The deposition and etching of layers by plasma discharges operating in pulsed mode have many important applications. The variation of the time parameters of the process (frequency and duty cycle) lead to noticeable modifications of the deposited layers and the etch rate. Plasma diagnostic are now available to measure the change in plasma composition and this is turn is often correlated with the quality of the process. In diamond thin films the quality of films produced is strongly correlated with the concentration of H-atoms, CH and C2 radicals and their evolution during the discharge regime and the afterglow. Indeed, these species are well known either as agents for graphite etching (H), or diamond precursors (CHx imaged by CH) or graphite precursors (C2Hx imaged by C2). In silicon etching anomalous side wall etching, called ‘notching’ in gate poly-Si etching, is suppressed in pulsed-power chlorine inductively coupled plasma. In order to understand the complex mechanisms involved in pulsed or indeed RF plasma a comprehensive suite of time and phase resolved measurements have been developed by Impedans. In this presentation we will show dependent measurements of ion energy distribution, plasma potential, electron and ion density/flux and electron temperature data in pulsed and RF plasma illustrating the complex changes occurring when time modulation is used in plasma processes.