Suppression of stochastic pulsation in laser-plasma interaction by smoothing methods

Hora, Heinrich; Aydın, Meral

doi:10.1103/physreva.45.6123

Cited by 34 publications

(31 citation statements)

References 19 publications

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“…The use of the complex refractive index changing spatially and temporally on the plasma temperature and density is correctly expressed in the second formulation by the rule that the real parts of the fields are to be used for the quadratic expressions of the laser field. In order to test our advanced version of the two-fluid hydrodynamic code, we computed the case of the same parameters as previously published (Hora and Aydin 1992) and confirmed identical results.…”

Section: Two-fluid Plasma Hydrodynamics Codesupporting

confidence: 55%

Computations for nonlinear force driven plasma blocks by picosecond laser pulses for fusion

Chen

Osman²,

Hora

et al. 2005

J. Plasma Phys.

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The concept of the fast ignitor for laser fusion has led to some modifications in applying petawatt-picosecond (PW-ps) laser-produced high intensity particle beams to ignite deuterium-tritium (DT) fuel. Some very anomalous measurements of ion emission from targets irradiated by picosecond laser pulses led to the development of a skin depth interaction scheme where a defined control of prepulses is necessary. Based on these experimental facts, we have applied a onedimensional two-fluid hydrodynamic code to understand how the nonlinear ponderomotive force generates two plasma blocks, one moving against the laser light (ablation) and the other moving into the target. This compressed block produces an ion current density of above 10 11 A cm −2 and an ion energy of about 100 keV. This may be a rather promising option to use PW-ps laser pulses for igniting fusion in solid density DT fuel, realizing very high gain controlled fusion reactions.

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Section: Two-fluid Plasma Hydrodynamics Codesupporting

confidence: 55%

Computations for nonlinear force driven plasma blocks by picosecond laser pulses for fusion

Chen

Osman²,

Hora

et al. 2005

J. Plasma Phys.

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“…The interaction of a short laser pulse with an inhomogeneous plasma layer was investigated with the use of the computation code of the advanced two-fluid plasma model [11,12]. This model is based on the nonthermalized direct electromagnetic interaction between the laser light and the fully ionized plasma.…”

Section: Two-fluid Hydrodynamic Modelmentioning

confidence: 99%

Numerical modelling of production of ultrahigh-current-density ion beams by short-pulse laser-plasma interaction

et al. 2004

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The basic features of generation of ion beams of ultrahigh (> 10 9 A/cm 2 ) current densities by the skin-layer subrelativistic interaction of a short (≤ 1 ps) laser pulse with an inhomogeneous plasma layer are studied with the use of a two-fluid hydrodynamic 1-D computer code. The calculations performed for pico -and subpicosecond 1.05 -μm laser pulses of intensity ∼ 10 16 ÷ 10 17 W/cm 2 confirm that non-linear ponderomotive forces induced by the laser pulse accelerate two thin (a few μm) plasma blocks of current densities in the range of 10 9 ÷ 10 11 A/cm 2 , propagating in forward and backward directions. The effect of initial plasma density gradient as well as the laser intensity and the pulse duration on characteristics of ion beams is demonstrated and discussed. : 52.38.Kd, 52.40.Nk PACS

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“…Since the iron was separated from the laser focus it was concluded that energetic electrons are synchronously produced with the maxima of the back-scattered light (Luther-Davies & Rode 1993). A general numerical treatment that follows the latter numerical observations can explain both the pulsation process and how to suppress it by broadband laser irradiation (section 4) (Hora & Aydin 1992). This is a kind of beam smoothing that was suggested as a possibility by Deng (1983) and before other smoothing techniques (random phase plate (Kato et al 1985) or short temporal coherence (Lehmberg & Obenschain 1983) were intuitively introduced.…”

Section: Introductionmentioning

confidence: 91%

Beam smoothing and temporal effects:Optimized preparation of laser beams for direct-drive inertial confinement fusion

et al. 1997

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Direct-drive laser fusion received a number of setbacks from the experimental observation in the 1960s and 1970s of very complex interactions in laser plasma experiments caused by a number of nonlinear and anomalous phenomena. Although smoothing methods were introduced intuitively or empirically-succeeding in reducing these difficulties -it was not until a few years ago that the 20-ps stochastic pulsation mechanism was discovered. We assume here that this 20-ps stochastic pulsation may be the major obstacle to achieving direct-drive fusion, even though it is now generally assumed that the major challenge to the achievement of direct-drive fusion is the Rayleigh-Taylor instability. While we do not discount the importance of the Rayleigh-Taylor mechanisms, we concentrate here on the analysis of the pulsation process. A method of analysis was developed, using time-dependent real-time computations employing a genuine two-fluid model, which includes the interior electric fields and the very large amplitude longitudinal plasma oscillations that are driven by the laser field. These mechanisms, which were first suggested in 1974, reveal themselves now as self-generated von-Laue gratings, preventing the propagation of laser radiation through the outermost plasma corona and preventing energy deposition by temporal interruption caused by thermal relaxation and the subsequent reestablishment of these gratings, and so on. The abolition of this pulsation by broad-band laser irradiation or other smoothing methods is now well understood. A synopsis of these developments is presented here, consistent with Rubbia's proposition of using the MJ drivers for laser fusion, the technology for which is now available.

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Suppression of stochastic pulsation in laser-plasma interaction by smoothing methods

Cited by 34 publications

References 19 publications

Computations for nonlinear force driven plasma blocks by picosecond laser pulses for fusion

Computations for nonlinear force driven plasma blocks by picosecond laser pulses for fusion

Numerical modelling of production of ultrahigh-current-density ion beams by short-pulse laser-plasma interaction

Beam smoothing and temporal effects:Optimized preparation of laser beams for direct-drive inertial confinement fusion

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