Experimental study on the characteristics of low power microwave plasma jet within local vacuum environment

Abstract

A microwave plasma jet based on a coaxial cavity can be generated in atmosphere and vacuum environments. It is shown that with argon gas and a power range of 53–60W, cavity efficiency ranges from 54% to 68%. The electron density distribution and the microwave return loss of the confined plasma jet adjacent to a metal object and their dependency on argon mass flow rate and power have been studied by applying emission/Langmuir probe and spatial reflected wave diagnostic equipments in a low scatter vacuum environment. The results show that the electron density ranges from 8.8×1014to7.53×1016∕m3, and the electron density on the centerline of the jet decreases exponentially from the nozzle exit plane, but its distribution off the centerline is in an upheaved curve. Increasing mass flow rate at constant power and increasing power at constant mass flow rate increase electron density mildly. From typical measurements of microwave return loss, it is noted that the plasma jet attenuates microwaves in a 6to8GHz range.

Generating large-area uniform microwave field for plasma excitation

“…Since the invention of microwave sources, microwave energy has been widely used in various applications and research fields. Microwave can be used to generate various plasma sources based on different mechanisms, like microwave plasma systems [1][2][3][4][5] and electron cyclotron resonance (ECR) systems. [6][7][8][9][10][11] It can also be employed directly to process or anneal materials, such as ceramics, ferrites, thin films, or even metal powders.…”