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Automated control and optimization of laser-driven ion acceleration

高功率激光科学与工程:英文版 2023年第3期11卷 32-40页

作者： B.Loughran M.J.V.streeter H.Ahmed s.astbury M.Balcazar M.Borghesi N.Bourgeois C.B.Curry s.J.D.Dann s.DiIorio N.P.Dover T.Dzelzainis O.C.Ettlinger M.Gauthier L.Giuffrida G.D.Glenn s.H.Glenzer J.s.Green R.J.Gray G.s.Hicks C.Hyland V.Istokskaia M.King D.Margarone O.McCusker P.McKenna Z.Najmudin C.Parisuaña P.Parsons C.spindloe D.R.symes A.G.R.Thomas F.Treffert N.Xu C.A.J.Palmer school of Mathematics and Physics Queen’s University BelfastBelfastUK Central Laser Facility STFC Rutherford Appleton LaboratoryDidcotUK Gérard Mourou Center for Ultrafast Optical science University of MichiganAnn ArborMIUSA sLAC National Accelerator Laboratory Menlo ParkCAUSA Department of Electrical and Computer Engineering University of AlbertaEdmontonABCanada The John Adams Institute for Accelerator science Imperial College LondonLondonUK ELI Beamlines Centre Institute of PhysicsCzech Academy of SciencesDolníBˇrežanyCzech Republic Department of Applied Physics Stanford UniversityStanfordCAUSA Department of Physics SUPAUniversity of StrathclydeGlasgowUK Faculty of Nuclear sciences and Physical Engineering Czech Technical University in PraguePragueCzech Republic Department of Mechanical Engineering Stanford UniversityStanfordCAUSA Institut für Kernphysik Technische Universität DarmstadtDarmstadtGermany

The interaction of relativistically intense lasers with opaque targets represents a highly non-linear,multi-dimensional parameter *** limits the utility of sequential 1D scanning of experimental parameters for the optimization of secondary radiation,although to-date this has been the accepted methodology due to low data acquisition *** repetition-rate(HRR)lasers augmented by machine learning present a valuable opportunity for efficient source ***,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 optimization 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 *** demonstration of automated optimization of laser-driven proton beams is a crucial step towards deeper physical insight and the construction of future radiation sources.

关键词： Bayesian optimization high repetition-rate laser-target interaction laser-driven particle acceleration proton generation

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Design and fabrication of gas cell targets for laboratory astrophysics experiments on the Orion high-power laser facility

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High Power Laser science and Engineering 2017年第3期5卷 62-66页

作者： C.spindloe D.Wyatt s.astbury G.F.swadling T.Clayson C.stehlé J.M.Foster E.Gumbrell R.Charles C.N.Danson P.Brummitt F.suzuki-Vidal science and Technology Facilities Council Harwell Science and Innovation Campus Blackett Laboratory Imperial College Lawrence Livermore National Laboratory LERMA Sorbonne UniversitésUPMC Univ.Paris06Observatoire de ParisPSL Research University AWE plc

This paper describes the design and fabrication of a range of ‘gas cell' microtargets produced by the Target Fabrication Group in the Central Laser Facility(CLF) for academic access experiments on the Orion laser facility at the Atomic Weapons Establishment(AWE). The experiments were carried out by an academic consortium led by Imperial College London. The underlying target methodology was an evolution of a range of targets used for experiments on radiative shocks and involved the fabrication of a precision machined cell containing a number of apertures for interaction foils or diagnostic windows. The interior of the cell was gas-filled before laser irradiation. This paper details the assembly processes, thin film requirements and micro-machining processes needed to produce the targets. Also described is the implementation of a gas-fill system to produce targets that are filled to a pressure of 0.1–1 bar. The paper discusses the challenges that are posed by such a target.

关键词： astrophysics microtargets

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Versatile tape-drive target for high-repetition-rate laser-driven proton acceleration

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High Power Laser science and Engineering 2023年第4期11卷 59-69页

