JPH0374029A - Gyrotron device - Google Patents

Abstract

PURPOSE:To work for big output and high frequency for facilitating the transmission of a generated electromagnetic wave by providing a specific optical resonator, an electron beam supplying means and an output wave transmission line. CONSTITUTION:An optical resonator 12 constituted by combination of a plurality of ring-shaped mirrors 41 while being provided with an electron beam induction path in the central part together with a part radiating an electromagnetic wave on the peripheral part as a hollow beam is used as a resonator 12. Further, an output transmission line transmits an electromagnetic wave outputted from the resonator 12 for being guided to a waveguide path consisting of a ring- shaped mirror group to be further guided to pass through a circular coaxial waveguide 52 and a circular waveguide 53 in series. The circular coaxial waveguide 52 is provided with an outer tube, whose diameter is decreasing as it goes to the downstream side, and a conical inner tube, while being connected to the circular waveguide 53 at the top position of the inner tube. Big output and high frequency can thereby be attained, while a generated electromagnetic wave is converted into a circular waveguide mode to be easily transmitted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Objective of the Invention (Field of Industrial Application) The present invention relates to a gyrotron device used for heating plasma in a nuclear fusion reactor.

(Prior Art) There are various means for heating the plasma of a nuclear fusion reactor, one of which is a high-frequency heating method using electron cyclotron resonance. Applying this method to plasma heating in fusion reactors requires an oscillation tube with a frequency in the millimeter wave band and high output. Gyrotron devices are seen as promising as this oscillation tube. Most gyrotron devices use an electron beam generated by a magnetron-type electron gun to oscillate within a waveguide-type resonator.

However, in a gyrotron device configured in this way, the heat load inside the resonator increases due to the inability to increase the resonator diameter, making it difficult to oscillate in a predetermined mode, making it difficult to increase output power and Frequency conversion was difficult.

In order to solve this problem, a quasi-optical gyrotron device using an optical resonator formed by combining a plurality of mirrors has recently been proposed. However, even with this type of gyrotron device, all of the problems mentioned above have not been solved, and the problem of how to convert the generated electromagnetic waves into a mode that is easy to transmit and send it out has not been solved. do not have.

(Problems to be Solved by the Invention) As described above, in the conventional gyrotron device, it is difficult to increase the output power and frequency, and there are also problems in terms of transmission.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a quasi-optical gyrotron device that can solve the above-mentioned problems.

[Structure of the Invention] (Means for Solving the Problems) In order to solve the above problems, in the gyrotron device according to the present invention, the resonator is constituted by a combination of a plurality of annular mirrors, and the central part An optical resonator is used, which is equipped with an electron beam transmission path and a peripheral part that emits electromagnetic waves as a hollow beam.

In addition, as an output wave transmission path for transmitting the electromagnetic waves output from the resonator, the electromagnetic waves are guided to a waveguide composed of a group of annular mirrors, and then guided through a circular coaxial waveguide and a circular waveguide in series. using things. The circular coaxial waveguide includes an outer tube whose diameter decreases toward the downstream side and a conical inner tube, and is connected to the circular waveguide at the apex position of the inner tube.

(Function) When a rotating electron beam is incident on the resonator having the above configuration while an axial magnetic field is applied, a high-power electromagnetic wave with a circumferential mode number of m-1 is excited within the resonator. The generated high-power electromagnetic waves are output from the resonator as a hollow beam. Thereafter, the number of modes in the circumferential direction is converted by a mode converter as necessary, and finally the mode is converted into a circular waveguide mode that is easy to transmit.

(Example) Examples will be described below with reference to the drawings.

FIG. 1 shows a schematic configuration of a quasi-optical gyrotron device according to an embodiment of the present invention.

This gyrotron device is roughly divided into an electron beam supply source 11, an optical resonator 12 that converts the energy of the electron beam supplied from the supply source 11 into electromagnetic waves, and a A transmission line 13 that guides electromagnetic waves to the required location, a magnetic field generating coil 14 formed of, for example, a superconducting coil that applies the necessary magnetic field to the electron beam source 11 in the axial direction, and a magnetic field that applies the necessary magnetic field to the resonator 12. It is composed of a magnetic field generating coil 15 which is also formed of a superconducting coil or the like and which applies the magnetic field in the axial direction.

