JPS58102438A - Electron beam gyro unit - Google Patents

Abstract

PURPOSE:To prevent the heating of a cathode caused by ion bombardment and stabilize cathode temperature by insulating the section between a metal cylindrical electrode that supports an output window and a collector and applying a negative bias to the collector of this metal cylindrical electrode. CONSTITUTION:In an electron gun assembly body 2 an electron gun electrode 11 containing an annular cathode 9, and a heater 10, and an annular anode 12 are assembled together coaxially with a tube axis 8. Besides, the section between a metal cylindrical electrode 6 that supports an output window 5 and a collector 4 is insulated and for example, -300V is applied to the metal cylindrical electrode. Thus, for the potential distribution on the tube axix, low potential can occur on top of the collector 4. Therefore, the ion ionized inside the collector 4 is sucked out from the metal cylindrical electrode 6. As a result, the ion bombardment of the electron gun electrode 11 can be prevented and the cathode temperature can be stabilized.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to large microwave quadrants based on the principle of electron cyclotron masers, such as gyrotrons, gyroklystrons and gyro traveling wave tubes.

Gyrotrons, gyro klystrons, gyro traveling wave tubes, etc. - Seiko beam gyro devices utilize the combination of the TE mode of a high frequency circuit and the cyclotron mode of an electron beam to generate a high-power electromagnetic wave eA. The high-frequency circuit is a circular waveguide or cylindrical cavity in which the HTE mode is excited. A magnetron-type device that forms and emits a hollow beam with little radiation is used. The frequency ω of the '1' E mode of the high frequency circuit and the cyclotron frequency ω of the electron beam. and is nf integer, ω
sanω. When the following synchronization conditions are satisfied, a strong interaction occurs and a high-power electromagnetic wave is generated within the high-frequency circuit. Such interaction using the cyclotron motion of the adult beam makes it possible for the dimensions of the single particle beam and high-frequency circuit to become large compared to the wavelength, making it possible for the conventional millimeter-wave system to have a traveling wave tube or two istrons on the screen. The power density between 4 and 4 can be avoided.

Based on the prototype results of the n-th gyrotron reported so far,
In the 28 (tHg band), a 7-pulse output of 200 kW is obtained with a high efficiency of more than 30%, and 'e
The x-beam JIP device is enjoying high expectations from all quarters as a high power source in the originary to sub-infrared wave bands. In particular, the ability to generate large amounts of power with high efficiency in the ξυ wave band is attractive as a means of adding plasma heat to fusion reactors. However, in order to realize such an electron beam gyro device, long pulse operation or continuous wave operation with a pulse width of approximately 0.1 to 10 seconds is required for Fi for plasma additional heat. There are many technical problems that need to be solved, and there is a lack of active research in various fields.

The most important technical requirement is stabilization of the cathode temperature. As mentioned above, in the electron gun of the electron beam gyro device, in order to increase the lateral beam energy and reduce the variation in beam energy, the cathode is used in the a-degree limited region, and the electron emission bell, that is, the one-meter electric field, is used. It is controlled by 1flEt-cando temperature. Electron beam gyro! The cathode material for f is porous tungsten impregnated with barium because it can achieve high machine fishing accuracy and high It flow W[n, and the cathode temperature is around 850°0. Selected. The heater power required to maintain this cathode temperature is
Although it varies depending on the size of the cathode, it is al Qw. Alternatively, the cathode is heated by energy other than the heater power, and the cathode temperature rises too much, causing a sudden increase in the beam current and causing the electron beam gyro device to run out of control.In extreme cases, the heater may break. There was a critical moment.

Micr, a famous H magazine published in the United States in November 1977.
Paper 1't3'yrotron-reb described in owave Systems News Vol. 7 November issue page 75
orn tube is amillimeter p
owerhouseJ(Tj”, Godlove+V,
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Granatstein) discloses a prior art technique in which an electromagnetic wave attenuator is provided between an electron gun and a high frequency circuit to prevent the cathode from being heated by high frequency power. however.

Even if the heating of the cathode by high-frequency power is prevented, when the pulse width of the beam voltage is expanded, the beam current suddenly increases, making it difficult to make long pulses or continuous wave operation of electron beam gyro equipment. .

