CA1291817C - Short-period electron beam wiggler - Google Patents
Short-period electron beam wigglerInfo
- Publication number
- CA1291817C CA1291817C CA000565933A CA565933A CA1291817C CA 1291817 C CA1291817 C CA 1291817C CA 000565933 A CA000565933 A CA 000565933A CA 565933 A CA565933 A CA 565933A CA 1291817 C CA1291817 C CA 1291817C
- Authority
- CA
- Canada
- Prior art keywords
- polepieces
- wiggler
- laser
- bars
- vacuum envelope
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired - Fee Related
Links
Classifications
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S3/00—Lasers, i.e. devices using stimulated emission of electromagnetic radiation in the infrared, visible or ultraviolet wave range
- H01S3/09—Processes or apparatus for excitation, e.g. pumping
- H01S3/0903—Free-electron laser
-
- H—ELECTRICITY
- H05—ELECTRIC TECHNIQUES NOT OTHERWISE PROVIDED FOR
- H05H—PLASMA TECHNIQUE; PRODUCTION OF ACCELERATED ELECTRICALLY-CHARGED PARTICLES OR OF NEUTRONS; PRODUCTION OR ACCELERATION OF NEUTRAL MOLECULAR OR ATOMIC BEAMS
- H05H7/00—Details of devices of the types covered by groups H05H9/00, H05H11/00, H05H13/00
- H05H7/04—Magnet systems, e.g. undulators, wigglers; Energisation thereof
Landscapes
- Physics & Mathematics (AREA)
- Engineering & Computer Science (AREA)
- Electromagnetism (AREA)
- Plasma & Fusion (AREA)
- Optics & Photonics (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Lasers (AREA)
- Particle Accelerators (AREA)
Abstract
Abstract of the Disclosure A free-electron laser has a wiggler for a linear electron beam comprising two sets of magnetic polepieces 26, 28 periodically spaced along opposite sides of the beam. The polepieces of one set 28 are displaced along the beam from the other set 26 by one-half period. A uniform longitudinal magnetomotive force generates fields between polepieces having transverse components 22 alternating between the sets 26, 28, providing a very short periodicity and hence, high frequency wave radiation.
Description
~2918~7 Short-Period Electron Beam Wiggler Field of the Invention The invention pertains to free-electron lasers in which electrons in a linear beam are periodically accelerated ("wiggled") perpendicular to the beam motion by periodic transverse magnetic fields. They radiate electromagnetic waves which are amplified and made coherent by reflections in a resonator such as the space between reflecting mirrors. To get high frequencies such as infrared, the beam velocity must be in the megavolt, relativistic range and the periodicity of the field must be very small.
Prior Art Periodically reversing magnetic fields have traditionally been generated by a stack of permanent magnets of alternating polarity. As the period gets shorter, the magnetomotive force is reduced, leakage flux increases and soon imposes a lower limit to the available periodicity when generating fields across gaps of separation usable to transmit the electron beam.
Summary cf the Invention An object of the invention is to provide a magnetic beam wiggler of very short period.
A further object is to provide a wiggler of minimum size, weight, and power consumption.
These objects are realized by forming the periodic magnet elements as opposed rows of floating ferromagnetic polepieces. Poles in opposite rows are staggered in the beam direction by one-half period.
A uniform, extended, exciting magnetomotive force is supplied from an external source, such as a solenoid coil. The flux generated between polepieces has a strong transverse component alternating between polepieces of the two rows.
Brief Description of the Drawings FIG. 1 is a section thru the beam direction of a periodic magnet system of the prior art.
FIG. 2 is a section similar to FIG. 1 of an alternative prior-art magnet system.
FIG. 3 is a section of a magnet system embodying the invention.
FIG. 4 is a sketch of magnetic elements of a free-electron laser embodying the invention.
FIG. 5 is a schematic partial section of the magnetic and optical structure of a free-electron laser embodying the invention.
FIG. 6 is a schematic section of an alternative laser construction.
Description of the Preferred Embodiments FIG. 1 (prior art) shows a simple periodic permanent magnet (PPM) system for guiding an electron beam in a wiggling motion. The originally linear beam 10 passes between opposed rows 1~, 14 of bar-shaped magnets 16 extending perpendicular to the plane of the section and to the direction of beam 10. Opposed pairs of magnets 16 are magnetized in the same direction perpendicular to the beam to produce a field 22 transverse to the beam motion.
