EP0049198B1 - Accélérateur d'électrons et générateur d'ondes millimétriques et infra-millimétriques comportant un tel accélérateur - Google Patents

Accélérateur d'électrons et générateur d'ondes millimétriques et infra-millimétriques comportant un tel accélérateur Download PDF

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Publication number
EP0049198B1
EP0049198B1 EP81401482A EP81401482A EP0049198B1 EP 0049198 B1 EP0049198 B1 EP 0049198B1 EP 81401482 A EP81401482 A EP 81401482A EP 81401482 A EP81401482 A EP 81401482A EP 0049198 B1 EP0049198 B1 EP 0049198B1
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EP
European Patent Office
Prior art keywords
electron
axis
magnetic field
along
generator
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Expired
Application number
EP81401482A
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German (de)
English (en)
French (fr)
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EP0049198A1 (fr
Inventor
Georges Mourier
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Thales SA
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Thomson CSF SA
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
    • H01J25/00—Transit-time tubes, e.g. klystrons, travelling-wave tubes, magnetrons
    • H01J25/02—Tubes with electron stream modulated in velocity or density in a modulator zone and thereafter giving up energy in an inducing zone, the zones being associated with one or more resonators

Definitions

  • the present invention relates to an electron accelerator which can be used in a millimeter and infra-millimeter wave generator. It also relates to generators comprising such accelerators.
  • Infra-millimeter wave generators such as free electron lasers are known, in particular by the article by L.R. Elias et al, published in 1976, in the review "Phisical review letters", volume 36, pages 717 et seq.
  • These periodic transverse accelerations are generally obtained by establishing either a helical magnetic field, of pitch P and of axis Oz, or two fields transverse to the axis Oz, of opposite directions and periodically distributed in space with the same period P .
  • the present invention relates to an electron accelerator and a millimeter and infra-millimeter wave generator comprising this accelerator which are of different design from what is known in the prior art.
  • the generator according to the present invention makes it possible to simultaneously obtain a high frequency and a radiated power, while maintaining dimensions similar to those of standard electronic tubes.
  • This generator is high, of the order of 50%, and with a current of about 10 mA in the cathode-anode bias circuit, a radiated power of 7.5 KW is obtained.
  • this generator does not require too high direct voltage (around 200 KV between the anode and the cathode) and that the value of this direct voltage can vary over a wide range.
  • the present invention relates to an electron accelerator comprising in a vacuum enclosure, an electron gun which produces an electron beam propagating along an Oz axis, said electron accelerator further comprising a coil which surrounds the enclosure and produces a magnetic field oriented along the axis, characterized in that it includes inside the enclosure, a delay line, supplied by a high frequency generator, this delay line allowing the establishment of a field longitudinal high frequency electric oriented along the Oz axis, in that the intensity of the magnetic field increases at the level of the delay line and in that the electron gun produces electrons whose speeds have a first component oriented according to the axis and corresponding to the Newtonian regime, as well as a non-zero transverse component.
  • the present invention also relates to a millimeter and infra-millimeter wave generator which comprises an electron accelerator according to the invention.
  • the electron beam enters a resonant cavity tuned to the frequency F M corresponding to a slightly higher pulsation MM . ° a
  • the coil which surrounds the vacuum enclosure at the level of the resonant cavity creates a uniform magnetic field along the Oz axis.
  • the electron accelerator according to the present invention can be used as will be seen in the following description in the millimeter and infra-millimeter wave generators.
  • the generator according to the invention has the same applications as the generators of the prior art for millimeter and infra-millimeter waves, namely radar emission, measurement in plasma installations, isotipic separation ...
  • FIG. 1 represents the distribution of the magnetic fields and an electronic trajectory in the lasers with free electrons according to the prior art which has been previously discussed.
  • the electron beam 1 rises and falls as shown in the figure and therefore undergoes transverse accelerations.
  • the electrons radiate a power which is proportional to the square of the transverse accelerations.
  • FIG. 4 represents a longitudinal view, along the axis Oz of an embodiment of the generator according to the invention.
  • Figure 2 shows the helical path followed by an electron at the exit of the electron gun.
  • This electron gun generally comprises a cathode 7 in the form of a ring which produces a hollow cylindrical beam.
