ABSTRACT
The experimental setup consists of a stainless-steel (grade: SS-304) vacuum chamber (VC) of length 50 cm and diameter 20 cm, with four cylindrical arms having numerous ports for pumping, gas inlet, vacuum gauges, and plasma diagnostics. The chamber can be evacuated to a base pressure of ~5 × 10−7 Torr using a Varian 301 Navigator turbomolecular pump (TMP) of pumping speed ~250 L/s, backed by a rotary pump with a speed of ~2 L/s, with respect to nitrogen. Argon (zero grade) is used as the experimental gas and is introduced into the chamber through the gas inlet (GI) with a stable flow maintained by an MKS-1179A (range: 50 sccm) mass flow controller. The neutral pressure inside the chamber is maintained by dynamic equilibrium between the inflow and outflow rates, and is measured by a Varian SenTorr system with a cold cathode ionization gauge (IG) for measurement from 10−3 to 10−7 Torr, and a ConvecTorr gauge (CG) for measurement from 10−3 to 103 Torr. A controllable leak valve (LV) is used for venting the chamber. Wilson seals (WS) are used for introducing the plasma diagnostic probes from the radial (RP) and axial (AP) ports, as shown in Figure 12.1.
