Kurzzeituntersuchung von laser- und bogengestützten Beschichtungsprozessen
Short-time investigation of laser and arc assisted deposition processes
Both in pulsed laser depositon (PLD) and in arc deposition the target material is evaporated and ionised in an explosive process of some nanoseconds duration. This process of explosive plasma formation is caused by very high power concentrations. Therefore power densities of 10 (exp 7) to 10 (exp 10) W/cm (exp 2) can produced by a highly focussed laser beam. Nearly the same energy density occurs automatically in the self-contracting current channel of the vacuum arc. Due to the high energy density, the plasmas of both sources are highly ionised and the ions have kinetic energies of some ten eV. On the other side, a great part of the eroded material is emitted as molten droplets. To improve the quality of deposited films, the portion of droplets should be reduced. Moreover, to expand its area of application, the energetical efficiency of PLD should be increased. To solve these current questions, the processes of explosive plasma production must be studied with an adequate temporal and l ocal resolution (nanosecondsmicrometer). Due to the insufficient local and temporal resolution of the available high speed cameras, a new system was especially designed for our tasks. This new technology high speed framing camera HSFC, developed by the PCO Computer Optics combines a microscopical resolution of 5 mm with a nanosecond time resolution and a very high optical sensitivity. In the present paper, first results are reported of the current program of high speed investigation of the explosive evaporation processes in PLD and arc deposition.