Simulation of laser-driven, ablated plasma flows in collisionless shock experiments on OMEGA and the NIF

Grosskopf, M.J.; Drake, R. P.; Kuranz, Carolyn; Rutter, Erica M.; Ross, J. S.; Kugland, N. L.; Plechaty, C.; Remington, B. A.; Spitkovsky, Anatoly; Gargaté, L.; Gregori, G.; Bell, A. R.; Murphy, C. D.; Meinecke, J.; Reville, Brian; Sakawa, Y.; Kuramitsu, Yasuhiro; Takabe, H.; Froula, D. H.; Fiksel, G.; Miniati, Francesco; Kœnig, M.; Ravasio, A.; Liang, Edison; Fu, Weiqi; Woolsey, N. C.; Park, H.-S.

doi:10.1016/j.hedp.2012.11.004

Cited by 5 publications

(2 citation statements)

References 36 publications

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“…This was not the case with the plasma outflow driven by a single laser spot (zero separation, Figure 2). In collisionless shock experiments using twohead on colliding jets [12,11,10,4], Weibel instability is invoked to generate filamentary B-fields, to mediate the shock formation and dissipation processes if the colliding plasmas are unmagnetized. However, if the colliding jets are already magnetized with perpendicular fields up to ∼ 20 kG, the shocks will behave very differently from pure Weibel shocks.…”

Section: Discussionmentioning

confidence: 99%

“…The increased density, temperature and velocity provide a more versatile platform for a variety of laboratory astrophysics experiments [12,11,10,4] with larger dynamic range. In this paper we investigate the effects of the ring pattern laser configuration on magnetic field generation, using a new version of the FLASH code, which includes the Biermann Battery (BB) or (∇P e × ∇n e ) term [1,5] for magnetic field creation, where P e and n e are electron pressure and density, respectively.…”

Section: Introductionmentioning

confidence: 99%

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Creation of magnetized jet using a ring of laser beams

Liang

Tzeferacos

et al. 2015

High Energy Density Physics

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We propose a new way of generating magnetized supersonic jets using a ring laser to irradiate a flat surface target. Using 2D FLASH code simulations which include the Biermann Battery term, we demonstrate that strong toroidal fields can be generated and sustained downstream in the collimated jet outflow far from the target surface. The field strength can be controlled by varying the ring laser separation, thereby providing a versatile laboratory platform for studying the effects of magnetic field in a variety of astrophysical settings.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Creation of magnetized jet using a ring of laser beams

Liang

Tzeferacos

et al. 2015

High Energy Density Physics

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Apar-T: code, validation, and physical interpretation of particle-in-cell results

Melzani

Winisdoerffer

Walder

et al. 2013

A&A

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We present the parallel particle-in-cell (PIC) code Apar-T and, more importantly, address the fundamental question of the relations between the PIC model, the Vlasov-Maxwell theory, and real plasmas. First, we present four validation tests: spectra from simulations of thermal plasmas, linear growth rates of the relativistic tearing instability and of the filamentation instability, and nonlinear filamentation merging phase. For the filamentation instability we show that the effective growth rates measured on the total energy can differ by more than 50% from the linear cold predictions and from the fastest modes of the simulation. We link these discrepancies to the superparticle number per cell and to the level of field fluctuations. Second, we detail a new method for initial loading of Maxwell-Jüttner particle distributions with relativistic bulk velocity and relativistic temperature, and explain why the traditional method with individual particle boosting fails. The formulation of the relativistic Harris equilibrium is generalized to arbitrary temperature and mass ratios. Both are required for the tearing instability setup. Third, we turn to the key point of this paper and scrutinize the question of what description of (weakly coupled) physical plasmas is obtained by PIC models. These models rely on two building blocks: coarse-graining, i.e., grouping of the order of p ∼ 10 10 real particles into a single computer superparticle, and field storage on a grid with its subsequent finite superparticle size. We introduce the notion of coarse-graining dependent quantities, i.e., quantities depending on p. They derive from the PIC plasma parameter Λ PIC , which we show to behave as Λ PIC ∝ 1/p. We explore two important implications. One is that PIC collision-and fluctuation-induced thermalization times are expected to scale with the number of superparticles per grid cell, and thus to be a factor p ∼ 10 10 smaller than in real plasmas, a fact that we confirm with simulations. The other is that the level of electric field fluctuations scales as 1/Λ PIC ∝ p. We provide a corresponding exact expression, taking into account the finite superparticle size. We confirm both expectations with simulations. Fourth, we compare the Vlasov-Maxwell theory, often used for code benchmarking, to the PIC model. The former describes a phase-space fluid with Λ = +∞ and no correlations, while the PIC plasma features a small Λ and a high level of correlations when compared to a real plasma. These differences have to be kept in mind when interpreting and validating PIC results against the Vlasov-Maxwell theory and when modeling real physical plasmas.

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Efficient shock drift acceleration in the collision of two asymmetric pair plasma shells

Zhou

Huang

et al. 2017

Physics of Plasmas

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The shock drift acceleration (SDA) process in the collision between two asymmetric relativistic pair plasma shells was investigated. It is found that the density ratio (nL/nR) of the two different plasma shells plays a crucial role in the SDA process and determines the efficiency of the SDA process. By increasing this parameter, the plasma bulk velocity and so as to the convection electric field in the downstream region can be much enhanced compared with the symmetric case, in which the densities in the two plasma shells are the same. As a result, the particles are efficiently accelerated by the large convection electric field and the efficiency of the SDA process is much increased as the density ratio is increased. Our particle-in-cell simulations demonstrate that the SDA efficiency can be improved by three to four times in the asymmetric case. In this way, more high energy particles could enter into the phase of the diffusive shock acceleration process.

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Simulation of laser-driven, ablated plasma flows in collisionless shock experiments on OMEGA and the NIF

Cited by 5 publications

References 36 publications

Creation of magnetized jet using a ring of laser beams

Creation of magnetized jet using a ring of laser beams

Apar-T: code, validation, and physical interpretation of particle-in-cell results

Efficient shock drift acceleration in the collision of two asymmetric pair plasma shells

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