EP0402631A1 - Gyrotron quasi optique - Google Patents

Gyrotron quasi optique Download PDF

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Publication number
EP0402631A1
EP0402631A1 EP90108882A EP90108882A EP0402631A1 EP 0402631 A1 EP0402631 A1 EP 0402631A1 EP 90108882 A EP90108882 A EP 90108882A EP 90108882 A EP90108882 A EP 90108882A EP 0402631 A1 EP0402631 A1 EP 0402631A1
Authority
EP
European Patent Office
Prior art keywords
quasi
yoke
resonator
magnetic field
electron beam
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.)
Withdrawn
Application number
EP90108882A
Other languages
German (de)
English (en)
Inventor
Bernd Dr. Jödicke
Hans-Günter Dr. Mathews
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ABB Asea Brown Boveri Ltd
ABB AB
Original Assignee
ABB Asea Brown Boveri Ltd
Asea Brown Boveri AB
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by ABB Asea Brown Boveri Ltd, Asea Brown Boveri AB filed Critical ABB Asea Brown Boveri Ltd
Publication of EP0402631A1 publication Critical patent/EP0402631A1/fr
Withdrawn legal-status Critical Current

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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
    • H01J25/025—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 with an electron stream following a helical path
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
    • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y10S505/00—Superconductor technology: apparatus, material, process
    • Y10S505/70—High TC, above 30 k, superconducting device, article, or structured stock

