Role of ponderomotive force in sustaining plasma discharge in a microwave induced plasma system

This paper discusses the nature of the plasma equilibrium in a microwave induced plasma under STP conditions. The plasma is generated out of water spray with dissolved minerals. It is known [] that plasma is not generated unless the water droplets are introduced in an iris region of the waveguide. To understand this, the plasma generation process was simulated in a coupled Matlab-Comsol simulation and different iris configurations were studied. The simulation confirms that the iris provides the necessary ponderomotive force required to confine the plasma. In the absence of the iris, plasma does not form in the simulation and in the experiment. This confirms that ponderomotive force is necessary for the plasma formation. The plasma and field profiles obtained in the simulation are presented and the role of the ponderomotive force is established.