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Hohenberger M, Albert F, Palmer NE, Lee JJ, Döppner T, Divol L, Dewald EL, Bachmann B, MacPhee AG, LaCaille G, Bradley DK, Stoeckl C. Time-resolved measurements of the hot-electron population in ignition-scale experiments on the National Ignition Facility (invited). Rev Sci Instrum 2014; 85:11D501. [PMID: 25430175 DOI: 10.1063/1.4890537] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
In laser-driven inertial confinement fusion, hot electrons can preheat the fuel and prevent fusion-pellet compression to ignition conditions. Measuring the hot-electron population is key to designing an optimized ignition platform. The hot electrons in these high-intensity, laser-driven experiments, created via laser-plasma interactions, can be inferred from the bremsstrahlung generated by hot electrons interacting with the target. At the National Ignition Facility (NIF) [G. H. Miller, E. I. Moses, and C. R. Wuest, Opt. Eng. 43, 2841 (2004)], the filter-fluorescer x-ray (FFLEX) diagnostic-a multichannel, hard x-ray spectrometer operating in the 20-500 keV range-has been upgraded to provide fully time-resolved, absolute measurements of the bremsstrahlung spectrum with ∼300 ps resolution. Initial time-resolved data exhibited significant background and low signal-to-noise ratio, leading to a redesign of the FFLEX housing and enhanced shielding around the detector. The FFLEX x-ray sensitivity was characterized with an absolutely calibrated, energy-dispersive high-purity germanium detector using the high-energy x-ray source at NSTec Livermore Operations over a range of K-shell fluorescence energies up to 111 keV (U Kβ). The detectors impulse response function was measured in situ on NIF short-pulse (∼90 ps) experiments, and in off-line tests.
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Affiliation(s)
- M Hohenberger
- Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623, USA
| | - F Albert
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - N E Palmer
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - J J Lee
- National Security Technologies LLC, Livermore, California 94551, USA
| | - T Döppner
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - L Divol
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - E L Dewald
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - B Bachmann
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - A G MacPhee
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - G LaCaille
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - D K Bradley
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
| | - C Stoeckl
- Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623, USA
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Döppner T, Dewald EL, Divol L, Thomas CA, Burns S, Celliers PM, Izumi N, Kline JL, LaCaille G, McNaney JM, Prasad RR, Robey HF, Glenzer SH, Landen OL. Hard x-ray (>100 keV) imager to measure hot electron preheat for indirectly driven capsule implosions on the NIF. Rev Sci Instrum 2012; 83:10E508. [PMID: 23127015 DOI: 10.1063/1.4731742] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
We have fielded a hard x-ray (>100 keV) imager with high aspect ratio pinholes to measure the spatially resolved bremsstrahlung emission from energetic electrons slowing in a plastic ablator shell during indirectly driven implosions at the National Ignition Facility. These electrons are generated in laser plasma interactions and are a source of preheat to the deuterium-tritium fuel. First measurements show that hot electron preheat does not limit obtaining the fuel areal densities required for ignition and burn.
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Affiliation(s)
- T Döppner
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA.
