US3331975A - Cooling apparatus for cathode getter pumps - Google Patents

Cooling apparatus for cathode getter pumps Download PDF

Info

Publication number
US3331975A
US3331975A US433992A US43399265A US3331975A US 3331975 A US3331975 A US 3331975A US 433992 A US433992 A US 433992A US 43399265 A US43399265 A US 43399265A US 3331975 A US3331975 A US 3331975A
Authority
US
United States
Prior art keywords
cathode
glow discharge
anode
cooling means
passageways
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Expired - Lifetime
Application number
US433992A
Other languages
English (en)
Inventor
Robert L Jepsen
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Varian Medical Systems Inc
Original Assignee
Varian Associates Inc
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority to GB1095383D priority Critical patent/GB1095383A/en
Application filed by Varian Associates Inc filed Critical Varian Associates Inc
Priority to US433992A priority patent/US3331975A/en
Priority to DE1539144A priority patent/DE1539144C3/de
Priority to FR49784A priority patent/FR1468317A/fr
Application granted granted Critical
Publication of US3331975A publication Critical patent/US3331975A/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Images

Classifications

    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J41/00—Discharge tubes for measuring pressure of introduced gas or for detecting presence of gas; Discharge tubes for evacuation by diffusion of ions
    • H01J41/12—Discharge tubes for evacuating by diffusion of ions, e.g. ion pumps, getter ion pumps
    • H01J41/18—Discharge tubes for evacuating by diffusion of ions, e.g. ion pumps, getter ion pumps with ionisation by means of cold cathodes
    • H01J41/20—Discharge tubes for evacuating by diffusion of ions, e.g. ion pumps, getter ion pumps with ionisation by means of cold cathodes using gettering substances

