Development of the CD Symcap platform to study gas-shell mix in implosions at the National Ignition Facility

Casey, D. T.; Smalyuk, V. A.; Tipton, Robert; Pino, Jesse; Grim, G.; Remington, B. A.; Rowley, D.; Weber, S. V.; Barrios, M. A.; Benedetti, L. R.; Bleuel, D. L.; Bond, E.; Bradley, D. K.; Caggiano, J. A.; Callahan, D. A.; Cerjan, C.; Chen, K. C.; Edgell, D. H.; Edwards, M. J.; Fittinghoff, D. N.; Frenje, J. A.; Johnson, M. Gatu; Glebov, V. Yu.; Glenn, S.; Guler, N.; Haan, S. W.; Hamza, A. V.; Hatarik, R.; Herrmann, H. W.; Hoover, D.; Hsing, W. W.; Izumi, N.; Kervin, P.; Khan, S. F.; Kilkenny, J. D.; Kline, J. L.; Knauer, J. P.; Kyrala, G. A.; Landen, O. L.; Ma, T.; MacPhee, A. G.; McNaney, J. M.; Mintz, M.; Moore, A. S.; Nikroo, A.; Pak, A.; Parham, T.; Petrasso, R. D.; Rinderknecht, H. G.; Sayre, D. B.; Schneider, M. B.; Stoeffl, W.; Tommasini, R.; Town, R. P. J.; Widmann, K.; Wilson, D. C.; Yeamans, C. B.

doi:10.1063/1.4894215

Cited by 46 publications

(16 citation statements)

References 66 publications

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“…This work is inspired by the idea of universal transport properties [51][52][53]. We have found that rescaling the viscosity asη = ηρ 1/5 /T 5/2 (6) works well if we fitη to a function exp[ax + bx 2 ] where x = ln[ρ/T 3 ]. In Eq.…”

Section: A Viscositymentioning

confidence: 99%

“…Invariably the ablator, the plastic shell holding the nuclear fuel, mixes with the fuel when imploded, changing the material properties and reducing the yield [4]. Recent studies have been designed to directly study this intriguing mixing process [5,6]. More generally, HED mixtures are found throughout astrophysics, examples range from interiors of planets [7] to white dwarfs [8].…”

Section: Introductionmentioning

confidence: 99%

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Transport properties and equation of state for HCNO mixtures in and beyond the warm dense matter regime

2015

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We present simulations of a four-component mixture of HCNO with orbital free molecular dynamics (OFMD). These simulations were conducted for 5-200 eV with densities ranging between 0.184 and 36.8 g/cm3. We extract the equation of state from the simulations and compare to average atom models. We found that we only need to add a cold curve model to find excellent agreement. Additionally, we studied mass transport properties. We present fits to the self-diffusion and shear viscosity that are able to reproduce the transport properties over the parameter range studied. We compare these OFMD results to models based on the Coulomb coupling parameter and one-component plasmas.

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Section: A Viscositymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Transport properties and equation of state for HCNO mixtures in and beyond the warm dense matter regime

2015

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“…MRS routinely measures the neutron spectrum from cryogenically layered DT target implosions [73], from which DT yield, areal density (ρR) and ion temperature are determined (ρR is inferred from the ratio of down-scattered neutrons (10-12 MeV) to primary neutrons (13-15 MeV)). MRS also measures directional flow velocities [74], neutron yields from the T+T reaction [76] and CH ablator areal density in symmetry-capsule implosions with low DT fuel-ρR [75]. MRS is ab initio calibrated and is one of only two independent ways of measuring absolute DT yields on the NIF; the other one is the NAD technique (described later in this section).…”

Section: Magnetic Recoil Spectrometer (Mrs)mentioning

confidence: 99%

“…A new study of the neutron spectrum from low energy T(T, 2n)α reactions utilizing T-filled fusion targets at the NIF has been reported [136]. The spectrum provides information about interactions among final-state particles and the T(T, 2n)α yield, which is important in ICF experiments studying hydrodynamic mix [137].…”

Section: The 3 H(t 2n) 4 He Reaction Analysismentioning

confidence: 99%

Dynamic high energy density plasma environments at the National Ignition Facility for nuclear science research

