Multi-temperature generalized Zhdanov closure for scrape-off layer/edge applications
M. Raghunathan, Y. Marandet, H. Bufferand, Giuseppe Ciraolo, Ph. Ghendrih, P. Tamain, É. Serre
Abstract
Abstract The derivation of the multi-temperature generalized Zhdanov closure is provided, starting from the most general form of the left-hand side of the moment-averaged kinetic equation with the Sonine–Hermite polynomial ansatz for an arbitrary number of moments. The process of arriving at the reduced higher-order moment equations, with its assumptions and approximations, is explicitly outlined. The generalized multi-species multi-temperature coefficients from our previous article are used to compute values of higher-order moments such as heat flux in terms of the lower-order moments. Transport coefficients and the friction and thermal forces for magnetic confinement fusion relevant cases with the generalized coefficients are compared to the scheme with the single-temperature coefficients previously provided by Zhdanov et al . It is found that the 21 N -moment multi-temperature coefficients are adequate for most cases relevant to fusion. Furthermore, the 21 N -moment scheme is also tested against the trace approximation to determine the range of validity of the trace approximation with respect to fusion-relevant plasmas. Possible refinements to the closure scheme are also illustrated to account for quantities which might be significant in certain schemes, such as the drift approximation.