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Mackinnon AJ, Kline JL, Dixit SN, Glenzer SH, Edwards MJ, Callahan DA, Meezan NB, Haan SW, Kilkenny JD, Döppner T, Farley DR, Moody JD, Ralph JE, MacGowan BJ, Landen OL, Robey HF, Boehly TR, Celliers PM, Eggert JH, Krauter K, Frieders G, Ross GF, Hicks DG, Olson RE, Weber SV, Spears BK, Salmonsen JD, Michel P, Divol L, Hammel B, Thomas CA, Clark DS, Jones OS, Springer PT, Cerjan CJ, Collins GW, Glebov VY, Knauer JP, Sangster C, Stoeckl C, McKenty P, McNaney JM, Leeper RJ, Ruiz CL, Cooper GW, Nelson AG, Chandler GGA, Hahn KD, Moran MJ, Schneider MB, Palmer NE, Bionta RM, Hartouni EP, LePape S, Patel PK, Izumi N, Tommasini R, Bond EJ, Caggiano JA, Hatarik R, Grim GP, Merrill FE, Fittinghoff DN, Guler N, Drury O, Wilson DC, Herrmann HW, Stoeffl W, Casey DT, Johnson MG, Frenje JA, Petrasso RD, Zylestra A, Rinderknecht H, Kalantar DH, Dzenitis JM, Di Nicola P, Eder DC, Courdin WH, Gururangan G, Burkhart SC, Friedrich S, Blueuel DL, Bernstein LA, Eckart MJ, Munro DH, Hatchett SP, Macphee AG, Edgell DH, Bradley DK, Bell PM, Glenn SM, Simanovskaia N, Barrios MA, Benedetti R, Kyrala GA, Town RPJ, Dewald EL, Milovich JL, Widmann K, Moore AS, LaCaille G, Regan SP, Suter LJ, Felker B, Ashabranner RC, Jackson MC, Prasad R, Richardson MJ, Kohut TR, Datte PS, Krauter GW, Klingman JJ, Burr RF, Land TA, Hermann MR, Latray DA, Saunders RL, Weaver S, Cohen SJ, Berzins L, Brass SG, Palma ES, Lowe-Webb RR, McHalle GN, Arnold PA, Lagin LJ, Marshall CD, Brunton GK, Mathisen DG, Wood RD, Cox JR, Ehrlich RB, Knittel KM, Bowers MW, Zacharias RA, Young BK, Holder JP, Kimbrough JR, Ma T, La Fortune KN, Widmayer CC, Shaw MJ, Erbert GV, Jancaitis KS, DiNicola JM, Orth C, Heestand G, Kirkwood R, Haynam C, Wegner PJ, Whitman PK, Hamza A, Dzenitis EG, Wallace RJ, Bhandarkar SD, Parham TG, Dylla-Spears R, Mapoles ER, Kozioziemski BJ, Sater JD, Walters CF, Haid BJ, Fair J, Nikroo A, Giraldez E, Moreno K, Vanwonterghem B, Kauffman RL, Batha S, Larson DW, Fortner RJ, Schneider DH, Lindl JD, Patterson RW, Atherton LJ, Moses EI. Assembly of high-areal-density deuterium-tritium fuel from indirectly driven cryogenic implosions. Phys Rev Lett 2012; 108:215005. [PMID: 23003274 DOI: 10.1103/physrevlett.108.215005] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/18/2011] [Indexed: 06/01/2023]
Abstract
The National Ignition Facility has been used to compress deuterium-tritium to an average areal density of ~1.0±0.1 g cm(-2), which is 67% of the ignition requirement. These conditions were obtained using 192 laser beams with total energy of 1-1.6 MJ and peak power up to 420 TW to create a hohlraum drive with a shaped power profile, peaking at a soft x-ray radiation temperature of 275-300 eV. This pulse delivered a series of shocks that compressed a capsule containing cryogenic deuterium-tritium to a radius of 25-35 μm. Neutron images of the implosion were used to estimate a fuel density of 500-800 g cm(-3).
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Affiliation(s)
- A J Mackinnon
- Lawrence Livermore National Laboratory, Livermore, California 94551, USA
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Döppner T, Thomas CA, Divol L, Dewald EL, Celliers PM, Bradley DK, Callahan DA, Dixit SN, Harte JA, Glenn SM, Haan SW, Izumi N, Kyrala GA, LaCaille G, Kline JK, Kruer WL, Ma T, MacKinnon AJ, McNaney JM, Meezan NB, Robey HF, Salmonson JD, Suter LJ, Zimmerman GB, Edwards MJ, MacGowan BJ, Kilkenny JD, Lindl JD, Van Wonterghem BM, Atherton LJ, Moses EI, Glenzer SH, Landen OL. Direct measurement of energetic electrons coupling to an imploding low-adiabat inertial confinement fusion capsule. Phys Rev Lett 2012; 108:135006. [PMID: 22540711 DOI: 10.1103/physrevlett.108.135006] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/26/2011] [Indexed: 05/31/2023]
Abstract
We have imaged hard x-ray (>100 keV) bremsstrahlung emission from energetic electrons slowing in a plastic ablator shell during indirectly driven implosions at the National Ignition Facility. We measure 570 J in electrons with E>100 keV impinging on the fusion capsule under ignition drive conditions. This translates into an acceptable increase in the adiabat α, defined as the ratio of total deuterium-tritium fuel pressure to Fermi pressure, of 3.5%. The hard x-ray observables are consistent with detailed radiative-hydrodynamics simulations, including the sourcing and transport of these high energy electrons.
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Affiliation(s)
- T Döppner
- Lawrence Livermore National Laboratory, Livermore, California 94550, USA
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