Acquisition and analysis of Langmuir probe characterization for ECR plasma

An Electron Cyclotron Resonance (ECR) plasma Source at 2450.MHz, 2 kW have been designed and developed. Plasma chamber was excited with 350 watts of microwave power with nitrogen gas and power was coupled to the plasma chamber through ridged waveguide. Plasma density and electron temperature were studied under various operating conditions like magnetic field, gas pressure and microwave power, Langmuir probe is used for plasma characterization using current-voltage (I-V) characteristics ion saturation method. The nitrogen plasma density of approximately 4.5 x 10(11) cm(-3) and electron temperature of cold: 3-10 eV, hot: 45-85 eV are obtained. This paper presents very simple techniques for measuring I-V characteristics of medium density in the order of 10(11) to 10(12) cm(-3) and plasma temperature of cold: 1 - 10 ev, hot: 25 - 100 eV. The scheme comprises of a very simple resistive circuit that gives signals proportional to current and voltage across the probe, These signals are then applied to the PC based data acquisition hardware through buffers. The scheme simply recorded data acquired from the plasma and then processed the data offline to generate various results. The program is developed in Lab-View, so that it can be applied to any platform using common laboratory instruments.