Pseudo-MHD ballooning modes in tokamak plasmas

The magnetohydrodynamic (MHD) description of a plasma is extended to allow electrons to have both fluid-like (w/kparallel > vTe) and adiabatic regime (w/kparallel < vTe) responses within an instability eigenmode. In the resultant open-quotes pseudo-MHDclose quotes model, magnetic field line bending can be significantly reduced in the adiabatic electron regime. This makes possible an important new class of ballooning-type, long parallel extent, geodesic-curvature-driven, robust MHD-like instabilities in tokamak plasmas for -d√β/dr > (21/6 /3)(s/R0q) where β double-bond 2μ0P/B2, s double-bond (r/q)(dq/dr). The marginally stable pressure profile is similar to that observed in ohmically heated tokamak plasmas