DETECTION OF DUST PARTICLES IN THE PLASMA BY LASER-INDUCED HEATING

Heating of dust particles suspended in a low pressure discharge by mea ns of a high power pulsed laser was analyzed. A detailed model of part icle heating and thermal decomposition was developed and experimentall y verified using 1 mu m Teflon-like particles in a radio-frequency arg on discharge. Laser-induced heating results in blackbody-like emission from the particles. This radiation can be easily recorded and a parti cle temperature of about 3500 K is determined by fitting the emission spectra. From the model it follows that the time resolved emission int ensity gives valuable information about the particles: the time delay between the onset of the laser pulse and the blackbody-like emission c orresponds to the heating time of the clusters and is dependent on the ir size. Moreover, the absolute emission intensity is proportional to the particle density. (C) 1996 American Vacuum Society.