  • Such electron guns are known in particular from the thesis defended on 12.07.79 at the Polytechnic Institute of Grenoble by J.L. ALIROT and entitled "Injector for high frequency wave generator tube of the gyrotron tube with central injection”.
  • the accelerator according to the invention can also operate without using a hollow cylindrical beam but by using a thin off-center beam.
  • the high continuous voltage applied between the cathode and the anode is chosen so as to impart the longitudinal speed V z to the electron beam.
  • a focusing coil 9 surrounds the vacuum chamber at the level of the electron gun.
  • the vacuum enclosure is made of an insulating material, glass or ceramic, because it receives the high DC voltage.
  • This coil 9 creates a magnetic field in the opposite direction to that which is created in the rest of the accelerator. This is necessary so that the electron beam has in the rest of the accelerator a spiral path centered on the axis.
  • the vacuum enclosure 5 After the electron gun, the vacuum enclosure 5 includes a delay line 10 arranged along the axis Oz and supplied by a high frequency generator 11.
  • This delay line must allow the establishment of a longitudinal high frequency electric field, along the axis Oz.
  • This delay line is generally formed by an iris guide, as shown in FIG. 4.
  • Other types of delay line could be used such as a helical delay line for example.
  • the frequency delivered by this generator 11 is independent of that delivered by the generator according to the invention; the frequency delivered by the generator 11 is generally much lower than that delivered by the generator according to the invention, and between 1 GHz and 10 GHz.
  • the electron beam 1 is subjected to a magnetic field which increases along the axis Oz and which is produced by a coil 12.
  • each electron As soon as it enters the iris guide 10, each electron describes a spiral trajectory which is closer to the Oz axis.
  • the increasing magnetic field makes it possible to increase the speed of rotation of the electrons around the Oz axis.
  • the longitudinal energy supplied by the H.F. generator 11 is transformed into transverse energy, and the electrons therefore receive significant transverse accelerations.
  • the magnetic field created by the coil 12 along the axis Oz is growing slowly. For example, each electron describes around ten orbits in the iris guide 10.
  • each electron places in a slowly growing magnetic field with Oz and in an electric amplifier field study E, according to Oz, which is produced by the HF 11 generator, each electron describes a spiral.
  • the component along the Oz axis of the force acting on the electrons has the expression: where C is a constant of the movement which is written: with r the radius of the orbit described by the electrons.
  • the energy transmitted to the electrons comes from the electric field of amplitude E, according to Oz, which is produced by the generator H.F. 11.
  • the speed V z can therefore be constant on the axis Oz.
  • the following relation must then be verified between the value of the electric field according to Oz, E, and the variations of the magnetic field according to Oz:
  • the vacuum enclosure 5 of the generator 2 has a diameter smaller than that which it presents at the level of the accelerator 3.
  • FIG. 5 which is a transverse view along the plane F of FIG. 4 of the generator according to the invention, we see the rectangular section of the mirrors 13.
  • the coil 12 creates a uniform magnetic field along the axis Oz.
  • the electron beam passes, after passing through the accelerator, between two parallel reflectors 14.
  • N is an integer
  • ⁇ M the wavelength of the coherent radiation that we will obtain and which will be specified below.
  • Each of the reflectors 14 has a semi-reflecting zone 15 which lets through a fraction of the radiation and reflects the rest and a reflecting zone 16.
  • the reflective area of one reflector faces the semi-reflective area of the other reflector, and vice versa.
  • the radiation is collected through the vacuum enclosure 5 which is made of glass at this location in two opposite directions on each zone which lets the radiation from the two deflectors pass.
  • the mirrors 13 make it possible to reduce the radiation in the direction Oz because it is not possible to let it propagate perpendicular to the reflectors because of the presence of the coil 12.
  • the second part 4 of the generator in which the millimeter and infra-millimeter orders are taken constitutes a resonant cavity tuned to the frequency F M corresponding to ⁇ M.
  • This cavity can be open, that is to say constituted for example by two parallel reflectors as is the case in the embodiment shown in FIG. 4.
  • This cavity can also be closed and made up, for example, of a waveguide portion.
  • the stimulated synchrotron radiation always occurs at a frequency very close to the resonator frequency and greater than the frequency of the synchrotron harmonic.
  • the accelerator according to the invention being linear makes it possible to vary, along the linear acceleration path, parameters, such as for example the thickness of the valves, as a function of z in order to adapt to the mass, to the velocity of particles which vary along the z axis.

