Laboratory measurements of energy partitioning and anomalous electron heating in magnetized, perpendicular collisionless shocks

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Main Authors: Valenzuela-Villaseca, V., Totorica, S., Griff-McMahon, J., Chen, L. -J., Malko, S., Heuer, P. V., Pongkitiwanichakul, P., Fox, W., Schaeffer, D. B.
Format: Preprint
Published: 2025
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author Valenzuela-Villaseca, V.
Totorica, S.
Griff-McMahon, J.
Chen, L. -J.
Malko, S.
Heuer, P. V.
Pongkitiwanichakul, P.
Fox, W.
Schaeffer, D. B.
author_facet Valenzuela-Villaseca, V.
Totorica, S.
Griff-McMahon, J.
Chen, L. -J.
Malko, S.
Heuer, P. V.
Pongkitiwanichakul, P.
Fox, W.
Schaeffer, D. B.
contents We present laboratory results on energy partitioning from supercritical, magnetized collisionless shock experiments ($\rm{M_A} \sim 8$, $\rm{M_{ms}}\sim 4$). We report the first observation of fully-developed laboratory shocks that evolve for more than seven upstream ion gyration periods and have a downstream region that extends more than four shocked ion gyroperiods. Thomson scattering measurements are used to measure electron and ion temperatures, plasma density, and flow speeds. We directly measure a compression ratio of $3.6\pm0.3$, consistent with shock jump conditions. A foot ahead of the shock exhibits super-adiabatic electron and ion heating. The downstream electron temperature has an $\approx 30\%$ excess above adiabatic and collisional electron-ion heating, implying significant collisionless anomalous electron heating. We find a downstream electron-ion temperature ratio $T_e^{(d)}/T_i^{(d)} = 0.8 \pm 0.3$, consistent with spacecraft observations but outside the range of predictions from theory and numerical simulations.
format Preprint
id arxiv_https___arxiv_org_abs_2509_12164
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Laboratory measurements of energy partitioning and anomalous electron heating in magnetized, perpendicular collisionless shocks
Valenzuela-Villaseca, V.
Totorica, S.
Griff-McMahon, J.
Chen, L. -J.
Malko, S.
Heuer, P. V.
Pongkitiwanichakul, P.
Fox, W.
Schaeffer, D. B.
Plasma Physics
High Energy Astrophysical Phenomena
Solar and Stellar Astrophysics
We present laboratory results on energy partitioning from supercritical, magnetized collisionless shock experiments ($\rm{M_A} \sim 8$, $\rm{M_{ms}}\sim 4$). We report the first observation of fully-developed laboratory shocks that evolve for more than seven upstream ion gyration periods and have a downstream region that extends more than four shocked ion gyroperiods. Thomson scattering measurements are used to measure electron and ion temperatures, plasma density, and flow speeds. We directly measure a compression ratio of $3.6\pm0.3$, consistent with shock jump conditions. A foot ahead of the shock exhibits super-adiabatic electron and ion heating. The downstream electron temperature has an $\approx 30\%$ excess above adiabatic and collisional electron-ion heating, implying significant collisionless anomalous electron heating. We find a downstream electron-ion temperature ratio $T_e^{(d)}/T_i^{(d)} = 0.8 \pm 0.3$, consistent with spacecraft observations but outside the range of predictions from theory and numerical simulations.
title Laboratory measurements of energy partitioning and anomalous electron heating in magnetized, perpendicular collisionless shocks
topic Plasma Physics
High Energy Astrophysical Phenomena
Solar and Stellar Astrophysics
url https://arxiv.org/abs/2509.12164