Electron cyclotron resonance breakdown studies in a linear plasma system

Electron cyclotron resonance (ECR) plasma breakdown is studied in a small linear cylindrical system with four different gases — hydrogen, helium, argon and nitrogen. Microwave power in the experimental system is delivered by a magnetron at 2.45 ± 0.02 GHz in TE₁₀ mode and launched radially to have extra-ordinary (X) wave in plasma. The axial magnetic field required for ECR in the system is such that the fundamental ECR surface (B = 875.0 G) resides at the geometrical centre of the plasma system. ECR breakdown parameters such as plasma delay time and plasma decay time from plasma density measurements are carried out at the centre using a Langmuir probe. The operating parameters such as working gas pressure (1 × 10⁻⁵−1× 10⁻² mbar) and input microwave power (160–800 W) are varied and the corresponding effect on the breakdown parameters is studied. The experimental results obtained are presented in this paper.