Pairs spaced successively in the beam direction have alternating polarity so the beam experiences an oscillating acceleration perpendicular to the paper.
Thus, electromagnetic waves are radiated, polarized perpendicular to the paper. Their internal generating frequency is the forward velocity of the beam divided by the magnet periodiocity. At relativistic velocity an electron is almost in synchronism with its "own" wave, which is radiated mostly in the forward direction. The wave frequency received by a motionless observer is doppler-shifted to a very high value, such as infrared. Ferromagnetic bars 18 join the magnets of each row 12, 14 to provide low reluctance flux return paths. It is seen that as the magnet period is reduced, the shunt leakage flux 20 between axially adjacent magnets becomes large compared to the useful transverse flux 22, limiting the practical lower value of the magnet period, and hence, the frequency generated. The high leakage flux requires a large mass of magnetic material. Of current interest are lasers for spacecraft where size and weight must be kept very small.
FIG. 2 is another old scheme analogous to that used in travelimg-wave tubes in which the magnets 16' are magnetized in the beam direction and are separated by ferromagnetic polepieces 24. Leakage flux 20' may be reduced somewhat, but the magnetomotive force available decreases with the period. No ferromagnetic flux return is used because the fields fall off rapidly away from the magnetic stack.
FIG. 3 is an axial section through a magnet assembly embodying the invention. It does not use short permanent magnets which would otherwise impose a limit on magnetomotive force. A first row of ferromagnetic polepieces 26 are extended perpendicular to the paper as bars, forming a linear array periodically spaced in the direction of beam lO".
A second row 28 forms an opposed similar array.
Polepieces 28 are displaced from polepieces 26 by a half-period in the beam direction. A unidirectional magnetomotive force is applied in the beam direction, lZ918~7 as by a solenoid electromagnet coil 30. It is surrounded by a ferromagnetic sheath 32 forming a flux return pa'ch to reduce leakage field in the environment and provide a uniform field. In the 5 interaction space the axial field component 34 serves to keep the beam focused but does not affect the electrons' wiggler periodicity produced by the transverse field components 36 alternating between poles of opposed arrays 26, 28. The useful field 10 strength is limited only by saturation of the ferromagnetic polepieces 26, 28, not by any permanent magnet material. The net result is a structure of small size, light weight and easy manufacture which provides short periodicity unmatched by the 15 prior art.
FIG. 4 is a sketch of the magnetic components of a beam wiggler embodying the invention.
For ease of manufacture and perfection of alignment and spacing, the ferromagnetic polepieces 20 26, 28 are supported and spaced by interleaving pieces of non-magnetic material. FIG. 4 il~ustrates the magnetic part of a practical structure. Pole-pieces 26', 28' are inserted in grooves in parallel comb-shaped, non-magnetic support bars 38, 40 as of 25 copper, which preferably form part of the vacuum envelope of the tube. Slots 42 can be made by mechanical or electric-discharge machining, thus providing accurate alignment and the uniform periodic spacing needed for a synchronous structure, as 30 well as mechanical support and thermal cooling.
An alternative construction is a stack of separate ferromagnetic polepices, as of iron, and interleaved separate nonmagnetic spacers, as of copper, the stacked parts being brazed together.
129~ 7 FIG. S is a partial-section isometric sketch of a free-electron laser structure with optical focusing mirrors 42 to make it part of a confocal resonator. Mirrors 42 have central apertures 44 for 5 passage of the electron beam. Alternatively, the undulator structure may be closed at its sides to form a waveguide 46 carrying a transverse electric field wave 48 polarized perpendicular to the partial-section plane of the paper. The mirrors 10 42 partially reflect this wave 48, providing electromagnetic feedback which makes the electron motions, and the radiation, coherent. Alternatively, an amplifier configuration is possible, dispensing witn the on-line mirrorsr but providing feedback via 15 an external path, such as a waveguide or series of external reflectors.
FIG. 6 illustrates an alternative laser construction having a coaxial geometry. All elements shown in cross-section are figures of revolution 20 about an axis 50. The cathode emissive surface 52 is a zone of a toroid. The electron beam 54 converges from cathode 52 to a hollow, cylindrical, linear beam 56 which flows between periodic stacks of ring-shaped ferromagnetic polepieces 26", 28".
