Enhancement of amplification characteristics in a plasma-filled Cherenkov laser at millimeter wavelengths

On the basis of the fluid model of the electron beam, amplification characteristics of a two-dimensional plasma-filled Cherenkov laser at 100 GHz bands are analyzed. By injecting a dense plasma into the background of a Cherenkov laser, the coupling between a relativistic electron beam and an electromagnetic wave at millimeter wavelengths has been improved, and the weak beam-wave interaction problem has become less serious. In particular, we show that due to electron-ion collisions in the background plasma, proper choices of parameters are essential for good operation in this regime. The numerical results indicate that a Cherenkov laser with background plasma can generate higher output power with a greatly enhanced growth rate at a more reasonable interaction length. The plasma injection, in addition, enables the device to gain more output power with a higher beam current. (C) 2000 American Institute of Physics. [S0021-8979(00)05604-8].