Spatial and temporal behavior of the plasma parameters in a pulsed magnetron discharge

We demonstrate the evolution of the electron, energy distribution and the plasma parameters in a high-density plasma in a pulsed magnetron discharge. The high-density plasma is created by applying a high power pulse (1-2.4 MW) with pulse lenght 100 μs and repetition frequency of 50 Hz to a planar magnetron discharge. The spatial and temporal behavior of the plasma parameters are investigated using a Langmuir probe; the electron energy distribution function, the electron density and the average electron energy. The electron energy distribution function during and shortly after the pulse can be represented by a bi-Maxwellian distribution indicating two energy groups of electrons. Furthermore, we report on the variation of the plasma parameters and electron energy distribution function with gas pressure in the pressure range 0.5-20 mtorr. We report electron density as high as 4 × 10¹⁸ m^-3 at 10 mtorr and 9 cm below the target in a pulsed discharge with average power 300 W. We estimate the travelling speed of the electron density peak along the axis of the discharge. The travelling speed decreases with increased gas pressure from 4 × 10⁵ cm/s at 0.5 mtorr to 0.87 × 10⁵ cm s^-1 at 10 mtorr. The effective electron temperature peaks at the same time independent of position in the discharge, which indicates a burst of high energy electrons at the end of the pulse.