Kinetic Theory of Drift‐Mirror Mode

Abstract We present a nonlocal gyrokinetic theory for the drift‐mirror mode in high‐ anisotropic plasmas. Here, represents the ratio of plasma pressure to magnetic pressure. The equilibrium distribution is established self‐consistently via guiding‐center Hamiltonian theory. To keep the nonuniformity and finite Larmor radius (FLR) effects on an equal footing, we derive the three‐field nonlocal eigenmode equations in Fourier space under the assumption of weak nonuniformity. It is found that the drift‐mirror mode is essentially a dissipative instability confined within the potential well due to the FLR effect. Numerical analyses demonstrate that the drift‐mirror mode originates from the coupling between shear Alfvén and mirror branch, where the ion‐sound wave component is negligible. Furthermore, the threshold of this nonlocal drift‐mirror mode is significantly lower than that of the conventional drift‐mirror mode.