This paper reports the impact craters formed by Ag microparticles impacts, comparing with the TOF-MS (Time-Of-Flight Mass Spectrometer) spectra obtained simultaneously. The TOF spectra suggested that ions were hardly produced on Al target compared to Mo and Au targets. To determine the reason for this and to select the best material that ionizes the impacting dust particles, we observed impact craters on these targets with SEM and STM. Our results suggest that the ionization depends on the materials and that the combination of target and projectile materials causes the differences of crater shape and the Ag residue distribution.
The production of plasma by hypervelocity impacts has been studied with the experimental investigations. Previous works suggested that the ionization required higher impact velocity above 10km/s, and that the threshold velocity depended on the characteristics of projectile or target materials such as the ionization energy and the temperature.