X-ray Thomson scattering diagnostics of impact ionization in laser-driven carbon foils

Sperling, P.; Zastrau, U.; Toleikis, S.; Glenzer, S. H.; Redmer, R.

doi:10.1088/0953-4075/48/12/125701

Cited by 3 publications

(4 citation statements)

References 49 publications

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“…Unless otherwise stated, the impact ionization is switched-off. Test runs showed that for the intensities considered here the effect of collisional ionization during the laser pulse is much smaller than that of field ionization [29,43].…”

Section: Plasma Generation In He Jetsmentioning

confidence: 88%

“…The collisions of charged particles and neutral particles are considered utilizing a Monte-Carlo scheme [50], where different processes might occur; the interaction of electrons with neutral particles may lead to impact ionization, excitation, or elastic scattering. Test runs showed that for the intensities considered here the effect of collisional ionization during the laser pulse is much smaller than that of field ionization [29,51].…”

Section: Plasma Generation In He Slabsmentioning

confidence: 88%

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The interaction of intense ultrashort laser pulses with cryogenic He planar jets

Shihab

Bornath

Redmer

2017

Plasma Phys. Control. Fusion

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We study the interaction of intense ultrashort laser pulses with cryogenic He jets using 2d/3v relativistic Particle-in-Cell simulations (XOOPIC). Of particular interest are laser intensities (10 15 − 10 20 ) W/cm 2 , pulse lengths ≤ 100 fs, and the frequency regime ∼ 800 nm for which the jets are initially transparent and subsequently not homogeneously ionized. Pulses ≥ 10 16 W/cm 2 are found to drive ionization along the jet and outside the laser spot, the ionization-front propagates along the jet at a fraction of the speed of light. Within the ionized region, there is a highly transient field, which may be interpreted as two-surface wave decay and as a result of the chargeneutralizing disturbance at the jet-vacuum interface. The ionized region has solid-like densities and temperatures of few to hundreds of eV, i.e., warm and hot dense matter regimes. Such extreme conditions are relevant for high-energy densities as found, e.g., in shock-wave experiments and inertial confinement fusion studies. The temporal evolution of the ionization is studied considering theoretically a pump-probe x-ray Thomson scattering (XRTS) scheme. We observe plasmon and non-collective modes that are generated in the jet, and their amplitude is proportional to the ionized volume.Our theoretical findings could be tested at free-electron laser facilities such as FLASH and the European XFEL (Hamburg) and the LCLS (Stanford).Keywords: Warm and hot dense matter, pump-probe x-ray Thomson scattering experiments, dense plasma jets, two surface plasmon decay.

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Section: Plasma Generation In He Jetsmentioning

confidence: 88%

Section: Plasma Generation In He Slabsmentioning

confidence: 88%

The interaction of intense ultrashort laser pulses with cryogenic He planar jets

Shihab

Bornath

Redmer

2017

Plasma Phys. Control. Fusion

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“…The density and temperature profiles throughout the target are usually inhomogeneous. The resulting compression factor, degree of ionization, and temperature are dependent on the intensity and length of the laser pulse, its shape, and spot size . XRTS is then used to probe the WHDM state.…”

Section: Introductionmentioning

confidence: 99%

Ionization dynamics of dense matter generated by intense ultrashort X‐ray pulses

Shihab

Bornath

Redmer

2019

Contributions to Plasma Physics

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We investigate a pump‐probe X‐ray Thomson scattering (XRTS) experiment that might be carried out at a free electron laser facility to study warm‐to‐hot states of dense matter. Ultrashort and intense X‐ray pulses with different energies (1,560–1,830 eV) heat a 1 µm thick Al target isochorically and create homogeneous and uncompressed warm‐to‐hot states of dense matter. A second pulse with variable delay probes this heated state via XRTS. The X‐ray laser–target interaction is modelled within radiation‐hydrodynamic simulations applying the HELIOS‐CR code. The HELIOS‐CR results qualitatively agree with Monte‐Carlo simulations, where the laser pulse absorption is simulated based on a uniform random sequence of events. The electron feature in the simultaneously observed X‐ray scattering spectrum is a function of the degree of ionization and the target temperature. Therefore, the temporal evolution of the plasmon peak measures the ionization dynamics on ultra‐short time scales. The XRTS spectrum is calculated based on the Chihara formula utilizing the Born‐Mermin approximation for the free electron dynamic structure factor. The proposed experiment will reveal important details of the ionization dynamics on ultra‐short time scales as well as of the relaxation on ps time scales.

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“…Via impact ionization, they heat the interior of the target [21,22]. This is an important effect for the fundamental understanding of the laser-driven generation of plasmas on ultra-short time scales [20,23], the excitation of clusters [24,25], and for applications like inertial confinement fusion.…”

Section: Introductionmentioning

confidence: 99%

Ultrafast electron kinetics in short pulse laser-driven dense hydrogen

Zastrau¹,

Sperling²,

Fortmann-Grote³

et al. 2015

J. Phys. B: At. Mol. Opt. Phys.

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Dense cryogenic hydrogen is heated by intense femtosecond infrared laser pulses at intensities of − 10 10 15 16 W cm −2 . Three-dimensional particle-in-cell (PIC) simulations predict that this heating is limited to the skin depth, causing an inhomogeneously heated outer shell with a cold core and two prominent temperatures of about 25 and 40 eV for simulated delay times up to +70 fs after the laser pulse maximum. Experimentally, the time-integrated emitted bremsstrahlung in the spectral range of 8-18 nm was corrected for the wavelength-dependent instrument efficiency. The resulting spectrum cannot be fit with a single temperature bremsstrahlung model, and the best fit is obtained using two temperatures of about 13 and 30 eV. The lower temperatures in the experiment can be explained by missing energy-loss channels in the simulations, as well as the inclusion of hot, non-Maxwellian electrons in the temperature calculation. We resolved the time-scale for laser-heating of hydrogen, and PIC results for laser-matter interaction were successfully tested against the experiment data.

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X-ray Thomson scattering diagnostics of impact ionization in laser-driven carbon foils

Cited by 3 publications

References 49 publications

The interaction of intense ultrashort laser pulses with cryogenic He planar jets

The interaction of intense ultrashort laser pulses with cryogenic He planar jets

Ionization dynamics of dense matter generated by intense ultrashort X‐ray pulses

Ultrafast electron kinetics in short pulse laser-driven dense hydrogen

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