The Sheared-Flow-Stabilized Z-Pinch Approach to Fusion Energy
Uri Shumlak · Brian A. Nelson · Ben J. Levitt
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In one page
Uri Shumlak and his Zap Energy colleagues brought a status report to the 2023 IEEE plasma science conference on the simplest fusion machine anyone is building. A Z pinch is a column of gas with a very large current driven straight down it: the current’s own magnetic field squeezes and heats the column, so there are no external magnets and no separate heating system to build. The approach was set aside in the 1960s because the column kinks and destroys itself within microseconds. Shumlak’s group, first at the University of Washington with Livermore collaborators and now commercially at Zap Energy, revived it by giving the plasma a velocity shear — the gas moves at different speeds at different radii, and that shear smooths the kink away before it can grow. Their Fusion Z-pinch Experiment reached pinch currents above 600 kA, electron and ion temperatures above 2 and 2.5 keV, and more than 200 million fusion neutrons in a single pulse. The successor machine, FuZE-Q, is operating and aimed at scientific breakeven.
Why it matters hereChapter 12 follows fusion as the energy substrate the rest of the programme rests on, and this is its compact end: no external magnet set, no auxiliary heating, a device small and cheap enough to iterate on in months rather than decades. Chapter 9 gets the plasmoid argument in its most testable form — a plasma column that organises, confines and compresses itself, with neutron measurements that show the reactions are thermal rather than an artefact of a fast particle beam.
What it claims
01The sheared-flow-stabilized Z-pinch concept was developed at the University of Washington with Lawrence Livermore National Laboratory collaborators, and is now on a path to commercialization at Zap Energy Inc. Recent experiments corroborate expected thermonuclear fusion reaction rates as the discharge current is scaled towards compact reactor conditions.ICOPS 2023 abstract, opening sentences; conference paper, page 1
On the bench now02The Fusion Z-pinch Experiment, FuZE, employs high power-handling electrodes, flexible gas injection, and independently switched capacitor bank modules, so that the discharge current and the gas distribution can be tailored to establish both the stabilizing sheared flow and the pinch current itself. Stability is a property of how the plasma is driven, not of an external magnet cage.ICOPS 2023 abstract, second paragraph; conference paper, page 1
On the bench now03Record performance reported to the conference: pinch currents greater than 600 kA, electron temperature greater than 2 keV, ion temperature greater than 2.5 keV, and neutron yield greater than 2 times 10 to the eighth per pulse.ICOPS 2023 abstract, results sentence; conference paper, page 1
On the bench now04The independent check that the neutrons are real fusion and not a fast-beam artefact: measuring how evenly the neutron energy is spread across directions bounds the energy of any deuteron beam in FuZE to 7.4 keV, with a statistical uncertainty of 5.6 and a systematic uncertainty of 3.7 keV, at average plasma currents of 370 kA and yields of 4 times 10 to the seventh neutrons per discharge. The majority of the neutron production is isotropic, consistent with thermonuclear origin.Ryan and colleagues, Nuclear Fusion, doi 10.1088/1741-4326/ada8bf, abstract and results
Published and peer-reviewed05The machine can now be simulated end to end. Whole-device resistive magnetohydrodynamic modelling of FuZE reproduces pinch densities of about 10 to the twenty-second per cubic metre and a deuterium-deuterium neutron rate of 10 to the seventh per microsecond sustained for about two microseconds, matching measured peak currents and voltages within ten per cent and total yield within about thirty per cent — a predictive capability for designing the next device rather than only explaining the last one.Datta, Meier and Shumlak, Nuclear Fusion, doi 10.1088/1741-4326/ad3fcb, abstract
Published and peer-reviewed06The named next measurement, and the parallel engineering: FuZE-Q, the next-generation device, is operational, and the effort is to scale pinch current, plasma density and plasma temperature to reach scientific breakeven. Alongside it Zap Energy develops the power-plant technologies — high-average-power repetitive pulsed power, high-duty-cycle cathodes, and liquid metal wall systems.ICOPS 2023 abstract, closing sentences; conference paper, page 1
What to watch
The way in
https://doi.org/10.1109/ICOPS45740.2023.10481340WHAT THIS RECORD IS. The site’s registry inherited a rights guess of ‘video’ for this item, and that is wrong: Crossref types it as a proceedings-article on page 1 to 1 of the 2023 IEEE International Conference on Plasma Science, held at Santa Fe, New Mexico, 21 to 25 May 2023 — a conference paper and its published abstract, given as an oral presentation, with no recording distributed by the publisher. It is therefore handled here as summary-only, and this page reproduces no text from it. Authors and affiliation: Uri Shumlak, Brian A. Nelson and Ben J. Levitt, all listed by Crossref at Zap Energy Inc., Seattle, Washington; Shumlak’s university affiliation is the University of Washington, where the concept was developed. LICENCE, CHECKED 2026-09-08. Crossref lists only IEEE’s own policy documents, at doi.org/10.15223/policy-029 and doi.org/10.15223/policy-037, for both content versions; Unpaywall returns is_oa false, oa_status closed, and no repository copy. No Creative Commons statement exists. SOURCE. IEEE Xplore answers automated requests for the document page with an empty 202 response, so the proceedings text could not be fetched. The authors’ own published conference abstract was read on 2026-09-08 from the OpenAlex record for this digital object identifier, and every claim below marked to the ICOPS 2023 abstract comes from it. GROUNDING IN THE OPEN LITERATURE. Because the proceedings item is a one-page abstract, the physics on this page is grounded in two peer-reviewed papers from the same group, both read on 2026-09-08 as open preprints: R. A. Ryan, P. E. Tsai, A. R. Johansen, A. Youmans, D. P. Higginson, J. M. Mitrani, C. S. Adams, D. A. Sutherland, B. Levitt and U. Shumlak, ‘Time-resolved measurement of neutron energy isotropy in a sheared-flow-stabilized Z pinch’, Nuclear Fusion, doi 10.1088/1741-4326/ada8bf, arXiv 2408.05171; and I. A. M. Datta, E. T. Meier and U. Shumlak, ‘Whole device modeling of the FuZE sheared-flow-stabilized Z pinch’, Nuclear Fusion, doi 10.1088/1741-4326/ad3fcb, arXiv 2401.10366. RELATED PAGES. The engineering half of the same programme, Zap Energy’s Century liquid-metal test system, is at /library/stm-49324933a9; the first sustained-neutron-production result from FuZE is at /library/stm-751d0ee864.
How to cite it
Uri Shumlak, Brian A. Nelson, Ben J. Levitt (2023) The Sheared-Flow-Stabilized Z-Pinch Approach to Fusion Energy. doi:10.1109/ICOPS45740.2023.10481340
Where it sits in the curriculum
Plasmoids, charge clusters and the orbsLattice confinement fusion