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 charact eristics of a two-dimensional plasma-filled Cherenkov laser at 100 GHz band s are analyzed. By injecting a dense plasma into the background of a Cheren kov laser, the coupling between a relativistic electron beam and an electro magnetic wave at millimeter wavelengths has been improved, and the weak bea m-wave interaction problem has become less serious. In particular, we show that due to electron-ion collisions in the background plasma, proper choice s of parameters are essential for good operation in this regime. The numeri cal results indicate that a Cherenkov laser with background plasma can gene rate higher output power with a greatly enhanced growth rate at a more reas onable interaction length. The plasma injection, in addition, enables the d evice to gain more output power with a higher beam current. (C) 2000 Americ an Institute of Physics. [S0021-8979(00)05604-8].