Historical research guide · 0522 · 2014

Experimental Demonstration of Fusion-Relevant Conditions in Magnetized Liner Inertial Fusion

M. R. Gomez · S. A. Slutz · A. B. Sefkow · D. B. Sinars · K. D. Hahn · S. B. Hansen · E. C. Harding · P. F. Knapp · P. F. Schmit · C. A. Jennings · T. J. Awe · M. Geissel · D. C. Rovang · G. A. Chandler · G. W. Cooper · M. E. Cuneo · A. J. Harvey-Thompson · M. C. Herrmann · M. H. Hess · O. Johns · D. C. Lamppa · M. R. Martin · R. D. McBride · K. J. Peterson · J. L. Porter · G. K. Robertson · G. A. Rochau · C. L. Ruiz · M. E. Savage · I. C. Smith · W. A. Stygar · R. A. Vesey

In one minute

Conventional inertial fusion needs implosion speeds above 350 kilometres a second and near-perfect spherical symmetry. Magnetized liner inertial fusion trades both away for a magnetic field. Matthew Gomez, Stephen Slutz and their Sandia colleagues report the first fully integrated test of the idea on the Z machine: a beryllium tube of deuterium gas, given a 10 tesla axial field, warmed by a 2.5 kilojoule laser pulse, then crushed by a 19 million amp current rising in a hundred nanoseconds. The field does two jobs at once. It insulates the fuel, so heat does not leak sideways out of the column, and it traps the charged fusion products inside. The implosion reached only 70 to 100 kilometres a second, yet the fuel stagnated at around 3 keV and produced up to two trillion fusion neutrons. Shots missing either the laser preheat or the field stayed at or below 1 keV and produced almost nothing. The secondary-neutron ratio shows the seed field was compressed and holding.

Connection

Chapter 12 argues that the environment a nucleus sits in changes how often it gets through the barrier it faces, and this is the experiment where a magnetic field buys most of the temperature that brute-force compression would otherwise have to supply. Chapter 9 gains a measured case of a self-consistent magnetised plasma column holding its own fusion products for the length of the burn.

From the source

The first fully integrated experiments on the magnetized liner inertial fusion concept combined all three of its elements at once: a deuterium-filled beryllium liner premagnetised to 10 T by the Applied B-field on Z system, preheated by the Z Beamlet laser at 2.5 kJ and 1 TW, and imploded by the Z machine’s 19 MA current with a 100 ns rise time.Abstract; target and drive description, paragraphs 5 to 7; Fig. 2
In the best-performing experiment the stagnation ion temperature was 2.5 plus or minus 0.5 keV and the electron temperature 3.5 plus or minus 0.5 keV, with a DD neutron yield of 1.9 plus or minus 0.4 times ten to the twelfth — reached with an implosion velocity of only 70 to 100 km/s, where conventional inertial confinement fusion relies on velocities above 350 km/s.Fig. 3 and its accompanying paragraph; opening paragraph
The magnetic field and the laser preheat are both necessary. In null experiments that omitted either one, the stagnation temperature was at most 1 keV and the DD yield did not exceed ten to the tenth, and the best fully integrated experiment out-yielded the best non-integrated one by more than a factor of 200.Paragraph following Fig. 3
The seed magnetic field was compressed and did confine the fusion products. For the measured areal density of about 2 mg per square centimetre, an unmagnetised implosion would give a secondary DT to primary DD yield ratio of order four times ten to the minus four; the measured ratio was above ten to the minus two, indicating that the field is extremely effective at trapping the fast tritons, with a beryllium mix fraction below 10 per cent.Paragraph beginning ‘A critical component of any MIF concept’
The neutrons are thermonuclear rather than beam-target in origin. The yield was isotropic across three polar angles to within the measurement uncertainty, the time-of-flight spectra were near-Gaussian, and the measured DD yields of five times ten to the eleventh to two times ten to the twelfth fall inside the range estimated independently from the measured fuel density, temperature, emitting volume and burn duration.Paragraph beginning ‘The results from these experiments validate key features’
The named next measurement is laser coupling. Pre-shot simulations predicted DD yields above ten to the thirteenth, and the observed yields are recovered when the simulation assumes only about 10 per cent of the laser energy reaches the fuel through the entrance-hole window, so higher pre-compression fuel temperatures — within reach of minor modifications to the laser and the target — are expected to improve performance.Final two paragraphs before the acknowledgements

The way in

https://doi.org/10.1103/PhysRevLett.113.155003

Historical source-access record. This guide links to the original; it does not reproduce the paper text.

LICENCE CHECK, 2026-09-08. The version of record is Physical Review Letters 113, 155003, published 6 October 2014, and Crossref records it under the APS default licence, with the accepted manuscript under the APS default accepted-manuscript licence after a twelve-month embargo. Neither is a Creative Commons grant, and no Creative Commons statement appears in the text. The work was done at Sandia National Laboratories under U.S. Department of Energy contract DE-AC04-94AL85000 for the National Nuclear Security Administration, so it is a contractor’s work rather than a United States Government work and is not in the public domain. TEXT. The full text read for this sheet is the accepted manuscript, Sandia report SAND2014-4519J, from the Office of Scientific and Technical Information at osti.gov/servlets/purl/1146936, and the claims below are read against it. The abstract reproduced here is the version of record’s, from the DOE PAGES record for the same paper, with its subscript markup cleared and its exponents restored; the accepted manuscript’s own abstract differs in a few figures, giving the machine as the 26 MA Z facility rather than the 19 MA drive current delivered, an implosion velocity of 70 to 100 km/s rather than a predicted peak of 70 km/s, and a hot-fuel width of 50 to 150 microns rather than 60 to 120. The manuscript body states the drive as the 100 ns risetime, 19 MA current of the Z machine, which agrees with the published abstract. Figure numbers in the claims are the manuscript’s. Read with the high-gain magnetized inertial fusion projection at /library/stm-b7ffaf8ee4.

How to cite it

M. R. Gomez, S. A. Slutz, A. B. Sefkow, D. B. Sinars, K. D. Hahn, S. B. Hansen, E. C. Harding, P. F. Knapp, P. F. Schmit, C. A. Jennings, T. J. Awe, M. Geissel, D. C. Rovang, G. A. Chandler, G. W. Cooper, M. E. Cuneo, A. J. Harvey-Thompson, M. C. Herrmann, M. H. Hess, O. Johns, D. C. Lamppa, M. R. Martin, R. D. McBride, K. J. Peterson, J. L. Porter, G. K. Robertson, G. A. Rochau, C. L. Ruiz, M. E. Savage, I. C. Smith, W. A. Stygar, R. A. Vesey (2014) Experimental Demonstration of Fusion-Relevant Conditions in Magnetized Liner Inertial Fusion doi:10.1103/PhysRevLett.113.155003

Where it sits in the curriculum

Fusion machines: pinches, focus devices and inertial drivers