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A stable discharge region of pulse modulated induction thermal plasma at atmospheric pressure has been determined in terms of the duty factor (DF) and the shimmer current level (SCL) both experimentally and numerically. The experiment was performed with a MOSFET-employed inverter-feed pulse modulated power supply unit having a maximum power of up to 50 kW. The on-time of the pulsing signal was fixed at 10 ms while the off-time was varied to determine the critical/minimum DF up to which plasma discharge sustained, for a fixed SCL. In this way, for different SCLs, critical/minimum DFs were determined for different gas combinations. The gas flow was composed of 100 lpm argon and 2.5 lpm H 2, N 2 or CO 2 as secondary gas through the sheath channel only. Steady state coil currents for Ar, Ar–H 2, Ar–N 2 and Ar–CO 2 were 244 A, 263 A, 296 A and 296 A, respectively. In the numerical part, a two …