Faraday rotation as a density diagnostic for helical axis stellarators
نویسنده
چکیده
It is shown that the Faraday ratation of a linexly polarized electromagnetic wave probing a helicalaxis-stellamtor plasma is a useful electron density diagnostic. The twisted magnetic geometry results in a large magnetic field component in the vettinl plane that is asumed to contain the probe beam(s). As a result, significant polarization rotations result for far-infrared beams traversing plasmas of modest densities and magnetic fields. Linearbirefringence-induced beam elliptiza~on is small and the sensitivity to secondary (bootsrrap) cumnts is weak. A new technique for measurement of the polarization state and its applicadon to densitomeuy of plasma confined by the H-l Heliac is discussed and modelled using the three-dimensional, free-boundary MHE equilibrium code. VMEC.
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