Ablation of silicate particles in high-speed continuum and transition flow with application to the collection of interplanetary dust particles

Abstract

A model for the ablation and deceleration of spheres in continuum and slip flow is presented. Experiments were conducted in which initially spherical 7.1 micron diameter soda-lime glass particles were launched from vacuum at ~4500 m s^(-1) through a 0.5 mil (13 micron) plastic film into a capture chamber containing xenon at 0.1 and 0.2 atm and 295 K. Samples of ablated particles were collected and inspected using scanning electron microscopy (SEM). It was found that the ratio of the ablated particle radius (R_f) to the initial radius (R_0) depends on the gas pressure such that at 0.1 atm, R_f/R_0 = 0.67 ± 0.08, and at 0.2 atm, R_f/R_0 = 0.88 ± 0.08. The model agrees with these results if the heat of ablation Q is set to 1.5 ± 0.2 MJ kg^(-1). This value of Q approximately corresponds to the energy needed to raise the particle temperature from 295 to 1300 K, the working point of soda-lime glass. This indicates that the mechanism of ablation is melting and blowing of material from the particle's surface.