W. Yao

École Polytechnique

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J. Fuchs

Commissariat à l'Énergie Atomique et aux Énergies Alternatives

A. Ciardi

Sorbonne Université

K. Burdonov

École Polytechnique

СА

С. А. Пикуз

P.N. Lebedev Physical Institute of the Russian Academy of Sciences

E. d’Humières

Commissariat à l'Énergie Atomique et aux Énergies Alternatives

P. Antici

Institut National de la Recherche Scientifique

B. Qiao

Peking University

X. T. He

Institute of Applied Physics and Computational Mathematics

J. Béard

Laboratoire National des Champs Magnétiques Intenses

E. Filippov

Spanish Center for Pulsed Lasers

Cooperative Institutions

Commissariat à l'Énergie Atomique et aux Énergies Alternatives

Centre National de la Recherche Scientifique

Institute of Modern Physics

École Polytechnique

Sorbonne Université

Laboratoire pour l'utilisation des lasers intenses

Peking University

CEA Paris-Saclay

Russian Academy of Sciences

Université Paris-Saclay

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Characterization of the stability and dynamics of a laser-produced plasma expanding across a strong magnetic field

Matter and Radiation at Extremes (2022)

W. Yao Julien Capitaine B. Khiar T. Vinci K. Burdonov

Magnetized laser-produced plasmas are central to many studies in laboratory astrophysics, in inertial confinement fusion, and in industrial applications. Here, we present the results of large-scale three-dimensional magnetohydrodynamic simulations of the dynamics of a laser-produced plasma expanding into a transverse magnetic field with a strength of tens of teslas. The simulations show the plasma being confined by the strong magnetic field into a slender slab structured by the magnetized Rayleigh–Taylor instability that develops at the plasma–vacuum interface. We find that when the initial velocity of the plume is perturbed, the slab can develop kink-like motions that disrupt its propagation.

Rayleigh–Taylor instability

Slab

10.1063/5.0058306

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Characterization and performance of the Apollon short-focal-area facility following its commissioning at 1 PW level

Matter and Radiation at Extremes (2021)

K. Burdonov A. Fazzini V. Lelasseux J. Albrecht P. Antici

We present the results of the first commissioning phase of the short-focal-length area of the Apollon laser facility (located in Saclay, France), which was performed with the first available laser beam (F2), scaled to a nominal power of 1 PW. Under the conditions that were tested, this beam delivered on-target pulses of 10 J average energy and 24 fs duration. Several diagnostics were fielded to assess the performance of the facility. The on-target focal spot and its spatial stability, the temporal intensity profile prior to the main pulse, and the resulting density gradient formed at the irradiated side of solid targets have been thoroughly characterized, with the goal of helping users design future experiments. Emissions of energetic electrons, ions, and electromagnetic radiation were recorded, showing good laser-to-target coupling efficiency and an overall performance comparable to that of similar international facilities. This will be followed in 2022 by a further commissioning stage at the multi-petawatt level.

Pulse duration

10.1063/5.0065138

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Citations (43)

Saturation of the compression of two interacting magnetic flux tubes evidenced in the laboratory

arXiv (Cornell University) (2024)

A. Sladkov C. Fegan W. Yao A. F. A. Bott S. N. Chen

Interactions between magnetic fields advected by matter play a fundamental role in the Universe at all possible scales. A crucial role these interactions play is in making turbulent fields highly anisotropic, leading to observed ordered fields. These in turn, are important evolutionary factors for all the systems within and around. Despite scant evidence, due to the difficulty in measuring even near-Earth events, the magnetic field compression factor in these interactions, measured at very varied scales, is limited to a few. However, compressing matter in which a magnetic field is embedded, results in compression up to several thousands. Here we show, using laboratory experiments and matching three-dimensional hybrid simulations, that there is indeed a very effective saturation of the compression when two independent magnetic fields are advected by plasmas encounter. We found that the observed saturation is linked to a build-up of the magnetic pressure at the inflows encounter point, which decelerates them and thereby stops further compression. Moreover, the growth of an electric field, induced by the incoming flows and the magnetic field, acts in redirecting the inflows transversely, further hampering field compression.

