Stabilizing effect of a high-frequency magnetic field on the trapped-particle instability

Abstract

The stabilizing effect which an oscillating magnetic field of frequency Ω perpendicular to the main toroidal field has on the collisionless trapped-particle instability is studied for frequencies in the range ωbe < Ω < Ωi, where ωbe is the electron bounce frequency and Ωi is the ion cyclotron frequency. It is found that the fastest-growing modes are stabilized when ε3/8 k⊥ v̄eB1/ΩB0 > 1, where k⊥ the wave number perpendicular to the main field B⃗, v̄e is the electron thermal velocity, B1 is the amplitude of the oscillating field, and ε−1= R0/r, the aspect ratio. The extension of the calculation to other modes is discussed, and an additional example is given.