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Title: Applied axial magnetic field effects on laboratory plasma jets: Density hollowing, field compression, and azimuthal rotation

We experimentally measure the effects of an applied axial magnetic field (B z) on laboratory plasma jets and compare experimental results with numerical simulations using an extended magnetohydrodynamics code. A 1 MA peak current, 100 ns rise time pulse power machine is used to generate the plasma jet. On application of the axial field, we observe on-axis density hollowing and a conical formation of the jet using interferometry, compression of the applied B z using magnetic B-dot probes, and azimuthal rotation of the jet using Thomson scattering. Experimentally, we find densities ≤ 5×10 17 cm -3 on-axis relative to jet densities of ≥ 3×10 18 cm -3. For aluminum jets, 6.5 ± 0.5 mm above the foil, we find on-axis compression of the applied 1.0 ± 0.1 T B z to a total 2.4 ± 0.3 T, while simulations predict a peak compression to a total 3.4 T at the same location. On the aluminum jet boundary, we find ion azimuthal rotation velocities of 15-20 km/s, while simulations predict 14 km/s at the density peak. We discuss possible sources of discrepancy between the experiments and simulations, including: surface plasma on B-dot probes, optical fiber spatial resolution, simulation density floors, andmore » 2D vs. 3D simulation effects. Lastly, this quantitative comparison between experiments and numerical simulations helps elucidate the underlying physics that determine the plasma dynamics of magnetized plasma jets.« less
Authors:
ORCiD logo [1] ;  [1] ;  [1] ;  [1] ; ORCiD logo [1] ;  [1]
  1. Cornell Univ., Ithaca, NY (United States). Lab. of Plasma Studies
Publication Date:
Grant/Contract Number:
NA0001836; PHY-1102471
Type:
Accepted Manuscript
Journal Name:
Physics of Plasmas
Additional Journal Information:
Journal Volume: 24; Journal Issue: 12; Journal ID: ISSN 1070-664X
Publisher:
American Institute of Physics (AIP)
Research Org:
Cornell Univ., Ithaca, NY (United States). Lab. of Plasma Studies
Sponsoring Org:
USDOE National Nuclear Security Administration (NNSA); National Science Foundation (NSF)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; extended magnetohydrodynamics; magnetohydrodynamics; plasma jet; jet; magnetic field; diagnostics; Thomson scattering; B-dot probes; interferometry
OSTI Identifier:
1411534
Alternate Identifier(s):
OSTI ID: 1411980

Byvank, T., Banasek, J. T., Potter, W. M., Greenly, J. B., Seyler, C. E., and Kusse, B. R.. Applied axial magnetic field effects on laboratory plasma jets: Density hollowing, field compression, and azimuthal rotation. United States: N. p., Web. doi:10.1063/1.5003777.
Byvank, T., Banasek, J. T., Potter, W. M., Greenly, J. B., Seyler, C. E., & Kusse, B. R.. Applied axial magnetic field effects on laboratory plasma jets: Density hollowing, field compression, and azimuthal rotation. United States. doi:10.1063/1.5003777.
Byvank, T., Banasek, J. T., Potter, W. M., Greenly, J. B., Seyler, C. E., and Kusse, B. R.. 2017. "Applied axial magnetic field effects on laboratory plasma jets: Density hollowing, field compression, and azimuthal rotation". United States. doi:10.1063/1.5003777.
@article{osti_1411534,
title = {Applied axial magnetic field effects on laboratory plasma jets: Density hollowing, field compression, and azimuthal rotation},
author = {Byvank, T. and Banasek, J. T. and Potter, W. M. and Greenly, J. B. and Seyler, C. E. and Kusse, B. R.},
abstractNote = {We experimentally measure the effects of an applied axial magnetic field (Bz) on laboratory plasma jets and compare experimental results with numerical simulations using an extended magnetohydrodynamics code. A 1 MA peak current, 100 ns rise time pulse power machine is used to generate the plasma jet. On application of the axial field, we observe on-axis density hollowing and a conical formation of the jet using interferometry, compression of the applied Bz using magnetic B-dot probes, and azimuthal rotation of the jet using Thomson scattering. Experimentally, we find densities ≤ 5×1017 cm-3 on-axis relative to jet densities of ≥ 3×1018 cm-3. For aluminum jets, 6.5 ± 0.5 mm above the foil, we find on-axis compression of the applied 1.0 ± 0.1 T Bz to a total 2.4 ± 0.3 T, while simulations predict a peak compression to a total 3.4 T at the same location. On the aluminum jet boundary, we find ion azimuthal rotation velocities of 15-20 km/s, while simulations predict 14 km/s at the density peak. We discuss possible sources of discrepancy between the experiments and simulations, including: surface plasma on B-dot probes, optical fiber spatial resolution, simulation density floors, and 2D vs. 3D simulation effects. Lastly, this quantitative comparison between experiments and numerical simulations helps elucidate the underlying physics that determine the plasma dynamics of magnetized plasma jets.},
doi = {10.1063/1.5003777},
journal = {Physics of Plasmas},
number = 12,
volume = 24,
place = {United States},
year = {2017},
month = {12}
}