Saturation (graph theory)

10.48550/arxiv.2404.12110

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Relay transport of relativistic flows in extreme magnetic fields of stars

Bulletin of the American Physical Society (2017)

W. Yao B. Qiao Zheng Xu Hua Zhang Henxin Chang

We find that the transport of relativistic flows in extreme magnetic fields can be achieved in a relay manner by considering the quantum electromagnetic cascade process, where photons play a key role as a medium. During the transport, the flow emits particle energy into photons via quantum synchrotron radiation, and then gains particles back by magnetic pair creation, forming a “particle-photon-particle” relay. Particle-in-cell simulations demonstrate that forward transport of the flow density is realized by a self-replenishment process with photon-pair cascades, while that of the flow energy is accomplished due to a new coupling path through radiation of photons. This novel transport mechanism is closely associated with jet generation and disk accretion around the neutron star of X-Ray Binaries, offering a potential explanation for the powerful jets observed there.

Energy transport

Source

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Enhanced Energy, Conversion Efficiency and Collimation of Protons Driven by High-Contrast and Ultra-Short Laser Pulses

W. Yao R. Lelièvre Tessa Waltenspiel Itamar Cohen A. Allaoua

Progress in laser-driven proton acceleration requires increasing the proton maximum energy and laser-to-proton conversion efficiency, while reducing the divergence of the proton beam. However, achieving all these qualities simultaneously has proven challenging experimentally, the increase in beam energy often coming at the cost of beam quality. Numerical simulations suggest that coupling multi-PW laser pulses with ultrathin foils could offer a route for such simultaneous improvement. Yet experimental investigations have been limited by the scarcity of such lasers and the need for very stringent temporal contrast conditions to prevent premature target expansion before the pulse maximum. Here, combining the newly commissioned Apollon laser facility that delivers high-power ultrashort (∼24fs) pulses, with a double plasma mirror scheme to enhance its temporal contrast, we demonstrate the generation of up to 35 MeV protons with only 5 J of laser energy. This approach also achieves improved laser-to-proton energy conversion efficiency, reduced beam divergence, and optimized spatial beam profile. Therefore, despite the laser energy losses induced by the plasma mirror, the proton beams produced by this method are enhanced on all accounts compared to those obtained under standard conditions. Particle-in-cell simulations reveal that this improvement results from the intensified electrostatic field caused by a more compact hot-electron distribution.

Collimated light

High energy

10.20944/preprints202405.1784.v1

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Enhanced Energy, Conversion Efficiency and Collimation of Protons Driven by High-Contrast and Ultrashort Laser Pulses

Applied Sciences (2024)

W. Yao R. Lelièvre Tessa Waltenspiel Itamar Cohen A. Allaoua

Progress in laser-driven proton acceleration requires increasing the proton maximum energy and laser-to-proton conversion efficiency while reducing the divergence of the proton beam. However, achieving all these qualities simultaneously has proven challenging experimentally, with the increase in beam energy often coming at the cost of beam quality. Numerical simulations suggest that coupling multi-PW laser pulses with ultrathin foils could offer a route for such simultaneous improvement. Yet, experimental investigations have been limited by the scarcity of such lasers and the need for very stringent temporal contrast conditions to prevent premature target expansion before the pulse maximum. Here, combining the newly commissioned Apollon laser facility that delivers high-power ultrashort (∼24fs) pulses with a double plasma mirror scheme to enhance its temporal contrast, we demonstrate the generation of up to 35 MeV protons with only 5 J of laser energy. This approach also achieves improved laser-to-proton energy conversion efficiency, reduced beam divergence, and optimized spatial beam profile. Therefore, despite the laser energy losses induced by the plasma mirror, the proton beams produced by this method are enhanced on all accounts compared to those obtained under standard conditions. Particle-in-cell simulations reveal that this improvement mainly results from a better space–time synchronization of the maximum of the accelerating charge-separation field with the proton bunch.

