Two-stream whistler-pumped free-electron laser

Abstract

The theory for the two-stream free-electron laser with the whistler wave as a slow electromagnetic wave wiggler is studied theoretically. The results show that for small values of plasma density, there are seven groups of orbits and the plasma density enhancement leads to increase in the number of trajectories. Also, increasing the plasma density causes growth in the axial velocity for groups (1–4) of orbits and a reduction for groups (6–7). It is shown that for groups (6–7), the effect of plasma is to increase the gain, and for groups (1–4) the effect of plasma is to decrease the gain. For group (1) the effect of plasma is to decrease the maximum frequency and for group (3) it is to increase the maximum frequency.