Detection of dust particles in the plasma by laser-induced heating

Heating of dust particles suspended in a low pressure discharge by means of a high power pulsed laser was analyzed. A detailed model of particle heating and thermal decomposition was developed and experimentally verified using 1 μm Teflon-like particles in a radio-frequency argon discharge. Laser-induced heating results in blackbody-like emission from the particles. This radiation can be easily recorded and a particle temperature of about 3500 K is determined by fitting the emission spectra. From the model it follows that the time resolved emission intensity gives valuable information about the particles: the time delay between the onset of the laser pulse and the blackbody-like emission corresponds to the heating time of the clusters and is dependent on their size. Moreover, the absolute emission intensity is proportional to the particle density.