Test-particle drifts in traveling waves with cyclotron frequencies.

When a test particle moves in the field of a traveling wave with the cyclotron frequency, a particle-acceleration difference is found to appear between the first half-cycle of the Larmor motion, during which the particle has a velocity component in the direction of the wave propagation, and the second half-cycle, during which it has a velocity component in the opposite direction. This asymmetric acceleration modifies the cyclotron-resonance trajectory, yielding the physical origin of the particle drift perpendicular both to the wave propagation and background magnetic-field lines. A perturbation method in the orbit theory sucessfully gives analytic expressions for and numerical calculations demonstrate the drift generation. The result is applicable to particle-flux control of magnetized plasmas. (c) 1995 The American Physical Society