Solutions to EMI problems in 50kW, RF ICP Reactor - A case study

A high power (50 kW) induction coupled plasma (ICP) reactor has been designed and developed in Laser & Plasma Technology Division, BARC. The reactor consists of a high power oscillator working at 3-4 MHz, an induction plasma torch, a reaction chamber and associated vacuum system. At higher power (>7 kW) DC power supply was not functioning properly due to EMI problem. The EMI also affected the nearby sensors and instruments. This paper discusses the nature of EMI problems in the system and control measures taken, to overcome the problems. A study has also been made to find out the strength of RF radiation field around the reactor when the ICP torch is not shielded and when it is shielding.