Diode laser-induced fluorescence measurements of metastable argon ions in a magnetized inductively coupled plasma

Velocity distribution functions of metastable argon ions (3d′4F7∕2) have been measured to obtain metastable ion density and temperature by the diode laser-induced fluorescence (LIF) technique in magnetized inductively coupled plasma as a function of pressure, rf power, and magnetic field strength. Calculated density from a rate equation agrees with the trends observed in the experimental data. From the calculation, the metastable ion density should be over 107cm−3 to obtain a LIF signal. From a dc bias experiment, it is suggested that the spatial potential can be the dominant ion heating source, and a simple global model for ion temperature is constructed. In this model, approximately 0.01% and 10% of total spatial potential energy can contribute to ion and neutral temperatures, respectively. The measured ion temperature agrees with the calculation.