Moment Approach to Deriving a Unified Parallel Viscous Stress in Magnetized Plasmas
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- Ji, JY. & Held, E.D. J Fusion Energ (2009) 28: 170. doi:10.1007/s10894-008-9169-7
In the moment approach, a parallel heat flux and a viscous stress are derived for arbitrary collisionality, which is becoming increasingly important in emerging concept devices. This derivation improves upon previous derivations by using the full linearized collision operators instead of the pitch-angle scattering operator and also by including the ion-electron collision operator. The parallel viscous stress can be computed by integrating thermodynamic drives along a magnetic field line weighted by kernel functions that are simple linear combinations of exponential functions. The convergence of the ion viscous stress is verified for sinusoidally varying drives with increasing number of moments.