Definitions

  • the invention relates to a quasi-optical gyrotron, in which two coils in a Helmholtz arrangement generate a static magnetic field which is axially symmetrical with respect to an electron beam axis, on the electron beam axis parallel to the magnetic field, electrons are forced to gyrate and excite an alternating electromagnetic field in a quasi-optical resonator , which comprises two mirrors arranged opposite one another on a resonator axis, the resonator axis between the two coils being aligned perpendicular to the electron beam axis.
  • a quasi-optical gyrotron of the type mentioned at the beginning is e.g. from the patent CH-664045 or from the article "The gyrotron, key component for high-power microwave transmitters", H.G. Mathews, Minh Quang Tran, Brown Boveri Review 6-1987, pp. 303-307.
  • microwave power of such gyrotrons at working frequencies of more than about 100 GHz has so far been limited to a few 100 kW, applications in the Plasma heating for fusion purposes continuous wave power of 1 MW and more can be generated.
  • a problem in the implementation of such high-performance gyrotron is the undesired heating of the resonator walls. Because of the finite electrical conductivity of the walls, the walls are heated by the HF field in the resonator. The achievable microwave power is thus limited by the maximum dissipation power that can be dissipated.
  • the solution is that the mirrors of the quasi-optical resonator have a superconducting mirror surface and that means for suppressing the magnetic field are provided at the location of the mirrors.
  • the essence of the invention is that the magnetic field that forces the electrons to gyrate must be as homogeneous as possible, but only in the area of the electron beam. A radial gradient outside this range is permissible.
  • the means according to the invention for shielding now have the result that a magnetic field gradient is created which ensures that the magnetic field drops so strongly in the radial direction that the superconductivity is not impaired.
  • a yoke is provided which essentially encloses the coils. I.e. it is designed so that it largely absorbs the magnetic flux outside the coils. This can be achieved with an essentially one-part as well as with a multi-part yoke.
  • the yoke must consist of a material with a high magnetic permeability.
  • the yoke preferably encloses the two coils in the manner of a hollow cylinder provided with a cover and a bottom.
  • the hollow cylinder has openings for the resonator.
  • the mirrors of the resonator are then arranged outside the hollow cylinder behind the openings.
  • the yoke consists of several yoke parts which are arranged around the coils at regular intervals.
  • a conceptually somewhat different embodiment consists in that the magnetic field at the location of the mirrors is compensated for by a corresponding opposing field.
  • the opposing field is generated by an additional coil arrangement outside the two coils responsible for gyration.
  • FIG. 1 shows the parts of an inventive quasi-optical gyrotron which are essential for explaining the invention.
  • An electron gun not shown in the figure, injects electrons in the form of e.g. annular electron beam 1.
  • the electrons run along an electron beam axis 2.
  • Two coils 3a and 3b are arranged on the electron beam axis 2 at a distance corresponding to their radius (so-called Helmholtz arrangement). They generate a static magnetic field aligned with the electron beam axis 2 (with a magnetic induction of typically 4 T and more), which forces the electrons to gyrate.
  • a quasi-optical resonator is arranged between the two coils 3a, 3b. It consists of two spherical, circular mirrors 4a and 4b, which are arranged opposite one another on a resonator axis 5.
  • the resonator axis is perpendicular to the electron beam axis 2.
  • the electrons excite an alternating electromagnetic field in the quasi-optical resonator, so that the desired microwaves can be coupled out in one of the two mirrors 4a and guided to a consumer through a window 7 and a waveguide 8.
  • the two coils 3a, 3b, the resonator and, of course, the electron beam 1 are located in a vessel 9 in a high vacuum.
  • a yoke 10 which essentially surrounds the two coils 3a, 3b. It consists of a material with a high magnetic permeability, preferably iron.
  • the yoke 10 has the shape of a hollow cylinder 11 of a length L, which is closed off in the axial direction by a cover 12 and a base 13.
  • the hollow cylinder 11 is coaxial to the electron beam axis 2.
  • the length L and an inner radius Ri of the hollow cylinder 11 are such that the two coils 3a, 3b in a Helmholtz arrangement, respectively. that this enclosing vessel 9, find space in it.
  • Cover 12 and bottom 13 of the hollow cylinder 11 are each provided with a passage opening for the electron beam 2.
  • the through openings are kept as small as possible.
  • the hollow cylinder 11 itself also has two diametrically opposite openings for the resonator. These openings are just so large that they do not disturb the alternating electromagnetic field in the resonator.
  • the two mirrors 4a, 4b form the walls of the resonator and each have a superconducting mirror surface 6a, respectively. 6b.
  • a cooling device not shown in the figure, keeps it at a temperature which is sufficiently low for superconductivity.
  • the superconducting mirror surfaces 6a, 6b are e.g. formed by a layer consisting of a high temperature superconductor.
  • the two spherical mirrors 4a, 4b are arranged outside the yoke 10 in front of the openings of the hollow cylinder 11. In a symmetrical embodiment, they are mutual Distance which is larger than an outer diameter Ra of the hollow cylinder 11.
  • the radius r is symmetrical on the abscissa, i.e. the distance from the electron beam axis 2, and on the ordinate the strength of the magnetic induction B is plotted.
  • the solid curve represents the course of the magnetic field in the presence of the yoke 10. In a region close to the axis, which corresponds to at least one diameter of the electron beam 1, the magnetic field is almost homogeneous. Then it decreases with increasing radius r until it is at least so small at the location of the mirrors 4a, 4b that the superconductivity is not impaired.
  • the dashed curve shows the course of the magnetic field without the yoke 10 according to the invention.
  • the magnetic field is homogeneous over a relatively wide area and only drops slowly with increasing radius.
  • FIG. 3 shows a section through the yoke 10.
  • the hollow cylinder 11 with length L has two openings for the resonator, one of which - designated by 14 - can be seen in the figure.
  • This opening 14 is located approximately in the middle of the hollow cylinder 11. It is typically circular, with the resonator axis passing through its center.
  • Bottom 13 and cover 12 each have a passage opening 16, respectively. 15 on. Finally, the inner radius Ri and outer radius Ra of the hollow cylinder are shown.
  • the yoke 10 of FIG. 1 results when two halves according to FIG. 3 are joined together accordingly.
  • Such a yoke creates the best possible shielding of the magnetic field.
  • it is difficult and possibly complex to assemble.
  • the disadvantages mentioned can be avoided with the embodiment described below.
  • Fig. 4 shows a quasi-optical gyrotron with a yoke, which consists of several yoke parts 17a, ..., 17f.
  • the following parts can be seen again in the figure:
  • the electron beam axis is perpendicular to the plane of the drawing.
  • the yoke comprises six, essentially identical yoke parts 17a, ..., 17f. These are at regular mutual intervals around the electron beam axis, respectively. the coils arranged around. Two diametrically opposed spaces serve as an opening for the resonator.
  • FIG. 5 shows two such yoke parts 17c, 17d with the gap-shaped intermediate space serving as opening 18.
  • the mirror 4b is at a distance from the electron beam axis 2 which is larger than the outside diameter of the yoke.
  • the yoke parts 17a, ..., 17f form segments of a hollow cylinder which is closed in the axial direction by a base and a cover. In principle, they are nothing else than azimuthally limited sections of a hollow cylindrical yoke, as has been explained with reference to FIGS. 1 and 3. They have the shape of a piece of cake.
  • the yoke formed from the six yoke parts 17a, .., 17f essentially completely encloses the coils. Because of the high magnetic permeability, most of the magnetic flux is concentrated on the yoke parts. Outside of the sleeve-shaped area encased by yoke parts, the magnetic field is sufficiently small.
  • a yoke with eight yoke parts is also considered a preferred embodiment of the invention.
  • the yoke parts need not be shaped exactly as has been described with reference to the figures. Rather, the invention also includes certain variations. These can be described as "removing material" from a sleeve-like yoke, as has been shown in FIGS. 1 and 3, in a suitable manner, so that the volume and weight of the yoke become smaller, but at the same time essentially maintain the magnetic shielding effect remains.
  • any material that has a magnetic permeability that is large in relation to that of the vacuum is suitable for the yoke.
  • iron is only a typical candidate.
  • An embodiment somewhat different from the previous examples does not use a yoke as a shield, but a compensating magnetic field. This is generated by two or more additional coils.
  • the additional coils are located outside the cylindrical volume encompassed by Helmholtz coils.
  • the additional coils are also coaxial with the electron beam axis.
  • the radius, distance and coil current of the additional coils are then to be dimensioned such that the strength of the magnetic field at the location of the mirrors of the resonator is overall below a threshold required for superconductivity.
  • the specific dimensions depend on various parameter values and can be easily calculated.
  • the "active" and the “passive” approach can also be combined by improving the effect of a geometrically simple yoke with suitably designed, small coils.

