The influence of magnetic fluctuations on collisional drift-wave turbulence

A two-dimensional isothermal collisional drift-wave turbulence model including magnetic fluctuations is studied numerically. The model has as limits the electrostatic collisional drift-wave and two-dimensional magnetohydrodynamic systems. The electromagnetic and electrostatic regimes for thermal gradient-driven (drift-wave) turbulence are decided by the parameter <(beta)over cap> = (4 pi nT/B-2)(L(s)(2)/L(n)(2)), where L(s) and L(n) are the parallel and background profile scale lengths, respectively. Significant electromagnetic effects were found only for <(beta)over cap>similar to 10 for most parameters, and were most pronounced in the strongly adiabatic regime for drift waves. The principal effect of the magnetic fluctuations is magnetic induction in the parallel force balance for electrons, which is linear. This diminishes the adiabaticity of the system by reducing the immediacy of the dissipative coupling between the density and electrostatic potential fluctuations. The transport was still found to be dominantly electrostatic even for <(beta)over cap>=10, although its level decreased with <(beta)over cap> due to reduced coherency in the coupling between EXB velocity and density fluctuations. (C) 1996 American Institute of Physics.