Investigating the Astrophysical Applicability of Radiative and Non-Radiative Blast wave Structure in Cluster Media

Moore, A. S.; Lazarus, James; Hohenberger, M.; Robinson, Joseph S.; Gumbrell, E. T.; Dunne, Mike; Smith, R. A.

doi:10.1007/s10509-006-9266-x

Cited by 21 publications

(16 citation statements)

References 22 publications

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“…1, the shock evolution is expected to depend on the deposited energy per unit length divided by the mass density. This should therefore be maintained equal in different gases to allow a direct comparison of the trajectories for identification of potential energy loss mechanisms [14]. In Ar and Kr, this is the case with 2.3 ± 0.6 × 10 4 Jcm 2 /g and 2.9 ± 0.5 × 10 4 Jcm 2 /g, respectively.…”

Section: Pacs Numbers: Valid Pacs Appear Herementioning

confidence: 99%

Observation of a Velocity Domain Cooling Instability in a Radiative Shock

et al. 2010

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We report on experimental investigations into strong, laser-driven, radiative shocks in noble-gas cluster media. Cylindrical shocks launched with several J exhibit strong radiative effects such as increased deceleration and radiative preheat. Using time-resolved propagation data from single-shot streaked Schlieren measurements we observe temporal modulations on shock position and velocity, which we attribute to the thermal cooling instability, an instability which until now has not been observed experimentally. PACS numbers: Valid PACS appear hereShocks are a common phenomenon in astrophysics and high-energy-density (HED) environments in general. A shock forms when material expands with supersonic speed into an ambient medium, faster than the surrounding material can adapt to the expansion. If the energy deposition initially launching the shock is limited in time, the shock is followed by a rarefaction which eventually catches up with the shock front and a blast wave is formed, often consisting of a thin shell containing much of the swept-up material [1].An understanding of shocks and the dynamics of thermal and dynamical instabilities in HED plasmas is vital for numerical models of complex plasma systems. In such environments, radiation can lead to fundamental structural and dynamical changes in the system evolution. A shock becomes radiative if the post-shock conditions lead to an efficient cooling rate through radiative energy losses. The radiation is transmitted through the shock shell and, in an optically thin case, is lost from the system. In contrast, if the upstream material ahead of the shock front is optically thick to parts of the emission spectrum, radiation can be reabsorbed leading to preheat and ionization of the material ahead of the shock front. This modifies the shock propagation dynamics and can lead to growth of instabilities [2,3].The temporal expansion of a shock radius is often described as a power-law type function of the formwhere E 0 denotes the deposited energy per unit length (in cylindrical geometry) and ρ is the mass density. The parameter α is the deceleration parameter determined by the geometry and the energy dissipation in the system, which for cylindrical, adiabatic blast waves is α = 0.5 [4]. Dissipative processes such as radiation or ionization necessarily reduce the polytropic index, γ, of the system, * Electronic address: M.Hohenberger@Imperial.ac.uk and therefore α, to a value below the adiabatic solution and the blast wave decelerates more quickly. In case where radiative losses in the shell are sufficiently large such that the shell cannot support itself any longer, it is pushed by the low-density but high-pressure interior of the shock and collapses to high densities. Specifically the transition to this pressure driven snowplow regime and the associated shell-thinning is thought to make the shock more susceptible to radiation-driven instabilities, one of which we address in detail in this paper. Radiative shocks can be studied experimentally by utilizing the efficient a...

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Section: Pacs Numbers: Valid Pacs Appear Herementioning

confidence: 99%

Observation of a Velocity Domain Cooling Instability in a Radiative Shock

et al. 2010

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“…The potential of such a medium to perform shock wave studies of astrophysical importance was realized and exploited at the Lawrence Livermore National Laboratory some years ago [1][2][3][4]. Since these pioneering experiments we have performed numerous blast wave experiments using low energy (<1 J) table-top lasers [5][6][7][8][9][10][11][12][13]. We have also conducted experiments [14] using the Vulcan laser facility to launch blast waves in clusters with much higher drive energies (>10 J) than previously used.…”

Section: Introductionmentioning

confidence: 99%

Investigations of laser-driven radiative blast waves in clustered gases

Symes

Hohenberger

Lazarus

et al. 2010

High Energy Density Physics

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“…Blast waves have been created in a number of gases using this technique. This technique has been used by Shigemori and Edwards et al at Lawrence Livermore [57,58], and by experimenters at the University of Texas [59,60] and Imperial College [61][62][63][64][65] to look at the formation of the shock front, the radiative precursor and the collapse of the blast wave shell brought on by radiative cooling. The use of the cluster jet allows experimenters to tailor the initial shape of the blast wave as well [60].…”

Section: Methods Of Accessing Radiative Blast Waves With High Energy mentioning

confidence: 99%

Laboratory simulations of astrophysical blast waves with high energy lasers

Ditmire¹,

Edens

2008

Laser & Photonics Reviews

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We review recent efforts to simulate aspects of supernova remnants in laboratory experiments by creating energetic explosions with high energy lasers. High energy pulsed lasers are uniquely suited for these kinds of studies. By focusing a laser with pulse energy of a few joules to many hundreds of joules onto a solid target or into a dense gas target, explosive shock waves of very high Mach number can be created. With a well chosen set of laser and target parameters it has been shown by a number of groups that radiative blast waves can be produced. Such blast waves have dynamics dominated by radiation transport and exhibit unusual characteristics, the most important of which include hydrodynamic instabilities which may play an important role in the structure of the interstellar medium. As a result there are now prospects for gaining new insights into astronomical observations of supernova remnants by studying laboratory laser driven plasma systems.Image of a blast wave in nitrogen driven by focusing a 1 kJ laser pulse onto a pin immersed in nitrogen gas.

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Investigating the Astrophysical Applicability of Radiative and Non-Radiative Blast wave Structure in Cluster Media

Cited by 21 publications

References 22 publications

Observation of a Velocity Domain Cooling Instability in a Radiative Shock

Observation of a Velocity Domain Cooling Instability in a Radiative Shock

Investigations of laser-driven radiative blast waves in clustered gases

Laboratory simulations of astrophysical blast waves with high energy lasers

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