A Cherenkov cyclotron autoresonance maser

A CARM is an efficient source of high frequency microwaves based on the negative mass instability. The output is Doppler-upshifted beyond the gyrotron frequency by the free electron factor of 2γ
²
. By loading the interaction tube with dielectric, the voltage requirements are substantially reduced. Despite the reduced voltage, a significant upshift can still occur, since the Cherenkov effect enhances the electron's velocity by ε
^1/2
, the refractive index of the dielectric