Burning plasmas with ultrashort soft-x-ray flashing

Hu, S. X.; Goncharov, V. N.; Skupsky, S.

doi:10.1063/1.4737157

“…The formula is subsequently modified to the widely used form of E ig = 140 ( ρ 100 g cm −3 ) − 1.85 kJ by 2D simulations and the ignition window in the energy, power and intensity space is discussed [19]. Recent studies claim the ignition energy can be as low as 1 kJ when ρr h ≈ 0.36 g cm −2 , T ≈ 20 keV, ρ ⩾ 700 g cm −2 with non-thermal soft x-rays as the heating source [20,21]. Most previous studies on the isochoric fast ignition model assumed hot spots in the spherical center of the fuel.…”

Section: Introductionmentioning

confidence: 99%

Formation of hot spots at end-on pre-compressed isochoric fuels for fast ignition

Xu,

Wu,

Jiang

et al. 2023

Nucl. Fusion

3

0

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It is crucial to form a hot spot that can drive a self-heating nuclear burn propagation into the surrounding cold fuel in ignition process of laser fusion. In this paper, we discuss the formation of a hemispherical hot spot located at the edge of an end-on precompressed isochoric fuel instead of a central spherical hot spot surrounded by cold fuel in a corona plasma shell. This configuration leads to a new energy loss mechanism named hot spot collapse, which originates from mass loss of the hot spot through the interface with the vacuum. A semi-analytical model is proposed including α particle induced burning, hot spot collapse and other energy loss processes. Then a modified ignition criterion is derived. The results show that the competition between the hot spot collapse and the burn propagation is crucial in the formation of the hot spot. The formation of such a hot spot at end-on precompressed isochoric fuels would require a somewhat higher initial temperature of T h = 9 keV for a hot spot with an initial areal density ρ d = 0.6 g c m − 2 . Simulations are performed with a 3D hybrid particle-in-cell/fluid code for the heating process by fast electrons and a 3D radiation hydrodynamics code for the burning process. Simulation results agree with the model. Our optimized result shows a 10 ps heating laser pulse with an energy as low as 39 kJ can lead to a fast ignition in the ideal case. This study provides an effective reference for design and evaluation of experiments planned for fast ignition schemes.

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“…A properly assembled core with an extremely high pressure (>100-300 Gbar) makes it possible to produce not only sufficient a particles from DT fusions but also to "bootstrap" the heat (a-particle stopping) in the hot spot. 7 If this occurs, a fusion burn wave could quickly propagate through the dense shell 8 and net energy gain is expected.…”

Section: Introductionmentioning

confidence: 99%

Impact of first-principles properties of deuterium–tritium on inertial confinement fusion target designs

Hu

¹

,

Goncharov

²

,

Boehly

³

et al. 2015

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A comprehensive knowledge of the properties of high-energy-density plasmas is crucial to understanding and designing low-adiabat, inertial confinement fusion (ICF) implosions through hydrodynamic simulations. Warm-dense-matter (WDM) conditions are routinely accessed by low-adiabat ICF implosions, in which strong coupling and electron degeneracy often play an important role in determining the properties of warm dense plasmas. The WDM properties of deuterium–tritium (DT) mixtures and ablator materials, such as the equation of state, thermal conductivity, opacity, and stopping power, were usually estimated by models in hydro-codes used for ICF simulations. In these models, many-body and quantum effects were only approximately taken into account in the WMD regime. Moreover, the self-consistency among these models was often missing. To examine the accuracy of these models, we have systematically calculated the static, transport, and optical properties of warm dense DT plasmas, using first-principles (FP) methods over a wide range of densities and temperatures that cover the ICF “path” to ignition. These FP methods include the path-integral Monte Carlo (PIMC) and quantum-molecular dynamics (QMD) simulations, which treat electrons with many-body quantum theory. The first-principles equation-of-state table, thermal conductivities (κQMD), and first principles opacity table of DT have been self-consistently derived from the combined PIMC and QMD calculations. They have been compared with the typical models, and their effects to ICF simulations have been separately examined in previous publications. In this paper, we focus on their combined effects to ICF implosions through hydro-simulations using these FP-based properties of DT in comparison with the usual model simulations. We found that the predictions of ICF neutron yield could change by up to a factor of ∼2.5; the lower the adiabat of DT capsules, the more variations in hydro-simulations. The FP-based properties of DT are essential for designing ICF ignition targets. Future work on first-principles studies of ICF ablator materials is also discussed.

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Ignition criteria for x-ray fast ignition inertial confinement fusion

Lee

¹

,

Robinson

²

,

Pasley

³

2020

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The derivation of the ignition energy for fast ignition inertial confinement fusion is reviewed and one-dimensional simulations are used to produce a revised formula for the ignition energy of an isochoric central hot-spot, which accounts for variation in the radius of the hot-spot rh as well as the density ρ. The required energy may be as low as 1 kJ when ρrh≈0.36 g cm−2, T≈20 keV, and ρ≥700 g cm−2. Although there are many physical challenges to creating these conditions, a possible route to producing such a hot-spot is via a bright source of non-thermal soft x-rays. Further one-dimensional simulations are used to study the non-thermal soft x-ray heating of dense DT and it is found to offer the potential to significantly reduce hydrodynamic losses as compared to particle driven fast ignition due to the hotspot being heated supersonically in a layer-by-layer fashion. A sufficiently powerful soft x-ray source would be difficult to produce, but line emission from laser-produced-plasma is the most promising option.

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Burning plasmas with ultrashort soft-x-ray flashing

Cited by 6 publications

References 48 publications

Formation of hot spots at end-on pre-compressed isochoric fuels for fast ignition

Formation of hot spots at end-on pre-compressed isochoric fuels for fast ignition

Impact of first-principles properties of deuterium–tritium on inertial confinement fusion target designs

Ignition criteria for x-ray fast ignition inertial confinement fusion

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