition of the sputtered cathode material on the anode surface is substantially uniform as compared with a conventional cold-cathode-discharge getter-ion pump in which such deposition occurs mainly on such parts of the plate-shaped anode that face the en-d opening of the hollow cylindrical cathode.

Referring now to FIGURES 2 and 3 which show a getter-ion pump 30 of the invention, av cathode structure 3i comprises a plurality of substantially rod-shaped emitter devices or cathodes 32, each having a substantially circular cross-section, and a pair of plate-shaped supporting members 33 for supporting, by way of a force fit between holes provided therein and the end portions of the cathodes 32, the cathodes 32 in their desired relative positions. An anode structure 35 comprises plate members 37 which are joined together so as to form hollow rectangular shaped condensation devices or anodes 36 each surrounding an associated cathode 32. The cathode 32 is formed, at least at its surface portion, of a material described in the preamble of the specification according to the purpose for which the getter-ion pump is mainly used for either exhausting or measuring purposes, and is provided at its axially central portion with a constriction or tapering 38 (see FIGURE 3) in such a manner that two identical conical frustrums are made integral in aligned relation and with their smaller bases being connected in common. The anode structure 35 is composed of the plate members 37 made of a metal such as titanium and is rnortised at crossing portions 36a while being spotwelded at abutting portions. The supporting members 33 of the cathode structure 31 which may be spaced by provision of shoulders at the ends of a cathode in the manner described in the patent application No. 132,468 aforementioned, is spaced in this getter-ion pump by two plate-shaped spacers 39. A vacuum envelope 46 for enclosing such anode and cathode structures 35 and 31 co-. prises a cup-shaped member 43 having a suction tube 41 and leadwire tube 42, and a plate-shaped member $4 welded to the cup-shaped member 43 so as to cover the same. The leadwire tube 42 has an annular member 49 brazed thereto at its outer end, a refractory insulator pipe S0 hermetically sealed at its inner end to the annular member 49, a tapered or cup-like member 4.8 hermetically sealed to the outer end of the insulator pipe Sti, and an anode lead rod 46 having the cup-like member 43 brazed thereto adjacent its outer end and having a small disc 45 attached thereto adjacent and radially inwardly spaced from the axially inner end of the leadwire pipe 42. At least such portions of the cup-like and annular members 43 and 49 that are hermetically sealed to the insulator pipe Si?, are made of a vacuum sealing material. One typical sealing material which may be employed in the above mentioned embodiment is presently identified by the trademark Kovan While this material has been found to be advantageous, it should be understood that its recitation here is merely exemplary.

The small disc 45 prevents the cathode material sputtered from the cathode 32 from depositing on the inner surface of the insulator pipe d0 to harm the insulation between the anode 36 and cathode 32. The envelope 40 is formed from a non-magnetic material such as stainless steel. Also, other components whose material has not been specified, are preferably made of a similar material.

lthough the getter-ion pump illustrated in FIGURES 2 and 3 comprises tour pump elements, or four sets ot the cathodes 32 and the surrounding anodes 36, the desired number of such elements may be either only one or less or more than four, depending only upon the needs of the user. The anode cross-section may have circular, hexagonal, or any other polygonal form.

Upon assembly of the getter-ion pump 3i), one of the cathode supporting members 33 is put into the cup-shaped envelope member 43 to which the suction pipe 41 and the leadwire pipe 42 provided with hermetically sealed anode lead rod 46 and others have already been attached. The anode structure is then attached to the inner end of the lead rod 46 by way of spot-welding thereto metal pieces 51 and 52 which are preliminarily spot-welded to the anode structure 35 so that the cathodes 32, when put afterward into the respective holes of the supporting member 33, may be in desired relation with respect to the anodes 36. The cathodes 32 are now put into the respective holes of the supporting member 33. The remaining member ofthe supporting member pair 33 is then disposed in position by placing the spacers 39 therebetween and by putting the free ends of the cathodes 32 into the respective holes of this supporting member 33 so as to complete the cathode structure 31. Thereafter, the plateshaped member 44 of the envelope 4t) is put on the latter supporting member 33 and hermetically welded at the peripheral edge to the cup-shaped member 43. Such welding maybe argon-arc welding or, alternatively, replaced by brazing. It is to be noted here that the depth D of the cup-shaped member 43 is equal to the sum of the thicknesses of the supporting members 33 plus the height of the spacers 39 and also equal to the lengths of the respective cathodes 32 and that the length 0f the anode lead rod 46 is so selected that the anode structure 35 may, when welded to the inner end thereof, bring about the desired spatial relation between the anodes 36 and cathodes 32.

