Hollow wall to stabilize and enhance ignition hohlraums

Vandenboomgaerde, M.; Grisollet, A.; Bonnefille, Max; Clérouin, Jean; Arnault, Philippe; Desbiens, Nicolas; Videau, L.

doi:10.1063/1.5008669

Cited by 8 publications

(6 citation statements)

References 23 publications

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“…For longer pulses, measures may need to be taken to avoid excessive hohlraum fill that could affect deposition of laser energy, particularly with the inner set of beams that could suffer from cross-beam-energy-transfer early in the pulse [27]. Novel hohlraum designs that aim to reduce laser hotspot motion [28] could be applied to mid-Z liners in order to counteract the increased wall motion that results from the lower-density liner. Also, the liner heating losses could be mitigated further by selectively lining only the surface of the hohlraum where the lasers are incident, thus allowing the X-rays to be incident on the high albedo Au rather than to having to first burn through the layer of Cu.…”

Section: Discussionmentioning

confidence: 99%

Investigation of the performance of mid-Z Hohlraum wall liners for producing x-ray drive

2021

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M-band transitions (n = 4 → 3) in Gold are responsible for a population of X-rays with energy > 1.8 keV in indirect drive inertial fusion. These X-rays can preheat the fuel, cause the ablatorfuel interface to become unstable to Rayleigh-Taylor instabilities, and introduce radiation nonuniformity to the X-ray drive. This work investigates the performance of mid-Z lined hohlraums for producing an efficient drive spectrum absent of M-band X-rays using the two-dimensional lagrangian radiation hydrodynamics code h2d. The removal of the M-band transitions is observed in the Culined hohlraum reducing the total X-ray energy above 1.8 keV to 58% that of the un-lined hohlraum. Total radiation energy in the Cu-lined hohlraum is 93% that of the energy in the pure Au hohlraum for a 1 ns pulse. However, the soft X-ray drive energy (below 1.8 keV) for the lined hohlraum is 98% that of the pure Au hohlraum.

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Section: Discussionmentioning

confidence: 99%

Investigation of the performance of mid-Z Hohlraum wall liners for producing x-ray drive

2021

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“…By coupling, we mean the non-negligible effect of the Coulomb interactions between the ions. A convenient measure of correlation in one-component plasma is The colour map shows the electronic density ranging from 10 19 for green (light grey) to 10 23 electrons/cm 3 for red (dark grey) (for more details see [13]).…”

Section: Introductionmentioning

confidence: 99%

“…An example of the different ICF mixing layers occurring in an indirect drive experiment (taken from [13]) is shown in Fig. 1.…”

Section: Introductionmentioning

confidence: 99%

“…By coupling, we mean the non-negligible effect of the Coulomb interactions between the ions. A convenient measure of correlation in one-component plasma is for red (dark grey) (for more details see [13]).…”

Section: Introductionmentioning

confidence: 99%

“…(Color online) Sketch of an ICF target showing the different elements: the DT fuel surrounded by the CH ablator, the filling gas made of He and the gold wall, during the compression process. The colour map shows the electronic density ranging from 10 19 for green (light grey) to 10 23 electrons/cm 3for red (dark grey) (for more details see[13]).…”

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confidence: 99%

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Static and dynamic properties of multi-ionic plasma mixtures

et al. 2020

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Complex plasma mixtures with three or more components are often encountered in astrophysics or in inertial confinement fusion (ICF) experiments. For mixtures containing species with large differences in atomic number Z, the modeling needs to consider at the same time the kinetic theory for low-Z elements combined with the theory of strongly coupled plasma for high-Z elements, as well as all the intermediate situations that can appear in multi-component systems. For such cases, we study the pair distribution functions, self-diffusions, mutual diffusion and viscosity for ternary mixtures at extreme conditions. These quantities can be produced from first principles using orbital free molecular dynamics at the computational expense of very intensive simulations to reach good statistics. Utilizing the first-principles results as reference data, we assess the merit of a global analytic model for transport coefficients, "Pseudo-Ions in Jellium" (PIJ), based on an iso-electronic assumption ( iso-ne). With a multi-component hypernetted-chain integral equation, we verify the quality of the iso-ne prescription for describing the static structure of the mixtures. This semi-analytical modeling compares well with the simulation results and allows one to consider plasma mixtures not accessible to simulations. Applications are given for the mix of materials in ICF experiments. A reduction of a multicomponent mixture to an effective binary mixture is also established in the hydrodynamic limit and compared with PIJ estimations for ICF relevant mixtures.

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Experimental investigation of size broadening of a Kα x-ray source produced by high intensity laser pulses

Gambari

Clady

Videau

et al. 2021

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The size of a hard Kα x-ray source ($${\mathrm{E}}_{{\rm{K}}_{\rm{\alpha }}}$$ E K α = 17.48 keV) produced by a high intensity femtosecond laser interacting with a solid molybdenum target is experimentally investigated for a wide range of laser intensity (I ~ 1017–2.8 × 1019 W/cm2) and for four values of the temporal contrast ratio (6.7 × 107 < CR < 3.3 × 1010). Results point out the size enlargement of the x-ray source with the increase of laser intensity and with the deterioration of temporal contrast. It amounts up to sixteen times the laser spot size at the highest laser intensity and for the lowest temporal contrast ratio. Using hydrodynamic simulations, we evaluate the density scale length of the pre-plasma L/λ just before the main pulse peak. This allows us to show that a direct correlation with the laser absorption mechanisms is not relevant to explain the large size broadening. By varying the thickness of the molybdenum target down to 4 µm, the impact of hot electron scattering inside the solid is also proved irrelevant to explain the evolution of both the x-ray source size and the Kα photon number. We deduce that the most probable mechanism yielding to the broadening of the source size is linked to the creation of surface electromagnetic fields which confine the hot electrons at the solid surface. This assumption is supported by dedicated experiments where the evolution of the size enlargement of the x-ray source is carefully studied as a function of the laser focal spot size for the highest contrast ratio.

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Hollow wall to stabilize and enhance ignition hohlraums

Cited by 8 publications

References 23 publications

Investigation of the performance of mid-Z Hohlraum wall liners for producing x-ray drive

Investigation of the performance of mid-Z Hohlraum wall liners for producing x-ray drive

Static and dynamic properties of multi-ionic plasma mixtures

Experimental investigation of size broadening of a Kα x-ray source produced by high intensity laser pulses

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