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  • Microwave Tubes (AREA)
  • Particle Accelerators (AREA)
EP90108882A 1989-06-12 1990-05-11 Gyrotron quasi optique Withdrawn EP0402631A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
CH2189/89A CH678243A5 (fr) 1989-06-12 1989-06-12
CH2189/89 1989-06-12

Publications (1)

Publication Number Publication Date
EP0402631A1 true EP0402631A1 (fr) 1990-12-19

Family

ID=4227975

Family Applications (1)

Application Number Title Priority Date Filing Date
EP90108882A Withdrawn EP0402631A1 (fr) 1989-06-12 1990-05-11 Gyrotron quasi optique

Country Status (5)

Country Link
US (1) US5134341A (fr)
EP (1) EP0402631A1 (fr)
JP (1) JPH0330242A (fr)
CH (1) CH678243A5 (fr)
RU (1) RU1835099C (fr)

Families Citing this family (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US5466885A (en) * 1990-09-27 1995-11-14 Furukawa Denki Kogyo Kabushiki Kaisha Magnetically shielding structure
EP2150965B1 (fr) * 2007-05-04 2011-08-31 Max-Planck-Gesellschaft zur Förderung der Wissenschaften e.V. Procédé et appareil de commande de balayage de collecteur d'un faisceau d'électrons

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH664045A5 (en) * 1984-10-02 1988-01-29 En Physiquedes Plasmas Crpp Ce Quasi-optical gyro-klystron for producing milli-meter waves - comprising resonator, drift-zone, second resonator and two annular field-coils to generate magnetic field

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3325678A (en) * 1966-06-02 1967-06-13 Gen Electric Magnetically shielded structure with adjustable cover member supporting a magnetron
US3466499A (en) * 1967-03-27 1969-09-09 Atomic Energy Commission Cancellation of external magnetic fields by inner and outer cylindrical current sheets
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
US4733133A (en) * 1985-11-26 1988-03-22 Applied Microwave Plasma Concepts, Inc. Method and apparatus for producing microwave radiation
JP2527554B2 (ja) * 1987-03-23 1996-08-28 大阪府 超電導磁気遮蔽体

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CH664045A5 (en) * 1984-10-02 1988-01-29 En Physiquedes Plasmas Crpp Ce Quasi-optical gyro-klystron for producing milli-meter waves - comprising resonator, drift-zone, second resonator and two annular field-coils to generate magnetic field

Non-Patent Citations (2)

* Cited by examiner, † Cited by third party
Title
BROWN BOVERI REVIEW, Nr. 6, 1987, Seiten 303-307, Baden, CH; H.G. MATHEWS et al.: "The gyroton - A key component of high-power microwave transmitters" *
INT. J. ELECTRONICS, Band 57, Nr. 6, 1984, Seiten 977-984; T.A. HARGREAVES et al.: "Experimental study of a single-mode quasi-optical gyrotron" *

Also Published As

Publication number Publication date
CH678243A5 (fr) 1991-08-15
JPH0330242A (ja) 1991-02-08
RU1835099C (ru) 1993-08-15
US5134341A (en) 1992-07-28

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