Referring to FGURE 4, a modification 53 of the getterion pump 3@ comprises cathodes S4 having their maximum diameters at their central portions 55. The cathodes 54 taper from the central portions 55 toward the ends thereof such that the configuration oi the cathodes 54 in embodiment 53 is the reverse of cathodes 31, shown in the embodiment of FIGURES 2 and 3. As a further modification, a cathode employed in the getter-ion pump of the invention may have its axially intermediate portion comprised of a succession of such constrictions and bulges, or swellings, as shown in FIGURES 3 and 4, respectively.

tlGURE 5 shows an exhausting system d@ in which use is made of a general type getter-ion pump 59 having a magnetic iield applying means 58 for producing a magnetic field in the direction of the axes of the cathodes such as shown in FIGURE 3 by pole pieces 55 and 57 for the getter-ion pump 36 of FIGURE 3 or 53 of FGURE 4. A flange 6l of the suction pipe 4l of the getter-ion pump 59 is hermetically connected by means of an interposed gasket (not shown) of oxygen-free copper or Tellon with another ange 63 of an exhaust pipe d2. The exhaust pipe 62 which has a valve 64, has also an auxiliary pump 65 such as an oil rotary pump, at an end of the exhaust pipe 62. A reservoir 66 to be evacuated is placed between the valve 64 and the getter-ion pump 59, and an auxiliary vacuum gauge 67 which is situated between the valve 64 and the auxiliary pump 65 is employed which can measure the degree of vacuum up to approximately 10-2 mm. Hg. The getter-ion pump S9 is provided with a direct-current, alternating-current, or impulse voltage across its anodes and cathodes from a power source 68 through the vacuum envelope Aitl or leadwire pipe 42, which are electrically connected to the cathodes, and through the anode lead rod 46 which is electrically connected to the anodes. The magnetic field applying means 5S may be a permanent magnet or an electromagnet operated by a direct-current or alternating-current power (not shown), provided the magnetic eld applying means 58 is capable of producing a spatial uniform held Of magnetic induction of up to about 2,00@ Gauss in the regions where the anode and cathodes of the getter-ion pump 59 are disposed. The power source 63 may have a maximum output voltage of l0 kV, with a drooping characteristic so as not to exceedingly heat the getter-ion pump, and a maximum load current of about 20 mA for about a lS-minute continuous run of a four-element pump of the type shown in FGURE 2. Preferably, the envelope 49 is grounded, while the anode lead and rod 46 is kept at a high voltage level. voir 66, the valve 64 is at first opened to evacuate the reservoir 66 and getter-ion pump 59 by the auxiliary pump 65 up to about lO-2 mm. Hg. The getter-ion pump 59 is then supplied with the electric power and the valve 64 is closed. Upon energization of getter-ion pump S9 a vacuum of approximately lO-5 mm. Hg is obtained.

Approximately three hours after energization of pump 59 a vacuum of l08 mm. Hg is obtained. Such degree of vacuum may be measured by the getterion pump 59 itself.