Definitions

  • a glow discharge apparatus including means for cooling the apparatus.
  • the cooling means comprises an elongated heat conductive tubular member through which a cooling fluid may be circulated, brazed to the edges of the cathode plates on the surfaces facing the anode.
  • This particular embodiment of the invention is widely used for evacuation during processing of the electronic tubes such as klystrons, magnetrons and traveling wave tubes where there is high out-gassing, for example, during the initial stages of the tube bake-out cycle and during activation of oxide-coated cathodes.
  • a glow discharge apparatus having an anode electrode, a pair of cathode electrodes, usually made of titanium, spaced from the anode electrode and having portions disposed opposite the anode electrode and means adapted to cool the cathode electrodes in intimate contact with the portions disposed opposite the anode electrode.
  • the cooling means may be an elongated heat conductive tubular member for circulating a cooling fluid and in those apparatuses which utilize an anode electrode having a plurality of openings therein defining a plurality of glow discharge passageways grouped transversely to the longitudinal axes of the passageways, the tubular member may either be intersected by or spaced from the axes of the glow discharge passageways.
  • the distance between the cooling tubulations was approximately 3 inches.
  • the temperature in the central regions of the cathodes would rise to 900 C. or higher.
  • the maximum cathode temperature less than about 300 C. (to prevent significant re-evolution of previously pumped hydrogen), it is necessary to provide cooling tubulations which are more closely spaced, for example, approximately 1 inch apart rather than 3 inches.
  • cooling means which may comprise an elongated heat conductive tubular member for circulating fluid, is placed in addition in intimate contact with the central portions of the cathode.
  • the cooling means may be arrayed in a variety of ways on the cathode. In one array the cooling means pass beneath the anode cell centers, that is, intersected by the cell axes. Since power tends to concentrate at the centers of the cells, placing the cooling means directly beneath the cell centers should improve heat transfer and lead to lower cathode temperatures.
  • the cooling means are deliberately spaced away from the anode cell axes, for example, along the anode cell interstices. Cathode erosion is greater at the cell centers. Eventually the cathode may be pierced completely. If the cooling means is placed directly beneath the cell axes, the cooling means may eventually puncture, leading to catastrophic p ump failure and letting the pump and device being evacuated up to water. The choice between these two means of cooling will depend on the application. Where the lowest cathode temperatures are required, the cooling tubulations should pass beneath the anode cell centers. Where catastrophic pump failure must be avoided, the cooling tubulations should be spaced away from the anode cell axes.
  • One feature of the present invention is the provision in a glow discharge apparatus of an anode electrode, a cathode electrode spaced from the anode electrode and having portions disposed opposite the anode electrode and means adapted to cool the cathode in intimate contact with the portions disposed opposite the anode electrode.
  • Another feature of the present invention is the provision in a glow discharge apparatus of an anode elec trode having a plurality of openings therein defining a plurality of glow discharge passageways grouped transversely to the longitudinal axes of the passageways, a cathode electrode spaced from the anode electrode and having portions disposed opposite the glOW discharge passageways, means adapted to cool the cathode in intimate contact with the portions disposed opposite the glow discharge passageways and either intersected by or spaced from the axes of the glow discharge passageways.
  • FIG. 1 is a plan view partly in cross-section of a novel glow discharge apparatus of the present invention
  • FIG. 2 is a cross-section taken along the lines 22 of FIG. 1;
  • FIG. 3 is a plan view similar to FIG. 1 of an alternate embodiment of the present invention.
  • a cup-shaped member 11 is closed off at its flanged open end 12 by a closure plate 13 welded thereto thereby forming an evacuable envelope 14.
  • a side wall 15 of envelope 14 is apertured to receive a hollow conduit 16 provided with a mounting flange 17 for communication with a structure to be evacuated (not shown).
  • Rod 19 is insulated from and carried on closure plate 13 through the intermediary of a high voltage teed-through 20.
  • the free end of rod 19 provides a terminal for applying a positive anode voltage, typically, 210 kv., with-respect to two substantially rectangular cathode plates 21,'for example, titanium.
  • the anode has 12 cells, approximately 1 inch square and 1 inch long.
  • the cathode plates 21 are spaced apart at their corners from each other and from anode 18 by means of spacers 22. At the opposite end the cathode plates are mechanically locked in position substantially parallel to and spaced from anode 18 by means of insulators 23 brazed toanode studs 24 and supported from the side walls 15,
  • the cathode plates are 4.75 inches long, 3.75 inches high, 0.125 inch thick and are spaced apart 1.625 inches.
  • a permanent magnet 28 having a pair of pole pieces 29 is positioned against clips 30 such that its magneticlines of flux, typically 1000 gauss thread through the individual cellular elements, of anode 18 and in substantial parallelism to the longitudinal axes thereof.
  • the novel cooling means 31 of the present invention includes a continuous, elongated heat conductive tubing such as titanium brazed to the portions of the titanium cathode plates 21 directly opposite cellular anode 18 on their surfaces facing away from anode 18, through the use of tube clips 33 and aluminum as the brazing material.
  • the ends of tubing 32. extend out of envelope 14 through apertures in end plate 13 which are closed by brazing cups 34.
  • the tubing 32 provides a path for a cooling fluid such as water in intimate contact with the portions of the cathode plates normally subjected to impinging positive ions produced by the glow discharge through the anode and between the cathode plates.
  • the tubing 32 is spaced from the individual anode cell axes which normally are the regions of most intense ion bombardment, lying along the anode cell interstices.
  • the applied potential produces a region of intense electric field between the cellular anode 18 and cathode plates 21.'This 6l6CtllC,'fild, acting in combina-. tion with the magnetic field, produces a breakdown of gas Within the pump resulting in a glow discharge within the individual cellular anode compartments and between the cathode plates 21.
  • the glow discharge results in positive ions being driven into the cathode plates 21 to produce dislodgment of reactive'cathode material which is thereby sputtered onto the nearby anode 18 to produce gettering of molecules in the gaseous state coming in contact therewith. In this manner the pressure within the envelope 14 and, therefore, structures communicating therewith, is reduced.
  • a cooling fluid such as water is circulated through the tubing 32. This circulation of fluid permits dissipation of heat in a more efficient manner than heretofore known from the ion bombarded portions of the cathode plates 21.
  • FIG. 3 thereis shown anotherembodiment of the present invention.
  • the apparatus of this embodiment is substantially the same as that of the apparatus shown in FIGS. 1 and 2 with the exception that the tubing 32 is intersected by the individual cell axes of the anode 18.
  • a glow discharge apparatus comprising:
  • an anode electrode having a plurality of openings therein defining a plurality of glow discharge passageways arranged in a pattern and grouped, transversely to the longitudinal axes of said passageways;
  • cooling means adapted to cool said cathode in intimate contact with said cathode portions disposed opposite said glow discharge passageways, said cooling means being formed in a non-linear shape whereby portions of the cooling means lie adjacent other portions of the cooling means, said adjacent portions being substantially spaced from each other,- and said shape of the cooling means being determined by saidpattern of the discharge passageways.
  • cooling means comprises anelongated heat conductive tubular member for circulating a cooling fluid.
  • the apparatus according to claim 4 including means for producing and directing a magnetic field axially of and within a plurality of said glow discharge passageways.
  • the apparatus according to claim 5 including means for applying a potential to said anode electrode positive with respect to said cathode electrode.

