Liquid crystal films as on-demand, variable thickness (50–5000 nm) targets for intense lasers

Poole, Patrick; Andereck, C. David; Schumacher, Douglass; Daskalova, Rebecca; Feister, Scott; George, Kevin; Willis, C.; Akli, K. U.; Chowdhury, Enam

doi:10.1063/1.4885100

Cited by 36 publications

(32 citation statements)

References 24 publications

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“…This pressure is larger than the vapor pressure of some liquid crystals [73]. At that pressure α is approximately 1.5 × 10 −9 kg/m 2 s. The resulting q C is of the order of 10/m.…”

Section: Appendix : Viscous Drag In Molecular Flow Regimementioning

confidence: 99%

Nonequilibrium fluctuations during diffusion in liquid layers

Brogioli

Vailati

2017

Phys. Rev. E

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Theoretical analysis and experiments have provided compelling evidence of the presence of long-range nonequilibrium concentration fluctuations during diffusion processes in fluids. In this paper, we investigate the dependence of the features of the fluctuations from the dimensionality of the system. In three-dimensional fluids the amplitude of nonequilibrium fluctuations can become several orders of magnitude larger than that of equilibrium fluctuations. Notwithstanding that, the amplitude of nonequilibrium fluctuations remains small with respect to the concentration difference driving the diffusion process. By extending the theory to two-dimensional systems, such as liquid monolayers and bilayers, we show that the amplitude of the fluctuations becomes much stronger than in three-dimensional systems. We investigate the properties of the fronts of diffusion and show that they have a self-affine structure characterized by a Hurst exponent H = 1. We discuss the implications of these results for diffusion in liquid crystals and in cellular membranes of living organisms.

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“…This pressure is larger than the vapor pressure of some liquid crystals [73]. At that pressure α is approximately 1.5 × 10 −9 kg/m 2 s. The resulting q C is of the order of 10/m.…”

Section: Appendix : Viscous Drag In Molecular Flow Regimementioning

confidence: 99%

Nonequilibrium fluctuations during diffusion in liquid layers

Brogioli

Vailati

2017

Phys. Rev. E

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“…What follows is the first experimental study of ultra-short pulse proton acceleration investigated with oblique laser incidence from the TNSA-dominant thickness regime down to that of relativistic transparency with a single target material. This is enabled first by high contrast (via a plasma mirror) interaction, as superior laser pulse quality is required for successful ion acceleration from ultra-thin targets, and secondly by an in situ target formation system using freely suspended liquid crystal films [27]. This material can be drawn across an aperture in a rigid frame with changes in wiping speed, temperature, and liquid crystal volume to form films several mm in diameter at repetition rates of 0.1 Hz and with thicknesses from 10 nm to several 10 s of μm [28].…”

Section: Introductionmentioning

confidence: 99%

Laser-driven ion acceleration via target normal sheath acceleration in the relativistic transparency regime

et al. 2018

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We present an experimental study investigating laser-driven proton acceleration via target normal sheath acceleration (TNSA) over a target thickness range spanning the typical TNSA-dominant regime (∼1 μm) down to below the onset of relativistic laser-transparency (<40 nm). This is done with a single target material in the form of freely adjustable films of liquid crystals along with high contrast (via plasma mirror) laser interaction (∼2.65 J, 30 fs, I 1 10 21 >´W cm −2 ). Thickness dependent maximum proton energies scale well with TNSA models down to the thinnest targets, while those under ∼40 nm indicate the influence of relativistic transparency on TNSA, observed via differences in light transmission, maximum proton energy, and proton beam spatial profile. Oblique laser incidence (45°) allowed the fielding of numerous diagnostics to determine the interaction quality and details: ion energy and spatial distribution was measured along the laser axis and both front and rear target normal directions; these along with reflected and transmitted light measurements on-shot verify TNSA as dominant during high contrast interaction, even for ultra-thin targets. Additionally, 3D particle-incell simulations qualitatively support the experimental observations of target-normal-directed proton acceleration from ultra-thin films.

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“…A. Maximum proton energy versus foil thickness Available experimental data 6,[16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32] for proton acceleration from sub-micron foils are listed in Table I. What these laser systems have in common is the large nanosecond prepulse contrast (10 10 and better), allowing interaction with sub-micron foils.…”

Section: Maximum Proton Energy Scalingmentioning

confidence: 99%

Proton acceleration from high-contrast short pulse lasers interacting with sub-micron thin foils

Petrov

McGuffey

Thomas

et al. 2016

Journal of Applied Physics

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A theoretical study complemented with published experimental data of proton acceleration from sub-micron (thickness < 1 lm) foils irradiated by ultra-high contrast (>10 10) short pulse lasers is presented. The underlying physics issues pertinent to proton acceleration are addressed using twodimensional particle-in-cell simulations. For laser energy e 4 J (intensity I 5 Â 10 20 W=cm 2), simulation predictions agree with experimental data, both exhibiting scaling superior to Target Normal Sheath Acceleration's model. Anomalous behavior was observed for e > 4 J (I > 5 Â 10 20 W=cm 2), for which the measured maximum proton energies were much lower than predicted by scaling and these simulations. This unexpected behavior could not be explained within the frame of the model, and we conjecture that pre-pulses preceding the main pulse by picoseconds may be responsible. If technological issues can be resolved, energetic proton beams could be generated for a wide range of applications such as nuclear physics, radiography, and medical science.

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Liquid crystal films as on-demand, variable thickness (50–5000 nm) targets for intense lasers

Cited by 36 publications

References 24 publications

Nonequilibrium fluctuations during diffusion in liquid layers

Nonequilibrium fluctuations during diffusion in liquid layers

Laser-driven ion acceleration via target normal sheath acceleration in the relativistic transparency regime

Proton acceleration from high-contrast short pulse lasers interacting with sub-micron thin foils

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