Studies on shock ignition targets for inertial fusion energy

Atzeni, S.; Schiavi, A.; Marocchino, A.; Giannini, Anna Maria; Mancini, Andrea; Temporal, M.

doi:10.1051/epjconf/20135901005

Cited by 5 publications

(5 citation statements)

References 19 publications

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“…High-resolution simulations including modes from 2 to 256 induced by nominal (expected) target surface perturbations and laser imprint [43] have shown that the final low-mode asymmetries can be large enough to quench ignition. Asymmetries of this level, just large enough to prevent ignition, can be remedied by increasing the ignitor spike power [43,88,95]. The stronger shock then provides enough hot spot energy to ignite the target, although the gain drops.…”

Section: Two-dimensional Effects: Short-wavelength (High-mode) Instab...mentioning

confidence: 99%

Shock ignition of thermonuclear fuel: principles and modelling

et al. 2014

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Shock ignition is an approach to direct-drive inertial confinement fusion (ICF) in which the stages of compression and hot spot formation are partly separated. The fuel is first imploded at a lower velocity than in conventional ICF. Close to stagnation, an intense laser spike drives a strong converging shock, which contributes to hot spot formation. Shock ignition shows potentials for high gain at laser energies below 1 MJ, and could be tested on the National Ignition Facility or Laser MegaJoule. Shock ignition principles and modelling are reviewed in this paper. Target designs and computer-generated gain curves are presented and discussed. Limitations of present studies and research needs are outlined.

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Section: Two-dimensional Effects: Short-wavelength (High-mode) Instab...mentioning

confidence: 99%

Shock ignition of thermonuclear fuel: principles and modelling

et al. 2014

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“…This makes them sensitive to long-scale asymmetries, resulting, e.g. from target mispositioning, as was shown in [14,31]. Sensitivity to mispositioning (and presumably to other sources of longscale perturbations) depend on target safety factors, as will be discussed in section 6.…”

Section: Target Designmentioning

confidence: 91%

“…Sensitivity to mispositioning (and presumably to other sources of longscale perturbations) depend on target safety factors, as will be discussed in section 6. Instead, fluid simulations (either with flux-limited electron thermal conductivity [13,14,31] or with non-local electron transport [50]) indicate that large spike asymmetries are tolerated, probably due to thermal smoothing in the rather thick thermal conduction layer between the critical radius and ablation front at the time of spike irradiation. According to the above studies, SI can achieve high gain at a laser energy and power achievable on the operating NIF facility [5] and on the LMJ facility [10], currently under construction.…”

Section: Target Designmentioning

confidence: 99%

“…We refer again to the HiPER target. Although very simple and probably unrealistic, this has been analyzed in-depth [13,14,19,29,31,49] and serves well as a propotype to understand trends. In figure 5 we show how the ITF* varies with the implosion velocity and spike power (The implosion velocity is varied by changing the peak power of the compression pulse; the duration of the peak flat-top is also adjusted to match the duration of the implosion.…”

Section: Increasing Itf* Of Si Designsmentioning

confidence: 99%

“…Here, as a first approach to the problem, we are studying a single effect, namely the displacement of the target center with respect to the center of the laser beams. We consider the simplified set up used in previous studies performed in the frame of the HiPER collaboration [13,14,31,50]. We assume radial laser rays and also neglect refraction.…”

Section: D Simulations: Sensitivity To Large-scale Asymmetries Versus...mentioning

confidence: 99%

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Shock ignition: a brief overview and progress in the design of robust targets

Atzeni¹,

Marocchino²,

Schiavi³

2014

Plasma Phys. Control. Fusion

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Shock ignition is a laser direct-drive inertial confinement fusion (ICF) scheme in which the stages of compression and hot spot formation are partly separated. The fuel is first imploded at a lower velocity than in conventional ICF, reducing the threats due to Rayleigh-Taylor instability. Close to stagnation, an intense laser spike drives a strong converging shock, which contributes to hot spot formation. This paper starts with a brief overview of the theoretical studies, target design and experimental results on shock ignition. The second part of the paper illustrates original work aiming at the design of robust targets and computation of the relevant gain curves. Following Chang et al (2010 Phys. Rev. Lett. 104 135002) a safety factor for high gain, ITF* (analogous to the ignition threshold factor ITF introduced by Clark et al (2008 Phys. Plasmas 15 056305)), is evaluated by means of parametric 1D simulations with artificially reduced reactivity. SI designs scaled as in Atzeni et al (2013 New J. Phys.15 045004) are found to have nearly the same ITF*. For a given target, such ITF* increases with implosion velocity and laser spike power. A gain curve with a prescribed ITF* can then be simply generated by upscaling a reference target with that value of ITF*. An interesting option is scaling in size by reducing the implosion velocity to keep the ratio of implosion velocity to self-ignition velocity constant. At a given total laser energy, targets with higher ITF* are driven to higher implosion velocity and achieve a somewhat lower gain. However, a 1D gain higher than 100 is achieved at an (incident) energy below 1 MJ, an implosion velocity below 300 km s −1 and a peak incident power below 400 TW. 2D simulations of mispositioned targets show that targets with a higher ITF* indeed tolerate larger displacements.

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The feasibility study of ion driven shock ignition of reactor-size targets in inertial confinement fusion

2018

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In this paper, we are intending to investigate the shock ignition approach to inertial confinement fusion (ICF) by using an ion beam driver to examine energy gain performance in reactor-size targets filled by cryogenic deuterium-tritium hydrogen isotopes. Here, pressure dynamics across the fuel layer affected by ignition beam parameters have been analyzed by using the DEIRA-4 simulation code, for the two targets that we chose for the case study. By choosing the proper pulse shaping and evaluation of finding the appropriate time and position of the inter-collision time between two compression and ignition pulses, it has been found that shock ignition can create the pressure more than 104 Gbar at the fuel center and therefore increase gain by 18% and 25% for Case 1 and Case 2, respectively. Ionic shock ignition can also decrease the ignition threshold; hence, it causes 19% reduction for Case 1 and 39% reduction for Case 2 of the internal beam energy. It has been shown that besides the lower implosion velocities relative to traditional central ignition, which are now maintained, the fuel pressure at stagnation becomes much higher than it is. In addition, the stable stagnation stage, ignition condition, and high-energy gain are achieved when the optimum configuration of the ignition beam has been derived. Our results show that we can attain pressures level of 200 Gbar < P < 500 Gbar and implosion velocities of 170 km s−1 < Uimp < 291 km s−1 which are in agreement with laser-driven shock ignition alternatives. The pressure range is more than the Standard ICF, laser-driven shock ignition, and impact fast ignition (IFI), and the implosion velocity range is less than Standard ICF and IFI.

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Studies on shock ignition targets for inertial fusion energy

Cited by 5 publications

References 19 publications

Shock ignition of thermonuclear fuel: principles and modelling

Shock ignition of thermonuclear fuel: principles and modelling

Shock ignition: a brief overview and progress in the design of robust targets

The feasibility study of ion driven shock ignition of reactor-size targets in inertial confinement fusion

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