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Hypervelocity Impact Flash and Plasma on Electrically Biased Spacecraft Surfaces

Hew, Y. M. and Goel, A. and Close, S. and Lee, N. (2018) Hypervelocity Impact Flash and Plasma on Electrically Biased Spacecraft Surfaces. International Journal of Impact Engineering, 121 . pp. 1-11. ISSN 0734-743X.

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Hypervelocity microparticles ( < 1 μg), traveling at speeds between 11 and 72 km/s with respect to the Earth, can impact spacecraft and form a small( ∼ 1 μm) and dense ( ∼ 10^(23) m^(−3)) plasma. This plasma can generate a strong optical emission (impact flash) and electromagnetic pulse (EMP), which can lead to spacecraft electrical anomalies when the impacted spacecraft surface carries electrical potential due to various space weather effects. A parameter of the impact plasma that strongly determines its behavior is its temperature. In order to understand the microparticle hypervelocity impact plasma and their associated threat to spacecraft electronics, we need to determine the impact plasma temperature under different spacecraft charging conditions. A non-intrusive method to study the impact plasma is by measuring the optical emission spectrum. In this paper, we present a theory of how hypervelocity impact light flash is generated by the plasma, supported by experiments at a ground-based 3 MV electrostatic dust accelerator using three spectral photomultiplier tubes at 450, 550, and 600 nm. This paper is the first to present results on hypervelocity impacts with various target electrical biases as a control variable to study the relationship between the impact plasma and the impact flash. The impact flash continuum spectrum is suggested to be produced by the acceleration of charged particles via spacecraft surface electrical biases, the oscillating internal electric field, and/or the local recombination effects within the impact plasma. The impact flash was found to emit blackbody radiation in the early time after the impact ( ∼ 200 ns). Using blackbody spectrum to estimate the plasma temperature and optical thickness, we found that an impact velocity range of 15 to 40 km/s yielded average plasma temperatures between 3300 and 6000 K depending on the target biases. Our measurements demonstrated a strong dependence of plasma temperature on the bias, which serves as new experimental evidence to support that impact flash is produced by the impact plasma. The correlations between the impactor characteristics such as mass, velocity, and charge production are also connected with the temperature and optical thickness measurement.

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Lee, N.0000-0001-5500-1324
Additional Information:© 2018 Published by Elsevier Ltd. Received 25 December 2017, Revised 14 April 2018, Accepted 18 May 2018, Available online 15 June 2018.
Subject Keywords:Hypervelocity Impact Flash; Hypervelocity Impact Plasma; Blackbody Radiation in Plasma
Classification Code:2010 MSC: 00-01; 99-00
Record Number:CaltechAUTHORS:20180615-094833280
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Official Citation:Y.M. Hew, A. Goel, S. Close, N. Lee, Hypervelocity impact flash and plasma on electrically biased spacecraft surfaces, International Journal of Impact Engineering, Volume 121, 2018, Pages 1-11, ISSN 0734-743X, (
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:87152
Deposited By: Tony Diaz
Deposited On:15 Jun 2018 18:27
Last Modified:14 Feb 2020 23:17

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