US3864572A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Electron beam apparatus comprising a point cathode
Assignee: US Philips Corp
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Filing: 1973-10-02
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Granted: 1975-02-04
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Expires: 1993-10-02
Abstract
Abstract The electron source of an electron beam apparatus comprises a cathode wire which is to be heated by a laser beam and which is to be displaced in the wire direction. This cathode wire has a thickness of from 10 to 30 microns. By applying a field strength of 105 to 106 KV/m to the heated wire tip and by controlling the laser intensity and the wire feed during operation by a signal derived from the emission of the wire tip, a tip is produced on the wire end having a curvature radius of approximately 1 micron. At a temperature just below the melting temperature of the wire a stable temperature field emission having a current density of up to better than 104 A/cm2 is thus realized.
Inventors
- 👤 Der Mast Karel Diederick Van
- 👤 James Edmond Barth
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 11:56
CPC Classifications
H; H01; H01J; H01J37/00; H01J37/02; H01J37/04; H01J37/06; H01J37/075; H01J3/00; H01J3/02; H01J3/024; H01J2237/00; H01J2237/06; H01J2237/063; H01J2237/06308; H01J2237/06316
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
122 words
An electron beam source, comprising: a cathode wire having a free tip; means for generating an electric field at said tip of approximately 105 to 106 KV/m for drawing electrons away from said tip; means for heating said tip to a temperature where deformation of said tip occurs due to said electric field; means for forming an electron beam from electrons drawn away from said tip; and means for supporting said cathode wire and for slowly advancing said wire in the axial direction thereof in accordance with the evaporation rate of said tip to maintain said tip in substantially the same position, whereby said tip is maintained substantially point-like with a substantially constant radius of curvature of approximately 0.2 to 2 microns.
Claim 2
Dependent Claim
122 words
An electron beam source, comprising: a cathode wire having a free tip; means for generating an electric field at said tip of approximately 105 to 106 KV/m for drawing electrons away from said tip; means for heating said tip to a temperature where deformation of said tip occurs due to said electric field; means for forming an electron beam from electrons drawn away from said tip; and means for supporting said cathode wire and for slowly advancing said wire in the axial direction thereof in accordance with the evaporation rate of said tip to maintain said tip in substantially the same position, whereby said tip is maintained substantially point-like with a substantially constant radius of curvature of approximately 0.2 to 2 microns.
Claim 3
Dependent Claim
149 words
An electron beam source, comprising: a cathode wire having a free tip; an anode positioned adjacent said tip, said anode having an aperture for forming a beam from electrons emitted from said tip; means for supplying to said anode a voltage sufficiently positive with respect to said tip to generate a field strength at said tip of approximately 105 to 106 KV/m; an auxiliary radiation source positioned to focus radiation on said tip to heat said tip to a temperature where deformation of said tip occurs due to said field strength at said tip; means for supporting said cathode wire and for slowly advancing said wire in the axial direction thereof in accordance with the evaporation rate of said tip to maintain said tip in substantially the same position, wHereby said tip is maintained substantially point-like with a substantially constant radius of curvature of approximately 0.2 to 2 microns.
Claim 4
Dependent Claim
149 words
An electron beam source, comprising: a cathode wire having a free tip; an anode positioned adjacent said tip, said anode having an aperture for forming a beam from electrons emitted from said tip; means for supplying to said anode a voltage sufficiently positive with respect to said tip to generate a field strength at said tip of approximately 105 to 106 KV/m; an auxiliary radiation source positioned to focus radiation on said tip to heat said tip to a temperature where deformation of said tip occurs due to said field strength at said tip; means for supporting said cathode wire and for slowly advancing said wire in the axial direction thereof in accordance with the evaporation rate of said tip to maintain said tip in substantially the same position, wHereby said tip is maintained substantially point-like with a substantially constant radius of curvature of approximately 0.2 to 2 microns.
Claim 5
Dependent Claim
25 words
An electron beam source as defined in claim 2 wherein said aperture of said anode is substantially aligned with the axis of said cathode wire.
Claim 6
Dependent Claim
45 words
An electron beam source as defined in claim 3 wherein said means for supporting and advancing comprises means for controlling the position of said wire in accordance with the anode current of said anode in a direction which tends to maintain said anode current constant.
Claim 7
Dependent Claim
22 words
An electron beam source as defined in claim 4 wherein said cathode wire has a diameter of approximately 10 to 30 microns.
Claim 8
Dependent Claim
18 words
An electron beam source as defined in claim 4 wherein said auxiliary radiation source comprises a continuous laser.
Claim 9
Dependent Claim
49 words
An electron beam source as defined in claim 4 and further comprising a second anode cooperating with said anode position adjacent said tip in forming a beam, said second anode having an aperture aligned with said aperture of said anode positioned adjacent said tip and aligned with said tip.
Claim 10
Dependent Claim
49 words
An electron beam source as defined in claim 7 and further comprising means for controlling the intensity of radiation focused on said tip in accordance with the anode current of said second anode in a direction which tends to maintain a constant said anode current of said second anode.
Claim 11
Dependent Claim
35 words
An electron beam source as defined in claim 8 wherein said cathode wire is a substantially straight tungsten wire, the tip thereof being heated by said auxiliary radiation source to a temperature of approximately 3,500*K.
References Cited (Backward Citations)
US3388280A
Cited
US3678333A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-02-03 | 1978-08-05 | 1979-02-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-02-03 | 1982-08-05 | 1983-02-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-02-03 | 1986-08-05 | 1987-02-04 | $7700.00 | Window Closed / Lapsed |