25 Beam 56 is kept focused by the axial d.c. magnetic field 58 from a solenoid magneti 30' (not shown).
The interaction is exactly the same as in the rectangular array of FIG. 5 except that the generated electromagnetic wave has a circular-electric-mode 30 symmetry. After passing between the magnet stacks 26", 28" the wave is radiated axially out through a dielectric vacuum window 58. The magnetic field 58 is reduced sharply past the polepiece stacks 26", 28" so that electron beam 50 expands and is 35 collected on the enlarged surface 60 of a portion ~29~81~
of the vacuum envelope where the power density is reduced. The output section geometry i5 thus somewhat similar to the familiar circular-electric-field gyrotron. The electromagnetic interaction is of course much different in that the periodic electron motion is produced by the spatially periodic magnetic field whereas in the gyrotron it is a result of the cyclotron rotation in a uniform magnetic field. The frequency limit of the gyrotron is limited by the available magnetic field strength.
In the present laser this limitation is not present, so much higher frequencies may be generated.
The frequency of the radiation is tunable by varying the energy (velocity) of the electron beam 10. In a typical installation, the beam would be energized by a linear electron accelerator (not shown) for which means to vary the energy are well known in the art. Like other lasers, the resonator is many wavelengths long, so the emitted frequency will be in one or more very closely spaced lines.
The above-described embodiment is exemplary and not limiting. The scope of the invention is to be limited only by the following claims and their legal equivalents.
Prior Art Periodically reversing magnetic fields have traditionally been generated by a stack of permanent magnets of alternating polarity. As the period gets shorter, the magnetomotive force is reduced, leakage flux increases and soon imposes a lower limit to the available periodicity when generating fields across gaps of separation usable to transmit the electron beam.
Summary cf the Invention An object of the invention is to provide a magnetic beam wiggler of very short period.
A further object is to provide a wiggler of minimum size, weight, and power consumption.
These objects are realized by forming the periodic magnet elements as opposed rows of floating ferromagnetic polepieces. Poles in opposite rows are staggered in the beam direction by one-half period.
A uniform, extended, exciting magnetomotive force is supplied from an external source, such as a solenoid coil. The flux generated between polepieces has a strong transverse component alternating between polepieces of the two rows.
Brief Description of the Drawings FIG. 1 is a section thru the beam direction of a periodic magnet system of the prior art.
FIG. 2 is a section similar to FIG. 1 of an alternative prior-art magnet system.
FIG. 3 is a section of a magnet system embodying the invention.
FIG. 4 is a sketch of magnetic elements of a free-electron laser embodying the invention.
FIG. 5 is a schematic partial section of the magnetic and optical structure of a free-electron laser embodying the invention.
FIG. 6 is a schematic section of an alternative laser construction.
Description of the Preferred Embodiments FIG. 1 (prior art) shows a simple periodic permanent magnet (PPM) system for guiding an electron beam in a wiggling motion. The originally linear beam 10 passes between opposed rows 1~, 14 of bar-shaped magnets 16 extending perpendicular to the plane of the section and to the direction of beam 10. Opposed pairs of magnets 16 are magnetized in the same direction perpendicular to the beam to produce a field 22 transverse to the beam motion.
Pairs spaced successively in the beam direction have alternating polarity so the beam experiences an oscillating acceleration perpendicular to the paper.
Thus, electromagnetic waves are radiated, polarized perpendicular to the paper. Their internal generating frequency is the forward velocity of the beam divided by the magnet periodiocity. At relativistic velocity an electron is almost in synchronism with its "own" wave, which is radiated mostly in the forward direction. The wave frequency received by a motionless observer is doppler-shifted to a very high value, such as infrared. Ferromagnetic bars 18 join the magnets of each row 12, 14 to provide low reluctance flux return paths. It is seen that as the magnet period is reduced, the shunt leakage flux 20 between axially adjacent magnets becomes large compared to the useful transverse flux 22, limiting the practical lower value of the magnet period, and hence, the frequency generated. The high leakage flux requires a large mass of magnetic material. Of current interest are lasers for spacecraft where size and weight must be kept very small.
FIG. 2 is another old scheme analogous to that used in travelimg-wave tubes in which the magnets 16' are magnetized in the beam direction and are separated by ferromagnetic polepieces 24. Leakage flux 20' may be reduced somewhat, but the magnetomotive force available decreases with the period. No ferromagnetic flux return is used because the fields fall off rapidly away from the magnetic stack.
