Plasma Current Effects on Unstable Resistive Drift-Alfvén Modes in a Magnetized Cylindrical Plasma

抄録

In a currentless plasma, there are many unstable drift-Alfvén 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 I_p, two opposite tendencies, stabilization and destabilization, are seen with the increase of I_p. When two eigenvalues (ω_rj,ω_ij) and (ω_rj+1,ω_ij+1), where j denotes the order of the eigenvalue from the largest one, for given m and n become close at I_p∼eq I_c in a large current regime, the real frequencies do not cross. However, sometimes the two growth rates cross or ω_ij=ω_ij+1 occurs, although the real frequencies satisfy ω_rj>ω_rj+1. The eigenfunctions of the resistive drift-Alfvén mode with (ω_rj,ω_ij) at I_p≤ I_c are similar to those with (ω_rj+1,ω_ij+1) at I_p≥ I_c, where ω_rj>ω_rj+1. These unstable modes may affect the magnetic spectrum of the drift-Alfvén frequency range.