Optimisation of UHF reflectometer device for study of plasma density profile and fluctuation in magnetically confined plasmas

摘要

In the correlation reflectometry method, two microwave signals (usually of the same polarization) are launched into plasma, reflected by a cut-off layer, received and analyzed. The spatial coherence of fluctuations is studied by changing the frequency of the second microwave signal against the first one. There is a problem of separation of these two signals as their frequencies are near to each other. This problem can be removed if one uses probing signals with different frequencies but reflected from the same plasma layer. This could be done if one uses the magnetized plasma probing via microwaves with different polarization - O- and X-mode probing. In this paper we describe the results of study of plasma fluctuation properties by using dual polarization single line microwave plasma probing in the reflex discharge. Experiments were done on the pulsed reflex discharge performed in the SS-vacuum chamber (length 150 cm, diameter 20 cm) that was put inside of magnetic solenoid producing a nearly homogeneous magnetic field up to 1.2 T.