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  • Particle Accelerators (AREA)
  • Lasers (AREA)
EP81401482A 1980-09-26 1981-09-24 Accélérateur d'électrons et générateur d'ondes millimétriques et infra-millimétriques comportant un tel accélérateur Expired EP0049198B1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
FR8020714 1980-09-26
FR8020714A FR2491256A1 (fr) 1980-09-26 1980-09-26 Accelerateur d'electrons et generateur d'ondes millimetriques et infra-millimetriques comportant un tel accelerateur

Publications (2)

Publication Number Publication Date
EP0049198A1 EP0049198A1 (fr) 1982-04-07
EP0049198B1 true EP0049198B1 (fr) 1984-11-14

Family

ID=9246330

Family Applications (1)

Application Number Title Priority Date Filing Date
EP81401482A Expired EP0049198B1 (fr) 1980-09-26 1981-09-24 Accélérateur d'électrons et générateur d'ondes millimétriques et infra-millimétriques comportant un tel accélérateur

Country Status (5)

Country Link
US (1) US4571524A (enrdf_load_stackoverflow)
EP (1) EP0049198B1 (enrdf_load_stackoverflow)
JP (1) JPS5789282A (enrdf_load_stackoverflow)
DE (1) DE3167219D1 (enrdf_load_stackoverflow)
FR (1) FR2491256A1 (enrdf_load_stackoverflow)

Families Citing this family (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4754196A (en) * 1986-12-10 1988-06-28 The United States Of America As Represented By The Secretary Of The Navy Axial injection orbitron
FR2625836B1 (fr) * 1988-01-13 1996-01-26 Thomson Csf Collecteur d'electrons pour tube electronique
JP2893457B2 (ja) * 1989-07-11 1999-05-24 栄胤 池上 高輝度電子ビーム発生方法
FR2672730B1 (fr) * 1991-02-12 1993-04-23 Thomson Tubes Electroniques Dispositif convertisseur de modes et diviseur de puissance pour tube hyperfrequence et tube hyperfrequence comprenant un tel dispositif.
US5280490A (en) * 1991-11-22 1994-01-18 Massachusetts Institute Of Technology Reverse guide field free electron laser
AU2001251222A1 (en) * 2000-03-31 2001-10-15 University Of Maryland, Baltimore Helical electron beam generating device and method of use
US8018158B2 (en) * 2007-04-20 2011-09-13 L-3 Communications Corporation Method and apparatus for interaction with a modulated off-axis electron beam
US10903035B2 (en) * 2018-03-12 2021-01-26 Wisconsin Alumni Research Foundation High-frequency vacuum electronic device
US11201028B2 (en) 2019-10-01 2021-12-14 Wisconsin Alumni Research Foundation Traveling wave tube amplifier having a helical slow-wave structure supported by a cylindrical scaffold
US11588456B2 (en) 2020-05-25 2023-02-21 Wisconsin Alumni Research Foundation Electroplated helical slow-wave structures for high-frequency signals

Family Cites Families (10)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR1369416A (fr) * 1963-06-12 1964-08-14 Csf Perfectionnements aux lignes à retard électroniques
US3474283A (en) * 1967-03-22 1969-10-21 Us Navy Cyclotron wave upconverter
US3463959A (en) * 1967-05-25 1969-08-26 Varian Associates Charged particle accelerator apparatus including means for converting a rotating helical beam of charged particles having axial motion into a nonrotating beam of charged particles
US3398376A (en) * 1967-12-11 1968-08-20 Jay L. Hirshfield Relativistic electron cyclotron maser
US3887832A (en) * 1973-06-25 1975-06-03 Aralco Auto-resonant acceleration of ions
US4143299A (en) * 1976-09-16 1979-03-06 The United States Of America As Represented By The Secretary Of The Navy Charged-particle beam acceleration in a converging waveguide
FR2401508A1 (fr) * 1977-06-27 1979-03-23 Commissariat Energie Atomique Injecteur d'electrons pour generateur hyperfrequence
US4224576A (en) * 1978-09-19 1980-09-23 The United States Of America As Represented By The Secretary Of The Navy Gyrotron travelling-wave amplifier
FR2445611A1 (fr) * 1978-12-29 1980-07-25 Thomson Csf Generateur d'ondes radioelectriques pour hyperfrequence
US4395656A (en) * 1980-12-24 1983-07-26 The United States Of America As Represented By The Administrator Of The National Aeronautics And Space Administration Gyrotron transmitting tube

Also Published As

Publication number Publication date
US4571524A (en) 1986-02-18
FR2491256A1 (fr) 1982-04-02
DE3167219D1 (en) 1984-12-20
EP0049198A1 (fr) 1982-04-07
JPS5789282A (en) 1982-06-03
JPH0320880B2 (enrdf_load_stackoverflow) 1991-03-20
FR2491256B1 (enrdf_load_stackoverflow) 1983-04-15

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