Experimental setup for the laboratory investigation of micrometeoroid ablation using a dust accelerator

Abstract

A facility has been developed to simulate the ablation of micrometeoroids in laboratory conditions. An electrostatic dust accelerator is used to generate iron particles with velocities of 10-70 km/s. The particles are then introduced into a chamber pressurized with a target gas, where the pressure is adjustable between 0.01 and 0.5 Torr, and the particle partially or completely ablates over a short distance. An array of biased electrodes above and below the ablation path is used to collect the generated ions/electrons with a spatial resolution of 2.6 cm along the ablating particles’ path, thus allowing the study of the spatiotemporal evolution of the process. For completely ablated particles, the total collected charge directly yields the ionization coefficient of a given dust material-target gas combination. The first results of this facility measured the ionization coefficient of iron atoms with N2, air, CO2, and He target gases for impact velocities >20 km/s, and are reported by Thomas et al. [Geophys. Res. Lett. 43, 3645 (2016)]. The ablation chamber is also equipped with four optical ports that allow for the detection of the light emitted by the ablating particle. A multichannel photomultiplier tube system is used to observe the ablation process with a spatial and temporal resolution of 0.64 cm and 90 ns. The preliminary results indicate that it is possible to calculate the velocity of the ablating particle from the optical observations, and in conjunction with the spatially resolved charge measurements allow for experimental validation of ablation models in future studies.

High‐Speed Drag Measurements of Aluminum Particles in Free Molecular Flow

“…It is separated from the high‐vacuum beamline of the dust accelerator by a two‐stage differential pumping system. The setup used for this experiment was described in detail by Thomas et al () and has been used to observe and characterize the ionization process that occurs during the ablation of particles at velocities >10 km/s (DeLuca et al, ; Thomas et al, ). For the experiments described here, aluminum particles with radii between 140 nm and 2.1 μm were shot at speeds of 1–10 km/s into air, argon, carbon dioxide, and nitrogen gases held at 0.20 Torr.…”

Impacts of Cosmic Dust on Planetary Atmospheres and Surfaces

“…The new laboratory experimental systems for simulating meteoric ablation (Bones et al 2016;Thomas et al 2017) are important for testing and improving ablation models, leading to more secure predictions of the fraction of incoming dust that ablates in a planetary atmosphere, the altitudes where different constituents are injected, and the fraction of unablated material that reaches the surface in the form of micrometeorites and cosmic spherules (Carrillo-Sánchez et al 2016). Future developments in this area should include ablation models that treat multiple mineral phases in a meteoroid, as well as fragmentation during atmospheric entry.…”

“…An electrostatic dust accelerator has recently been used to generate metallic particles with velocities of 10-70 km s −1 , which are then introduced into a pressurized chamber where the particle partially or completely ablates over a short distance. The deceleration is used to determine the rate of mass loss, and an array of biased electrodes above and below the ablation path collect the ions and electrons produced along the ablation path, from which the ionization efficiency can be determined (Thomas et al 2016(Thomas et al , 2017. A model like CABMOD can then be used to calculate the height profile of the injection rates of the meteoritic constituents into a planetary atmosphere.…”

Laboratory space physics: Investigating the physics of space plasmas in the laboratory

“…During the initial year of the campaign in 2017, experiments observed whistler waves driven by runaway electrons, relevant to the physics of the Van Allen radiation belts. 423 Laboratory experiments also contribute to the investigation of other aspects of space and planetary environments beyond the physics of plasmas, including the study of the physics of ice under the cryogenic vacuum conditions of space, 424,425 investigation the formation of ice in dusty plasma environments, 347,348 the ablation of micrometeoroids in Earth's atmosphere, 426 the effect of micrometeoroid impact on icy surfaces, 427 and the determination of the surface chemistry of planets and moons, such as Titan. [428][429][430] Viewed collectively as a national resource for the laboratory investigation of the physics of space plasmas, akin to the collection of spacecraft missions that comprise the Heliophysics System Observatory, these facilities have the capability the contribute uniquely to progress in our understanding of space physics.…”