US3869632A - Glow cathode - Google Patents

Glow cathode Download PDF

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Publication number
US3869632A
US3869632A US391056A US39105673A US3869632A US 3869632 A US3869632 A US 3869632A US 391056 A US391056 A US 391056A US 39105673 A US39105673 A US 39105673A US 3869632 A US3869632 A US 3869632A
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United States
Prior art keywords
mounting
electron emitter
glow cathode
electron
glow
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Expired - Lifetime
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US391056A
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English (en)
Inventor
Friedhelm Schulz
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Gesellschaft fuer Kernforschung mbH
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Gesellschaft fuer Kernforschung mbH
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J27/00—Ion beam tubes
    • H01J27/02—Ion sources; Ion guns
    • H01J27/022—Details

Definitions

  • This device can be operated at a gas pressure of approximately 0.2 to 0.5 Torr and a heating voltage of 100 to 200 volts to provide deute- References cued rium orhydrogen ions for a cyclotron UNITED STATES PATENTS 1972.078 2/1961 Levi .1 313/346 R 1 .Clalms, 2 Drawmg Flgures GLOW CATHODE
  • the present invention relates to a glow cathode with g a current input and output and to the use of such a glow cathode.
  • a tungsten wire bar heated with 100 to 300 amperes direct current serves as the glow cath ode.
  • a low pressure gas discharge burns at a low gas pressure (e.g. Torr deuterium gas) between the glow cathode and the burn chamber which is formed of graphite.
  • the discharge plasma is constricted by a strong magnetic field which is disposed in theplane of the tungsten wire bar or in a plane parallel thereto to form a more or less precisely defined column between the glow cathode and a reflector for electrons which is insulated from the burn chamber.
  • the reflector is negatively charged during operation.
  • the ions are extracted transversely to the magnetic field through a slit in the burn chamber by a high frequency voltage at an acceleration sector.
  • An increase in the ion yield through an increase in the heating of the glow cathode of the ion source, or of the gas pressure in the burn chamber or of the discharge voltages is secured only at the expense of an even shorter life for the ion source.
  • the relatively large area of the tungsten wire bar as the emission surface for the electrons and the area ofthe reflector prevent an increase in the electron density in the discharge plasma, make a perfect congruence in the centering more difficult and permit no further approximation of the reflector and the glow cathode due to the mechanical constriction in the burn chamber of'the ion source in the area of the slit for taking off the ions.
  • the tungsten wire bars are hot resistant against ion bombardment and are not stable enough against transverse magnetic forces.
  • FIG. 1 is a sectional view of a preferred embodiment I of the present invention.
  • FIG. 2 is a sectional view of a detail.
  • any of the metals or metal carbides which are used in known electron sources may be used, but tungsten is preferred.
  • graphite is preferred as the mounting material in electricalcontact with the electron emitter of this invention. but other materials having the indicated physical and electrical properties may be used.
  • FIG. l is a vertical view. partly in section. of an electron source embodying this invention.
  • FIG. 2 isanother vertical view, also partly in section,
  • tion emits electrons andin which the direct vicinity, at 7 electron-emitting means composed of a highly refractory, substantially infusible material having a high elec tron work function.
  • the mounting for the emitter means is more-or-less in the form of an inverted U with the upper, arcuate connecting portion having a cross section of lesser area than that of the lower depending arms.
  • FIG. I shows the lower portion of an ion source for an isochron cyclotron (not shown) in which, by a low pressure gas discharge of ap proximately 0.2 to 0.5 Torr, deuterium or hydrogen ions are produced in the throat 2 of a burn chamber 1.
  • the discharge burns between emitter means 3 and a reflector (not shown) in the throat 2 at a heating voltage between and 200 volts.
  • the magnetic field is disposed in or parallel to the sectional plane of the illustrated device.
  • the ions produced in the discharge plasma are extracted by a high frequency voltage (approximately 40 kV and 33 MHz) (1 MHz lMC/s) in an acceleration sector (not shown) in a direction transversely to the magnetic field through a slit (also not shown) in the wall of the burn chamber throat 2.
  • a high frequency voltage approximately 40 kV and 33 MHz
  • the glow cathode 3 can be designed as a pill or button, which may be rectangular or cylindrical with straight or tapering sides, and is heated by a direct current of lOO to 300 amperes. This strong direct current heats the emitter 3 in such a Way that with an arc voltage of approximately 200 V an arc current of 1.5 ampere can flow for the discharge plasma. resulting in an arc output of 300 watt.
  • the electron emitter 3 which may be made of a metal or a metal carbide such as, for example, tungston hafnium carbide, zirconium carbide, molybdenum carbide, or an alloy of 1 these carbides, is mounted in conductive elements 5 and 6 which consist of a highly refractory, substantially infusible material with a high electron workfunction. This is preferably graphite.
  • the current conductors 5 and 6 form the arms of a U-shaped device, and each has a cross section larger than that of the arcuate connecting portion 7, so that in this region the resistance to the heating current for the emittermeans 3 isincreased.
  • Portion 7 is provided with a bore 8 which .is conically tapered, flaring outwardly at its upper region and terminating at its lower region in a recess 9 of reduced cross section with such dimensions as to at least partially enclose the pill 3 and retain it snugly.
  • bo're 8 can be so designed that the tip 4 of the emitter means will extend beyond the surface of portion 7.
  • the material of portion 7 which contacts the pill 3 must be such that the two do not react chemically.
  • the arms 5 and 6 of the retaining means each of which may be made of a single piece of graphite in the same manner as the curved portion 7 are provided, respectively, with leads l and 11 which serve as connections to the source of current for operating the device.
  • these leads l0 and 11 are designed in the form of rods which are inserted into recesses 12 and 13 in the arms and 6, and are retained therein threadedly, frictionally, or in any other conventional manner out of contact with the electron emitter button 3, as it-may be observed in FIG. 1. a
  • FIG. 2 is a vertical view of the glow cathode transversely of the are 7 of the mounting means.
  • the cross section of the arcuate retainer 7 is less, at least in the region 9 containing the pill or button 3 therein, than the cross section of the arms 5 or 6.
  • a bore 14 is preferably the mounting means, through which a pin may be inse'rted to eject the spent pill out of recess 9.
  • Glow cathode comprising: a. an electron emitter of button shape, made of a metal or metal carbide having a high melting point; b. an electrically conductive mounting made of a highly refractory, substantially infusible material having a high electron work function, said electron emitter being held bysaid mounting; and
  • lead wire means in contact with said mounting and out of contact with said electron emitter for passing an electric current through said electron emitter for heating the same.
  • Glow cathode as defined in claim 3, including means defining a bore in said connecting portion of said mounting, said electron emitter being disposed in.
  • electron emitter is in the form of a cylinder made of, hafnium carbide, zirconium carbide", molybdenum carbide or alloy of these carbides.
US391056A 1972-09-01 1973-08-24 Glow cathode Expired - Lifetime US3869632A (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
DE2242986A DE2242986C3 (de) 1972-09-01 1972-09-01 Glühkathode

