Properties of the ion sheath expansion in plasma are investigated for atarget voltage with a finite rise time. A theoretical model for ionsheath expansion is developed when the negative target voltage increases linearly. The theory predicts that the sheath expansion is proportional to the square root of time at the beginning and is proportional to the 56 power of time later on. An experimental measurement has been carried out and the measured data are compared with theoretical results. It is shown that the sheath front propagates very fast at the beginning and slows down later, even for continuously rising negative voltage ontarget.

http://dx.doi.org/10.1063/1.873673