It, in the getter-ion pump 30 shown in FIGURES 3 and 4, the maximum diameter of the cathodes 32 is 5 mm. and the sides of the cross-sectional squares of the anode structures 36 are each 25 mm., the preferable potential derence V and magnetic lield B are 6 KV. D.C. and 1,500 Gauss, respectively. In operation of such a getter-ion pump 3i?, as shown in

FGURES

2 and 3, the cathodes On evacuating the reser-` 32 emit electrons through cold-cathode discharge. The emitted electrons produce positive ions through ionization of the residual gas within the envelope 49 in the manner explained in detail with reference to FIGURE 1. The positive ions bombard the cathodes 32 to sputter the cathode material and to emit the secondary electrons. The secondary electrons are accelerated so as to have velocity components in the direction of the magnetic field to produce a large positive ion current in the manner explained also with reference to FIGURE 1, because the surfaces of the cathodcs 32 are inclined with respect to the direction of the magnetic field or, in other words, the electric fields adjacent such surfaces have electric field components in the direction of the magnetic field. As described, what is important in the getter-ion pum of the invention is to provide an electric field which has components in the immediate region of the cathode surface in the direction of the magnetic field. Therefore, there are many embodiments and modifications other than the embodiments and modifications so far explained, Some of such embodiments and modications will be described with reference to FIGURES 6 through l5.

Referring to FIGURES 6 and 7, a second preferred embodiment 'id of the invention shown therein comprises an anode structure '7l which is divided, at a central portion thereof in the direction of the magnetic field, into two anode assemblies 72 which, in turn, are united together at their end portions 72a adjacent the leadwire pipe 42 by a channel-shaped member '74 having inwardly directed flanges 73 which are welded. to such anode portions 72a. Anodes 72 have their opposite end portions 72b adjacent the suction pipe 4I by another similar channel-shaped member 75 welded to such portions and preferably provided with a hole 7/ in its base '76. A plurality of cathodes 7S have at their axially central portions a common plate member 79 which is made integral with the cathodes Titi and spaced from the two` anode assemblies 72. lt is preferable in the anode structure 71 of this type that the total axial length of an anode 36 may, although dependent on the distance between the anode assemblies 72 and the supporting members 33 for the cathodes 78, be less than 1.5 times the diameter of a circular cylindrical anode or the distance between the opposing sides of a square cylindrical anode 36. The anode-cathade arrangement of the embodiment shown in FIGURES 6 and 7 cause the electrons emitted from the cathode structure to be directed substantially diagonally away from the Vertical axis of vertically aligned members 7S in rder to produce the necessary electric field components which are in alignment with the direction of the applied magnetic field.

Experiments have shown that with the ratio greater than l.5, the pump operates merely at a lower vacuum. For instance, a pump in which the ratio is 1.6 had substantially no pumping speed and a pumping speed of 2 l./sec. when the pressure of the vacuum is less than 1x10-4 mm. Hg and 4X lr6-4 mm. Hg, respectively.

Referring to FlGURES 8 and 9, a third embodiment Si? shown therein comprises anodes 81 having at their axially central portions plate-shaped pieces Se which, in turn, have at their center portions cir-cular or square holes S3, respectively, for providing spaces between such pieces and the cathodes S2. The anode-cathode structure of the embodiment shown in FIGURES 8 and 9 cause the direction of electrons moving away from the cathode members 82 to have velocity components in the direction of the applied magnetic field in a manner substantially similar to that described with respect to the previously discussed embodiments.

Referring to FIGURE 10, a modification 85 shown therein comprises anodes S1 having at their opposite ends such similar plate-shaped

pieces

86 and 87 that cover the ends.

Referring now to FIGURES 11 and l2, a fourth embodiment 9i? shown therein comprises hollow circular or

square anodes

91, 92, and others, a centrally disposed substantially rod-shaped cathode 93 and radially outwardly situated

cylindrical cathodes

94, 95, and others, which all are arranged coaxially in an alternating fashion equally spaced from one another. By making the axial length of the anodes 9i, 92, (and others) shorter than those of the

cathodes

93, 94, 95, (and others) an electric field is produced in the getter-ion pump 9h that has, in the neighborhood o the cathode surface, field components in the direction of the magnetic field. The outer cathodes 94, 95 (and others) have apertures 96 which mainly serve for facilitating circulation of the residual gas.

