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Kurzzeituntersuchungen von laser- und bogengestützten Beschichtungsprozessen

Short-time investigation of laser and arc-assested deposition processes
: Siemroth, P.; Witke, T.; Schülke, T.; Lenk, A.


Surface and coatings technology 68 (1994), S.713-718
ISSN: 0257-8972
Fraunhofer IWS ()
arc; Beschichtung; Bogen; deposition; explosive plasma production; explosive Plasmaerzeugung; high speed framing camera; Hochgeschwindigkeitskamera; Laserpulsabscheidung; nanosecond processes; Nanosekundenprozesse; pulsed laser deposition

Both in pulsed laser depositon (PLD) and in are 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 107 to 1010 W/cm2 can produced by a highly focused 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 Energie 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 local resolution (nanose condsmicrometer). 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.