Influence of spatial-intensity contrast in ultraintense laser–plasma interactions

Wilson, R.; King, M.; Butler, N. M. H.; Carroll, D. C.; Frazer, Timothy P.; Duff, M. J.; Higginson, A.; Dance, R. J.; Jarrett, J.H.; Davidson, Z. E.; Armstrong, Chris; Liu, H; Hawkes, S.; Clarke, R. J.; Neely, D.; Gray, R. J.; McKenna, P.

doi:10.1038/s41598-022-05655-4

Cited by 3 publications

(1 citation statement)

References 39 publications

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“…There also appears to be enhanced proton flux for zero defocus, z T = 0 µm, but with the application of significant astigmatism Z −2 2 = ±1.2 µm when compared with the increased flux achieved just through defocusing with no astigmatism. This indicates that the proton acceleration process is not just intensity dependent, but is also sensitive to the spatial intensity profile on-target [58].…”

Section: Automated Grid Scansmentioning

confidence: 99%

Automated control and optimization of laser-driven ion acceleration

Loughran

Streeter

Ahmed

et al. 2023

High Pow Laser Sci Eng

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The interaction of relativistically intense lasers with opaque targets represents a highly non-linear, multi-dimensional parameter space. This limits the utility of sequential 1D scanning of experimental parameters for the optimisation of secondary radiation, although to-date this has been the accepted methodology due to low data acquisition rates. High repetition-rate (HRR) lasers augmented by machine learning present a valuable opportunity for efficient source optimisation. Here, an automated, HRR-compatible system produced high fidelity parameter scans, revealing the influence of laser intensity on target pre-heating and proton generation. A closed-loop Bayesian optimisation of maximum proton energy, through control of the laser wavefront and target position, produced proton beams with equivalent maximum energy to manually-optimized laser pulses but using only 60% of the laser energy. This demonstration of automated optimisation of laser-driven proton beams is a crucial step towards deeper physical insight and the construction of future radiation sources.

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Section: Automated Grid Scansmentioning

confidence: 99%

Automated control and optimization of laser-driven ion acceleration

Loughran

Streeter

Ahmed

et al. 2023

High Pow Laser Sci Eng

Self Cite

View full text Add to dashboard Cite

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Optimization and control of synchrotron emission in ultraintense laser–solid interactions using machine learning

Goodman

King

Dolier

et al. 2023

High Pow Laser Sci Eng

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The optimum parameters for the generation of synchrotron radiation in ultraintense laser pulse interactions with planar foils are investigated with the application of Bayesian optimisation, via Gaussian process regression, to 2D particle-incell simulations. Individual properties of the synchrotron emission, such as the yield, are maximised, and simultaneous mitigation of bremsstrahlung emission is achieved with multi-variate objective functions. The angle-of-incidence of the laser pulse onto the target is shown to strongly influence the synchrotron yield and angular profile, with oblique incidence producing the optimal results. This is further explored in 3D simulations, in which additional control of the spatial profile of synchrotron emission is demonstrated by varying the polarisation of the laser light. The results demonstrate the utility of applying a machine learning-based optimisation approach and provide new insights into the physics of radiation generation in multi-petawatt laser-foil interactions, which will inform the design of experiments in the QED-plasma regime.

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Perspectives on laser-plasma physics in the relativistic transparency regime

et al. 2023

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With the advent of multi-petawatt lasers, the relativistic transparency regime of laser-plasma interactions becomes readily accessible for near-solid density targets. Initially opaque targets that undergo relativistic self-induced transparency (RSIT) have already shown to result in promising particle acceleration and radiation generation mechanisms, as well as relativistic optical and photonics phenomena that modify the spatial, temporal, spectral and polarization properties of the laser pulse itself. At the maximum laser intensities currently available, this opaque-to-RSIT transition regime can be achieved through ultrafast ionization, heating and expansion of initially ultrathin foil targets. Here, we review findings from our programme of work exploring this regime experimentally and numerically, including changes to the laser energy absorption, mechanisms for laser-driven particle acceleration and the generation of a relativistic plasma aperture. New physics induced by this aperture, such as the production of intense light with higher order spatial modes and higher harmonics, and spatially-structured and temporally-varying polarization states, is summarized. Prospects for exploring the physics of the RSIT regime with higher intensity and high repetition rate lasers, including expected new phenomena such as high-field effects and the application of new techniques such as machine learning, are also discussed; outlining directions for the future development of this promising laser-plasma interaction regime.

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Influence of spatial-intensity contrast in ultraintense laser–plasma interactions

Cited by 3 publications

References 39 publications

Automated control and optimization of laser-driven ion acceleration

Automated control and optimization of laser-driven ion acceleration

Optimization and control of synchrotron emission in ultraintense laser–solid interactions using machine learning

Perspectives on laser-plasma physics in the relativistic transparency regime

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