Nuclear Fusion Reactions in Solid-Deuterium Laser-Produced Plasma

Floux, F.; Cognard, D.; Denoeud, L G.; Piar, G.; Parisot, D.; Bobin, J. L.; Delobeau, F.; Fauquignon, C.

doi:10.1103/physreva.1.821

Cited by 83 publications

(34 citation statements)

References 4 publications

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“…Conventional fast neutron sources include deuterium−deuterium (D−D) and deuteriumtritium (D−T) fusion generators, as well as light-ion, photoneutron and spallation sources. Laser plasma interactions in the relativistic regime can also generate charged particles and subsequently accelerate them to energies high enough to trigger nuclear fusion reactions, resulting in neutron production [4][5][6][7][8][9][10][11][12][13][14][15][16] . Recent advances in ultra-high power laser technology now enable tabletop scale systems, which may be further reduced in size for use as drivers for portable neutron generators in the future.…”

mentioning

confidence: 99%

High repetition-rate neutron generation by several-mJ, 35 fs pulses interacting with free-flowing D2O

Hah

Petrov

Nees

et al. 2016

Applied Physics Letters

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Using several-mJ energy pulses from a high-repetition rate ( 1 ⁄2 kHz), ultrashort (35 fs) pulsed laser interacting with a ∼ 10 µm diameter stream of free-flowing heavy water (D 2 O), we demonstrate a 2.45 MeV neutron flux of 10 5 /s. Operating at high intensity (of order 10 19 Wcm −2 ), laser pulse energy is efficiently absorbed in the pre-plasma, generating energetic deuterons. These collide with deuterium nuclei in both the bulk target and the large volume of low density D 2 O vapor surrounding the target to generate neutrons through d (d, n) 3 He reactions. The neutron flux, as measured by a calibrated neutron bubble detector, increased as the laser pulse energy was increased from 6 mJ to 12 mJ. A quantitative comparison between the measured flux and results derived from 2D particle-in-cell simulations show comparable neutron fluxes for similar laser characteristics to the experiment. The simulations reveal that there are two groups of deuterons; forward moving deuterons generate D−D fusion reactions in the D 2 O stream and act as a point source of neutrons, while backward moving deuterons propagate through the low-density D 2 O vapor filled chamber and yield a volumetric source of neutrons.Energetic neutrons have numerous applications in many fields, including medicine 1 , homeland security 2 , and material science 3 . Conventional fast neutron sources include deuterium−deuterium (D−D) and deuteriumtritium (D−T) fusion generators, as well as light-ion, photoneutron and spallation sources. Laser plasma interactions in the relativistic regime can also generate charged particles and subsequently accelerate them to energies high enough to trigger nuclear fusion reactions, resulting in neutron production [4][5][6][7][8][9][10][11][12][13][14][15][16] . Recent advances in ultra-high power laser technology now enable tabletop scale systems, which may be further reduced in size for use as drivers for portable neutron generators in the future. One of the methods for neutron production is through the acceleration of high-energy ions (keV-MeV) impinging upon an appropriate converter target, such as deuterated plastic. Typically, thin solid targets are used in these experiments to accelerate deuterons.Using solid targets in the form of a thin (1µm) foil has some drawbacks for high repetition-rate (>kHz) operation; for example, one has to replace the target after each shot. To resolve target life-time issues, fast target replacement schemes have been introduced by some groups 8,15,[17][18][19] . In particular, using ∼ 100 mJ of pulse energy at 10 Hz repetition-rate, Ditmire et. al. 8 used deuterium clusters, which were rapidly heated by the laser pulse (on a femtosecond time scale) and launched few a) Now at Physics Department, Lancaster University, UK keV deuterons to drive D−D fusion reactions.In this Letter, we report the production of neutrons using a high repetition-rate ( 1 ⁄2 kHz) femtosecond laser at high intensities (> 10 19 Wcm −2 for vacuum focus) but low pulse energies (several-mJ) interacting with a heavy...

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confidence: 99%

High repetition-rate neutron generation by several-mJ, 35 fs pulses interacting with free-flowing D2O

Hah

Petrov

Nees

et al. 2016

Applied Physics Letters

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“…They found "a somewhat higher rate of neutron production," meaning one to three neutrons per shot. Significantly, greater neutron counts were reported in 1970 by Floux et al 69 at Limeil. They irradiated cryogenic D 2 targets using slightly larger energies (30-50 J) and substantially longer laser pulses (of $10-ns duration), at focused intensities of a few times 10 13 W/cm 2 .…”

