JPS6235500A - Antenna apparatus - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an antenna device that transmits high-power microwaves from an atmospheric pressure side to a vacuum side.

(Prior Art) A plasma generation device as shown in Fig. 4 is known, which uses an antenna device that transmits high-power microwaves from the atmospheric pressure side to the vacuum side (Industrial Materials, Uni [2], ( 198
1), P, 59-64).

In this device, microwaves generated from a microwave oscillator 1 are transmitted through a waveguide 2 and then emitted into a vacuum chamber 6 by an antenna device. Waveguide 2 that separates the vacuum side from
A tubular antenna 4 that penetrates through an opening 3 provided in the tube wall of
and a dielectric vacuum seal portion 5 that surrounds the antenna 4 with a space therebetween. Cooling gas flows into the antenna 4 to cool the antenna device.

(Problems to be Solved by the Invention) A drawback of the conventionally used plasma generator shown in FIG. 4 is that the vacuum seal portion is damaged by collision due to the generated plasma.

Furthermore, when an external magnetic field, such as a multi-cusp magnetic field, is applied to such a plasma generator, the high-temperature, high-density plasma confined in the magnetic field collides with the vacuum seal of the dielectric, causing the vacuum seal to partially close. It becomes high temperature. As a result, the vacuum seal part cracks and breaks due to the resulting thermal distortion, resulting in the vacuum being destroyed.

Furthermore, in addition to the desired ion species, the plasma contains various ions such as carbon, iron, nickel, etc.
These ion species collide with the vacuum seal, causing sputtering and impregnation of the ion species into the dielectric material of the vacuum seal. This risks reducing the wall thickness of the vacuum seal, weakening the material strength, and impregnation of ionic species can cause loss of microwave power in the dielectric material, as well as local temperature increases. There was a risk that it would rise and destroy the dielectric material.

That is, an object of the present invention is to improve such an antenna device and provide an antenna device that radiates microwaves into plasma more efficiently.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides an antenna that is installed by penetrating an opening provided in a wall separating an atmospheric pressure side and a vacuum side, and a space where the antenna is installed. An antenna device comprising a vacuum seal portion of a dielectric material surrounding the vacuum seal portion, and transmitting high power microwaves from an atmospheric pressure side to a vacuum side through the vacuum seal portion, wherein the vacuum seal portion is provided with a thin gap outside the dielectric material. The present invention proposes an antenna device characterized by being covered with a tube.

Note that the length of the slit in the conductive outer cylinder is preferably a half wavelength of the microwave used, and the width of the slit is preferably narrower than the Debye length. Further, it is preferable that the distance between the vacuum and empty seal portion and the conductive outer cylinder be equal to or less than the mean free path of charged particles.

(Function) In the present invention, since the conductive outer cylinder with a narrow gap is installed outside the vacuum seal part, a kind of coaxial waveguide is formed by the antenna and the conductive outer cylinder. , microwaves are radiated into the diluted gas inside the vacuum chamber through the slits in the conductive outer cylinder.

Furthermore, if the width of the slit provided in the conductive outer cylinder is narrower than the Debye length, ion species from the plasma may enter through the slit in the conductive outer cylinder and collide with the vacuum seal. There is no. Even if the width of the slit is wider than the Debye length, the number of ions penetrating into the conductive sleeve is reduced to the area of the slit equal to the total surface area of the conductive sleeve.

(Example) Hereinafter, the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic side sectional view of a plasma generator using the antenna device of the present invention. Microwaves generated from a microwave generator (not shown) are transmitted through the waveguide 2 and emitted into the vacuum chamber 6 by the antenna device according to the present invention.

In the antenna device, a conductive outer cylinder 7 is arranged outside a ceramic vacuum seal part 5 surrounding the antenna 4, and an end of the conductive outer cylinder on the atmospheric pressure side is electrically connected to the waveguide 2. ing.

As shown in FIG. 2, the conductive outer cylinder 7 is provided with a plurality of slits 71 whose length is 1/2 of the wavelength of the microwave used and whose width □ is narrower than the Debye length. There is.

The microwave transmitted from waveguide 2 is
□The light is introduced into a coaxial waveguide consisting of the antenna 4 and the conductive outer cylinder 7, and is radiated into the vacuum chamber 6 through the slit 71 provided in the conductive outer cylinder 7, and is supplied to the plasma.

In this case, an electric field as shown in FIG. 3 is formed in the antenna portion, and microwaves are radiated from the slit 71.

Note that the narrow gap 71 of the conductive outer cylinder 7 does not need to be along the circumferential direction of the outer cylinder 7 as in the above embodiment, but may be provided at an angle with respect to the circumferential direction.

(Effects of the Invention) According to the present invention, plasma containing ions and electrons is prevented from entering the vacuum seal part by the conductive outer cylinder, so the ceramic part that makes up the vacuum seal part is always clean. There is no local loss of microwaves. As a result, the antenna section can always stably radiate microwaves.

Moreover, the vacuum seal part is no longer damaged.

[Brief explanation of drawings]

FIG. 1 is a side sectional view of a plasma generator using the antenna device of the present invention, FIG. 2 is a schematic diagram of a conductive outer cylinder according to the present invention, and FIG. 3 shows the electromagnetic field distribution in the antenna device of the present invention. FIG. 4 is a side sectional view of a conventional plasma generator using a conventional antenna device. l...Microwave oscillator, 2...Waveguide, 3...Aperture, 4...Tubular antenna, 5...Vacuum Seal portion, 6... Vacuum chamber, 7... Conductive outer cylinder. Figure 1 MEBY91L Figure 2 Figure 3 Figure 4WJ

Claims (1)

[Claims] An antenna installed by penetrating an opening provided in a wall separating an atmospheric pressure side and a vacuum side, and a dielectric vacuum seal portion surrounding this antenna with a space, An antenna device that transmits high-power microwaves from an atmospheric pressure side to a vacuum side through a seal portion, wherein the vacuum seal portion is covered with a conductive outer cylinder provided with a slit.