Ion Cyclotron Instabilities in Short Mirror Machine Plasmas

An appropriate finite geometry theoretical model of a magnetic mirror machine is examined for ion cyclotron instabilities. The normal modes of the finite model are shown to be unstable even in the presence of large magnetic field gradients. The effect upon the ion cyclotron instability of particle mirroring is discussed. Electron Landau damping is shown to be stabilizing for these modes, but low mirror ratio machines will require high electron temperatures to stabilize instabilities at frequencies near the high harmonics of ωci.