Microwave Driven Plasma Ball Generator For Illumination And Rf Applications

Abstract

The production of glow-discharge plasmas by enhanced electric fields inside a spherical porous cavity resonator (SPCR) was studied using laboratory experiments with support by electromagnetic (EM) theory 1 and plasma production equations. The laboratory experiments showed the generation of a stable plasma clouds with a coax-driven stub inserted in the side of the SPCR. The intensity of the light from the cloud became saturated with increased input power. The frequency for production of the densest and brightest plasma ball shifted with increased pump wave power. These experimental observations were investigated using theoretical investigations of the RF driven plasma. The electromagnetic models of the EM wave interactions with the plasma cloud showed (1) formation of the most intense fields at the critical surface where the plasma frequency equals the pump frequency, (2) up shifting of the SPCR plus plasma cloud resonance frequency with the enhancements in plasma cloud density, and (3) reduction of the internal EM wave amplitude from damping by electron-neutral collisions. Cavity amplification saturation and resonator frequency shifting with increased pump power makes the limits the use of the microwave driven SPCR as an illumination source. The SPCR can provide a plasma cloud that has both microwave scatter and compact antenna applications. The EM wave interaction property of the plasma cloud that extends outside the SPCR has been explored in the laboratory using transmissions at 2.45 GHz 2 and 14.1 GHz.