作者： N.Xu M.J.V.streeter O.C.Ettlinger H.Ahmed s.astbury M.Borghesi N.Bourgeois C.B.Curry s.J.D.Dann N.P.Dover T.Dzelzainis V.Istokskaia M.Gauthier L.Giuffrida G.D.Glenn s.H.Glenzer R.J.Gray J.s.Green G.s.Hicks C.Hyland M.King B.Loughran D.Margarone O.McCusker P.McKenna C.Parisuaña P.Parsons C.spindloe D.R.symes F.Treffert C.A.J.Palmer Z.Najmudin John Adams Institute for Accelerator science Blackett LaboratoryImperial College LondonLondonUK school of Maths and Physics Queen’s University BelfastBelfastUK Central Laser Facility STFC Rutherford Appleton LaboratoryDidcotUK sLAC National Accelerator Laboratory Menlo ParkUSA ELI Beamlines Centre Institute of PhysicsCASDolni BrezanyCzech Republic Faculty of Nuclear sciences and Physical Engineering Czech Technical University in PraguePragueCzech Republic Department of Physics SUPAUniversity of StrathclydeGlasgowUK Department of Mechanical Engineering Stanford UniversityStanfordUSA Department of Applied Physics Stanford UniversityStanfordUSA Department of Electrical and Computer Engineering University of AlbertaEdmontonCanada Institut für Kernphysik Technische Universität DarmstadtDarmstadtGermany

We present the development and characterization of a high-stability,multi-material,multi-thickness tape-drive target for laser-driven acceleration at repetition rates of up to 100 *** tape surface position was measured to be stable on the sub-micrometre scale,compatible with the high-numerical aperture focusing geometries required to achieve relativistic intensity interactions with the pulse energy available in current multi-Hz and near-future higher repetition-rate lasers(>kHz).Long-term drift was characterized at 100 Hz demonstrating suitability for operation over extended *** target was continuously operated at up to 5 Hz in a recent experiment for 70,000 shots without intervention by the experimental team,with the exception of tape replacement,producing the largest data-set of relativistically intense laser–solid foil measurements to *** tape drive provides robust targetry for the generation and study of high-repetitionrate ion beams using next-generation high-power laser systems,also enabling wider applications of laser-driven proton sources.

关键词： high-repetition-rate laser target laser-plasma acceleration proton generation tape-drive target

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EMP control and characterization on high-power laser systems

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High Power Laser science and Engineering 2018年第2期6卷 55-62页

作者： P.Bradford N.C.Woolsey G.G.scott G.Liao H.Liu Y.Zhang B.Zhu C.Armstrong s.astbury C.Brenner P.Brummitt F.Consoli I.East R.Gray D.Haddock E Huggard E J.R.Jones E.Montgomery I.Musgrave E Oliveira D.R.Rusby C.spindloe B.summers E.Zemaityte Z.Zhang Y.Li P.McKenna D.Neely Department of Physics York Plasma InstituteUniversity of YorkHeslingtonYork YO10 5DDUK Central Laser Facility STFC Rutherford Appleton LaboratoryDidcot OX110QXUK Key Laboratory for Laser Plasmas(Ministry of Education)and school of Physics and Astronomy Shanghai Jiao Tong UniversityShanghai 200240China Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China school of Physical sciences University of Chinese Academy of SciencesBeijing 100049China Department of Physics sUPA University of StrathclydeGlasgow G40NGUK ENEA-C.R.Frascati-Dipartimento FsN Via E.Fermi 4500044 FrascatiItaly space science Department STFC Rutherford Appleton LaboratoryDidcot OX110QXUK

Giant electromagnetic pulses(EMP) generated during the interaction of high-power lasers with solid targets can seriously degrade electrical measurements and equipment. EMP emission is caused by the acceleration of hot electrons inside the target, which produce radiation across a wide band from DC to terahertz frequencies. Improved understanding and control of EMP is vital as we enter a new era of high repetition rate, high intensity lasers(e.g. the Extreme Light Infrastructure).We present recent data from the VULCAN laser facility that demonstrates how EMP can be readily and effectively reduced. Characterization of the EMP was achieved using B-dot and D-dot probes that took measurements for a range of different target and laser parameters. We demonstrate that target stalk geometry, material composition, geodesic path length and foil surface area can all play a significant role in the reduction of EMP. A combination of electromagnetic wave and 3 D particle-in-cell simulations is used to inform our conclusions about the effects of stalk geometry on EMP,providing an opportunity for comparison with existing charge separation models.