FIG. 3 is an axial section through a magnet assembly embodying the invention. It does not use short permanent magnets which would otherwise impose a limit on magnetomotive force. A first row of ferromagnetic polepieces 26 are extended perpendicular to the paper as bars, forming a linear array periodically spaced in the direction of beam lO".
A second row 28 forms an opposed similar array.
Polepieces 28 are displaced from polepieces 26 by a half-period in the beam direction. A unidirectional magnetomotive force is applied in the beam direction, lZ918~7 as by a solenoid electromagnet coil 30. It is surrounded by a ferromagnetic sheath 32 forming a flux return pa'ch to reduce leakage field in the environment and provide a uniform field. In the 5 interaction space the axial field component 34 serves to keep the beam focused but does not affect the electrons' wiggler periodicity produced by the transverse field components 36 alternating between poles of opposed arrays 26, 28. The useful field 10 strength is limited only by saturation of the ferromagnetic polepieces 26, 28, not by any permanent magnet material. The net result is a structure of small size, light weight and easy manufacture which provides short periodicity unmatched by the 15 prior art.
FIG. 4 is a sketch of the magnetic components of a beam wiggler embodying the invention.
For ease of manufacture and perfection of alignment and spacing, the ferromagnetic polepieces 20 26, 28 are supported and spaced by interleaving pieces of non-magnetic material. FIG. 4 il~ustrates the magnetic part of a practical structure. Pole-pieces 26', 28' are inserted in grooves in parallel comb-shaped, non-magnetic support bars 38, 40 as of 25 copper, which preferably form part of the vacuum envelope of the tube. Slots 42 can be made by mechanical or electric-discharge machining, thus providing accurate alignment and the uniform periodic spacing needed for a synchronous structure, as 30 well as mechanical support and thermal cooling.
An alternative construction is a stack of separate ferromagnetic polepices, as of iron, and interleaved separate nonmagnetic spacers, as of copper, the stacked parts being brazed together.
129~ 7 FIG. S is a partial-section isometric sketch of a free-electron laser structure with optical focusing mirrors 42 to make it part of a confocal resonator. Mirrors 42 have central apertures 44 for 5 passage of the electron beam. Alternatively, the undulator structure may be closed at its sides to form a waveguide 46 carrying a transverse electric field wave 48 polarized perpendicular to the partial-section plane of the paper. The mirrors 10 42 partially reflect this wave 48, providing electromagnetic feedback which makes the electron motions, and the radiation, coherent. Alternatively, an amplifier configuration is possible, dispensing witn the on-line mirrorsr but providing feedback via 15 an external path, such as a waveguide or series of external reflectors.
FIG. 6 illustrates an alternative laser construction having a coaxial geometry. All elements shown in cross-section are figures of revolution 20 about an axis 50. The cathode emissive surface 52 is a zone of a toroid. The electron beam 54 converges from cathode 52 to a hollow, cylindrical, linear beam 56 which flows between periodic stacks of ring-shaped ferromagnetic polepieces 26", 28".
25 Beam 56 is kept focused by the axial d.c. magnetic field 58 from a solenoid magneti 30' (not shown).
The interaction is exactly the same as in the rectangular array of FIG. 5 except that the generated electromagnetic wave has a circular-electric-mode 30 symmetry. After passing between the magnet stacks 26", 28" the wave is radiated axially out through a dielectric vacuum window 58. The magnetic field 58 is reduced sharply past the polepiece stacks 26", 28" so that electron beam 50 expands and is 35 collected on the enlarged surface 60 of a portion ~29~81~
of the vacuum envelope where the power density is reduced. The output section geometry i5 thus somewhat similar to the familiar circular-electric-field gyrotron. The electromagnetic interaction is of course much different in that the periodic electron motion is produced by the spatially periodic magnetic field whereas in the gyrotron it is a result of the cyclotron rotation in a uniform magnetic field. The frequency limit of the gyrotron is limited by the available magnetic field strength.
In the present laser this limitation is not present, so much higher frequencies may be generated.
The frequency of the radiation is tunable by varying the energy (velocity) of the electron beam 10. In a typical installation, the beam would be energized by a linear electron accelerator (not shown) for which means to vary the energy are well known in the art. Like other lasers, the resonator is many wavelengths long, so the emitted frequency will be in one or more very closely spaced lines.
