Microwave Resonance Shift Method in Stellarator Plasma Density Measurements.
TEXAS UNIV AUSTIN ELECTRONICS RESEARCH CENTER
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To investigate the trapping efficiency of a hot electron plasma and its confinement in a toroidal magnetic field configuration, a small, adiabatically heated, symmetric stellarator has been constructed. Various diagnostic methods are used to find various plasma parameters electron density and temperature, confinement time, etc. One technique to find electron density and confinement time is to use the microwave cavity frequency shift method. This method is especially applicable in the case of this stellarator since the size of the stainless steel toroidal container is such that it can support the lowest resonant modes with frequencies about 4 GHz. The resonance frequency shift method pertaining to a cylindrical resonator is reviewed, and the theory applicable to the toroidal geometry is discussed. The resonant mode structure in a toroidal resonator is described. It is shown in numerical examples that the presence of plasma will cause a considerable shift in the resonant frequency of the cavity. This frequency shift is directly proportional to plasma density and is also influenced by the magnetic field. Author Modified Abstract
- Fusion Devices (Thermonuclear)
- Plasma Physics and Magnetohydrodynamics