Patent US4331936A successfully refreshed from Google Patents.
US4331936A
Expired / Lapsed
US
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Free electron laser employing an expanded hollow intense electron beam and periodic radial magnetic field
Assignee: United States Department of the Air Force
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Filing: 1979-11-09
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Granted: 1982-05-25
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Expires: 1999-11-09
Abstract
Abstract The generation of very high power pulses of coherent electromagnetic radiation that are continuously tunable in frequency is accomplished by means of a free electron laser in which a hollow relativistic electron beam is projected along the longitudinal axis of an evacuated drift tube. A first magnetic field expands the electron beam into an annular peripheral interaction region of the drift tube where the beam interacts with a second periodic radial magnetic field. Frequency is varied by changing the electron velocity of the electron beam or by changing the periodicity of the radial magnetic field. The device can be made to operate as an oscillator by the inclusion of resonant cavity defining mirrors within the interaction region, or as an amplifier by injecting a coherent radiation signal into the interaction region. Both oscillator and amplifier functions can be incorporated into a single device. Linewidth is narrowed by utilizing a Smith-Fox interferometer to couple the generated coherent radiation into an output light pipe.
Inventors
- 👤 S. Perry Schlesinger
- 👤 Thomas C. Marshall
- 👤 David B. McDermott
- 👤 Victor L. Granatstein
- 👤 Robert K. Parker
- 👤 Phillip A. Sprangle
- 👤 Philip C. Efthimion
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 13:00
CPC Classifications
H; H01; H01S; H01S3/00; H01S3/09; H01S3/0903
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
109 words
A source of high power coherent radiation comprising an evacuated drift tube having an output for coherent radiation, means for generating an intense relativistic electron beam projecting a cylindrical beam of relativistic electrons along the longitudinal axis of said drift tube, a first means for producing a magnetic field positioned to effect expansion of said cylindrical beam into an annular peripheral interaction region of said drift tube, and a second means for producing a magnetic field adapted to provide a periodic radial magnetic field in said interaction region, said periodic radial magnetic field interacting with the expanded cylindrical beam of relativistic electrons to effect the generation of coherent radiation.
Claim 2
Dependent Claim
109 words
A source of high power coherent radiation comprising an evacuated drift tube having an output for coherent radiation, means for generating an intense relativistic electron beam projecting a cylindrical beam of relativistic electrons along the longitudinal axis of said drift tube, a first means for producing a magnetic field positioned to effect expansion of said cylindrical beam into an annular peripheral interaction region of said drift tube, and a second means for producing a magnetic field adapted to provide a periodic radial magnetic field in said interaction region, said periodic radial magnetic field interacting with the expanded cylindrical beam of relativistic electrons to effect the generation of coherent radiation.
Claim 3
Dependent Claim
40 words
A source of high power coherent radiation as defined in claim 1 including means for varying the frequency of the coherent radiation resulting from the interaction of the expanded cylindrical beam of relativistic electrons and said periodic radial magnetic field.
Claim 4
Dependent Claim
33 words
A source of high power coherent radiation as defined in claim 2 wherein the means for varying the frequency of coherent radiation comprises means for varying the axial electron velocity of said beam.
Claim 5
Dependent Claim
34 words
A source of high power coherent radiation as defined in claim 2 wherein said means for varying the frequency of coherent radiation comprises means for varying the periodicity of said periodic radial magnetic field.
Claim 6
Dependent Claim
31 words
A source of high power coherent radiation as defined in claim 2 including mirror means defining a resonant cavity within said drift tube, said interaction region being within said resonant cavity.
Claim 7
Dependent Claim
25 words
A source of high power coherent radiation as defined in claim 2 including an input for injecting a coherent modulation signal into said interaction region.
Claim 8
Dependent Claim
35 words
A source of high power coherent radiation as defined in claim 2 wherein said output for coherent radiation comprises a light pipe, radiation generated in said interaction region being diffraction coupled into said light pipe.
Claim 9
Dependent Claim
27 words
A source of high power coherent radiation as defined in claim 7 including interferometer means coupling coherent radiation generated in said interaction region into said light pipe.
Claim 10
Dependent Claim
166 words
A source of high power coherent radiation comprising an evacuated drift tube having an output for coherent radiation, means for generating an intense relativistic electron beam projecting a cylindrical beam of relativistic electrons along the longitudinal axis of said drift tube, a first means for producing a magnetic field positioned to effect expansion of said cylindrical beam into a first annular peripheral interaction region of said drift tube; contraction of said cylindrical beam at the end of said first interaction region; and, subsequent expansion of said cylindrical beam into a second annular peripheral interaction region of said drift tube, a second means for producing a magnetic field positioned to provide a periodic radial magnetic field in said first interaction regions, a third means for producing a magnetic field positioned to provide a periodic radial magnetic field in said second interaction region; and mirror means, said mirror means defining a resonant cavity within said drift tube, said first annular peripheral interaction region being within said resonant cavity.
Claim 11
Dependent Claim
166 words
A source of high power coherent radiation comprising an evacuated drift tube having an output for coherent radiation, means for generating an intense relativistic electron beam projecting a cylindrical beam of relativistic electrons along the longitudinal axis of said drift tube, a first means for producing a magnetic field positioned to effect expansion of said cylindrical beam into a first annular peripheral interaction region of said drift tube; contraction of said cylindrical beam at the end of said first interaction region; and, subsequent expansion of said cylindrical beam into a second annular peripheral interaction region of said drift tube, a second means for producing a magnetic field positioned to provide a periodic radial magnetic field in said first interaction regions, a third means for producing a magnetic field positioned to provide a periodic radial magnetic field in said second interaction region; and mirror means, said mirror means defining a resonant cavity within said drift tube, said first annular peripheral interaction region being within said resonant cavity.
References Cited (Backward Citations)
US3789257A
Cited
US3958189A
Cited
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| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1985-05-24 | 1985-11-23 | 1986-05-25 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1989-05-24 | 1989-11-23 | 1990-05-25 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1993-05-24 | 1993-11-23 | 1994-05-25 | $7700.00 | Window Closed / Lapsed |