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Studies of the laser evaporation process and unipolar arcing inside a scanning electron microscope



Journal of Physics. D. Applied Physics 25 (1992), pp.875-880 : Abb.,Lit.
ISSN: 0022-3727
Journal Article
Fraunhofer IWS ()
langmuir probe; Langmuirprobe; laser evaporation; Laserstrahlverdampfen; plasma temperature; Plasmatemperatur; unipolar arcing in situ; unipolarer Bogen

The beam of a Q-switched Nd-glass laser has been guided into a scanning electron microscope with the aim of observing target erosion in situ. The erosion caused by one shot was found to be highly inhomogeneous, with craters distributed irregularly across the irradiated spot. The ion energy distribution, ion density, and electron temperature of the plasma cloud emanating from the Cu, Ti, and YBasub2Cusub3Osub7 targets were measured by means of a Langmuir probe. The ion energy distributions turned out to be nearly Maxwellian, with an average energy of about 20 eV, which is higher than expected from laser heating but similar to the energy of ions emitted from cathode spots of vacuum arcs. From our observations we conclude that, with incident power densities of 10high7-10high8 W cmhigh-2, target erosion is increased by unipolar arcing.