Emission characteristics and dynamics of the stagnation layer in colliding laser produced plasmas

Hough, P.; McLoughlin, Conor; Harilal, S. S.; Mosnier, Jean-Paul; Costello, J. T.

doi:10.1063/1.3282683

Cited by 40 publications

(18 citation statements)

References 33 publications

(25 reference statements)

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“…Related studies include counter-streaming laser-produced plasmas supporting hohlraum design for indirect-drive inertial confinement fusion [17][18][19] and for studying astrophysically relevant shocks, [20][21][22][23][24] colliding plasmas using wire-array Z pinches, 25,26 and applications such as pulsed laser deposition 27 and laser-induced breakdown spectroscopy. 28 Primary issues of interest in these studies include the identification of shock formation, the formation of a stagnation layer [29][30][31] between colliding plasmas, and the possible role of two-fluid and kinetic effects on plasma interpenetration. [32][33][34][35] In this paper we present detailed measurements of the stagnation layer that forms between two obliquely merging supersonic plasma jets in a semi-to fully collisional a) Electronic mail: emerritt@lanl.gov b) Electronic mail: scotthsu@lanl.gov regime.…”

Section: Introductionmentioning

confidence: 99%

Experimental evidence for collisional shock formation via two obliquely merging supersonic plasma jets

et al. 2014

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We report spatially resolved measurements of the oblique merging of two supersonic laboratory plasma jets. The jets are formed and launched by pulsed-power-driven railguns using injected argon, and have electron density ∼ 10 14 cm −3 , electron temperature ≈ 1.4 eV, ionization fraction near unity, and velocity ≈ 40 km/s just prior to merging. The jet merging produces a few-cm-thick stagnation layer, as observed in both fastframing camera images and multi-chord interferometer data, consistent with collisional shock formation [E. C. Merritt et al., Phys. Rev. Lett. 111, 085003 (2013)].

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Section: Introductionmentioning

confidence: 99%

Experimental evidence for collisional shock formation via two obliquely merging supersonic plasma jets

et al. 2014

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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.…”

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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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“…22 Since then, some theoretical and experimental works have been reported for understanding of these processes and hence to tune experiments. [23][24][25][26][27][28] Various configurations of colliding plasma plumes like colliding collinearly, crossed, or orthogonal have been proposed. The techniques are essentially based on interaction of two seed plasmas created using two laser beams or two beams derived from single source using wedge plate/small angle prism.…”

Section: Introductionmentioning

confidence: 99%

Dynamics of laser ablated colliding plumes

Gupta¹,

Pandey²,

Thareja

2013

Physics of Plasmas

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We report the dynamics of single and two collinearly colliding laser ablated plumes of ZnO studied using fast imaging and the spectroscopic measurements. Two dimensional imaging of expanding plume and temporal evolution of various species in interacting zones of plumes are used to calculate plume front velocity, electron temperature, and density of plasma. The two expanding plumes interact with each other at early stage of expansion ($20 ns) resulting in an interaction zone that propagates further leading to the formation of stagnation layer at later times (>150 ns) at the lateral collision front of two plumes. Colliding plumes have larger concentration of higher ionic species, higher temperature, and increased electron density in the stagnation region. A one-to-one correlation between the imaging and optical emission spectroscopic observations in interaction zone of the colliding plumes is reported. V C 2013 American Institute of Physics.

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Emission characteristics and dynamics of the stagnation layer in colliding laser produced plasmas

Cited by 40 publications

References 33 publications

Experimental evidence for collisional shock formation via two obliquely merging supersonic plasma jets

Experimental evidence for collisional shock formation via two obliquely merging supersonic plasma jets

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

Dynamics of laser ablated colliding plumes

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