US3383541A - Glow discharge cathode having a large electron beam emitting aperture - Google Patents

Glow discharge cathode having a large electron beam emitting aperture Download PDF

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Publication number
US3383541A
US3383541A US508302A US50830265A US3383541A US 3383541 A US3383541 A US 3383541A US 508302 A US508302 A US 508302A US 50830265 A US50830265 A US 50830265A US 3383541 A US3383541 A US 3383541A
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United States
Prior art keywords
cathode
aperture
electron beam
wall
glow discharge
Prior art date
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Expired - Lifetime
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US508302A
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English (en)
Inventor
Fernand J Ferreira
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RTX Corp
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United Aircraft Corp
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Filing date
Publication date
Application filed by United Aircraft Corp filed Critical United Aircraft Corp
Priority to US508302A priority Critical patent/US3383541A/en
Priority to GB51397/66A priority patent/GB1170435A/en
Priority to SE15686/66A priority patent/SE315340B/xx
Priority to DE19661589005 priority patent/DE1589005B1/de
Priority to FR83926A priority patent/FR1499093A/fr
Application granted granted Critical
Publication of US3383541A publication Critical patent/US3383541A/en
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
    • H01J37/02—Details
    • H01J37/04—Arrangements of electrodes and associated parts for generating or controlling the discharge, e.g. electron-optical arrangement or ion-optical arrangement
    • H01J37/06—Electron sources; Electron guns
    • H01J37/077—Electron guns using discharge in gases or vapours as electron sources
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J17/00—Gas-filled discharge tubes with solid cathode
    • H01J17/02—Details
    • H01J17/04—Electrodes; Screens
    • H01J17/06—Cathodes
    • H01J17/066—Cold cathodes
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J2893/00—Discharge tubes and lamps
    • H01J2893/0064—Tubes with cold main electrodes (including cold cathodes)
    • H01J2893/0065—Electrode systems
    • H01J2893/0066—Construction, material, support, protection and temperature regulation of electrodes; Electrode cups