关键词： high energy density physics high-power laser related laser components laser plasmas interaction target design and fabrication

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Effect of Eu3+,Bi3+,and Li+ doping on luminescent property of GdNbO4

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Journal of Rare Earths 2024年第1期42卷 66-75页

作者： s.W.Wi Y.s.Lee Department of Physics and Integrative Institute of Basic sciences Soongsil University

We investigated the emission properties of Eu3+-doped GdNbO4-based oxide phosphors,aiming at improving the Eu3+emission by codoping of Bi3+and Li+.Eu3+singly doped,Eu3+and Bi3+doubly doped,and Eu3+,Bi3+,and Li+triply doped GdNbO4were prepared using a high-temperature solid-state reaction *** red-orange emissions from Eu3+in the singly doped samples are significantly improved by the codoping of Bi3+,mainly due to the energy transfer from Bi3+to Eu3+.The additional codoping of Li+is found to increase the Eu3+emission *** improvement might be attributed to the increase in the photoluminescent quantum yield originating from larger grain sizes and better crystallinity.A detailed analysis of the X-ray diffraction pattern and the asymmetric ratio estimated from the photoluminescence spectra show that the local lattice environment around Eu3+in GdNbO4does not change significantly with the codoping of Bi3+and Li+.Our results indicate that Li+doping is a promising way to improve the emission properties of rare-earth ion-doped GdNbO4phosphors.

关键词： Eu 3+ GdNbO 4 Codoping of Li + Photoluminescence sensitizer Rare earths

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First evidence for chiral wobbling of triaxial nuclei

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Nuclear science and Techniques 2024年第7期35卷 4-7页

作者： s.Frauendorf Department of Physics and Astronomy University of Notre DameNotre DameIN 46556USA

Chirality(Greek“handiness”)is a property of many com-plex *** molecules exist in two forms,one being the mirror image of the *** for our hands,it is impossible to make the images identical by a suitable *** two forms are called left-handed and *** have the same binding energy,because the electro-magnetic interaction,which holds the molecule together,does not change under a *** properties that are insensitive to the geometry are also the *** different geometry is the reason why the left-handed form turns the polarization plane of transmitted light in one direction by some angle while the right-handed form turns it in the oppo-site direction by the same ***,the geometrical differences between the two species may have other *** two species of the carvon molecule shown in Fig.1 taste quite differently.

关键词： turns Chiral mirror

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Tribological behavior of lubricant-impregnated porous polyimide

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Friction 2024年第4期12卷 711-725页

作者： Jinbang LI Ningning ZHOU Janet s.s.WONG school of Mechanical Engineering and Mechanics Ningbo UniversityNingbo 315211China Beijing Key Laboratory of Long-life Technology of Precise Rotation and Transmission Mechanisms Beijing Institute of Control EngineeringBeijing 100029China Department of Mechanical Engineering Imperial College LondonLondon SW72AZUK

Porous materials impregnated with lubricants can be used in conditions where limited lubricant is *** this work,three porous polyimides(PPI)with different densities were ***(PAO)impregnated PPI(iPPI)discs were rubbed against steel and sapphire *** operando observations of the iPPI-sapphire contacts show that oil is released under an applied load,forming a meniscus around *** at the outlet is created at high sliding *** amount of released oil increases with increasing PPI *** moduli,E*,estimated based on the actual contact size show that trapped oil in iPPIs contributes to load *** higher speeds,tribological rehydration of the contact occurs in low density iPPI,with that E*rises with *** high density PPIs,high speeds give a constantly high E*which is limited by the viscoelastic properties of the PPI network and possibly the rate of oil *** of iPPI-steel contacts is governed by the mechanical properties of the PPI,the flow of the lubricant,and the roughness of the PPI *** low-and medium-density(highly porous,high roughness)PPIs,large amount of oil is released,and lubrication is mainly via lubricant restricted in the contact in the pores and possibly tribological *** high density(low porosity)PPI,with lower roughness,hydrodynamic lubrication is achieved which gives the lowest *** results show that polymeric porous materials for effective lubrication require the optimization of its surface roughness,stiffness,oil flow,and oil retentions.

关键词： polyimide porous material friction mechanism polymer limited lubrication

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Enhancing fatigue performance of AZ31 magnesium alloy components fabricated by cold metal transfer-based wire arc directed energy deposition through LPB

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Journal of Magnesium and Alloys 2024年第4期12卷 1638-1662页

作者： shambhu Kumar Manjhi srikanth Bontha A.s.s.Balan Department of Mechanical Engineering National Institute of Technology KarnatakaSurathkalSrinivasanagarMangaloreKarnataka 575025India

