Optical emission spectroscopy and charge collector time-of-flight meas
urements have been used to study interaction of laser ablation carbon
plasma with grid screens in vacuum under conditions typical for pulsed
laser deposition of thin diamondlike films. The effect of velocity di
stribution transformation of the ion, flow has been observed and studi
ed in a variety of experimental conditions. Our results indicate that
the observed phenomenon is due to interaction of two plasma flows, the
initial expanding one and the fraction of that flow scattered by the
substrate or the screen. Three typical modes of velocity distribution
function transformation have been observed depending on the plasma den
sity: linear attenuation of the flow density, nonlinear attenuation of
the slow ''tail'' of the velocity distribution function, and nonlinea
r transformation of the entire velocity spectrum. The latter regime oc
curs when plasma is throttling through the fine mesh screen. Our obser
vations show that the reported phenomenon may substantially affect dep
osited him properties. (C) 1995 American Institute of Physics.