Cerjan

Bernstein

Hopkins

et al. 2018

J. Phys. G: Nucl. Part. Phys.

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The generation of dynamic high energy density plasmas in the pico-to nanosecond time domain at high-energy laser facilities affords unprecedented nuclear science research possibilities. At the National Ignition Facility (NIF), the primary goal of inertial confinement fusion research has led to the synergistic development of a unique high brightness neutron source, sophisticated nuclear diagnostic instrumentation, and versatile experimental platforms. These novel experimental capabilities provide a new path to investigate nuclear processes and structural effects in the time, mass and energy density domains relevant to astrophysical phenomena in a unique terrestrial environment. Some immediate applications include neutron capture cross-section evaluation, fission fragment production, and ion energy loss measurement in

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“…These implosions, driven with the NIC four-shock low-foot pulse shape at 420 TW, 1.9 MJ, continued to show unacceptable levels of mix despite the thicker ablator. The more recent results we present here use the high-foot drive, giving higher initial radiation temperature in the "foot" of the pulse, placing the implosion on a higher DT fuel adiabat (∼2-2.5) and thereby increasing both ablation rates and density gradient scale lengths of the shell [11,12]. Using this pulse shape, targets identical to the nominal NIC Rev.…”

mentioning

confidence: 99%

Thin Shell, High Velocity Inertial Confinement Fusion Implosions on the National Ignition Facility

Ma¹,

Hurricane²,

Callahan³

et al. 2015

Phys. Rev. Lett.

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Experiments have recently been conducted at the National Ignition Facility utilizing inertial confinement fusion capsule ablators that are 175 and 165 μm in thickness, 10% and 15% thinner, respectively, than the nominal thickness capsule used throughout the high foot and most of the National Ignition Campaign. These three-shock, high-adiabat, high-foot implosions have demonstrated good performance, with higher velocity and better symmetry control at lower laser powers and energies than their nominal thickness ablator counterparts. Little to no hydrodynamic mix into the DT hot spot has been observed despite the higher velocities and reduced depth for possible instability feedthrough. Early results have shown good repeatability, with up to 1=2 the neutron yield coming from α-particle self-heating. DOI: 10.1103/PhysRevLett.114.145004 PACS numbers: 52.57.Fg In the quest to achieve ignition through the inertial confinement fusion scheme [1], one of the critical challenges is to drive a symmetric implosion at high velocities without hydrodynamic instabilities becoming detrimental. At the National Ignition Facility (NIF) [2,3], the indirectdrive approach is being pursued, where laser energy is incident on the inner wall of a high-Z hohlraum to generate a high flux of soft x rays which then ablatively drives the implosion of a spherical capsule. In a rocketlike momentum conservation reaction, as the ablator material absorbs the x rays and explodes outward, the shell and fuel layer are accelerated inward. In order to achieve thermonuclear burn, the fuel must reach a peak velocity of V fuel ≥ 350 km=s in order to assemble a hot spot of sufficient temperature (> 4 keV) with a hot spot areal density of ρR > 0.3 g=cm 2 and DT fuel with ρR > 1 g=cm 2 [4].An efficient acceleration of the shell is a tradeoff between minimum remaining unablated mass (i.e., ablation pressure can do its work on the least amount of payload mass) while protecting the fuel and hot spot from feedthrough of instabilities that grow at the ablation front and penetrate in. Because shell velocity scales with laser energy, and inversely with ablator mass, ablator thickness can be traded for laser energy. Here we report on experiments building on the high-adiabat, high-foot implosions described in Refs. [5][6][7], but now using 10% and 15% thinner ablators to achieve similar velocities with less laser energy and power. These experiments have demonstrated improved shape control, good repeatability, and performance scaling with laser power and energy. Crucially, little to no mix of ablator material into the hot spot has been observed, despite the higher velocities. These thinner ablator implosions have also shown significant α-particle deposition leading to considerable self-heating.Previous work during the National Ignition Campaign (NIC) had shown that instabilities seeded at the ablation front were a significant source of mix into the hot spot on the highest velocity NIC shots [8]. Backlit measurements of the shell as it converged [9] showed a lower-tha...

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Development of the CD Symcap platform to study gas-shell mix in implosions at the National Ignition Facility

Cited by 46 publications

References 66 publications

Transport properties and equation of state for HCNO mixtures in and beyond the warm dense matter regime

Transport properties and equation of state for HCNO mixtures in and beyond the warm dense matter regime

Dynamic high energy density plasma environments at the National Ignition Facility for nuclear science research

Thin Shell, High Velocity Inertial Confinement Fusion Implosions on the National Ignition Facility

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