Laboratory investigation of ion expansion produced by hypervelocity dust impacts

In this laboratory study we present investigation of the angular distribution of expanding ions produced by hypervelocity dust impacts. Spacecraft operated by electric field antennas can characterize interplanetary and interstellar dust populations within our solar system from dust impacts. The recorded dust impact waveforms are diverse and their shape depends on the antenna mode of operation (dipole vs. monopole), impact location with respect to the antennas, spacecraft potential or dust particles properties. A unique experimental setup with delay line detector (DLD) is developed for measuring characteristics of the ion cloud expanding from the impact generated plasma. Dust particles of micron and sub-micron size are accelerated to velocities 1—80 km/s using the electrostatic dust accelerator operated at the University of Colorado. The ions produced after impact of accelerated particles on tungsten target plate are detected using the DLD that provides the position of their detection and time-of-flight. The angular distribution of ions with respect to target normal is calculated from these positions. The preliminary results indicate that the impact-generated ions expand in the form of a narrow cone and the cone angle increases with increasing dust speed.