Section: A the Quest For Neutronsmentioning

confidence: 66%

Direct-drive inertial confinement fusion: A review

et al. 2015

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The direct-drive, laser-based approach to inertial confinement fusion (ICF) is reviewed from its inception following the demonstration of the first laser to its implementation on the present generation of high-power lasers. The review focuses on the evolution of scientific understanding gained from target-physics experiments in many areas, identifying problems that were demonstrated and the solutions implemented. The review starts with the basic understanding of laser–plasma interactions that was obtained before the declassification of laser-induced compression in the early 1970s and continues with the compression experiments using infrared lasers in the late 1970s that produced thermonuclear neutrons. The problem of suprathermal electrons and the target preheat that they caused, associated with the infrared laser wavelength, led to lasers being built after 1980 to operate at shorter wavelengths, especially 0.35 μm—the third harmonic of the Nd:glass laser—and 0.248 μm (the KrF gas laser). The main physics areas relevant to direct drive are reviewed. The primary absorption mechanism at short wavelengths is classical inverse bremsstrahlung. Nonuniformities imprinted on the target by laser irradiation have been addressed by the development of a number of beam-smoothing techniques and imprint-mitigation strategies. The effects of hydrodynamic instabilities are mitigated by a combination of imprint reduction and target designs that minimize the instability growth rates. Several coronal plasma physics processes are reviewed. The two-plasmon–decay instability, stimulated Brillouin scattering (together with cross-beam energy transfer), and (possibly) stimulated Raman scattering are identified as potential concerns, placing constraints on the laser intensities used in target designs, while other processes (self-focusing and filamentation, the parametric decay instability, and magnetic fields), once considered important, are now of lesser concern for mainline direct-drive target concepts. Filamentation is largely suppressed by beam smoothing. Thermal transport modeling, important to the interpretation of experiments and to target design, has been found to be nonlocal in nature. Advances in shock timing and equation-of-state measurements relevant to direct-drive ICF are reported. Room-temperature implosions have provided an increased understanding of the importance of stability and uniformity. The evolution of cryogenic implosion capabilities, leading to an extensive series carried out on the 60-beam OMEGA laser [Boehly et al., Opt. Commun. 133, 495 (1997)], is reviewed together with major advances in cryogenic target formation. A polar-drive concept has been developed that will enable direct-drive–ignition experiments to be performed on the National Ignition Facility [Haynam et al., Appl. Opt. 46(16), 3276 (2007)]. The advantages offered by the alternative approaches of fast ignition and shock ignition and the issues associated with these concepts are described. The lessons learned from target-physics and implosion experiments are taken into account in ignition and high-gain target designs for laser wavelengths of 1/3 μm and 1/4 μm. Substantial advances in direct-drive inertial fusion reactor concepts are reviewed. Overall, the progress in scientific understanding over the past five decades has been enormous, to the point that inertial fusion energy using direct drive shows significant promise as a future environmentally attractive energy source.

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“…Also, the fusion rate will depend drastically on the initial states polarizations. Back in 1970, a French group of the CEA reported the observation of neutron emission from DD fusion after focusing a 3GW fast laser on a piece of D 2 ice [5]. More recently, quantitative data resulting from the irradiation of C 2 D 4 targets with laser pulses (200 mJ, 160 fs, 4.5 m FWHM, 790 nm, ∼10 18 W/cm 2 , 10 Hz) have been published.…”

Section: Tentative Setupmentioning

confidence: 99%

Polarization: A must for fusion

Didélez

Deutsch

2013

EPJ Web of Conferences

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Abstract. The complete polarization of DT fuel would increase the fusion reactivity by 50% in magnetic as well as in inertial confinements. The persistence of polarization in a fusion process could be tested, using a terawatt laser hitting a polarized HD target. The polarized deuterons heated in the plasma induced by the laser can fuse producing a 3 H e and a neutron in the final state. The angular distribution of the emitted neutrons and the change in the corresponding total Cross Section (CS) can sign the polarization persistence. The polarization of solid H 2 , D 2 or T 2 Hydrogen isotopes is very difficult. However, it has been possible to polarize HD, a hetero-molecular form of Hydrogen, by static polarization, at very low temperature and very high field. The radioactivity of DT molecules forbids there high polarization by the static method, therefore one has to develop the Dynamic Nuclear Polarization (DNP) by RF transitions. The DNP of HD has been investigated in the past. The magnetic properties of HD and DT molecules are very similar, it is therefore expected that any polarization result obtained with HD could be extrapolated to DT.

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Nuclear Fusion Reactions in Solid-Deuterium Laser-Produced Plasma

Cited by 83 publications

References 4 publications

High repetition-rate neutron generation by several-mJ, 35 fs pulses interacting with free-flowing D2O

High repetition-rate neutron generation by several-mJ, 35 fs pulses interacting with free-flowing D2O

Direct-drive inertial confinement fusion: A review

Polarization: A must for fusion

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