As shown in FIG. 2, the electron beam supply source 11 includes a vias-type electron gun 21 that generates a pencil-shaped electron beam, and a drift tube 22 connected to the output end of this electron gun. Pencil-shaped electron beam 2
It is composed of a double helical coil 24 that generates a helical wiggler magnetic field for giving swirling motion to the magnet 3, and a magnetron type electron gun 25.

The bias type electron gun 21 includes a cathode 26 and an anode 27, and generates a pencil-shaped electron beam 23. This pencil-shaped electron beam 23 travels within a drift tube 22 arranged such that its terminal end passes through the magnetron type electron gun 25 . At this time, the rotating motion is performed under the influence of the helical wiggler magnetic field applied by the double helical coil 24 and the axial magnetic field applied by the magnetic field generating coil 14.

On the other hand, the magnetron type electron gun 25 has a hollow cathode 3
0, an annular control electrode 31 disposed outside the cathode 30, and a hollow anode 32 disposed coaxially with the cathode 30, and generates a hollow electron beam 33 from the cathode 30. do. This hollow electron beam 33 rotates under the influence of the magnetic field applied by the magnetic field generating coil 14. These hollow rotating electron beams 33 and the above-mentioned pencil-shaped rotating electron beam 23
is input into the resonator 12.

As shown in FIG. 3, the resonator 12 includes an annular mirror 41 disposed in the axial direction with reference to the travel axes of the pencil-shaped rotating electron beam 23 and the hollow rotating electron beam 33; It is composed of a mirror 42. The annular mirror 41 is made of a conductive material, has an inner circumferential surface shaped like a side surface of a truncated cone, and has a curved surface that is axially symmetrical, with the small-diameter opening side serving as an electron beam source. 11
It is placed on the side. In addition, an annular flat mirror 42
is made of a conductive material and is arranged to cover the large-diameter opening side of the annular mirror 41. As shown in FIG. 4, this annular flat mirror 42 has a slit 43 through which the electromagnetic waves are made into a hollow beam.
are formed in multiple radial shapes.

An axial magnetic field is applied within the resonator 12 by the magnetic field generating coil 15 described above. When a pencil-shaped rotating electron beam 23 is incident along the axis of the resonator 12 to which an axial magnetic field is applied, electromagnetic waves propagate within the resonator 12 in the direction shown by the arrow in FIG. A standing wave is generated and oscillates.

At this time, the number of circumferential modes of the electromagnetic waves oscillated is selectively m
ml. The oscillation output of only the pencil-shaped rotating electron beam 23 is small. However, since the hollow rotating electron beam 33 with a large current enters, the electromagnetic waves excited by the pencil-shaped rotating electron beam 23 are amplified to generate high-output electromagnetic waves. The generated electromagnetic waves pass through a slit 43 provided in the annular flat mirror 42, become a hollow electromagnetic wave beam 44, and are radiated to the transmission path 13.

As shown in FIG. 1, the transmission path 13 includes a plurality of annular mirrors 51a and 51b having axially symmetrical curved surfaces.

51C, 51e, circular coaxial waveguide 521 circular waveguide 53
It is constructed by connecting coaxially.

The hollow electromagnetic wave beam 44 incident on the transmission path 13 is
As shown by solid line arrows in the figure, each annular mirror 51 as
It is transmitted while being reflected and focused at 51 bs... Note that the electron beam 33 that has passed through the resonator 12
is collected by a beam collector 54 provided in the middle of the transmission path 13. This beam collector 54 is cooled by a cooling system (not shown). Annular mirror 51
The hollow electromagnetic wave beam 44 transmitted while being reflected by a, 51b, .

As shown in FIG. 6, the circular coaxial waveguide 52 is composed of an outer tube 55 whose inner surface is mirror-finished, an inner tube 56 whose outer surface is mirror-finished, and a support member 57 that supports the inner tube 56. has been done. The outer tube 55 and the inner tube 56 are both formed in a shape whose diameter decreases toward the downstream side.

For example, the inner tube 56 is formed into a conical shape. The circular coaxial waveguide 52 is connected to the circular waveguide 53 at the apex position of the inner tube 56. Therefore, the hollow electromagnetic wave beam 44 incident between the outer tube 55 and the inner tube 56 of the circular coaxial waveguide 52 is finally converted into a circular waveguide mode that is easy to transmit.

