A study to select suitable window materials for the Microwave Propagation through Electron Cyclotron Resonance Plasma

Abstract

The performance of an electron cyclotron resonance ion source depends upon the coupling efficiency of microwave power into plasma. The efficiency of production of ions and the stability of ion current primarily depend upon the intensity of injected microwave power. Microwave windows have a major role to maintain a stable injected microwave power density. A suitable microwave window essentially imparts a good impedance matching between the launching hardware and the plasma load. A study has been carried out using High Frequency Structure Simulator (HFSS) code with a view to choosing a dielectric material with suitable mass density for the efficient propagation through microwave plasma. In the present study, the Bminimum mirror confined highly non-linear Electron Cyclotron Resonance (ECR) plasma may be considered as a dielectric medium with continuously varying permittivity. The mass density of plasma for a specific element also varies depending upon the environmental conditions inside the cavity. This study also enables us to find out the electric field inside the plasma considering the incident and the reflected components generated due to the variation in its dielectric property. Keywords-Microwave Window; ECR Plasma; Wave Propagation; HFSS code; Permittivity.