Definitions

  • ABSTRACT F THE DISCLOSURE A large apertured hollow cathode is described for producing a collimated beam of electrons and wherein the aperture is either equal or larger than the cathode fall or bears a predetermined relationship to the entire frontal beam emitting surface of the cathode.
  • These narrow apertured hollowcathodes have hollow chambers fabricated from a wire mesh or solid metal with a single aperture in one end.
  • a wel1-detned pencil beam of high current density, high energy electrons emanate from the aperture.
  • the hollow cathode has a cathode fall region adjacent its external surface.
  • the electrons for the beam are obB tained, however, from a plasma generated by an intense discharge within the chamber enclosed by the cathode. If the aperture through which the electron beam emerges is then so shaped to where at least one cross-sectional di mension is less than the size of the cathode fall region, an electrostatic focussing eifect o n lthe electrons is obn tained and a well-defined beam is produced.
  • the aperture has at least one cross-sectional-diu mension -which is less than the cathode fall distance D., and the beam produced by it is noticeably smaller' than the aperture. It has been found however that a stableelecd tron 'beam can also be produced if the aperture becomes equal or larger at long as the side walls still defnefa cavity within which the electron beam can be formed.
  • the size of the aperture is characterized by the shape of the electron beam it produces. The shape of the beam having cross-sectional dimensions that are equal or larger than the corresponding aperture dimensions. Althouglithe relatively large aperture size of the cavity reduces. the focussing action, the electron beam that emergesfrom the cavity may be advantageously used for the working of materials.
  • FIGURE l' shows a cross-sectional view of a large apertured hollow annular cathode of this invention.
  • FIGURE 2 shows a prior art narrow apertured hollow cathode.
  • FIGURE 3 is a side view of a large apertured hollow cathode.
  • FIGURE 4 illustrates a wide apertured hollow cathode of the single bounding wall type.
  • FIGURE 5 is an end. view of the cathode of FIG URE 4.
  • a hollow annular cathode 1 is located in a chamber 3 of which a portion of one of its walls 5 is shown.
  • the chamber 3 is evacuated to the appropriate pressures necessary for establishing an electron beam from the hollow cathode.
  • the cathode 1 has a peripheral rear wall 7 and extending inwardly therefrom two side walls 9 and 11.
  • the side walls 9 and 11 intersect the extremitiesof rear wall 7 at right angles so that an annular cavity 14 is formed.
  • the cathode 1 has an annular aperture 16 which is formed by the inward ends of walls 9 and 11..
  • the cathode 1 is annular but other closed circuitous arrangements of the cathode are possible, such as for the working of irregularly shapedv ⁇ workpieces.
  • a workpiece 18 Coaxial with the annular cathode is a workpiece 18 which serves an anode and is connected to the positive side of a high voltage source 20.
  • the positive side of the high voltage power supply may be connected to any large com ductive surface within the chamber 3.
  • the negative side of the source 20 is connected to the cathode 1 via the high voltage cable 22 and conductor feedthrough assembly 24.
  • the cathode 1 is supported at several places around its perimeter with nonconductive pin assembly 26.
  • the feedn through assembly 24 and the pin support assembly 26 may be of the type described in the copending applica tion by Allan P. Walch, entitled, Mounting for a Glow Discharge Cathode, Ser. No, 508,201, filed Nov. 1.7, 1965, and assigned to the same assignee.
  • the gap between the shield and the cathode is adjusted according to well-known gas pressure scaling laws.
  • FIGURE 2 shows a prior art narrow apertured hollow cathode without a shield as described in my copending application Ser. No. 417,399.
  • the cathode 30 is provided with an aperture 32 of height A and length L in one wall 34 which has a height H.
  • the aperture may be circular if its length L is small in 4 which case a pencil beam maybe produced from the deu vice.
  • the aperture-to-wall ratio of A/H is less than .7 and the aperture has at least one cross-sectional dirnena sion such as A which is less than the cathode fall Dc.
  • the hollow cathode 1 when charged to the proper potential and exposed to the proper pressure level will produce a well-defined electron beam whose width is ape proximately that of the aperture 16.
  • the electrons for the beam are produced to a large extent as a result of the trapping effect in the cavity 14.
  • the plasma in this cavity can be made more intense by adding extensions such as 36 and 38 in FIGURE 3 to narrow the aperture 16. There is a well-defined limit, however, to the size of these extensions and this may be determined bythe relationship 'between the A dmen sion of the aperture and H dimension of the wall in which it appears. Below approximately an A/I-I ratio of .7
  • the beam protruding from theqcathode is much smaller than the aperture and has the characteristic of prior art narrow apertured hollow cathode electron beams.
  • this ratio of .7 the beam produced vby the cathode is substantially determined by the size of the aperture and exhibits great stability with varying gas pressures and anode-to-cathode potentials. Gas pressures in excess of 200 microns and at voltages of 10 kilovolts or more may be usedvto produce an electron beam whose stability is unaffected 'by voltage variations and gas density excur-s sions. 0f course, in cases where there is no aperture wall, the ratio approaches unity but this ratio still produces a stable beam.
  • the aperture 16 is usually also provided with cross-sectional dimensions which are equal or larger than the cathode fall distance Dc.
  • the cathode fall dis tance encompasses for most applications that distance from the cathode where most of the potential rise from cathode to anode occurs. These distances may be determined ex perimentally or may beobtained for instance of FIGURE 8.10, p. 229, from the book Gaseous Conductor by James Dillon Cabine, a 1958 Dover publication.
  • FIGURE 3 Having described an annular arrangement, other configurations are possible such as a cylindrical device as in FIGURE 3 where one wall of the cylinder is provided with an aperture whose cross-sectionaldimensions meet the criteria of the annular arrangement described above.
  • the aperture-to-wall dimensions cannot fall 'below .7 if the large stable beam etect'is to be maintained.
  • FIGURE 4 shows a cathode having a single backwall 7 and a single bounding wall 9C
  • the end view of FIG z URE 4 is shown in FIGURE 5 and shows the cylindrical arrangement of the cathode structuretherein.
  • a shield 28 is selectively spaced from the cathode structure to provide the suppression of the glow discharge from the wal.s enclosed.
  • the aperture 16' of the cathode structure is greater than the cathode fall.
  • the cavityf14' is suicient to produce the beam of electrons from the hot plasma present therein.
  • the aperture 16,#again is greater than the "cathode fall to permit a wide beam of electrons to be emitted from the annular cavity 14.
  • said vcathode structure having a peripheral' wall
  • said-,bounding walls further forming an aperture
  • said aperture having all its cross-sectional dimensions substantially equal or greater than the cathode fall
  • an aperture wall extending from at least one of said bounding walls across the aperture to reduce atl least one( of the cross-sectional dimensions of said aperture and where the reduced aperture dimensions rbears a ratio with respect to the unreduced aperture diQ v mension of greater than .7.
  • said bounding wall further forming..lan opening
  • an aperture wall extending from said bounding wall across the opening to form an aperture having crosssectional dimensions smaller than the corresponding dimensions of the opening, and t where said corresponding cross-sectional dimensions of the aperture and the opening bear a respective ratio l greater than .7.
  • a hollow cathode structure operating at a high nega 5 tive potential with respect to an anode in a gaseous chamber evacuated to a predetermined density range of the gas comprising:
  • said cathode structure having a peripheral wall
  • said bounding walls further forming an opening
  • an aperture wall extending from at least one of said bounding walls across the opening to form an aperture having a cross-sectional dimension smaller than the corresponding dimension of the opening
  • a shield selectively spaced from and enclosing said peripheral and bounding walls, said shield inhibiting the4 generation of electrons from the enclosed walls.
  • a hollow cathode structure operating at a high negative potential with respect to an anode in a gaseous chamber evacuated to a predetermined density range of the gas comprising: t
  • said cathode structure having a back wall
  • said bounding wall further dening an opening
  • a shield selectively spaced from and enclosing said peripheral and bounding walls, said shield inhibiting the generation of electrons from the enclosed walls.
  • a hollow cathode structure having an aperture-'and operating ata high negative potential with respect to an anode in a gaseous chamber evacuated to a predetermined density range' of the gas comprising:
  • said cathode structure having a peripheral wall
  • said bounding walls further forming an opening opu posite said peripheral wall
  • the electron bea-m is characterized by having cross-sectional dimensions that are larger than the corresponding aperture dimensions
  • a shield selectively spaced from and enclosingsaid peripheral and bounding Walls, said shield inhibiting the generation of electrons from the enclosed walls.
  • a hollow cathode structure having an aperture and y operating at a high negative potential ⁇ with respect to .an
  • anode in a gaseous chamber evacuated to a predetermined density range of the gas comprising:
  • said cathode structure having a. back w-all
  • said bounding wall further dening an opening opposite said peripheral wall

