Neoclassical viscosity of L = 1 helical-axis heliotron plasmas for arbitrary collision frequencies and radial electric fields

Numerical methods for solving the monoenergetic drift kinetic equation (DKE) are powerful tools for obtaining viscosity coefficients. However, these methods do not apply when the collision frequency and radial electric field become large. For example, when the radial electric field becomes large, poloidal resonance effect occurs and degrades the accuracy of the numerical solutions to DKE. But when we calculate the neoclassical viscosity in Heliotron J, which is an L = 1 helical-axis heliotron device, we cannot neglect the resonance effect in the presence of high-Z ions. In this study, we combine viscosity coefficients calculated by the numerical method with those obtained from analytical solutions that take the effects of the first poloidal resonance into account. We use this method to obtain monoenergetic viscosity coefficients for arbitrary collision frequencies and radial electric fields in the L = 1 heliotron device. (author)