Comment on the drift mirror instability

Drift mirror instability is investigated in a slightly inhomogeneous plasma in a low-frequency, long-wavelength limit of the Vlasov–Maxwell equation. It is shown that previously derived threshold conditions for the drift mirror instability in the case of one cold species are incorrect and that it is hard to get analytically a simple threshold condition for the drift mirror instability in this case. It is argued that the same is true for the drift mirror instability in general.