Abstract
A RF plasma impedance meter was developed to measure the time varying impedance during the power on period of an inductively-coupled pulsed plasma, where a shape adjustable coil and a conventional 13.56 MHz RF power were used. During the power on period, both RF voltage and current on the ICP coil initially increased to a peak value and then slightly decreased up to roughly 1-20% until the power was turned off for all modulations. The relative phase between voltage and current also followed a similar temporal dependence. The real input RF power was also obtained. Measurement results show that neither RF current nor input power is constant even for a square wave modulation.