On the scaling of the energy gain of ICF targets

Basko, M. M.

doi:10.1088/0029-5515/35/1/i07

Cited by 21 publications

(20 citation statements)

References 17 publications

(10 reference statements)

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“…In Ref. [7] it was estimated analytically (but for a different pressure profile) that ρrT s,ig ∝ v im ξ s .…”

Section: Dynamic Assembled State Scalingmentioning

confidence: 99%

“…It was found that in all cases there was a clear optimum with respect to ξ s at ξ s = 0.55-0.57. The ignition threshold ρrT s,ig is insensitive to α variations, but does increase with the implosion velocity (due to the reduction of the tamping effect by the cold fuel [7]), although somewhat weaker than in direct proportion to v im . As a result, we obtained the following assembled state scaling law:…”

Section: Dynamic Assembled State Scalingmentioning

confidence: 99%

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Ignition energy scaling of inertial confinement fusion targets

Basko

Johner

1998

Nucl. Fusion

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ABSTRACT. Scaling of the ignition energy threshold Eig with the implosion velocity vim and isentrope parameter α of imploding spherical DT shells is investigated by performing one dimensional (1-D) hydrodynamic simulations of the implosion and hot spot formation dynamics. It is found that the a and b exponents in the power law approximation Eig ∝ α a v −b im depend crucially on the subset of initial configurations chosen to establish the scaling law. When the initial states are generated in the same way as in the Livermore study (W.K. Levedahl, J.D. Lindl, Nucl. Fusion 37 (1997) 165), the same scaling, Eig ∝ α 1.7 v −5.5 im , is recovered. If, however, the initial states are generated by rescaling the parent configuration according to the hydrodynamic similarity laws, a different scaling is obtained, Eig ∝ α 3.0 v −9.1 im , which is very close to the α 3 v −10 im dependence predicted by the simple isobaric model for assembled fuel states. The latter is more favourable than the Livermore scaling when rescaling the fusion capsules to higher implosion velocities, but requires the peak drive pressure to be increased as P ∝ v 5 im .

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“…In Ref. [7] it was estimated analytically (but for a different pressure profile) that ρrT s,ig ∝ v im ξ s .…”

Section: Dynamic Assembled State Scalingmentioning

confidence: 99%

Section: Dynamic Assembled State Scalingmentioning

confidence: 99%

Ignition energy scaling of inertial confinement fusion targets

Basko

Johner

1998

Nucl. Fusion

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“…IV, must first be accounted for. From the previous work on capsule ignition energy [3][4][5][6][7], it is known that the minimum ignition energy (and hence also the ignition margin) is a very strong function of the fuel entropy or adiabat. Ideally, then, if a power law fit is to be found for the margin as a function of the scale, velocity, and perturbation fraction, the entropy should be held constant across the various scales, velocities, and perturbation fractions.…”

Section: Data Base Results and Scaling Lawsmentioning

confidence: 99%

“…In principle, these 1-D variations in the entropy may be compensated for in the 2-D data set using the scalings of the minimum ignition energy found in 1-D [3][4][5][6][7]. That is, since Eq.…”

Section: Data Base Results and Scaling Lawsmentioning

confidence: 99%

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Robustness studies of ignition targets for the National Ignition Facility in two dimensions

2008

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Inertial confinement fusion capsules are critically dependent on the integrity of their hot spots to ignite. At the time of ignition, only a certain fractional perturbation of the nominally spherical hot spot boundary can be tolerated and the capsule still achieve ignition. The degree to which the expected hot spot perturbation in any given capsule design is less than this maximum tolerable perturbation is a measure of the ignition margin or robustness of that design. Moreover, since there will inevitably be uncertainties in the initial character and implosion dynamics of any given capsule, all of which can contribute to the eventual hot spot perturbation, quantifying the robustness of that capsule against a range of parameter variations is an important consideration in the capsule design. Here, the robustness of the 300eV indirect drive target design for the National Ignition Facility [Lindl et al., Phys. Plasmas 11, 339 (2004)] is studied in the parameter space of inner ice roughness, implosion velocity, and capsule scale. A suite of 2000 two-dimensional simulations, run with the radiation hydrodynamics code LASNEX, is used as the data base for the study. For each scale, an ignition region in the two remaining variables is identified and the ignition cliff is mapped. In accordance with the theoretical arguments of Levedahl and Lindl [Nucl. Fusion 37, 165 (1997)] and Kishony and Shvarts [Phys. Plasmas 8, 4925 (2001)], the location of this cliff is fitted to a power law of the capsule implosion velocity and scale. It is found that the cliff can be quite well represented in this power law form, and, using this scaling law, an assessment of the overall (one- and two-dimensional) ignition margin of the design can be made. The effect on the ignition margin of an increase or decrease in the density of the target fill gas is also assessed.

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