Two-dimensional MHD simulations of a neon Z pinch on Hawk
J. W. Schumer · D. Mosher · B. Moosman · B. V. Weber · R. J. Commisso · Niansheng Qi · J. Schein · M. Krishnan
Abstract and summary · read the original at the source
In one page
A Z pinch is the most direct way there is to squeeze a plasma. Run an enormous current down a column of gas and the magnetic field that current makes pulls the column in on itself. On the Naval Research Laboratory’s Hawk generator a shell of neon is puffed through a nozzle and imploded in about 250 nanoseconds. Schumer, Mosher, Moosman, Weber and Commisso at NRL, with Qi, Schein and Krishnan of Alameda Applied Sciences, simulated that implosion in two dimensions with the MACH2 magnetohydrodynamic code and checked it against pictures of the real thing — laser shearing interferometer images that read out the electron density of the collapsing sheath shot by shot. To make the comparison honest they started the simulation from the measured gas distribution rather than an idealised one, and added neon ionisation and equation-of-state models to the code so the radiation would be computed consistently. The computed densities track the measured ones as the snowploughed channel forms and collapses.
Why it matters hereChapter 9 is about self-organising, self-compressing plasma structures, and the imploding pinch is the laboratory’s cleanest example of one; chapter 12 needs compression schemes whose behaviour can be predicted before the shot, and this paper is the moment a pinch simulation is held up against interferometry of the real implosion and matches.
What it claims
01Two-dimensional magnetohydrodynamic simulations run with the MACH2 code were benchmarked against laser shearing interferometer images of the evolving electron-density sheath during 250-nanosecond neon gas-puff Z pinch implosions on the Naval Research Laboratory Hawk generator.Abstract, sentence 1; IEEE Transactions on Plasma Science 30, 488 (2002)
Published and peer-reviewed02The starting point of the simulation was not an idealised profile: the initial density distribution was calculated using a ballistic-flow-model fit to the measured initial gas-density distributions of the puff.Abstract, sentence 2
Published and peer-reviewed03The implosion was modelled using an applied current profile, single-temperature energy equations and black-body-limited optically thin radiation, and for consistency with that radiation model neon ionisation and equation-of-state models were added to MACH2.Abstract, sentences 3 and 4
Published and peer-reviewed04The computed magnetohydrodynamic ion-density distributions compare well with the interferometer images as the snowploughed plasma channel evolves during the implosion — that is, the code reproduces the measured collapse rather than merely resembling it.Abstract, sentence 5
Published and peer-reviewed05Current-channel evolution derived from one-dimensional snowplow calculations compares well with the two-dimensional results for the same current history and initial density distribution, which indicates that axial mass flow does not strongly affect the implosion dynamics.Abstract, final sentence
Published and peer-reviewed06What to watch: the simulations also show features that may be helpful for understanding the early and weak K-shell radiation observed near the nozzle in Double-Eagle gas-puff experiments — the measurement that would settle it is time-resolved K-shell imaging near the nozzle on a machine of that class, compared against the same modelling.Abstract, sentence 6
What to watch
Read it · abstract
Abstract
Two-dimensional magnetohydrodynamic (MHD) simulations using MACH2 are benchmarked against laser shearing interferometer (LSI) images of the evolving electron-density sheath during 250-ns neon gas-puff Z pinch implosions on the Naval Research Laboratory Hawk generator. The initial density distribution for the MHD simulations is calculated using a ballistic-flow-model fit to the measured initial gas-density distributions. The implosion is modeled using an applied current profile, single-temperature energy equations, and black-body-limited optically thin radiation. For consistency with the radiation model, neon ionization and equation-of-state models have been added to MACH2. Computed MHD ion-density distributions compare well with LSI images as the snowplowed plasma channel evolves during implosion. The MHD results also show features that may be helpful for understanding early and weak K-shell radiation observed near the nozzle in Double-Eagle gas-puff experiments. Current-channel evolution derived from one-dimensional snowplow calculations compare well to the MHD results for the same current history and initial density distribution, indicating that axial mass flow does not strongly impact the implosion dynamics.
J. W. Schumer, D. Mosher, B. Moosman, B. V. Weber, R. J. Commisso, Niansheng Qi, J. Schein and M. Krishnan, Two-dimensional MHD simulations of a neon Z pinch on Hawk, IEEE Transactions on Plasma Science 30, issue 2, pages 488 to 497, April 2002. The published article is at doi.org/10.1109/TPS.2002.1024281.
Authors and affiliations. Schumer, Mosher, Moosman, Weber and Commisso, Pulsed Power Physics, United States Naval Research Laboratory, Washington, DC; Qi, Schein and Krishnan, Alameda Applied Sciences Corporation, California.
(Abstract only — no other text of the article is reproduced here; see the rights note above. On this site the wire-array implosion model from the same laboratory is at /library/stm-fbf26262c6, the two-wire Z-pinch plasma dynamics paper is at /library/stm-704d7be815, and the prepulse-current fiber pinch is at /library/stm-06c1a40035.)
The way in
https://doi.org/10.1109/tps.2002.1024281SOURCE NOT REACHED IN FULL. IEEE holds this article closed. Unpaywall, OpenAlex and Semantic Scholar all report no open version and no repository copy on 2026-09-08, and Semantic Scholar’s record states plainly that the abstract field has been elided by the publisher. The Naval Research Laboratory may hold a corresponding technical report; DTIC’s search API and its citation pages both refused automated requests the same day, so no report text was read. What is reproduced below is the authors’ own abstract as deposited with the publisher and carried by OpenAlex — nothing else from the article is reproduced. Every locator therefore points to a sentence of that abstract or to the bibliographic record: IEEE Transactions on Plasma Science, volume 30, issue 2, pages 488 to 497, April 2002. Affiliations are from the OpenAlex authorship records: Schumer, Mosher, Moosman, Weber and Commisso at the United States Naval Research Laboratory; Qi, Schein and Krishnan at Alameda Applied Sciences Corporation. Author given names are printed as the journal printed them, initials included, rather than expanded from guesswork.
How to cite it
J. W. Schumer, D. Mosher, B. Moosman, B. V. Weber, R. J. Commisso, Niansheng Qi, J. Schein, M. Krishnan (2002) Two-dimensional MHD simulations of a neon Z pinch on Hawk. doi:10.1109/tps.2002.1024281
Where it sits in the curriculum
Plasmoids, charge clusters and the orbsLattice confinement fusion