Landscapes

  • Electron Tubes For Measurement (AREA)
  • Particle Accelerators (AREA)
  • Plasma Technology (AREA)
US433992A 1965-02-19 1965-02-19 Cooling apparatus for cathode getter pumps Expired - Lifetime US3331975A (en)

Priority Applications (4)

Application Number Priority Date Filing Date Title
GB1095383D GB1095383A (enrdf_load_stackoverflow) 1965-02-19
US433992A US3331975A (en) 1965-02-19 1965-02-19 Cooling apparatus for cathode getter pumps
DE1539144A DE1539144C3 (de) 1965-02-19 1966-02-08 lonengetterpumpe
FR49784A FR1468317A (fr) 1965-02-19 1966-02-16 Appareil à décharge luminescente

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US433992A US3331975A (en) 1965-02-19 1965-02-19 Cooling apparatus for cathode getter pumps

Publications (1)

Publication Number Publication Date
US3331975A true US3331975A (en) 1967-07-18

Family

ID=23722383

Family Applications (1)

Application Number Title Priority Date Filing Date
US433992A Expired - Lifetime US3331975A (en) 1965-02-19 1965-02-19 Cooling apparatus for cathode getter pumps

Country Status (3)

Country Link
US (1) US3331975A (enrdf_load_stackoverflow)
DE (1) DE1539144C3 (enrdf_load_stackoverflow)
GB (1) GB1095383A (enrdf_load_stackoverflow)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3994625A (en) * 1975-02-18 1976-11-30 Varian Associates Sputter-ion pump having improved cooling and improved magnetic circuitry
US20070286738A1 (en) * 2006-06-12 2007-12-13 Varian, Inc. Vacuum ion-getter pump with cryogenically cooled cathode
US9053917B2 (en) 2013-03-29 2015-06-09 Agilent Technologies, Inc. Vacuum fired and brazed ion pump element

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2167275A (en) * 1935-10-07 1939-07-25 Gen Electric X Ray Corp High voltage x-ray tube
US3149774A (en) * 1961-01-27 1964-09-22 Varian Associates Getter ion pump method and apparatus

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2167275A (en) * 1935-10-07 1939-07-25 Gen Electric X Ray Corp High voltage x-ray tube
US3149774A (en) * 1961-01-27 1964-09-22 Varian Associates Getter ion pump method and apparatus

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3994625A (en) * 1975-02-18 1976-11-30 Varian Associates Sputter-ion pump having improved cooling and improved magnetic circuitry
US20070286738A1 (en) * 2006-06-12 2007-12-13 Varian, Inc. Vacuum ion-getter pump with cryogenically cooled cathode
US9053917B2 (en) 2013-03-29 2015-06-09 Agilent Technologies, Inc. Vacuum fired and brazed ion pump element

Also Published As

Publication number Publication date
DE1539144C3 (de) 1975-11-27
GB1095383A (enrdf_load_stackoverflow)
DE1539144A1 (de) 1970-12-03
DE1539144B2 (de) 1975-04-10

Similar Documents

Publication Publication Date Title
EP0054621B1 (en) High temperature ion beam source
US2993638A (en) Electrical vacuum pump apparatus and method
US4061944A (en) Electron beam window structure for broad area electron beam generators
US4694222A (en) Ion plasma electron gun
US4028583A (en) High power-double strapped vane type magnetron
US3109123A (en) Electron discharge devices with a sharp edged cathode
US3956712A (en) Area electron gun
US2512858A (en) Electron discharge device
US3331975A (en) Cooling apparatus for cathode getter pumps
US2075855A (en) Magnetron
US3540812A (en) Sputter ion pump
US3789310A (en) High-emission cold cathode
US3161802A (en) Sputtering cathode type glow discharge device vacuum pump
US2844752A (en) Electron discharge device
US2428661A (en) Electric discharge device of the gas filled type
US3149774A (en) Getter ion pump method and apparatus
US2650997A (en) Heat shielded cathode
US3416722A (en) High vacuum pump employing apertured penning cells driving ion beams into a target covered by a getter sublimator
US3916247A (en) Shell type magnetron device
US3070719A (en) Cathodes for magnentically-confined glow discharge apparatus
US3218502A (en) High power electron discharge device
US3376455A (en) Ionic vacuum pump having multiple externally mounted magnetic circuits
US3125283A (en) Vacuum pump
US2454031A (en) Electric discharge device of the magnetron type
US3271614A (en) Electron discharge device envelope structure providing a radial force upon support rods