The expansion of a plasma into a vacuum

Crow, J. E.; Auer, Péter; Allen, J. E.

doi:10.1017/s0022377800025538

Cited by 339 publications

(246 citation statements)

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“…Figure 2 shows the equilibrium charge buildup within the ion core, ∆Q, and the total kinetic energy of the electrons, E (accounting for all confined electrons, inside and outside the ion core), as a function ofT 0 . Considering that the analytical results [10] for semi-infinite planar expansions must be recovered in the spherical case forT 0 ≪ 1 (as λ D ≪ R 0 ), a simple fit for ∆Q has been found, in the form…”

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confidence: 99%

Kinetics of the Collisionless Expansion of Spherical Nanoplasmas

et al. 2006

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The collisionless expansion of spherical plasmas composed of cold ions and hot electrons is analyzed using a novel kinetic model, with special emphasis on the influence of the electron dynamics.Simple, general laws are found, relating the relevant expansion features to the initial conditions of the plasma, determined from a single dimensionless parameter. A transition is identified in the behavior of the ion energy spectrum, which is monotonic only for high electron temperatures, otherwise exhibiting a local peak far from the cutoff energy.

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Kinetics of the Collisionless Expansion of Spherical Nanoplasmas

et al. 2006

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“…The expansion of a plasma into a vacuum without energy absorption was considered by Gurevitch et al n and Crow et al} 2 As expected, three different flow regions 7 emerge naturally from our asymptotic analysis for e«l and (ae 4/3 ) 3/2 » 1: a region of shocked material moving isentropically into the undisturbed cold medium, a plasma deflagration layer where radiation is absorbed and heat conduction and ion-electron energy exchange are important, and a region of low density plasma expanding into the vacuum. Figure 1 shows an overall picture of the motion obtained from the asymptotic results for those three regions, in a typical laser plasma [Nd glass laser, 0 o = 5xlO 12 Wcm" 2 , T=70 nsec, deuterium at solid density: w 0^5 xlO 22 cm" 3 , for which e ^ 1/50, (ae 4/3 ) 3/2 ^10.4]; the excellent matching between the solutions for the different regions confirms the validity of the asymptotic analysis.…”

Section: T/t(t^t)mentioning

confidence: 99%

Self-similar motion of laser half-space plasmas. I. Deflagration regime

Sanmartin

Barrero

1978

The Physics of Fluids

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The one-dimensional self-similar motion of an initially cold, half-space plasma of electron density « 0 , produced by the (anomalous) absorption of a laser pulse of irradiation = (j> 0 f/T(0< (< T) at the critical density n c (« c /« 0 =eoK e ) 213 , where k, m, are Boltzmann's constant and the ion mass, and K e X (electron temperature) 5 ' 2 = heat conductivity. If a >e -4 ' 3 , a deflagration wave separates an isentropic compression with a shock bounding the undisturbed plasma, and an isentropic expansion flow to the vacuum. The structures of these three regions are completely determined; in particular, the Chapman-Jouguet condition is proved and the density behind the deflagration is found. The deflagration-compression thickness ratio is large (small) for a^e -5 ' 3 (a>e -5 ' 3 ). The compression to expansion ratio for both energy and thickness is 0(e" 2 ). For Z,-large, a deflagration exists even if a~e~4 13 . Condition a>e~4' 3 may be applied to pulses that are not linear.

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“…Understanding hohlraum physics is crucial to achieving ignition at the NIF; many fundamental physics questions can be more easily studied at smaller-scale facilities such as OMEGA at the University of Rochester 7 . Fast ions and hot electrons produced in laser-plasma interactions (LPI) are known effects, and studied theoretically [8][9][10][11] and experimentally 12,13 . In ICF ignition experiments, hot electrons produced by LPI are energetic enough to penetrate the ablator material and deposit energy in the cryogenic fuel, which increases the fuel a) Electronic mail: zylstra@mit.edu adiabat and thus reduces the fuel compressibility.…”

Section: Introductionmentioning

confidence: 99%

Measurements of hohlraum-produced fast ions

Zylstra

Séguin

et al. 2012

Physics of Plasmas

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We report the first fast ion measurements in indirect-drive experiments, which were taken on OMEGA hohlraum and halfraum shots using simple filtered CR-39, a nuclear track detector, and a charged-particle spectrometer. Protons are observed in two energy regimes that are associated with different fast ion production mechanisms. In the first, resonance absorption at the hohlraum wall early in the laser pulse accelerates runaway electrons. In the second, fast electrons are produced with high energy from the two-plasmon decay (TPD) instability in the exploding laser entrance hole (LEH), or from Stimulated Raman Scattering (SRS) in the underdense gas fill. In both cases, the runaway electrons set up a strong electrostatic field that accelerates the measured ions. The former mechanism is observed to have an energy conversion efficiency ∼ (0.6 − 4) × 10 −4 into fast protons depending on the hohlraum and drive. The latter mechanism has an estimated conversion efficiency from the main drive of ∼ (0.5 − 2) × 10 −5 depending on assumptions made.

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The expansion of a plasma into a vacuum

Abstract: This paper reports calculations of the collision-free expansion of a semi-infinite plasma. It is shown that the ion front is accelerated to velocities comparable with the thermal velocity of the electrons.

Cited by 339 publications

References 4 publications

Kinetics of the Collisionless Expansion of Spherical Nanoplasmas

Kinetics of the Collisionless Expansion of Spherical Nanoplasmas

Self-similar motion of laser half-space plasmas. I. Deflagration regime

Measurements of hohlraum-produced fast ions

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