Cold Metal Transfer-Based Wire Arc Directed Energy Deposition(CMT-WA-DED)presents a promising avenue for the rapid fabrication of components crucial to automotive,shipbuilding,and aerospace ***,the susceptibility to fatigue of CMT-WA-DED-produced AZ31 Mg alloy components has impeded their widespread adoption for critical load-bearing *** this study,a comprehensive investigation into the fatigue behaviour of WA-DED-fabricated AZ31 Mg alloy has been carried out and compared to commercially available wrought AZ31 *** findings indicate that the as-deposited parts exhibit a lower fatigue life than wrought Mg alloy,primarily due to poor surface finish,tensile residual stress,porosity,and coarse grain microstructure inherent in the WA-DED *** Plasticity Burnishing(LPB)treatment is applied to mitigate these issues,which induce significant plastic deformation on the *** treatment resulted in a remarkable improvement of fatigue life by 42%,accompanied by a reduction in surface roughness,grain refinement and enhancement of compressive residual stress ***,during cyclic deformation,WA-DED specimens exhibited higher plasticity and dislocation density compared to both wrought and WA-DED+LPB specimens.A higher fraction of Low Angle Grain Boundaries(LAGBs)in WA-DED specimens contributed to multiple crack initiation sites and convoluted crack paths,ultimately leading to premature *** contrast,wrought and WA-DED+LPB specimens displayed a higher percentage of High Angle Grain Boundaries(HAGBs),which hindered dislocation movement and resulted in fewer crack initiation sites and less complex crack paths,thereby extending fatigue *** findings underscore the effectiveness of LPB as a post-processing technique to enhance the fatigue performance of WA-DED-fabricated AZ31 Mg alloy *** study highlights the importance of LPB surface treatment on AZ31 Mg components produced by CMT-WA-DED to remove surface d

关键词： Wire arc additive manufacturing AZ31 Mg alloy Low plasticity burnishing Low cycle fatigue test strain amplitude

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Ren-integrable and ren-symmetric integrable systems

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Communications in Theoretical Physics 2024年第3期76卷 62-69页

作者： s Y Lou school of Physical science and Technology Ningbo UniversityNingbo315211China

A new type of symmetry,ren-symmetry,describing anyon physics and corresponding topological physics,is ***-symmetry is a generalization of super-symmetry which is widely applied in super-symmetric physics such as super-symmetric quantum mechanics,super-symmetric gravity,super-symmetric string theory,super-symmetric integrable systems and so *** and Grassmann numbers are,in some sense,dual conceptions,and it turns out that these conceptions coincide for the ren situation,that is,a similar conception of ren-number(R-number)is devised for *** particular,some basic results of the R-number and ren-symmetry are exposed which allow one to derive,in principle,some new types of integrable systems including ren-integrable models and ren-symmetric integrable *** examples of ren-integrable KdV-type systems and ren-symmetric KdV equations are explicitly given.

关键词： symmetries integrable systems anyon physics extended supersymmetry ren-symmetry

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AutoRhythmAI: A Hybrid Machine and Deep Learning Approach for Automated Diagnosis of Arrhythmias

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Computers, Materials & Continua 2024年第2期78卷 2137-2158页

作者： s.Jayanthi s.Prasanna Devi Department of Computer science and Engineering SRM Institute of Science and Technology-Vadapalani CampusChennaiTamil NaduIndia

In healthcare,the persistent challenge of arrhythmias,a leading cause of global mortality,has sparked extensive research into the automation of detection using machine learning(ML)***,traditional ML and AutoML approaches have revealed their limitations,notably regarding feature generalization and automation *** glaring research gap has motivated the development of AutoRhythmAI,an innovative solution that integrates both machine and deep learning to revolutionize the diagnosis of *** approach encompasses two distinct pipelines tailored for binary-class and multi-class arrhythmia detection,effectively bridging the gap between data preprocessing and model *** validate our system,we have rigorously tested AutoRhythmAI using a multimodal dataset,surpassing the accuracy achieved using a single dataset and underscoring the robustness of our *** the first pipeline,we employ signal filtering and ML algorithms for preprocessing,followed by data balancing and split for *** second pipeline is dedicated to feature extraction and classification,utilizing deep learning ***,we introduce the‘RRI-convoluted trans-former model’as a novel addition for binary-class *** ensemble-based approach then amalgamates all models,considering their respective weights,resulting in an optimal model *** our study,the VGGRes Model achieved impressive results in multi-class arrhythmia detection,with an accuracy of 97.39%and firm performance in precision(82.13%),recall(31.91%),and F1-score(82.61%).In the binary-class task,the proposed model achieved an outstanding accuracy of 96.60%.These results highlight the effectiveness of our approach in improving arrhythmia detection,with notably high accuracy and well-balanced performance metrics.

关键词： Automated machine learning neural networks deep learning arrhythmias

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