Sensor for plasma density profile measurement in magnetic
fusion machine
Richard Schubert, Sensors and Actuators A, 41-42, pp. 53-57, 1994 Abstract A method is presented for the measurement of the electron density in
an experimental plasma fusion device by means of microwave reflectometry.
Since microwaves with increasing frequency can penetrate deeper into the
plasma, it is possible to sample the electron density distribution by frequency-sweep
techniques. For the first time the system allows a non-contact measurement
of the electron density profile in the outermost region of a magnetically
confined plasma without separate calibration. The influence of strong electron
density fluctuations of up to 50% with frequencies up to 500 kHz has been
eliminated by a fast sweep from 60 to 80 GHz with a sweep time of about
150 ms. In connection with microwave plasma
heating experiments at 2.4 GHz, the theoretically predicted dependence
of the reflection coefficient of the heating wave on the electron density
has been confirmed.
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