Growth rates of the m=0 mode for Bennett equilibria with varying radial density and temperature profiles

The linear growth of axisymmetric (m=0) perturbations for various Bennett pinch equilibria are studied numerically with the ALEGRA-MHD code [A. C. Robinson, C. J. Garasi, T. A. Haill, R. L. Morse, and P. H. Stoltz, Proceedings of the 26th IEEE Conference on Plasma Science (IEEE, Piscataway, NJ, 1999), p. 306]. Growth rates are calculated for both skin and diffuse current profiles with varied density and temperature profiles. A destabilizing effect of radially increasing temperature profiles is presented. A factor of three increase in the growth rate over a constant-temperature equilibrium is noted for an equilibrium which is ten times hotter on the edge than at the core. A qualitative explanation is given in terms of the sound speed in the radial region where the mode resides.