JPS58191980A - Measuring device of plasma current - Google Patents

Abstract

PURPOSE:To make an integrator and an optical telemeter part unnecessary and improve the precision of measurement, by utilizing the optical Farady effect to connect directly an optical fiber cable to a vacuum vessel. CONSTITUTION:The light emitted from a polarizer 12 has the plane of vibration changed by an angle theta because of the optical Farady effect due to a magnetic field phi applied to the coil-shaped part of an optical fiber cable 13. The light from a light emitting element 11 is a kind of electromagnetic wave and has a plane of vibration; and since the optical fiber cable 13 to which vibrating waves passing only at a certain angle are transmitted by the polarizer 12 is coil-shaped in a vacuum vessel 1, a magnetic field is generated when a current due to a plasma current is flowed, and the angle of the plane of vibration of light is affected. This angle theta is expressed by thetaalphaKH when the intensity of the magnetic field is denoted as H and K is a constant, and the angle theta is determined by the position of the plasma. The optical signal whose plane of vibration is shifted at the angle theta is inputted to an analyzer 14, and the light of only horizontal components is taken out, and its optically attenuated light level is detected by a photodetector 15 and is inputted to a recorder 16, thereby measuring the pertinent plasma current.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a plasma current measuring device, and more specifically, to a plasma current measuring device for measuring plasma current in a tokamak-type vacuum vessel.

Conventionally, there is a device of this type that detects changes in magnetism caused by plasma current in a vacuum container, and this can be explained with reference to Figure 1. A conductor probe λ having a coil 2a for the purpose is cast and derived, and this conductor probe λ is connected to the conductor probe λ.

Integrator 3 that integrates the differential signal detected by the conductor probe λ
, furthermore, an optical transmitter q that converts an analog signal into a frequency converter and converts an electrical signal into an optical signal.

An optical fiber cable S connecting the vacuum container chamber and the ilj control space is connected to an optical receiver 6 that converts optical signals into electrical signals and converts signals having a frequency into DC signals. The output signal of the optical receiver B is input to the recorder 7, and the plasma current inside the vacuum vessel is recorded by waveform observation by the recorder 7. The optical transmitter optical fiber cable S and the optical receiver 6 constitute an optical telemeter section that is not affected by external surges from the vacuum container/to the recorder 7. With this configuration, an electromotive force is generated in the coil 2 arranged in the vacuum vessel only when the magnetic flux changes due to a magnetic flux change generated by the plasma current inside the vacuum vessel.This electric signal is generated only when the magnetic flux changes. Since the signal is generated, the integrator 3 extracts it as an analog signal. However, the cable section from the vacuum vessel/to the control room generates external surges and noise signals, and in order to ensure accurate measurements, it is necessary to use the optical transmitter q,
Optical fiber composed of optical fiber cable S and optical receiver 6
2 parts of rReno are required.

The conventional device 4 was configured as described above.

The optical telemeter unit and integrator must be installed near the vacuum container to prevent external surges and noise. I need to set up a box. 1. There was an error-generating device such as an optical telemeter between the coil and the recorder, which caused problems in terms of measurement accuracy.

This invention is an attempt to solve the above problems in the conventional method, and by inserting an optical fiber cable into a vacuum container and utilizing the optical Faraday effect, it is possible to generate plasma by high-precision light-to-air conversion. The object is to provide a current measuring device.

An embodiment of the present invention will be described below with reference to the drawings. It is equipped with a polarizer/2 that allows light from the light emitting element// to pass through only the vibration plane in a certain direction, and the light that has passed through the polarizer/2 is guided into the vacuum container// by an optical fiber cable 13.

The optical fiber cable /3 is formed in a coil shape inside the vacuum vessel /, and the optical fiber cable /3 is optically coupled to the analyzer /S which exits from the vacuum vessel / and passes light only on the vibration plane in a certain direction.
converts the optical signal from the analyzer /& into an electrical signal and inputs it to the recorder 76.

Next, the operation will be explained using FIG. In the figure,
The light emitted from the polarizer/c shows that the vibration plane changes by an angle θ due to the optical Faraday effect due to the magnetic field φ applied to the coiled part of the optical fiber cable/3. Therefore, the light from the light emitting element // is a type of electromagnetic wave and has a vibration surface.

A vibration wave that passes only at a certain angle is sent to the optical fiber cable 3 using a polarizer. Since the optical fiber cable /3 is coiled inside the vacuum container /, when a current due to the plasma flow flows, a magnetic field is generated, which affects the angle of the light vibration plane. This angle θ is expressed as o''kH, where the strength of the magnetic field is H, and k is a constant.The angle θ is determined by the position of the plasma.In this way, the optical signal whose vibration surface is at an angle θ is detected by the analyzer lq. , increase the light of only the horizontal component, detect the attenuated light level with the light receiving element/S, and input it to the recorder 76.

The plasma current can be measured.

In the present embodiment, the plasma current t flow inside the vacuum container was detected, but it can also be used to detect the plasma position inside the vacuum container, and the same effect can be obtained.

JU As mentioned above, this invention utilizes the optical Faraday effect and connects the optical fiber cable directly to the vacuum 8 device, eliminating the need for the conventional integrator and optical telemeter section, resulting in high accuracy. This has the effect of making the device cheaper.

[Brief explanation of the drawing]

FIG. 1 is a schematic block diagram of a conventional apparatus, FIG. 2 is a schematic block diagram of an embodiment of the present invention, and FIG. 3 is a diagram illustrating the operation of the same. /...Vacuum container ii...Light emitting element, 7.2...Polarizer, /3...Optical fiber cable /Q...Analyzer, is
. . . Light receiving element, /6 . . Recorder. In each figure, the same reference numerals indicate the same or corresponding parts. Agent Shin Kuzuno −

Claims (1)

[Scope of Claims] (1) A light-emitting section consisting of a light-emitting element and a polarizer, a light-receiving section consisting of an analyzer and a light-receiving element, and the polarized light passing through a vacuum container in which a plasma current is generated and the analyzer. and a coiled portion of the optical fiber cable, which is located within the vacuum field 2 and whose passing light is polarized by the Faraday effect of the magnetic field accompanying the plasma current. Plasma current measuring device. (, 2) The plasma current measuring device according to claim 1, which measures the plasma current by detecting the amount of optical attenuation due to polarization in the coiled portion. (3) Claim 1 for detecting plasma position
Plasma current measuring device as described in section.