Plasma ion stratification by weak planar shocks

Simakov, Andrei N.; Keenan, Brett; Taitano, William; Chacòn, Luis

doi:10.1063/1.4995427

Cited by 18 publications

(30 citation statements)

References 46 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Interspecies ion separation and velocity separation were experimentally observed [19][20][21][22][23]. Additional simulation and theoretical research on multi-ion-species plasmas examined how ion species diffusion causes species separation [24][25][26][27][28][29][30]. The present research reports direct observations of the spatial profile of a multi-ion-species shock, showing shock-front separation and species-dependent shock widths in collisional plasma shocks.…”

mentioning

confidence: 63%

“…First-principles theory of interspecies ion diffusion and simulations based on the theory predict that lighter ions diffuse farther ahead within a collisional plasma shock (closer to the pre-shock region) than heavier ions [11][12][13][14][15][16][17][18][24][25][26][27][28][29][30]. The diffusion mechanisms are classical diffusion based on the mass concentration gradient, barodiffusion based on the ion pressure gradient, thermodiffusion based on ion and electron temperature gradients, and electrodiffusion based on the electric field (negative gradient of the electric potential).…”

mentioning

confidence: 99%

See 1 more Smart Citation

Observation of shock-front separation in multi-ion-species collisional plasma shocks

et al. 2020

View full text Add to dashboard Cite

We observe shock-front separation and species-dependent shock widths in multi-ion-species collisional plasma shocks, which are produced by obliquely merging plasma jets of a He/Ar mixture (97% He and 3% Ar by initial number density) on the Plasma Liner Experiment [S. C. Hsu et al., IEEE Trans. Plasma Sci. 46, 1951]. Visible plasma emission near the He-I 587.6-nm and Ar-II 476.5-514.5-nm lines are simultaneously recorded by splitting a single visible image of the shock into two different fast-framing cameras with different narrow bandpass filters (589 ± 5 nm for observing the He-I line and 500 ± 25 nm for the Ar-II lines). For conditions in these experiments (pre-shock ion and electron densities ≈ 5 × 10 14 cm −3 , ion and electron temperatures of ≈ 2.2 eV, and relative plasma-merging speed of 22 km/s), the observationally inferred magnitude of He/Ar shock-front separation and the shock widths themselves are < 1 cm, which correspond to ∼ 50 post-shock thermal ion-ion mean free paths. The experiments are in reasonable qualitative and quantitative agreement with results from 1D multi-fluid simulations using the chicago code. Moreover, the experiment and simulation results are consistent with first-principles theoretical predictions that the lighter He ions diffuse farther ahead within the overall shock front than the heavier Ar ions.

show abstract

mentioning

confidence: 63%

mentioning

confidence: 99%

Observation of shock-front separation in multi-ion-species collisional plasma shocks

et al. 2020

View full text Add to dashboard Cite

show abstract

“…The temperature separation between ion species, 2 and 1 (in a steady-state shock) will be given by the difference of their respective fluid energy equations, i.e. 27 3 2…”

Section: A the Theory Of Ion Temperature Separationmentioning

confidence: 99%

“…For example, the basic structure of any plasma shock is a function of the Mach number. There are three principal regimes: 1) the weak shock limit (M − 1 1), which admits an analytical treatment; 27 2) an intermediate regime (M − 1 ∼ 1); and 3) the strong-shock limit (M 1). The weak limit is characterized by extremely weak ion species separation in concentration ∝ (M − 1) 2 and temperature ∝ (M − 1) 3 .…”

Section: Introductionmentioning

confidence: 99%

Ion species stratification within strong shocks in two-ion plasmas

et al. 2018

Self Cite

View full text Add to dashboard Cite

Strong collisional shocks in multi-ion plasmas are featured in many environments, with Inertial Confinement Fusion (ICF) experiments being one prominent example. Recent work [Keenan et al., Phys. Rev. E 96, 053203 (2017)] answered in detail a number of outstanding questions concerning the kinetic structure of steady-state, planar plasma shocks, e.g., the shock width scaling by Mach number, M . However, it did not discuss shock-driven ion-species stratification (e.g., relative concentration modification, and temperature separation). These are important effects, since many recent ICF experiments have evaded explanation by standard, single-fluid, radiation-hydrodynamic (rad-hydro) numerical simulations, and shock-driven fuel stratification likely contributes to this discrepancy. Employing the stateof-the-art Vlasov-Fokker-Planck code, iFP, along with multi-ion hydro simulations and semi-analytics, we quantify the ion stratification by planar shocks with arbitrary Mach number and relative species concentration for two-ion plasmas in terms of ion mass and charge ratios. In particular, for strong shocks, we find that the structure of the ion temperature separation has a nearly universal character across ion mass and charge ratios. Additionally, we find that the shock fronts are enriched with the lighter ion species, and the enrichment scales as M 4 for M 1.

show abstract

“…[6]). This is relevant, as the state-of-the-art for simulating ICF capsule implosions is radiation-hydrodynamics (rad-hydro), which is only strictly valid in systems with small Knudsen numbers and therefore only accurate for weak shocks with M ∼ 1 [7]. Nevertheless, rad-hydro has been used extensively to investigate strong plasma shocks [8][9][10][11][12][13].…”

mentioning

confidence: 99%

Fully kinetic simulations of strong steady-state collisional planar plasma shocks

Anderson,

Chacón,

Taitano

et al. 2021

Preprint

Self Cite

View full text Add to dashboard Cite

We report on the first steady-state simulations of strong plasma shocks with fully kinetic ions and electrons, independently confirmed by two fully kinetic codes (an Eulerian continuum and a Lagrangian particle-in-cell). While kinetic electrons do not fundamentally change the shock structure as compared with fluid electrons, we find an appreciable rearrangement of the preheat layer, associated with nonlocal electron heat transport effects. The electron heat flux profile qualitatively agrees between kinetic and fluid electron models, suggesting a certain level of "stiffness", though substantial nonlocality is observed in the kinetic heat flux. We also find good agreement with nonlocal electron heat-flux closures proposed in the literature. Finally, in contrast to the classical hydrodynamic picture, we find a significant collapse in the 'precursor' electric-field shock at the preheat layer edge, which correlates with the electron-temperature gradient relaxation.

show abstract

Plasma ion stratification by weak planar shocks

Cited by 18 publications

References 46 publications

Observation of shock-front separation in multi-ion-species collisional plasma shocks

Observation of shock-front separation in multi-ion-species collisional plasma shocks

Ion species stratification within strong shocks in two-ion plasmas

Fully kinetic simulations of strong steady-state collisional planar plasma shocks

Contact Info

Product

Resources

About