Whistler-mode electron cyclotron emission as an electron temperature diagnostic for magnetic mirror devices

A non-relativistic formulation has been developed which calculates the whistler-mode electron cyclotron emission spectrum in the direction parallel to the magnetic field for a plasma containing an isotropic Maxwellian electron component and an anisotropic bi-Maxwellian electron component. The formulation is valid for arbitrary densities of both components and the model utilizes the radiation transfer equation to obtain the intensity of the emitted radiation. The calculations are intended for use with mirror devices and the motivation is to use cyclotron emission as an electron temperature diagnostic. The projected plasma parameters for the TMX-Upgrade machine have been considered as an example, where the plasma is assumed to have a cold- and a hot-electron component (nsub(e) approx.= 1012-1013cm-3, Tsub(cold) approx.= 1 keV, Tsub(hot) approx.= 50 keV). A procedure is described by which the axial cold-electron temperature profile can be obtained from spectral measurements of the cyclotron emission. The effect of the hot-electron population has been considered in detail and it is shown that in certain circumstances their influence on the emitted spectrum is small. For those cases where hot electrons dominate the emission, the model can be used to obtain important information about hot-electron behaviour. (author)