A pulse-modulated rf inductively coupled thermal plasma, which has extended control in its applications in pulse mode, was diagnosed both experimentally 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 sustained. Pulse-modulated plasmas were generated for different operating conditions (at atmospheric pressure, 2-20 ms on-time, 60-70% shimmer current level) and corresponding spectroscopic measurements were carried out. For different pulse on-times, the limit of the respective off-times for which pulse mode of plasma exists were determined and, thus, a typical operating zone of pulse-modulated plasma was proposed in both experimental and theoretical efforts. A two-dimensional model was solved numerically at atmospheric pressure (760 Torr) with various duty factors and shimmer current levels. A portion of theoretically predicted results were compared with the experimental results where reasonable agreement was found.