Experimental study of KrF-laser<i>–</i>high-<i>Z</i>-plasma interaction dominated by radiation transport

Pd, Gupta; Yy, Tsui; Popil, R.; Fedosejevs, R.; Aa, Offenberger

doi:10.1103/physreva.34.4103

Cited by 12 publications

(4 citation statements)

References 27 publications

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“…Laser absorption efficiencies reaching 80% can be expected in such experiments [63] . If the laser irradiance reaches over the limit of I L , the nature of the laser-plasma coupling changes and the incident radiation starts driving plasma waves within the target [63][64][65] . If the temperature increases too much, the efficiency of the collisional absorption is reduced [61] .…”

Section: Generation Of Wdmmentioning

confidence: 99%

Experimental methods for warm dense matter research

Falk

2018

High Pow Laser Sci Eng

112

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The study of structure, thermodynamic state, equation of state (EOS) and transport properties of warm dense matter (WDM) has become one of the key aspects of laboratory astrophysics. This field has demonstrated its importance not only concerning the internal structure of planets, but also other astrophysical bodies such as brown dwarfs, crusts of old stars or white dwarf stars. There has been a rapid increase in interest and activity in this field over the last two decades owing to many technological advances including not only the commissioning of high energy optical laser systems, z-pinches and X-ray free electron lasers, but also short-pulse laser facilities capable of generation of novel particle and X-ray sources. Many new diagnostic methods have been developed recently to study WDM in its full complexity. Even ultrafast nonequilibrium dynamics has been accessed for the first time thanks to subpicosecond laser pulses achieved at new facilities. Recent years saw a number of major discoveries with direct implications to astrophysics such as the formation of diamond at pressures relevant to interiors of frozen giant planets like Neptune, metallic hydrogen under conditions such as those found inside Jupiter’s dynamo or formation of lonsdaleite crystals under extreme pressures during asteroid impacts on celestial bodies. This paper provides a broad review of the most recent experimental work carried out in this field with a special focus on the methods used. All typical schemes used to produce WDM are discussed in detail. Most of the diagnostic techniques recently established to probe WDM are also described. This paper also provides an overview of the most prominent examples of these methods used in experiments. Even though the main emphasis of the publication is experimental work focused on laboratory astrophysics primarily at laser facilities, a brief outline of other methods such as dynamic compression with z-pinches and static compression using diamond anvil cells (DAC) is also included. Some relevant theoretical and computational efforts related to WDM and astrophysics are mentioned in this review.

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Section: Generation Of Wdmmentioning

confidence: 99%

Experimental methods for warm dense matter research

Falk

2018

High Pow Laser Sci Eng

112

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“…The resulting velocity and depth of penetration of the radiatively driven ionization wave is 1 to 2 orders of magnitude greater than that observed at low intensity. Previous measurements of radiative transport effects have been largely composed of long pulse ͑ϳ1 ns͒ studies where the effects of radiative transport have been inferred by indirect means [7] or by direct measurement of radiative transport effects in thin foils [8,9] or foams [10] driven by a separate lasercreated x-ray source. In these experiments the drive laser pulse width was comparable to or longer than the time scale for the energy transport.…”

mentioning

confidence: 99%

Supersonic Ionization Wave Driven by Radiation Transport in a Short-Pulse Laser-Produced Plasma

et al. 1996

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Through the use of an ultrashort (2 ps) optical probe, we have time resolved the propagation of an ionization wave into solid fused silica. This ionization wave results when a plasma is created by the intense irradiation of a solid target with a 2 ps laser pulse. We find that the velocity of the ionization wave is consistent with radiation driven thermal transport, exceeding the velocity expected from simple electron thermal conduction by nearly an order of magnitude. [S0031-9007(96)00542-X] PACS numbers: 52.50.Jm, 52.25.Fi, 52.40.Nk, 52.70.Kz Progress in understanding the interaction of intense, ultrashort laser pulses with plasmas has been quite dramatic in the previous decade [1]. This progress has been fueled by a desire to study plasma conditions at very high temperatures and electron densities, a condition made possible by the development of intense picosecond lasers which can rapidly heat a plasma before significant hydrodynamic expansion can take place [2]. Understanding of the physics behind energy transport mechanisms in these plasmas is central to these studies. This is not only because of the fundamental nature of these mechanisms to the understanding of plasma physics in general, but also because a clear picture of energy transport is required to fully understand the dynamics of ultrashort pulse x-ray generation [3], a very important application of short-pulse produced plasmas [4].One important ultrafast process driven by energy transport is the formation of an ionization wave that propagates with a supersonic velocity into the solid after the target surface has been heated by an intense short pulse [5]. This process has been studied previously at intensities of ,5 3 10 14 W͞cm 2 where the plasmas formed exhibited temperatures of 50 eV or less [6]. In these studies the velocity of the ionization wave was inferred from the Doppler shift exhibited by a probe beam reflected off the expanding ionization front within the cold fused silica substrate. This experiment found that the velocity of the ionization wave could be well explained by standard electron thermal conduction in this low intensity regime.In this Letter we report the first time resolved measurements of the spatial extent of an ionization wave produced with high intensity (up to 10 17 W͞cm 2 ) picosecond pulses. At this intensity we find that the velocity of the ionization wave cannot be explained by simple electron thermal conduction. We find that our measurements are, instead, consistent with radiative thermal conduction. The resulting velocity and depth of penetration of the radiatively driven ionization wave is 1 to 2 orders of magnitude greater than that observed at low intensity. Previous measurements of radiative transport effects have been largely composed of long pulse ͑ϳ1 ns͒ studies where the effects of radiative transport have been inferred by indirect means [7] or by direct measurement of radiative transport effects in thin foils [8,9] or foams [10] driven by a separate lasercreated x-ray source. In these experiments the drive...

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“…For the Al-overlayer target, the difference is approximately constant, whereas for the Au-overlayer target, this difference increases as laser intensity increases, owing to the slower scaling of electron temperature (Gupta et al 1986) for Au plasma in comparison with Al plasma. For the Al-overlayer target, the difference is approximately constant, whereas for the Au-overlayer target, this difference increases as laser intensity increases, owing to the slower scaling of electron temperature (Gupta et al 1986) for Au plasma in comparison with Al plasma.…”

Section: Resultsmentioning

confidence: 96%

“…In high-Z plasma ablation, two regions dominate the different transport mechanisms, namely, where electron thermal transport and radiation can exist (Gupta et al 1986), and two groups of ions are identified in blowoff plasma, the first due to thermal ablation and the second due to radiation heating (Gupta et al 1986;Borodziuk et al 1990).…”

Section: Introductionmentioning

confidence: 99%