Investigation of the toroidal flow damping in the edge plasma of J-TEXT tokamak with an electrode biasing.

The toroidal flow damping has been investigated in the edge plasma of J-TEXT tokamaks with an electrode biasing (EB). The estimated viscosity of the toroidal flow after the bias turning off is about 67 times of the classical viscosity and four times of the neo-classical viscosity, which infers that the flow damping is anomalous in the transition phase. In the equilibrium phase, the torque densities driven by the EB, the momentum transport, and the neo-classical toroidal viscosity (NTV) under different bias conditions are calculated, which show that the NTV torques are comparable with the other terms. According to the angular momentum balance equation, the remnant damping torque densities and the effective damping coefficients have been obtained. Considering that the remnant damping is mainly contributed by the neutral particle damping, this investigation provides a method to estimate the neutral particle density ( n H ), which gives that the n H in the edge plasma of J-TEXT is in the range of 1–4 (×10¹⁷ m⁻³). [ABSTRACT FROM AUTHOR]