The above-described embodiment is exemplary and not limiting. The scope of the invention is to be limited only by the following claims and their legal equivalents.
Claims (29)
1. A magnetic wiggler for a linear electron beam comprising:
a passageway for said beam, a first set of ferromagnetic polepieces periodically spaced in the direction of flow of said beam, separated by non-magnetic spaces, and positioned on a first side of said passageway;
a second set of ferromagnetic polepieces on the opposing side of said passageway, periodically spaced to alternate in said direction of beam flow with polepieces of said first set; and means for generating a relatively uniform magnetomotive force in said direction of beam flow, to generate a component of magnetic field transverse to said passageway alternating between polepieces of said two sets.
a passageway for said beam, a first set of ferromagnetic polepieces periodically spaced in the direction of flow of said beam, separated by non-magnetic spaces, and positioned on a first side of said passageway;
a second set of ferromagnetic polepieces on the opposing side of said passageway, periodically spaced to alternate in said direction of beam flow with polepieces of said first set; and means for generating a relatively uniform magnetomotive force in said direction of beam flow, to generate a component of magnetic field transverse to said passageway alternating between polepieces of said two sets.
2. The wiggler of claim 1 wherein said means for generating said magnetomotive force is a solenoid electromagnet surrounding said beam and said polepieces.
3. The wiggler of claim 1 wherein said polepieces are parallel bars defined by a first and a second parallel planes containing said direction of flow, said bars extending perpendicular to said direction.
4. The wiggler of claim 3 wherein said polepieces of a set are separated by interleaved bars of non-magnetic material.
5. The wiggler of claim 4 wherein said polepieces and interleaved bars are bonded together to form a rigid, extended sheet.
6. The wiggler of claim 5 wherein said sheet forms part of a vacuum envelope surrounding said wiggler.
7. The wiggler of claim 4 wherein the bars of each of said sets are disposed in notches in a sheet of non-magnetic material extending in said direction of flow.
8. The wiggler of claim 7 wherein said sheet forms a part of the vacuum envelope surrounding said wiggler.
9. The wiggler of claim 1 wherein said passageway is a hollow cylinder with axis in said direction of flow and said polepieces are substantially complete rings coaxial with said axis.
10. The wiggler of claim 9 wherein said polepieces of each set are separated by interleaved rings of non-magnetic material.
11. The wiggler of claim 10 wherein said polepieces and said rings are bonded together to form rigid, extended cylinders.
12. The wiggler of claim 11 wherein the outer of said cylinders forms part of the vacuum envelope of said tube.
13. The wiggler of claim 9 wherein said polepieces are disposed in radial notches in non-metallic cylinders.
14. The wiggler of claim 13 wherein the outer of said cylinders forms part of the vacuum envelope of said tube.
15. A free-electron laser comprising:
a vacuum envelope;
means for generating a linear electron beam within said envelope;
means for wiggling said beam transverse to its direction of propagation comprising; on each of two opposite sides of said beam a set of floating ferro-magnetic polepieces spaced periodically along the direction of propagation of said beam, said polepieces of one set being displaced in said direction by one-half of said period from said polepieces of the other set, and means for sustaining a unidirectional magnetomotive force in said direction of propagation;
means for collecting said beam;
means spaced along said beam for guiding electromagnetic waves parallel to said direction of propagation to form an electromagnetic resonator; and means for transmitting electromagnetic energy from said vacuum envelope surrounding said beam.
a vacuum envelope;
means for generating a linear electron beam within said envelope;
means for wiggling said beam transverse to its direction of propagation comprising; on each of two opposite sides of said beam a set of floating ferro-magnetic polepieces spaced periodically along the direction of propagation of said beam, said polepieces of one set being displaced in said direction by one-half of said period from said polepieces of the other set, and means for sustaining a unidirectional magnetomotive force in said direction of propagation;
means for collecting said beam;
means spaced along said beam for guiding electromagnetic waves parallel to said direction of propagation to form an electromagnetic resonator; and means for transmitting electromagnetic energy from said vacuum envelope surrounding said beam.
16. The laser of claim 15 wherein said means for generating said magnetomotive force is a solenoid electromagnet surrounding said beam and said polepieces.
