Studies of interaction of plasma pulse with solid substrate as observed by optical spectroscopy

In our previous experiments it has been found that bombardment of solid substrates, especially those having low heat conductivity, with plasma pulses of power density in MW cm-2 range, produced by a rod plasma injector type of device leads to some loss of their mass. The aim of this paper is to clarify whether this mass loss is due to evaporation, sputtering, or ablation effects. In addition, we intended also to cast some light on the coating formation mechanism in the process referred to as 'deposition by pulsed erosion (DPE)'. The dynamics of plasma-solid interaction was observed with the use of time-resolved optical spectroscopy technique. The obtained results lead to two main conclusions. First, an interaction of gaseous plasma pulse of an energy density of 5 J cm-2 with the surface of a solid sample (Al2O3 containing alloyed Ti) causes its ablation and forms (in case of Ti electrodes) an Al-Ti plasma plume of a temperature of (2-3)x104 K. Second, the duration of a gaseous plasma pulse in DPE operation mode is approximately 1 μs