Collimated light

10.3390/app14146101

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Optimizing the laser coupling, matter heating, and particle acceleration from solids by using multiplexed ultraintense lasers

arXiv (Cornell University) (2022)

W. Yao M. Nakatsutsumi S. Buffechoux P. Antici Macro Borghesi

Realizing the full potential of ultrahigh-intensity lasers for particle and radiation generation will require multi-beam arrangements due to technology limitations. Here, we investigate how to optimize their coupling with solid targets. Experimentally, we show that overlapping two intense lasers in a mirror-like configuration onto a solid with a large preplasma can greatly improve the generation of hot electrons at the target front and ion acceleration at the target backside. The underlying mechanisms are analyzed through multidimensional particle-in-cell simulations, revealing that the self-induced magnetic fields driven by the two laser beams at the target front are susceptible to reconnection, which is one possible mechanism to boost electron energization. In addition, the resistive magnetic field generated during the transport of the hot electrons in the target bulk tends to improve their collimation. Our simulations also indicate that such effects can be further enhanced by overlapping more than two laser beams.

Particle (ecology)

10.48550/arxiv.2208.06272

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Prompt Emission of High-energy Nonthermal Photons from a Radiation-dominated Relativistic Magnetic Reconnection

The Astrophysical Journal (2021)

Y. Xie Zhouqiao Zhao Zhu Lei W. Yao Chen Zhou

In astrophysics, relativistic magnetic reconnection, where particles can accelerate in a region of a strong electric field and weak magnetic field, is a key physical process for the explanation of high-energy photon synchrotron emission above 160 MeV, the limit given by the balance between the accelerating electric force and the radiation reaction force. However, the reconnection dynamics—more importantly, the particle acceleration and photon emission dynamics—in this radiation-dominated, relativistic regime have not been self-consistently investigated yet. In this paper, through theoretical derivation of the modified relativistic tearing instability (RTI) and kinetic particle-in-cell simulations, we find that, because of the radiation reaction, the compression of the reconnecting current sheet is significantly enhanced, leading to an increase in the RTI growth rate in the short-wavelength range. As a result, during reconnection, the current sheet is fragmented into a chain of many more magnetic null points separated by much smaller plasmoids, which eventually gives rise to significant improvement of particle acceleration efficiency and shortening of photon emission duration. In the simulations, prompt emission at duration ωpeΔT ≃ 233 (reduced by a factor of 3) of high-energy nonthermal photons with a hard power law of index 2.11 for photon energies <100 MeV and index 1.39 for those >100 MeV is observed. These characteristics are consistent with the observed emission properties of short gamma-ray bursts, particularly of GRB 090510, supporting the radiation-dominated reconnection scenario.

Plasmoid

Current sheet

10.3847/1538-4357/ac1b29

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Magnetic reconnection in the high-energy density regime

Plasma Physics and Controlled Fusion (2017)

B. Qiao Z. Xu W. Yao H. X. Chang X. T. He

Magnetic reconnection (MR) in the high-energy-density (HED) regime is comprehensively investigated by particle-in-cell simulations. In the HED regime, the MR process is driven by two colliding magnetized plasma bubbles produced by intense lasers, where there are ambiguities in distinguishing the actual MR consequences from the pure bubble squeezing effects, because both lead to similar behaviors. After discerning these similarities, such as two-fluid effects, plasma heating and jetting, we establish the direct relevance between the actual consequences of MR with the electron dissipation region, magnetic energy conversion and the relaxation of plasma density gradient. With additional discussions of the 3D effects and relativistic features, the results will guide the future HED experiments for MR and other laboratory astrophysics studies.

Energy density

10.1088/1361-6587/aa6803

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An online readout CMOS detector to measure ion spectra produced by high-repetition-rate high-power lasers

arXiv (Cornell University) (2023)

K. Burdonov R. Lelièvre P. Forestier-Colleoni T. Ceccotti Mihai Cuciuc

We present the design and the absolute calibration of charged particle high-repetition-rate online readout CMOS system tailored for high-power laser experiments. This system equips a Thomson parabola (TP) spectrometer, used at the Apollon petawatt scale laser facility to measure the spectra of protons produced by high-intensity laser-target interactions. The RadEye1 CMOS matrixes array detectors are paired with a custom triggering system for image grabbing. This allows us to register the proton and ion signals remotely at a high-repetition-rate. The latter is presently of one shot/min, but the frame grabbing enables the system to be compatible with modern high-power lasers running e.g. at 10 Hz. We detail here the implementation, in the harsh electromagnetic environment of such interactions, of the system, and its absolute calibration of the RadEye CMOS matrices, which was performed for proton energies from 4 MeV to 20 MeV.

10.48550/arxiv.2303.08529

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