An object of the present invention is to realize long pulse or continuous wave operation of an electron beam gyro device by stabilizing the cathode temperature.

In this invention, ions ionized by an electron beam are
This was done by focusing on the fact that the kinetic energy lost during collision of electrons accelerated toward the negative potential electron gun electrode is converted into heat, which causes the cathode temperature to increase. That is, it is known that in a typical JIS device, a degree of vacuum of 10-' to 10-' TOrr is maintained by an ion pump, and the main component of the residual gas is hydrogen molecules. When hydrogen molecules in such a residual gas are bombarded with an electron beam with an energy of about gQkeV, the ionized hydrogen ions are accelerated toward the electron gun electrode at a negative potential.The impact energy at that time is equal to that of continuous wave operation. Case number 1
It reaches 0W. This is almost the same energy as the heater power, and even if heating by high-frequency power is prevented, the cathode temperature will rise due to heating by this ion bombardment, making the operation of the electron beam gyro device unstable. A friend to share.

The electron beam gyrating device of the present invention insulates between the metal cylindrical electrode supporting the output window and the collector, and the metal cylindrical electrode supporting the output window has a resistance of 200 to 500 with respect to the collector.
By applying a low voltage of V, highly separated ions are sucked out from within the t-electron beam gyro device to prevent heating of the cathode due to ion bombardment.

Another effect of the present invention is that the secondary electrons generated in the collector are decelerated by the negative bias, so that the impact of the secondary electrons on the output window is alleviated.

Yet another effect is that the insulating gap provided between the collector and the metal cylindrical electrode acts as a so-called moat filter that absorbs unnecessary modes generated within the electron beam gyro device.

FIG. 1 is an overall view of a gyrotron l embodying the present invention, and the figure shows an electron gun assembly 2, a high frequency circuit 3, a collector 4, an exit window 5', and a supported metal cylinder. Electrode 6
A tertiary structure is shown in which the output waveguides 7 and 7 are arranged along the tube axis 8.

- The sub-gun assembly 2 has an annular cathode 9 and an electron gun electrode 11 including a heater 10, and an annular anode I2 coaxially with respect to the tube axis 8. Typical values are heater 1o
A source of 10VI 5A is supplied by Hita electron #13, a beam magnetic pressure of -80 kV is applied to the electron gun electrode 11 and cathode 9 by the high voltage power supply 14, and an accelerating voltage of -54 kV is applied to the anode 12. applied. Electron gun solenoid 15, energized by a suitable DC power supply, generates a DC magnetic field along tube axis 8 passing through electron gun electrode 11 and anode 12. Direct current applied between cathode 9 and anode 14 -
Due to the interaction of the pressure and the direct current magnetic field set by the child gun solenoid 15, a hollow helical beam is formed and ejected from the electron gun assembly 2.

The middle 71!4 child beams are accelerated into the high frequency circuit 3. The main solenoid 16 generates a pigeon-strength DC magnetic field f: in a portion along the high frequency circuit 3. The magnetic field strength is large enough to cause the hollow electron beam to spiral at a relativistic electron cyclotron frequency close to the millimeter wave operating frequency of tube I.

In the center of the high-frequency circuit 3Fi, the tube 1c) includes a daily cavity 17 for simultaneous imaging in TE... mode at the operating frequency, and on the electron gun side there is a small diameter part where the mode is cut off at Th:o. The collector side has a large diameter so that the TEon mode can propagate. Cylindrical sky 111i
11. So that the angular frequency of the cyclotron mode of the hollow electron beam is synchronized with the 'eat mode in 7.
, by adjusting the main solenoid 10, a strong interaction is created between the Kameko beam and the electromagnetic waves in the cylindrical cavity 17, which is converted into the kinetic energy of the electron beam and generates a large power Oa.
tMagnetic waves are generated. The details of the interaction between the hollow electron beam and the electromagnetic waves in the TE mode are described in the above-mentioned paper. 7 to an external load.