Referring to FIGURE 13, a modification 97 shown therein has cathodes whose axially central portions 93, 99 (and others) are outwardly expanded from the ends thereof towards the center. Alternatively, the cathodes may be provided with inwardly going portions from the ends thereof towards the center in contrast to the outwardly going portions 93, 99 (and others). Furthermore, the anodes may be possessed of either centrally or endwise disposed plate-shaped pieces described with reference to the embodiments of FIGURES 8 through 10.

Finally referring to FIGURES 14 and 15, a fifth embodiment itl@ shown therein comprises cathode plates lill, M22, w3, 15N-, and so on each being of length L2 and similar anode plates 1%, 167, 198, and so on having lengths L1 which are shorter in the direction of the magnetic field than the cathode plates lill, 132, lti, Idd, and so on and which are made integral by means of a plate member 105, which all are arranged alternatingly, equally spaced, and in such a manner that the anode plate 165, 1.97, 68, and so on may be disposed with respect to the cathode plate itil, 162, 83, 164, and so on centrally in the direction of the magnetic field and that the spaces between the anodes 16M, 197, 16S, and so on and the cathodes 1M, 102, 1&3, 164, and so on may preferably be directed towards the suction pipe 4l. The getter-ion pump 10b is preferable in that the residual gas will easily diffuse into the getter-ion pump 100 from the exhaust pipe 62 shown in FIGURE 5.

In an electron discharge device such as a magnetron that is provided with a magnet, it is :possible to form a getter-ion pump either by arranging the pump elements within the envelope of the electron `discharge device or by making portions of the electrodes of the electron discharge device serve as the pump element. With such an arrangement, it is possible to set a getter-ion pump in operation concurrently with the electron discharge device without any additional magnet, and thus to maintain the electron discharge device at a high vacuum to lengthen the serviceable life.

Although some specific embodiments and modifications have so far been explained, it will be appreciated that other embodiments and modifications are conceivable in accordance with the spirit of the invention. For instance, either the surface of a cathode supporting member 33 may be covered with refractory insulator such as ceramics or the supporting member 33 itself may be made of such insulator, with a view to preventing a portion of the electrons emitted from a cathode such as thel cathode 32 of the first embodiment 32? shown in

FlGURES

2 and 3, from being absorbed by the conductive supporting member 33 when they reach the surface of such supporting member 33 on account of their velocity components in the direction of the magnetic field and on account of their long mean free paths at an especially high vacuum. In such a modification, the surface of the modified supporting member is negatively charged to repel the electrons which otherwise would reach such surface, with the resuit that electrons participating in ionization of the residual gas are increased. With the same view, a particular electrode such as the electrode 33a may be disposed inwardly of the supporting member 33 in electrically insulated relation to the cathodes and the adjacent supporting member 33 so as to be supplied through the vacuum envelope 40 with a voltage which is negative with respect to the cathodes 32. It is also possible in order to provide the electric field adjacent the cathode surface with components in the direction of the magnetic field, to arrange a grid of 'suitable pitch such as found in a triode either coaxially or parallel to each cathode so that such grids may be supplied with a voltage which is different from those for the anodes and cathodes. One possible arrangement is shown by grid 33.5 of FIGURE 7. It is, therefore, to be understood that the claims of the invention cover all the electron-discharge Vacuum apparatus set forth therein below.

Although this invention has been described with respect to preferred embodiments thereof, it should be understood that many variations and modifications will now be obvious to those skilled in the art, and it is preferred therefore that the scope of this invention be limited not by the specific disclosure herein but only by the appended claims.