In this embodiment, in order to convert the circumferential mode of the electromagnetic wave oscillated by the resonator 12 into another mode, the transmission line 13 is
A mode converter 58 is interposed at an intermediate position, that is, at a position upstream of the circular coaxial waveguide 52. This mode converter 58 converts the number of modes in the circumferential direction to m-0, for example, and divides the mirror surface formed on the inner surface into a plurality of parts in the circumferential direction, and each divided mirror The normal vector set on the inner surface of M is set so as not to point toward the central axis. By giving an appropriate normal vector to the inner surface in this manner, it is possible to convert, for example, the m-1 mode to the m-0 mode.

As a result, the mode within the circular waveguide 53 can be set to T E .

Further, in this embodiment, the pencil-shaped electron beam 23 generated by the bias-type electron gun 21 is collected on the inner surface of the inner tube 56 of the coaxial waveguide 52. That is, the inner tube 5
6 is used as a beam collector. therefore,
In this example, the inner tube 56 and the support material 57 are made to have a certain thickness, and the coolant is allowed to flow through the support material 57 and into the coolant passage formed in the inner tube 56.

However, in order to prevent reflection of electromagnetic waves, the support member 57 is formed into a knife shape at the entrance of the coaxial waveguide. Further, in FIG. 1, 59 indicates a window member for isolating the inside of the apparatus from the atmosphere, and 60 indicates an exhaust port.

The present invention is not limited to the embodiments described above, but can be modified in various ways. For example, deflection magnets may be arranged to direct the electron beam toward the beam collector.

Furthermore, the mode converter 58 is not necessarily required. In addition, various modifications can be made without departing from the gist of the present invention.

[Effects of the Invention] As described above, according to the present invention, since the resonator having the above configuration is used, the resonator can be made larger than that using a waveguide type resonator, and as a result, the resonance It is possible to reduce the heat load generated on the wall surface of the vessel, and moreover, in a predetermined mode (for example,
) can be selectively oscillated, making it possible to achieve large output and high frequency. Furthermore, the generated electromagnetic waves can be converted into a circular waveguide mode that is easy to transmit and sent out.

[Brief explanation of drawings]

FIG. 1 is a schematic configuration diagram of a gyrotron device according to an embodiment of the present invention, FIG. 2 is a configuration diagram of an electron beam source in the device, and FIG. 3 is a vertical cross-sectional view of a resonator in the device.
Figure 4 is a plan view of the annular flat mirror incorporated in the resonator, Figure 5 is a cross-sectional view of the mode converter incorporated in the gyrotron device, and Figure 6 is the cross-sectional view of the −
It is an X-ray section arrow view. 11... Electron beam source, 12... Resonator, 13
...Transmission line, 14.15...Magnetic field generating coil, 21
...Beers type electron gun, 22...Drift tube,
23... Pencil-shaped rotating electron beam, 24... Double spiral coil, 25... Magnetron type electron gun, 33
... Hollow rotating electron beam, 41 ... Annular mirror 42 ... Annular flat mirror 43 ... Slit,
44...Hollow electromagnetic wave beam, 51a, 51b. 51c, 51d, 51e...Axisymmetric annular curved mirror 52...Circular coaxial waveguide, 53...Circular waveguide, 54...Beam collector. Figure 5

Claims (4)

[Claims] (1) In a quasi-optical gyrotron device that includes a resonator formed by combining multiple mirrors, it is configured by combining multiple annular mirrors and has an electron beam transmission path in the center. an optical resonator comprising a peripheral part that emits electromagnetic waves as a hollow beam; an electron beam supply means for inputting a rotating electron beam into the resonator; and an electromagnetic wave output from the resonator. A gyrotron comprising: a circular coaxial waveguide and an output wave transmission line that guides the output wave to a waveguide composed of a group of annular mirrors, and then passes through a circular coaxial waveguide and the circular waveguide in series. Device. (2) The gyrotron device according to claim 1, wherein the electron beam supply means is mainly composed of a bias type electron gun and a magnetron type electron gun. (3) The circular coaxial waveguide includes an outer tube whose diameter decreases toward the downstream side and a conical inner tube, and is connected to the circular waveguide at the apex position of the inner tube. The gyrotron device according to claim 1, characterized in that: (4) The gyrotron device according to claim 1 or 3, wherein the inner tube of the circular coaxial waveguide also serves as an electron beam collector.