Plasma current effects on unstable resistive drift-Alfven modes in a magnetized cylindrical plasma

In a currentless plasma, there are many unstable drift-Alfven modes with different radial eigenfunctions with fixed poloidal and toroidal mode numbers, m and n, respectively. When growth rates of unstable modes are plotted as a function of total plasma current Ip, two opposite tendencies, stabilization and destabilization, are seen with the increase of Ip. When two eigenvalues (ωrj, ωij) and (ωrj+1, ωij+1), where j denotes the order of the eigenvalue from the largest one, for given m and n become close at Ip≅Ic in a large current regime, the real frequencies do not cross. However, sometimes the two growth rates cross or ωij=ωij+1 occurs, although the real frequencies satisfy ωrj > ωrj+1. The eigenfunctions of the resistive drift-Alfven mode with (ωrj, ωij) at Ip ≤ Ic are similar to those with (ωrj+1, ωij+1) at Ip ≥ Ic, where ωrj > ωrj+1. These unstable modes may affect the magnetic spectrum of the drift-Alfven frequency range. (author)