Modification and Mass Loss of Melamine Formaldehyde Particles in Dusty Plasma Formed in Heavy Noble Gas

The results are presented from experiments on determining the size of melamine formaldehyde dust particles during their long-term stay in the dust-plasma trap formed in the glow discharge in argon. It is shown that in 30 min, the diameter of particles decreases from 7.3 (initial diameter) to 3.5 μm; accordingly, the particles lose almost 90% of their mass. Three stages were distinguished of particle degradation in time. In the stage of maximum rate of particle size decrease, particles lose 20 pg/min. The data obtained are compared with the available measurement results for discharges in neon. It was ascertained that the rate of particle size decrease depends on the mass of plasma-forming gas. In argon and krypton, at the identical discharge parameters, the degradation of particles of the same initial size occurs faster than in neon. However, the starting time of intense mass loss more strongly depends on the particle size than on the type of gas. The data are compared with the existing physical model of particle degradation, and recommendations are proposed for performing long-term experiments with melamine formaldehyde particles.