ROLE OF PARTICLE CHARGE IN IMPACT IONIZATION BY CHARGED MICROPARTICLES

The role of particle charge in generating ionization of projectile and target in impacts of iron microparticles on copper has been investiga ted at impact velocities above 1 km s(-1). Charged microparticles are accelerated in an electrostatic accelerator and their surface charge s ubsequently reduced in flight by passage through a thin conducting fil m. It is found that a reduction in projectile charge of 80% at 5 km s( -1) reduces noticeably the degree of impact ionization. This supports the recent assertion that heating due to current flow between the part icle and target immediately prior to impact may play a significant rol e in impact ionization at such velocities. (C) 1998 Elsevier Science B .V. All rights reserved.