The embodiments of the invention in which an exclusive privilege or property is claimed are defined as follows:

1. An electron-discharge vacuum apparatus for use in a vacuum system capable of providing a magnetic field aligned in a first direction comprising cathode means; anode means positioned a spaced distance from said cathode means and adapted to form an open region between said cathode and anode means substantially in alignment with said first direction; said anode and cathode means being adapted for connection to an energy source to produce an electric field therebetween; said anode and cathode means being positioned so that said electric field has a component in alignment with said iirst direction in the immediate region of said cathode means; said cathode means comprising an elongated substantially cylindrical shaped member having its longitudinal axis substantially in alignment with said first direction; said anode means comprising an elongated substantially square shaped shell surrounding said cathode means; the longitudinal axis of said shell being substantially ,in alignment with said first direction; each anode member of said anode means having four sides forming a substantially square opening, the width of any side of said anode member being at least 1.5 times the length of said anode member.

2. An electron-discharge vacuum apparatus for use in a vacuum system capable of providing a magnetic field aligned in a first direction comprising cathode means; anode means positioned a spaced distance from said cathode means and adapted to form an open region between said cathode and anode means substantially in alignment with said first direction; said anode and cathode means being adapted for connection to an energy source to produce an electric field therebetween; said anode and cathode means being positioned so that said electric field has a component in alignment with said first direction in the immediate region of said cathode means; said cathode means comprising an elongated substantially cylindrical shaped member having its longitudinal axis substantially in alignment with said iirst direction; said anode means comprising an elongated metallic shell surrounding said cathode means; the longitudinal axis of said shell being substantially in alignment with said first direction; a plate shaped member having a centrally located aperture; said plate shaped member being positioned substantially perpendicular to said anode shell and intermediate the ends thereof; the periphery of said plate shaped member engaging the inner surface of said anode shell; said cathode member being inserted through said aperture; the surface of said cathode member being spaced a predetermined distance from the periphery of said aperture.

3. An electron-discharge vacuum apparatus for use in a vacuum system capable of providing a magnetic field aligned in a first direction comprising cathode means; anode means positioned a spaced distance from said cathode means and adapted to form an open region between said cathode and anode means substantially in alignment with said first direction; said anode and cathode means being adapted for connection to an energy source to produce an electric field therebetween; said anode and cathode means being positioned so that said electric field has a component in alignment with said first direction in the immediate region of said cathode means; said cathode means comprising an elongated substantially cylindrical shaped member having its longitudinal axis substantially in alignment with said first direction; said anode means comprising an elongated metallic shell surrounding said cathode means; the longitudinal axis of said shell being substantially in alignment with said first direction; a plate shaped member having a centrally located aperture; said plate shaped member being positioned substantially perpendicular to said anode shell and adjacent one end thereof; the periphery of said plate shaped member engaging the inner surface of said anode shell; said cathode member being inserted through said aperture; the surface of said cathode member being spaced a predetermined distance from the periphery of said aperture.

4. An electron-discharge vacuum apparatus for use in a vacuum system capable of providing a magnetic field aligned in a iirst direction comprising:

cathode means;

anode means positioned a spaced distance from said cathode means and adapted to form an open region between said cathode and anode means substantially in alignment with said first direction;

said anode and cathode means being adapted for connection to an enercy source to produce an electric field therebetween;

said anode and cathode means being positioned so that said electric field has a component in alignment with said first direction in the immediate region of said cathode means being comprised of a plurality of cathode members;

said anode means comprising a plurality of anode members, each of said anode members substantially surrounding an associated cathode member;

the length of said cathode member measured in said first direction being substantially greater than the length of said anode members measured in said first direction;

the surface of said cathode means being substantially parallel to said iirst direction;

each of said anode members having four sides forming a substantially square opening, the width of any side of said anode being at least 1.5 times the length of said anode measured in said first direction.

5. The device of claim 4 wherein said cathode means is comprised of an elongated substantially cylindrical shaped member having its longitudinal axis substantially in alignment with said rst direction; said cathode member being tapered from its central portion towards the ends thereof.

6. The device as set forth in claim 4 wherein said cathode means is comprised of an elongated substantially cylindrical shaped member having its longitudinal axis substantially in alignment with said first direction; said cathode member being tapered inwardly from its ends toward the central portion thereof.

