Plasma enhancement of radial acceletron

Summary form only given. Plasma enters many high power microwave sources inadvertently, and often has a disruptive effect on the operation of the source. Recent numerical studies, however, have shown that the presence of plasma in some of the high power microwave sources using intense charged beams, when properly introduced, may actually enhance the efficiency of the source. These findings have been confirmed by experimental results for two high power microwave sources. The enhancements have been partly attributed to the neutralizing effect of the positively charged plasma on lowering the disruptive space charge effects of the electron beam used to generate the RF, and partly to a modification of the dispersion relation leading to higher group velocities for the traveling RF waves. Mode selection may also be favorably affected by the presence of plasma in the source. Transit-time oscillators, because of their intense and well confined beam, are likely to benefit from plasma enhancement. Here we present the results of numerical simulations carried out to study the effect of plasma on an acceletron device. Both neutral as well as positively charged plasmas have been explored. The acceletron device is run in TM/sub 001/ mode and generates a 3.2 GHz steady oscillation without any competing modes. The effect of the plasma at several different densities has been explored. Our results indicate a significant enhancement of the acceletron operation due to the plasma. Other plasma densities are being studied. The PIC code used in simulations was the MRC 2/sub 1/2/ dimensional code MAGIC.