Inertially confined fusion plasmas dominated by alpha-particle self-heating

Abstract

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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Figure 1: Hotspot pressure versus coasting time (implosion speed).
Figure 2: 3D implosion morphology and implosion data located in a parameter space relevant to ignition.
Figure 3: The scaling of fusion yield with fuel kinetic energy.
Figure 4: X-ray energy radiated by hotspots from a variety of implosion experiments.

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Acknowledgements

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.

Author information

O.A.H. high-foot (HF) team co-lead dynamic model development and synthesis; D.A.C. HF team co-lead hohlraum drive and symmetry; D.T.C. DT shots (experiments) co-RI (responsible individual); E.L.D. 1DConA (velocity measurement) Shot RI, re-emit (X-ray re-emission experiment) Shot RI and data analysis and hot-electron analysis; T.R.D. 1D design physics and scoping; T.D. DT Shot RI and hard X-ray imaging analysis; S.H. DT ice layer characterization and instability growth-factor calculations; D.E.H. integrated hohlraum–capsule pulse-shape design physics and integrated post-shot modelling; L.F.B.H. keyhole (shock wave timing) shot pulse-shape design and post-shot modelling; O.J. hohlraum model design and development; A.L.K. integrated post-shot modelling and asymmetry analysis; S.L. keyhole Shot RI; T.M. DT Shot RI and hotspot shape analysis; A.G.M. capsule X-ray yield, data analysis tools, and 1DConA co-RI; J.L.M. hohlraum model development and re-emit design; J.M. hohlraum and backscatter physics experiments; A.P. DT Shot co-RI, re-emit Shot RI and analysis, and hotspot shape analysis; H.-S.P. DT Shot RI; P.K.P. post-shot data analysis and hotspot model energy, pressure, and alpha-heating analysis; J.E.R. Symcap (hotspot symmetry measurement) Shot RI and backscatter analysis; H.F.R. keyhole platform design and hot-electron studies; J.S.R. hohlraum experiments; J.D.S. 1D post-shot modelling; B.K.S. development model database for alpha-heating analysis and NToF data analysis; P.T.S. hotspot, dynamic model development, and fit of Qcond to SESAME database; R.T. 1DConA shot co-RI, data analysis and unfold of 2DConA data; F.A. FFLEX (hot-electron) data analysis; L.R.B. time-resolved hotspot shape X-ray measurement; R.B. FNADS (nuclear activation) spatial analysis; E.B. NToF data analysis; D.K.B. 2DConA (ablator shape) platform development; J.C. NToF data analysis; P.M.C. keyhole VISAR data analysis; C.C. 3D hotspot model analysis; J.A.C. GRH (gamma reaction history); R.D.S. DT ice layer cryogenics; D.E. south-pole bang-time data analysis; M.J.E. Program Director; D.F. NIS (neutron imaging system) LLNL RS (responsible scientist); M.A.B.G. 2DConA Shot RI; A.H. target fabrication engineering; R.H. NToF data analysis; H.H. GRH data analysis; M.H. FFLEX data synthesis; D.H. target engineering; J.L.K. Symcap Shot RI and Dante (low-resolution X-ray temperature measurement) analysis; B.K. DT ice layer cryogenics and cryo-team science lead; G.K. X-ray imaging and analysis; G.G. fields and performs data analysis for the neutron imaging time-of-flight system; J.E.F. 2DConA data analysis; J.F. MRS (magnetic recoil spectrometer) diagnostic analysis; N.I. X-ray image data analysis; M.G.J. MRS diagnostic analysis; S.F.K. X-ray image analysis; J.K. nuclear data analysis; T.K. DT fuelling and tritium facility lead; O.L. fuel velocity inference; F.M. NIS LANL RS and performs data reduction, analysis, and error determination; P.M. hohlraum cross-bean energy transfer model and analysis; A.M. Dante diagnostic RS; S.R.N. 2DConA Shot co-RI, DIXI X-ray data analysis; A.N. target fabrication engineering; T.P. cryogenics and DT fuel team; R.R.R. 2DConA data analysis; D.S. GRH; M.S. soft X-ray imaging analysis; D.S. spectral radio-chemistry data analysis; D.S. backscatter analysis; R.P.J.T. 2DConA platform design; A.W. high energy density program lead; K.W. Dante diagnostic RS; C.W. NIS diagnostic RI; P.V. develops algorithms to extract source information from NIS coded aperture; C.Y. FNADS (flange nuclear activation diagnostic system) analysis.

Correspondence to O. A. Hurricane.

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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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