Particle acceleration, resonant and transition dampings, and arrest of the wave collapse

Abstract

It is demonstrated that charged particle acceleration due to the resonant and transitional dampings can arrest the wave collapse at more than 10 Debye length. In a strong magnetic field, the wave collapse is arrested even for the sizes of cavities two or three times larger than this value. The nature of the sudden stop (arrest) of the collapse is the coherency of modes in the cavity induced by the nonlinear process of self-contraction. This natural effect makes all modes in the cavity energetically bounded. Thus, if in the Fourier decomposition there exists a damped harmonic even with a small amplitude, its damping is then shared between all the modes of the cavity. A short historical review on the particle acceleration is given with the emphasis on the acceleration by electrostatic waves. It is emphasized that the acceleration by electrostatic lower-hybrid waves is the most effective provided that there is a continuous creation of electrostatic cavities of a "cigar type" with a dipole moment almost perpendicular to the external magnetic field.