Prediction of operating region of pulse-modulated radio frequency inductively coupled thermal plasma

A pulse-modulated rf inductively coupled thermal plasma, which has extended control in its applications in pulse mode, was diagnosed both experimental ly and numerically to determine the critical values of the duty factor and shimmer current level down to which the pulse mode of the plasma is sustain ed. Pulse-modulated plasmas were generated for different operating conditio ns (at atmospheric pressure, 2-20 ms on-time, 60-70% shimmer current level) and corresponding spectroscopic measurements were carried out. For differe nt pulse on-times, the limit of the respective off-times for which pulse mo de of plasma exists were determined and, thus, a typical operating zone of pulse-modulated plasma was proposed in both experimental and theoretical ef forts. A two-dimensional model was solved numerically at atmospheric pressu re (760 Torr) with various duty factors and shimmer current levels. A porti on of theoretically predicted results were compared with the experimental r esults where reasonable agreement was found.