Modeling ion interpenetration, stagnation, and thermalization in colliding plasmas

Jones, Michael E.; Winske, D.; Goldman, S. R.; Kopp, R. A.; Rogatchev, V. G.; Бельков, С. А.; Gasparyan, P. D.; Dolgoleva, G. V.; Zhidkov, N. V.; Ivanov, N. V.; Kochubej, Yu. K.; Nasyrov, G. F.; Pavlovskii, V. A.; Смирнов, В. В.; Romanov, Yu. A.

doi:10.1063/1.871765

Cited by 22 publications

(8 citation statements)

References 24 publications

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“…Stagnation of the expanding capsule ablator and hohlraum case plasmas may lead to emission that is not accounted for in LASNEX [10] [11] [12] [13] [14]. The electron temperature Table 3.…”

Section: Stagnationmentioning

confidence: 99%

Computer simulations of laser hot spots and implosion symmetry kiniform phase plate experiments on Nova

et al. 2000

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LASNEX computer code simulations have been performed for radiation symmetry experiments on the Nova laser with vacuum and gas-filled hohlraum targets [R.L. Kauffman, et al. Phys. Plasmas 5, 1927 (1998)]. In previous experiments with unsmoothed laser beams, the symmetry was substantially shifted by deflection of the laser beams. In these experiments, laser beams have been smoothed with Kiniform Phase Plates in an attempt to remove deflection of the beams. The experiments have shown that this smoothing significantly improves the agreement with LASNEX calculations of implosion symmetry. The images of laser produced hot spots on the inside of the hohlraum case have been found to differ from LASNEX calculations, suggesting that some beam deflection or self-focusing may still be present or that emission from interpenetrating plasmas is an important component of the images. The measured neutron yields are in good agreement with simulations for vacuum hohlraums but are far different for gas-filled hohlraums.

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“…Stagnation of the expanding capsule ablator and hohlraum case plasmas may lead to emission that is not accounted for in LASNEX [10] [11] [12] [13] [14]. The electron temperature Table 3.…”

Section: Stagnationmentioning

confidence: 99%

Computer simulations of laser hot spots and implosion symmetry kiniform phase plate experiments on Nova

et al. 2000

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“…Physics issues arising in these studies include plasma interpenetration [11][12][13][14][15][16], shock formation [17], and the formation and dynamics of a stagnation layer [18][19][20]. In this work, we present experimental results on two obliquely merging supersonic plasma jets, which are in a different and more collisional parameter regime than many of the colliding plasma examples mentioned above.…”

mentioning

confidence: 92%

Experimental Characterization of the Stagnation Layer between Two Obliquely Merging Supersonic Plasma Jets

Merritt

Hsu

et al. 2013

Phys. Rev. Lett.

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We present spatially resolved measurements characterizing the stagnation layer between two obliquely merging supersonic plasma jets. Intra-jet collisionality is very high (λii ≪ 1 mm), but the inter-jet ion-ion mean free paths are on the same order as the stagnation layer thickness (a few cm). Fast-framing camera images show a double-peaked emission profile transverse to the stagnation layer, with the central emission dip consistent with a density dip observed in the interferometer data. We demonstrate that our observations are consistent with collisional oblique shocks.Colliding plasmas have been studied in a variety of contexts, e.g., counterstreaming laser-produced plasmas supporting hohlraum design for indirect-drive inertial confinement fusion [1][2][3], forming and studying astrophysically relevant shocks [4][5][6][7][8], and for applications such as pulsed laser deposition [9] and laser-induced breakdown spectroscopy [10]. Physics issues arising in these studies include plasma interpenetration [11][12][13][14][15][16], shock formation [17], and the formation and dynamics of a stagnation layer [18][19][20]. In this work, we present experimental results on two obliquely merging supersonic plasma jets, which are in a different and more collisional parameter regime than many of the colliding plasma examples mentioned above. Ours and other recent jet-merging experiments [21,22] were conducted to explore the feasibility of forming imploding spherical plasma liners via an array of merging plasma jets [23][24][25][26][27], which could have applications in forming cm-, µs-, and Mbar-scale plasmas for fundamental high-energy-density-physics studies [28] and as a standoff driver for magnetoinertial fusion [23,[29][30][31][32]. Prior experiments studying the stagnation layer between colliding laser-produced or wire-array z-pinch [33] plasmas were on smaller spatial scales (mm or smaller) that could not be fully resolved by measurements. New results in the present work are the experimental identification and characterization of a few-cm thick stagnation layer between colliding plasmas, and the demonstration that our observations are consistent with hydrodynamic oblique shock theory [34].Experiments reported here are conducted on the Plasma Liner Experiment (PLX) [35], in which two supersonic argon plasma jets are formed and launched by plasma railguns [36]. Plasma jet parameters at the exit of the railgun nozzle (peak n e ≈ 2 × 10 16 cm −3 , peak T e ≈ 1.4 eV, V jet ≈ 30 km/s, Mach number M ≡ V jet /C s,jet ≈ 14, diameter = 5 cm, and length ≈ 20 cm) and their evolution during subsequent jet propagation have been characterized in detail [35]. The jet magnetic field inside the railgun is ∼3 T, but the classical magnetic diffusion time is a few µs [35], and thus • apart, two merging plasma jets, R-Z coordinates used in the paper, approximate interferometer/spectrometer linesof-sight (Z ≈ 84 cm), and CCD camera field-of-view.we ignore the effects of a magnetic field by the time of jet merging (> 20 µs). Experimental data ...

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“…For the simple case of particle ions of ZT e /T i for stable simulation. This restriction is particuadvanced in the ambipolar field due to quasineutral isothermal larly relevant to recent applications to laser generated plasfluid electrons, the heating rate is observed to be weakly dependent mas including simulations of colliding plasmas [4,5] and on time step, inversely proportional to the number of simulation particles per grid cell and strongly increasing with increasing stimulated Brillouin scattering [6][7][8]. Even when ZT e /T i is ZT e /T i .…”

mentioning

confidence: 98%

Numerical Heating in Hybrid Plasma Simulations

Rambo

1997

Journal of Computational Physics

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Modeling ion interpenetration, stagnation, and thermalization in colliding plasmas

Cited by 22 publications

References 24 publications

Computer simulations of laser hot spots and implosion symmetry kiniform phase plate experiments on Nova

Computer simulations of laser hot spots and implosion symmetry kiniform phase plate experiments on Nova

Experimental Characterization of the Stagnation Layer between Two Obliquely Merging Supersonic Plasma Jets

Numerical Heating in Hybrid Plasma Simulations

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