Alpha-particle self-heating, the process of deuterium–tritium fusion reaction products depositing their kinetic energy locally within a fusion reaction region and thus increasing the temperature in the reacting region, is essential for achieving ignition in a fusion system. Here, we report new inertial confinement fusion experiments where the alpha-particle heating of the plasma is dominant with the fusion yield produced exceeding the fusion yield from the work done on the fuel (pressure times volume change) by a factor of two or more. These experiments have achieved the highest yield (26 ± 0.5 kJ) and stagnation pressures (≍220 ± 40 Gbar) of any facility-based inertial confinement fusion experiments, although they are still short of the pressures required for ignition on the National Ignition Facility (∼300–400 Gbar). These experiments put us in a new part of parameter space that has not been extensively studied so far because it lies between the no-alpha-particle-deposition regime and ignition.
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We gratefully acknowledge thoughtful discussions with R. Betti (LLE), D. Clark, J. Hammer, J. Hayes, M. C. Herrmann, W. Hsing, B. Kauffman, J. Kilkenny, R. Kirkwood, B. MacGowan, A. Mackinnon, N. Meezan, J. Nuckolls, L. Peterson, J. Pino, K. Raman, B. A. Remington, M. Rosen, V. Smalyuk, C. Thomas and B. Van Wonterghem. Thanks to the NIF’s operations, diagnostics, cryogenics, target, and project engineering teams (B. Burr, P. Kervin, L. Kot, J. Meeker, D. Swift and B. Young). Thanks to external collaborators at LANL (diagnostics), GA (targets), LLE (diagnostics), the MIT Plasma Science and Fusion Center (MRS diagnostic), CEA and AWE. This work was performed under the auspices of the US Department of Energy by Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344.
The authors declare no competing financial interests.
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Hurricane, O., Callahan, D., Casey, D. et al. Inertially confined fusion plasmas dominated by alpha-particle self-heating. Nature Phys 12, 800–806 (2016) doi:10.1038/nphys3720
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