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  • Chemical & Material Sciences (AREA)
  • Analytical Chemistry (AREA)
  • Electron Sources, Ion Sources (AREA)
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US508302A 1965-11-17 1965-11-17 Glow discharge cathode having a large electron beam emitting aperture Expired - Lifetime US3383541A (en)

Priority Applications (5)

Application Number Priority Date Filing Date Title
US508302A US3383541A (en) 1965-11-17 1965-11-17 Glow discharge cathode having a large electron beam emitting aperture
GB51397/66A GB1170435A (en) 1965-11-17 1966-11-16 Glow Discharge Hollow Cathode
SE15686/66A SE315340B (enrdf_load_stackoverflow) 1965-11-17 1966-11-16
DE19661589005 DE1589005B1 (de) 1965-11-17 1966-11-17 Vorrichtung zum Bearbeiten von Gegenstaenden mit Elektronenstrahlen
FR83926A FR1499093A (fr) 1965-11-17 1966-11-17 Cathode creuse à grande ouverture

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US508302A US3383541A (en) 1965-11-17 1965-11-17 Glow discharge cathode having a large electron beam emitting aperture

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US3383541A true US3383541A (en) 1968-05-14

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US508302A Expired - Lifetime US3383541A (en) 1965-11-17 1965-11-17 Glow discharge cathode having a large electron beam emitting aperture

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US (1) US3383541A (enrdf_load_stackoverflow)
DE (1) DE1589005B1 (enrdf_load_stackoverflow)
FR (1) FR1499093A (enrdf_load_stackoverflow)
GB (1) GB1170435A (enrdf_load_stackoverflow)
SE (1) SE315340B (enrdf_load_stackoverflow)

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3466487A (en) * 1967-06-16 1969-09-09 United Aircraft Corp Device for moving a beam of charged particles
US3614510A (en) * 1968-06-04 1971-10-19 United Ekingdom Atomic Energy Nonthermionic cathode discharge devices
US4461970A (en) * 1981-11-25 1984-07-24 General Electric Company Shielded hollow cathode electrode for fluorescent lamp
EP0732719A1 (en) 1995-03-14 1996-09-18 Osram Sylvania Inc. Discharge device having cathode with micro hollow array

Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3172007A (en) * 1962-01-15 1965-03-02 Stauffer Chemical Co Folded filament beam generator
US3262003A (en) * 1962-05-25 1966-07-19 Martin Marietta Corp Perforated hollow cathode discharge device

Family Cites Families (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE896533C (de) * 1939-04-12 1953-11-12 Aeg Einrichtung zur Erzeugung eines Strahles von positiven Ionen oder von Elektronen

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3172007A (en) * 1962-01-15 1965-03-02 Stauffer Chemical Co Folded filament beam generator
US3262003A (en) * 1962-05-25 1966-07-19 Martin Marietta Corp Perforated hollow cathode discharge device

Cited By (9)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3466487A (en) * 1967-06-16 1969-09-09 United Aircraft Corp Device for moving a beam of charged particles
US3614510A (en) * 1968-06-04 1971-10-19 United Ekingdom Atomic Energy Nonthermionic cathode discharge devices
US4461970A (en) * 1981-11-25 1984-07-24 General Electric Company Shielded hollow cathode electrode for fluorescent lamp
EP0732719A1 (en) 1995-03-14 1996-09-18 Osram Sylvania Inc. Discharge device having cathode with micro hollow array
US5686789A (en) * 1995-03-14 1997-11-11 Osram Sylvania Inc. Discharge device having cathode with micro hollow array
US5939829A (en) * 1995-03-14 1999-08-17 Osram Sylvania, Inc. Discharge device having cathode with micro hollow array
US6072273A (en) * 1995-03-14 2000-06-06 Osram Sylvania Inc. Discharge device having cathode with micro hollow array
US6346770B1 (en) 1995-03-14 2002-02-12 Osram Sylvania, Inc. Discharge device having cathode with micro hollow array
US6518692B2 (en) 1995-03-14 2003-02-11 Old Dominion University Discharge device having cathode with micro hollow array

Also Published As

Publication number Publication date
FR1499093A (fr) 1967-10-20
GB1170435A (en) 1969-11-12
DE1589005B1 (de) 1970-02-26
SE315340B (enrdf_load_stackoverflow) 1969-09-29

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