On the other hand, the hollow electron beam diverges due to the space charge force of the electrons in the area of the collector 4 where the magnetic field from the main solenoid 16 disappears, and is captured by the collector 4. At this time, most of the kinetic energy of the Kameko beam is consumed on the surface of the collector 4 as thermal energy. Therefore, the surface temperature of the collector 4 reaches approximately 400° C., and gas molecules are easily released from the surface of the collector 4.

Gas molecules liberated from the high-temperature metal surface collide with a high-energy electron beam and become ionized.

The ionized ions are trapped inside the hollow electron beam whose potential is lowered due to the space charge, and are lifted in the direction of the lower potential in the tube axis direction.

In the conventional gyrotron, the potential distribution on the tube axis is like the curve 30 indicated by the point - in FIG.
The ions collide with the tip of the electron gun electrode 11, which has the lowest potential, making the temperature of the cathode unstable. On the other hand, in the gyrotron 1 of the present invention, 1,300 V is applied to the metal cylindrical electrode 6 supporting the output window 5, so the potential distribution on one tube axis is as shown in the actual curve 31 in FIG. A region with a low potential is created at the tip of the collector 4.

Therefore, the ions ionized inside the collector 4 are sucked out from the metal cylindrical electrode 6, and the ion bombardment of the d-gun electrode 11 is prevented from rising. , the stabilization of the cathode temperature is outstanding.

Also, when the hollow electron beam is captured by the collector 4,
There is a drawback that a secondary block is generated and this secondary block impacts the output window 5, which deteriorates the output window 5. According to the present invention, since a negative bias of -300 V is applied to the metal cylindrical electrode 6, there is an effect of decelerating the secondary section toward the output window 5, and the output window 5 is deteriorated by the secondary section. can be prevented.

Furthermore, since the resonance mode of 1jil 17 in the cylinder is TEall, it is generated internally, and the electromagnetic wave of the nine major forces propagates from the output waveguide 7 to the external load as the 1°Eo3 mode, but it leads to mismatch in the external load and to the external load. Due to deformation of the waveguide, etc., the mode-resolved reflected waves result in the gyrotron IK.

Among the mode-resolved reflected waves, the components other than the rl+E on mode component have a tube wall current component in the tube axis direction, so absorption occurs at the 18° and 19° portions of the insulation ceramic between the electrodes, resulting in a reduction in capital. Moreover, between the cylindrical cavity 17 and the electron gun assembly 2, the inner diameter of the high frequency circuit 3 is made small so that the '1'E component is cut off, so that the electron gun electrode 11 is heated by the high frequency power. can also be prevented.

As described above, if the gyrotron of the present invention is used, high frequency '
It not only prevents heating of the cathode due to the rectangular shape, but also prevents the rise in temperature of the cathode due to ion bombardment, making it a long pulse.

The cathode temperature can be stabilized during continuous operation.

[Brief explanation of the drawing]

Figure 1 is Honjitsu E! FIG. 2 is a general view of an embodiment of a gyrotron implementing A, and FIG. 2 is a curve diagram showing a comparison of # position distribution on the tube axis in the gyrotron according to the prior art and the embodiment shown in FIG. l...gyrotron, 2...electron gun assembly. 3°...High frequency circuit% 4...Collector, 5...Output window, 6...Metal cylindrical cage f
it, 7... Output waveguide, 9...
Cathode, 10... Heater % 11... Mark Seiko gun electrode, 13... Heater 'lt#, 14...
...High voltage power supply, 15...'-Sub gun solenoid, 16...Main solenoid, 17...
Cylindrical cavity, 18s19...Insulating ceramics
30 + 31...Potential distribution curve on the tube axis.

Claims (1)

[Claims] An electron gun assembly for forming and ejecting an electron beam that carries out a hollow spiral movement, a high frequency circuit including a circular waveguide or an inner space-time cavity along the hollow electron beam, and a front electron beam. The collector that captures is arrayed n. In an electron beam gyro device in which an output window and an output waveguide are attached to the tip of the collector, an insulation t'L is provided between the metal cylindrical electrode supporting the output window and the collector, supporting the output window. An electron beam gyro device characterized in that a metal cylindrical electrode is biased to a negative potential with respect to a collector.