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

Penetration of a high-frequency (hf) electromagnetic field into a semibound ed plasma in the presence of trapped particles is considered. It is shown t hat the trapping of particles by the hf field considerably changes the cond ition for its propagation. In the stationary case, with increasing the hf f ield amplitude at the boundary, the frequency above which the plasma is tra nsparent continually decreases. But the trapping of particles was found to give a lower limit for this critical frequency, i. e., this lower limit goe s to zero when there is no trapping continually as the incident field ampli tude increases, meanwhile the length of penetration increases and approache s a finite limit, in contrast to the untrapped case, where it increases mon otonically. Moreover, when the hf field amplitude at the boundary exceeds s ome critical value, the plasma will become transparent and the localized st ructure of the hf field will change to an oscillatory structure. (C) 1999 A merican Institute of Physics. [S1070- 664X(99)02802-5].