Simulating plasma production from hypervelocity impacts

Abstract

Hypervelocity particles, such as meteoroids and space debris, routinely impact spacecraft and are energetic enough to vaporize and ionize themselves and as well as a portion of the target material. The resulting plasma rapidly expands into the surrounding vacuum. While plasma measurements from hypervelocity impacts have been made using ground-based technologies such as light gas guns and Van de Graaff dust accelerators, some of the basic plasma properties vary significantly between experiments. There have been both ground-based and in-situ measurements of radio frequency (RF) emission from hypervelocity impacts, but the physical mechanism responsible and the possible connection to the impact-produced plasma are not well understood. Under certain conditions, the impact-produced plasma can have deleterious effects on spacecraft electronics by providing a new current path, triggering an electrostatic discharge, causing electromagnetic interference, or generating an electromagnetic pulse. Multi-physics simulations of plasma production from hypervelocity impacts are presented. These simulations incorporate elasticity and plasticity of the solid target, phase change and plasma formation, and non-ideal plasma physics due to the high density and low temperature of the plasma. A smoothed particle hydrodynamics method is used to perform a continuum dynamics simulation with these additional physics. By examining a series of hypervelocity impacts, basic properties of the impact produced plasma plume (density, temperature, expansion speed, charge state) are determined for impactor speeds between 10 and 72 km/s. For a large range of higher impact speeds (30–72 km/s), we find the temperature is unvarying at 2.5 eV. We also find that the plasma plume is weakly ionized for impact speeds less than 14 km/s and fully ionized for impact speeds greater than 20 km/s, independent of impactor mass. This is the same velocity threshold for the detection of RF emission in recent Van de Graaff experiments, suggesting that the RF is correlated to the formation of fully ionized plasma.

Magnetic Field Effect on Antenna Signals Induced by Dust Particle Impacts

“…For ions, the bias voltage increased to −5 and −20 V reduces the fraction of escaping ions to about 55% and 25%, respectively, compared to the 0 V bias case (Figures 3g and 3h). On the other hand, the hydrodynamic simulations of dust impact events performed by Fletcher et al (2015) predicted significantly lower temperatures (about 4 eV at 20 km/s impact speed) than those reported by Collette et al (2016), or in this article. The ion energies were calculated from the widths of mass lines measured in a linear time-of-flight analyzer setup.…”

“…The ion energies were calculated from the widths of mass lines measured in a linear time-of-flight analyzer setup. On the other hand, the hydrodynamic simulations of dust impact events performed by Fletcher et al (2015) predicted significantly lower temperatures (about 4 eV at 20 km/s impact speed) than those reported by Collette et al (2016), or in this article. Field (B ≠ 0) Now let us investigate the variation of the signals with the magnetic field.…”

Microscopic Change in Hardened Cement Paste due to High-Speed Impact

“…a frame rate of 270 000/s and luminescence of plasma was observed at the impact point. The generation of plasma has been observed in the impact test of other materials (Song et al 2016;Fletcher et al 2015). However, to the best of the authors' knowledge, this is the first time it is observed in cementitious material.…”

One‐Year Analysis of Dust Impact‐Like Events Onto the MMS Spacecraft

“…The amplitude strongly increases with the velocity (power ranges from 3.8 to 4.2; Collette et al, 2014) and linearly with mass (power of 3 in size). The fact that impacts of smaller dust grains are much more probable than impacts of bigger ones (Grün et al, 1985) implies that we should expect much more events with small amplitudes for events related to the dust impact. It is possible to see that the pulses with higher amplitudes are less frequent than smaller ones and it is in a good agreement with the assumption that the pulses are generated by the dust impacts.…”