7. An electron-discharge vacuum apparatus for use in a vacuum system capable of providing a magnetic field aligned in a first direction comprising:

cathode means;

said anode and cathode means being adapted for connection to an energy source to produce an electric field therebetween;

said anode and cathode means being positioned so that said electric field has component in alignment with said first direction in the immediate region of said cathode means being comprised of a plurality of cathode members;

the length of said cathode member measured in said first direction being.,y substantially greater than the length of said anode members measured in said rst direction;

the surface of said cathode means being substantially parallel to said first direction;

each of said anode members having four sides forming a substantially square opening, the Width of any side of said anode being at least 1.5 times the length of said anode measured in said rst direction;

said cathode means comprising an elongated rod of substantially circular cross-section having its longitudinal axis in alignment with said rst direction and being tapered from the intermediate portion towards the er1-ds thereof.

t5. An electron-discharge vacuum apparatus for use in a vacuum system capable of providing a magnetic eld aligned in a tiret direction comprisinv:

cathode means;

anode means positioned a spaced distance from said cathode means and adapted to form an open region between said cathode and anode means substantially in alignment with said irst direction;

said anode and cathode means being adapted for connection to an energy source to produc-e an electric field therebetween;

said anode and cathode means being positioned so that said electric eld has a component in alignment with said iirst direction in immediate region of said cathode means;

said cathode means comprising an elongated substantially conical shaped member having its longitudinal axis Substantially in alignment with said first direction and said conical surface being inclined relative to the direction of the magnetic field for the purpose of imparting a velocity component in the position of said cathode longitudinal axis to electrons emitted from said cathode;

said anode means comprising an elongated multi-sided shell surrounding and spaced from said cathode means;

the longitudinal axis of said shell being substantially in alignment with said rst direction.

References Cited bythe Examiner UNITED STATES PATENTS 2,993,638 7/1961 Hall et al. 230--69 DONLE. i. STOCKING, Primary Examiner.

WARREN E. COLEMAN, LAURENCE V. EFNER,

Examiners.

Claims

1. AN ELECTRON-DISCHARGE VACUUM APPARATUS FOR USE IN A VACUUM SYSTEM CAPABLE OF PROVIDING A MAGNETIC FIELD ALIGNED IN A FIRST DIRECTION COMPRISING CATHODE MEANS; ANODE MEANS POSITIONED A SPACED DISTANCE FROM SAID CATHODE MEANS AND ADAPTED TO FORM AN OPEN REGION BETWEEN SAID CATHODE AND ANODE MEANS SUBSTANTIALLY IN ALIGNMENT WITH SAID FIRST DIRECTION; SAID ANODE AND CATHODE MEANS BEING ADAPTED FOR CONNECTION TO AN ENERGY SOURCE TO PRODUCE AN ELECTRIC FIELD THEREBETWEEN; SAID ANODE AND CATHODE MEANS BEING POSITIONED SO THAT SAID ELECTRIC FIELD HAS A COMPONENT IN ALIGNMENT WITH SAID FIRST DIRECTION IN THE IMMEDIATE REGION OF SAID CATHODE MEANS; SAID CATHODE MEANS COMPRISING AN ELONGATED SUBSTANTIALLY CYLINDRICAL SHAPED MEMBER HAVING ITS LONGITUDINAL AXIS SUBSTANTIALLY IN ALIGNMENT WITH SAID FIRST DIRECTION; SAID ANODE MEANS COMPRISING AN ELONGATED SUBSTANTIALLY SQUARE SHAPED SHELL SURROUNDING SAID CATHODE MEANS; THE LONGITUDINAL AXIS OF SAID SHELL BEING SUBSTANTIALLY IN ALIGNMENT WITH SAID FIRST DIRECTION; EACH ANODE MEMBER OF SAID ANODE MEANS HAVING FOUR SIDES FORMING A SUBSTANTIALLY SQUARE OPENING, THE WIDTH OF ANY SIDE OF SAID ANODE MEMBER BEING AT LEAST 1.5 TIMES THE LENGTH OF SAID ANODE MEMBER.