SU1216714A1 - Interferometer for plasma diagnostics - Google Patents

Abstract

The invention provides improved measurement accuracy. The oscillations of the microwave generator 1 by the frequency, are divided by the film power divider (VDM) 2. The oscillations reflected from the GSRM 2 film enter the mixer 3 of the reference channel. Oscillations that have passed through the film enter the plasma chamber 7 and then pass to the mixer 4 of the measuring channel. The microwave oscillations from the local oscillator 5, frequency i, entered on the fourth arm of the PTP 2, are shared by it. Oscillations that have passed the film flow into the mixer 3, and oscillations reflected from it pass through the plasma chamber 7 to the mixer 4. From the outputs of the mixers 3 and 4, the oscillations of the difference frequency ui; step on phase meter 9. Phase shift determines the electron plasma concentration. 1 il. Q with sl

Description

one.

The invention relates to a technique for measuring at microwave frequencies and can be used to determine the electron concentration of a stationary or gaz plasma.

The purpose of the invention is to improve the measurement accuracy.

The drawing shows the structural electrical circuit of the interferometer for plasma diagnostics.

Interferometer for diagnostics. Plasma contains -HF-generator 1, I film divider 2 power, first and second mixers 3 and 4, local oscillator 5, input 6 of the microwave signal in plasma chamber 1, output 8 of the microwave signal from the plasma chamber 7, phase meter 9.

An interferometer for plasma diagnostics works as follows.

The oscillations from the microwave generator I are frequency separated by a film-type power splitter into reference and measuring channels. The power reflected from the film divider 2 is transmitted to the first mixer 3 of the reference channel. Fluctuations that have passed through the film enter through the inlet 6 into the plasma chamber 7, are taken out by the outlet 8 and then pass to the second mixer 4 of the measuring scale. Microwave oscillations from the local oscillator 5 frequency, separated by the same film divider 2 measuring signal. The oscillations that have passed through the film enter the first mixer 3 of the reference channel. The oscillations reflected from the film enter through the inlet 6 into the plasma chamber and are received in outlet 8 and enter the second mixer 4 of the measuring channel. At the outputs of the first and second mixers 3 and 4 of the reference and measuring channels, oscillations of the difference frequency are output to the phase meter 9, indicative of a phase shift cj between these oscillations, judged by

142

on the electron concentration ng of the investigated plasma.

The measured phase shift is mainly due to the dispersion properties of the medium under study. For the case, ui f, -i; j i (the formula relating to plasma parameters is as follows:

27iiL / (

CF,

Where

i,

pe - plasma hour 9-10 tons;

L is the linear dimensions of the plasma; C is the speed of light in free space. The phase shift Cf, obtained with this interferometer is less than 2 TH, therefore it is easily indicated by a phase meter 9, which allows determining the parameters of a high-density plasma, stationary in time, or a high-density gas-discharge plasma with large transverse dimensions. By choosing ±, and fg, for a given range of detectable concentrations, a conveniently measured value of cp can be obtained,

Claims (1)

Invention Formula Plasma diagnostic interferometer containing a series-connected microwave generator, a film power divider, a first mixer and a phase meter, as well as a local oscillator, input of a microwave signal into the plasma chamber connected to the third arm film power divider, the output of the microwave signal from the plasma chamber connected to the input of the second mixer, the output of which is connected to the second input of the phase meter, which is only due to the fact that, in order to increase the measurement accuracy, the output of the local oscillator is . Compiled by R.Kuznetsova Editor I.Savko, Tehred O.Vash1-bus 997/55 Circulation 778 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Branch PPP Patent, Uzhgorod, st. Project, 4 Proofreader L. Pilipenko