TY - EJOUR
AB - 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%.
T1 - Magnetohydrodynamic stability of free-boundary quasi-axisymmetric stellarator equilibria with finite bootstrap current
IS - 2
DA - 2004
AU - Cooper, W. A.
AU - Margalet, S. F. I.
AU - Allfrey, S. J.
AU - Kisslinger, J.
AU - Wobig, H. F. G.
AU - Narushima, Y.
AU - Okamura, S.
AU - Suzuki, C.
AU - Watanabe, K. Y.
AU - Yamazaki, K.
AU - Isaev, M. Y.
JF - Fusion Science and Technology
SP - 365-377
VL - 46
EP - 365-377
ID - 120142
SN - 1536-1055
SN - 1536-1055
ER -