EP0200035A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Electron beam source
Assignee: International Business Machines Corp
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Filing: 1986-04-08
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Granted: —
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Expires: 2006-04-08
Abstract
Abstract A high current density hollow cathode electron beam source for use in various E-beam apparatus is described. Bombardment of an electron emissive surface within the hollow cathode by energetic gas ions causes electrons to be emitted by secondary emission rather than thermionic emission effects. Once initialized by an external ionization voltage the device is essentially self sustaining and operates near room temperature, rather than at thermionic emission temperatures, and with reduced voltages. The drawing shows the hollow cathode into which plasma gas is introduced via port 40 and the electron beam exits via aperture 36 to grid 58. lonization of the gas is initiated by voltage source 54 and the electron beam is sustained by voltage 57.
Inventors
- 👤 Jerome John Cuomo
- 👤 Harold Richard Kaufman
- 👤 Stephen Mark Rossnagel
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-08 07:21
CPC Classifications
H; H01; H01J; H01J1/00; H01J1/02; H01J1/025
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
140 words
Electron beam apparatus comprising a hollow cathode structure including an outer enclosure (32), having a tone end thereof a wall (34), said wall having an aperture (36) therethrough for electron beam emission, a second wall (38) at the opposite end of said enclosure, a means (40) for admitting an ionizable gas into said enclosure, the enclosure and walls defining the interior chamber (44) at least a part of the interior (50) surface of said chamber, having a low work function electron emissive coating thereon which readily emits electrons under bombardment by ions from said gas, and means for filling the interior volume with an ionized gas plasma whereby high energy electrons are emitted from said surface by secondary emission effects and low energy electrons released by collisions between said high energy electrons and gas ions are emitted through the aperture.
Claim 2
Dependent Claim
140 words
Electron beam apparatus comprising a hollow cathode structure including an outer enclosure (32), having a tone end thereof a wall (34), said wall having an aperture (36) therethrough for electron beam emission, a second wall (38) at the opposite end of said enclosure, a means (40) for admitting an ionizable gas into said enclosure, the enclosure and walls defining the interior chamber (44) at least a part of the interior (50) surface of said chamber, having a low work function electron emissive coating thereon which readily emits electrons under bombardment by ions from said gas, and means for filling the interior volume with an ionized gas plasma whereby high energy electrons are emitted from said surface by secondary emission effects and low energy electrons released by collisions between said high energy electrons and gas ions are emitted through the aperture.
Claim 3
Dependent Claim
79 words
Electron beam apparatus as claimed in claim 1, further including means for initiating operation of the device including a (n external) high-voltage discharge for initially ionizing the gas within the said chamber whereby the gas ions collide with said electron emitting surface to release high energy electrons therefrom, said high energy electrons in turn colliding with gas molecules within said chamber to, in effect, sustain the ionized condition of said gas even after the initial high voltage is removed.
Claim 4
Dependent Claim
27 words
Electron beam apparatus as claimed in claim 2, wherein the ionizable gas comprises hydrogen, helium, Ne or combinations of these and reactive gates including O2, N2and Ar.
Claim 5
Dependent Claim
41 words
Electron beam apparatus as claimed in claim 3, wherein the electron emissive surface comprises a layer of oxides and halides including MgO, MgF2, NaCl, ZnO, Al 2 O 3 , SiOs, BaOSrO and combinations of these and other oxides and halides.
Claim 6
Dependent Claim
45 words
Electron beam apparatus as claimed in claim 2 wherein the secondary electron emissive surface is located on those surfaces of said chamber which produce high energy electrons leaving said surfaces in a direction substantially normal to the electron beam emanating from said hollow cathode structure.
Claim 7
Dependent Claim
130 words
Electron beam apparatus, comprising a hollow cathode structure including an outer enclosure, having at one end thereof a wall, said wall having an aperture therethrough for electron beam emission, a second wall at the opposite end of said enclosure, means for admitting an ionizable gas into said chamber, the enclosure and watts defining an interior chamber, at best, some of the interior surfaces of said chamber having a low work function secondary electron emissive coating thereon which readily emits electrons under bombardment by ions from said gas, means for admitting an ionizable gas plasma into said interior chamber,a nd means for establishing a strong magnetic field transverse to electron beam flow through said aperture in said one end wall whereby energetic electrons are substantially prohibited from passing through said aperture.
Claim 8
Dependent Claim
130 words
Electron beam apparatus, comprising a hollow cathode structure including an outer enclosure, having at one end thereof a wall, said wall having an aperture therethrough for electron beam emission, a second wall at the opposite end of said enclosure, means for admitting an ionizable gas into said chamber, the enclosure and watts defining an interior chamber, at best, some of the interior surfaces of said chamber having a low work function secondary electron emissive coating thereon which readily emits electrons under bombardment by ions from said gas, means for admitting an ionizable gas plasma into said interior chamber,a nd means for establishing a strong magnetic field transverse to electron beam flow through said aperture in said one end wall whereby energetic electrons are substantially prohibited from passing through said aperture.
Claim 9
Dependent Claim
51 words
Electron beam apparatus as claimed in claim 6, wherein said magnetic field establishing means comprises a pole piece located within said aperture defining an opening for ionized gas and electron flow between itself and the walls of said aperture and means for supplying a strong magnetic field to said pole piece.
Claim 10
Dependent Claim
54 words
Electron beam apparatus as claimed in claim 7, wherein said means for supplying a strong magnetic field comprises a permanent magnet located within said hollow cathode internal chamber and attached to provide a low permeability path to said pole piece at one end and to the structure defining said hollow cathode at the other.
Claim 11
Dependent Claim
77 words
Electron beam apparatus as claimed in claim 6, further including means for intitiating operation of the device including a high-voltage discharge for initially ionizing the gas within the said chamber whereby the gas ions collide with said electron emitting surface to release high energy electrons therefrom, said high energy electrons in turn colliding with gas molecules within said chamber to, in effect, sustain the ionized condition of said gas even after the initial high voltage is removed.
References Cited (Backward Citations)
No citation records indexed.
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