Stellarator bootstrap current and plasma flow velocity at low collisionality

摘要

The bootstrap current and flow velocity of a low-collisionality stellaratorplasma are calculated. As far as possible, the analysis is carried out in auniform way across all low-collisionality regimes in general stellaratorgeometry, assuming only that the confinement is good enough that the plasma isapproximately in local thermodynamic equilibrium. It is found that conventionalexpressions for the ion flow speed and bootstrap current in thelow-collisionality limit are accurate only in the $1/\nu$-collisionality regimeand need to be modified in the $\sqrt{\nu}$-regime. The correction due tofinite collisionality is also discussed and is found to scale as $\nu^{2/5}$.