17. The laser of claim 15 wherein said polepieces are parallel bars defined by a first and a second parallel planes containing said direction of flow!
said bars extending perpendicular to said direction of propagation.
said bars extending perpendicular to said direction of propagation.
18. The laser of claim 17 wherein the bars of each of said sets are disposed in notches in a bar of non-magnetic material extending in said direction of propagation.
19. The laser of claim 17 wherein said polepieces of a set are separated by interleaved bars of non-magnetic material.
20. The laser of claim 19 wherein said polepieces and interleaved bars are bonded together to form a rigid, extended sheet.
21. The laser of claim 20 wherein said sheet forms part of a vacuum envelope surrounding said wiggler.
22. The laser of claim 19 wherein the bars of each of said sets are disposed in notches in a sheet of non-magnetic material extending in said direction of flow.
23. The laser of claim 22 wherein said sheet forms part of said vacuum envelope.
24. The laser of claim 15 wherein said electron beam is a hollow cylinder with axis in said direction of propagation, and said polepieces are substantially complete rings coaxial with said axis.
25. The laser of claim 15 wherein said polepieces in each of said sets are separated by interleaving rings of non-magnetic material.
26. The laser of claim 25 wherein said polepieces and said non-magnetic rings of a set are bonded to form an extended cylinder.
27. The laser of claim 26 wherein said cylinder outside said beam forms part of said vacuum envelope.
28. The laser of claim 25 wherein said polepieces are disposed in radial notches in the walls of non-magnetic cylinders.
29. The laser of claim 26 wherein the outer of said cylinders forms part of said vacuum envelope.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US4707887A | 1987-05-05 | 1987-05-05 | |
| US047,078 | 1987-05-05 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1291817C true CA1291817C (en) | 1991-11-05 |
Family
ID=21946958
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA000565933A Expired - Fee Related CA1291817C (en) | 1987-05-05 | 1988-05-04 | Short-period electron beam wiggler |
Country Status (4)
| Country | Link |
|---|---|
| JP (1) | JPS63299391A (en) |
| CA (1) | CA1291817C (en) |
| DE (1) | DE3813460A1 (en) |
| FR (1) | FR2615033B1 (en) |
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9247630B2 (en) | 2011-11-11 | 2016-01-26 | The Regents Of The University Of California | Surface-micromachined micro-magnetic undulator |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| JP3249930B2 (en) * | 1997-04-14 | 2002-01-28 | 信越化学工業株式会社 | Insert light source |
| DE202007019359U1 (en) | 2007-03-01 | 2012-03-08 | Babcock Noell Gmbh | Winding body for electromagnetic undulators |
| DE102008053162B3 (en) * | 2008-10-24 | 2010-07-29 | Karlsruher Institut für Technologie | Undulator for generating synchrotron radiation |
| US11373834B2 (en) * | 2016-07-22 | 2022-06-28 | Devesh S. BHOSALE | Apparatus for generating electromagnetic waves |
Family Cites Families (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3789257A (en) * | 1972-11-14 | 1974-01-29 | Us Navy | Coherent microwave generators |
| US4298824A (en) * | 1979-12-18 | 1981-11-03 | Dartmouth College | Millimeter and sub-millimeter radiation source |
| US4494039A (en) * | 1982-10-19 | 1985-01-15 | The United States Of America As Represented By The Secretary Of The Navy | Gyrotron traveling-wave device including quarter wavelength anti-reflective dielectric layer to enhance microwave absorption |
-
1988
- 1988-04-21 DE DE19883813460 patent/DE3813460A1/en not_active Withdrawn
- 1988-04-26 JP JP10152088A patent/JPS63299391A/en active Pending
- 1988-05-02 FR FR8805869A patent/FR2615033B1/en not_active Expired - Fee Related
- 1988-05-04 CA CA000565933A patent/CA1291817C/en not_active Expired - Fee Related
Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US9247630B2 (en) | 2011-11-11 | 2016-01-26 | The Regents Of The University Of California | Surface-micromachined micro-magnetic undulator |
Also Published As
| Publication number | Publication date |
|---|---|
| JPS63299391A (en) | 1988-12-06 |
| DE3813460A1 (en) | 1988-11-24 |
| FR2615033A1 (en) | 1988-11-10 |
| FR2615033B1 (en) | 1993-09-10 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| MKLA | Lapsed |