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Experimental investigation of the compression and heating of an MHD-driven jet impacting a target cloud

Seo, Byonghoon and Bellan, Paul M. (2018) Experimental investigation of the compression and heating of an MHD-driven jet impacting a target cloud. Physics of Plasmas, 25 (11). Art. No. 112703. ISSN 1070-664X. https://resolver.caltech.edu/CaltechAUTHORS:20181107-130421517

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Abstract

Adiabatic compression has been investigated by having an MHD-driven plasma jet impact a gas target cloud. Compression and heating of the jet upon impact were observed and compared to theoretical predictions. Diagnostics for comprehensive measurements included a Thomson scattering system, a fast movie camera, a translatable fiber-coupled interferometer, a monochromator, a visible-light photodiode, and a magnetic probe array. Measurements using these diagnostics provided the time-dependent electron density, electron temperature, continuum emission, line emission, and magnetic field profile. Increases in density and magnetic field and a decrease in jet velocity were observed during the compression. The electron temperature had a complicated time dependence, increasing at first, but then rapidly declining in less than 1 μs which is less than the total compression time. Analysis indicates that this sudden temperature drop is a consequence of radiative loss from hydrogen atoms spontaneously generated via three-body recombination in the high-density compressed plasma. A criterion for how fast compression must be to outrun radiative loss is discussed not only for the Caltech experiment but also for fusion-grade regimes. In addition, the results are analyzed in the context of shocks the effects of which are compared to adiabatic compression.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1063/1.5045678DOIArticle
ORCID:
AuthorORCID
Seo, Byonghoon0000-0001-5782-5669
Bellan, Paul M.0000-0002-0886-8782
Additional Information:© 2018 Published by AIP Publishing. Received 22 June 2018; accepted 22 October 2018; published online 7 November 2018. The authors would like to thank Dr. Amelia Greig at Cal Poly San Luis Obispo for her effort on the preliminary jet-impact experiment when working at Caltech as a postdoctoral fellow. The authors would also like to acknowledge useful discussions with Dr. Hui Li at the Los Alamos National Laboratory; Dr. Li developed numerical models which are related to this experiment and which will be reported elsewhere. This research was supported by USDOE ARPA-E Grant No. DE-AR0000565.
Funders:
Funding AgencyGrant Number
Department of Energy (DOE)DE-AR0000565
Issue or Number:11
Record Number:CaltechAUTHORS:20181107-130421517
Persistent URL:https://resolver.caltech.edu/CaltechAUTHORS:20181107-130421517
Official Citation:Experimental investigation of the compression and heating of an MHD-driven jet impacting a target cloud. Byonghoon Seo and Paul M. Bellan. Physics of Plasmas 2018 25:11
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:90717
Collection:CaltechAUTHORS
Deposited By: Tony Diaz
Deposited On:07 Nov 2018 21:17
Last Modified:05 Nov 2019 17:41

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