@article{Cooper:120142,
title = {Magnetohydrodynamic stability of free-boundary quasi-axisymmetric stellarator equilibria with finite bootstrap current},
author = {Cooper, W. A. and Margalet, S. F. I. and Allfrey, S. J. and Kisslinger, J. and Wobig, H. F. G. and Narushima, Y. and Okamura, S. and Suzuki, C. and Watanabe, K. Y. and Yamazaki, K. and Isaev, M. Y.},
journal = {Fusion Science and Technology},
number = {2},
volume = {46},
pages = {365-377},
year = {2004},
abstract = {The impact of the bootstrap current is investigated on the equilibrium properties of a two-period quasi-axisymmetric stellarator reactor with free boundary and on the corresponding ideal magnetohydrodynamic stability properties. Although the magnetic field strength B spectrum is dominated by a m/n = 1/0 component, the discrete filamentary coils trigger some small-amplitude symmetry-breaking components that can disturb,the quasi-symmetry of B. Finite beta causes the plasma column to shift outward in the absence of bootstrap current. With a self-consistent bootstrap current in the 1/v regime, the plasma becomes more elongated and more distorted in the horizontally elongated up-down symmetric cross section. At beta similar or equal to 3.25%, the plasma can be restored to its near-vacuum shape with the application of a vertical field with coil currents 20% of those of the modular coils, but at the expense of a significant mirror component in the B-field spectrum. The bootstrap current causes the rotational transform iota profile to increase above the critical resonant value (iota(c) = 1/2 for beta greater than or equal to 1.1%) and combines with the Pfirsch-Schluter current to destabilize a m/n = 2/1 external kink mode for beta greater than or equal to 1.8%.},
}