Publications (1)

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US3869632A true US3869632A (en) 1975-03-04

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ID=5855189

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US391056A Expired - Lifetime US3869632A (en) 1972-09-01 1973-08-24 Glow cathode

Country Status (9)

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US (1) US3869632A (sv)
CA (1) CA1030589A (sv)
CH (1) CH557597A (sv)
DE (1) DE2242986C3 (sv)
FR (1) FR2198249B1 (sv)
GB (1) GB1433238A (sv)
IT (1) IT991864B (sv)
NL (1) NL7311915A (sv)
SE (1) SE389255B (sv)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2003075305A2 (en) * 2002-03-06 2003-09-12 Applied Materials, Inc. Indirectly heated button cathode for an ion source
US20040061068A1 (en) * 2002-09-30 2004-04-01 Applied Materials, Inc. Indirectly heated button cathode for an ion source

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2192751B (en) * 1986-07-14 1991-02-13 Denki Kagaku Kogyo Kk Method of making a thermionic cathode structure.

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2972078A (en) * 1959-01-23 1961-02-14 Philips Corp Carburization of dispenser cathodes
US3270239A (en) * 1963-09-20 1966-08-30 Union Carbide Corp Solar simulation apparatus
US3732454A (en) * 1971-11-24 1973-05-08 Hitachi Ltd Glow discharge tube for atomic light-absorption analysis

Family Cites Families (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB1046639A (en) * 1964-08-17 1966-10-26 Gen Electric Improvements in dispenser cathode
DE2029571C3 (de) * 1970-06-16 1980-09-11 Kernforschungszentrum Karlsruhe Gmbh, 7500 Karlsruhe Ionenquelle für ein Zyklotron

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2972078A (en) * 1959-01-23 1961-02-14 Philips Corp Carburization of dispenser cathodes
US3270239A (en) * 1963-09-20 1966-08-30 Union Carbide Corp Solar simulation apparatus
US3732454A (en) * 1971-11-24 1973-05-08 Hitachi Ltd Glow discharge tube for atomic light-absorption analysis

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2003075305A2 (en) * 2002-03-06 2003-09-12 Applied Materials, Inc. Indirectly heated button cathode for an ion source
WO2003075305A3 (en) * 2002-03-06 2003-11-27 Applied Materials Inc Indirectly heated button cathode for an ion source
US20040061068A1 (en) * 2002-09-30 2004-04-01 Applied Materials, Inc. Indirectly heated button cathode for an ion source
US6878946B2 (en) 2002-09-30 2005-04-12 Applied Materials, Inc. Indirectly heated button cathode for an ion source

Also Published As

Publication number Publication date
SE389255B (sv) 1976-10-25
CH557597A (de) 1974-12-31
DE2242986B2 (de) 1980-09-04
GB1433238A (en) 1976-04-22
IT991864B (it) 1975-08-30
NL7311915A (sv) 1974-03-05
CA1030589A (en) 1978-05-02
FR2198249B1 (sv) 1976-05-14
FR2198249A1 (sv) 1974-03-29
DE2242986C3 (de) 1981-05-07
DE2242986A1 (de) 1974-03-07

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