Influence of particle trapping on the penetration of high-frequency electromagnetic field into a semibounded plasma

Abstract

Penetration of a high-frequency (hf) electromagnetic field into a semibounded plasma in the presence of trapped particles is considered. It is shown that the trapping of particles by the hf field considerably changes the condition for its propagation. In the stationary case, with increasing the hf field amplitude at the boundary, the frequency above which the plasma is transparent continually decreases. But the trapping of particles was found to give a lower limit for this critical frequency, i.e., this lower limit goes to zero when there is no trapping continually as the incident field amplitude increases, meanwhile the length of penetration increases and approaches a finite limit, in contrast to the untrapped case, where it increases monotonically. Moreover, when the hf field amplitude at the boundary exceeds some critical value, the plasma will become transparent and the localized structure of the hf field will change to an oscillatory structure.