Anisotropic Pressure, Transport, and Shielding of Magnetic Perturbations

We compute the effect on a tokamak of applying a nonaxisymmetric magnetic perturbation δΒ. An equilibrium with scalar pressure p yields zero net radial current, and therefore zero torque. Thus, the usual approach, which assumes scalar pressure, is not self-consistent, and masks the close connection which exists between that radial current and the in-surface currents, which provide shielding or amplification of δΒ. Here, we analytically compute the pressure anisoptropy, anisoptropy, pll, p⊥ ≠ p, and from this, both the radial and in-surface currents. The surface-average of the radial current recovers earlier expressions for ripple transport, while the in-surface currents provide an expression for the amount of self-consistent shielding the plasma provides