Laboratory evidence for proton energization by collisionless shock surfing

Yao, Wenyan; Fazzini, A.; Chen, S. N.; Burdonov, K.; Antici, P.; Béard, J.; Bolaños, S.; Ciardi, A.; Diab, Reda; Filippov, E.; Kisyov, S.; Lelasseux, V.; Miceli, M.; Moreno, Q.; Nastasa, Viorel; Orlando, S.; Pikuz, S. A.; Popescu, D.; Revet, G.; Ribeyre, X.; d’Humières, E.; Fuchs, Julien

doi:10.1038/s41567-021-01325-w

Cited by 15 publications

(37 citation statements)

References 78 publications

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“…In our situation, the shocks are perpendicular, i.e., the angle between the magnetic field and the shock propagation direction is θ Bn ≈ 90°, and are characterized by a β = P therm /P mag ≈ 0.1, hence the critical Mach number has a value M cr ms ∼ 2.6 (Edmiston & Kennel 1984). The shocks obtained in our experiment are supercritical up to 3-4 ns after the laser beams hit the targets and turn into subcritical for later times (Yao et al 2021). Indeed, they propagate with an initial velocity of v s ≈ 1500 km/s, which corresponds to M ms ≈ 3.3 > M cr ms , and when they eventually interact, they have a velocity of a few hundreds of km/s, which gives, for v s ≈ 500 km/s, M ms ≈ 1.1 < M cr ms .…”

Section: Resultsmentioning

confidence: 60%

“…The plasma flows expand in the low-density ambient hydrogen, which is quickly ionized by the x-rays produced by the irradiated targets, and shocks are generated as a result of the combined action of the supersonic piston expansion and of the externally applied B-field. In fact, the strong external magnetic field of 20 T is critical in providing additional pressure so that a magnetized shock can form in the hydrogen plasma (Yao et al 2021), as in its absence we would get a shock only in the presence of a denser background plasma. As a result, for early times, i.e., before ∼ 12 ns, we observe two well-developed shocks propagating against each other.…”

Section: Resultsmentioning

confidence: 99%

“…The pistons expand more slowly due to the increase of the magnetic pressure behind the shock. These hydrodynamic simulations performed with FLASH are capable of describing the overall dynamic of the system, but they were not able to quantitatively reproduce the temperatures measured in the experiment (Yao et al 2021), likely due to the fact that the kinetic effects associated to our collisionless system cannot be taken into account. That is why we have performed also PIC simulations to take them into account.…”

Section: Mhd Simulationsmentioning

confidence: 97%

“…The analysis of the Thomson scattered light was performed by comparison of the experimental images (recorded by the streak cameras) with the theoretical curves of the scattered spectrum for coherent TS in non-collisional plasmas, with the instrumental function width of 5.9 nm for the electron spectrometer and 0.12 nm for the ion spectrometer taken into account. We point out that the TS laser probe induces some heating in the hydrogen ambient gas (details can be found in Yao et al 2021). With TS, we can get a spatially and temporally resolved measurement of the plasma density and temperature.…”

Section: Setup and Diagnosticsmentioning

confidence: 99%

“…Accelerated ions with energy in the tens of MeV have been measured from the collision of two subcritical shocks at a small angle (Dudkin et al 2000), however their numbers are extremely small and there is still an ongoing effort to determine the acceleration mechanism. Recently, high-power lasers and externally controlled magnetic field generation have opened the door to investigations of astrophysically relevant collisionless shock studies on particle acceleration (Li et al 2019;Fiuza et al 2020;Yao et al 2021Yao et al , 2022. Here, we created in the laboratory subcritical perpendicular collisionless shocks, i.e., inside an external magnetic field perpendicular to the shock propagation direction.…”

Section: Introductionmentioning

confidence: 99%

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Particle energization in colliding subcritical collisionless shocks investigated in the laboratory

Fazzini¹,

Yao²,

K.³

et al. 2022

Preprint

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Context. Colliding collisionless shocks appear in a great variety of astrophysical phenomena and are thought to be possible sources of particle acceleration in the Universe. Aims. The main goal of our experimental and computational work is to understand what is the effect of the interpenetration between two subcritical collisionless shocks on particle energization. Methods. To investigate the detailed dynamics of this phenomenon, we have performed a dedicated laboratory experiment. We have generated two counter-streaming subcritical collisionless magnetized shocks by irradiating two teflon (CF 2 ) targets with 100 J, 1 ns laser beams on the LULI2000 laser facility. The interaction region between the plasma flows was pre-filled with a low density background hydrogen plasma and initialized with an externally applied homogeneous magnetic field perpendicular to the shocks. We have also modeled the macroscopic evolution of the system via hydrodynamic simulations and the microphysics at play during the interaction via Particle-In-Cell simulations.Results. We report here on measurements of the plasma density and temperature during the formation of the supercritical shocks, their transition to subcritical, and final interpenetration. We found that in the presence of two shocks the ambient ions reach energies around 1.5 times of the ones obtained with single shocks. Both the presence of the downstream zone of the second shock and of the downstream zone common for the two shocks play a role in the different energization: the characteristics of the perpendicular electric fields in the two areas allow, indeed, certain particles to keep being accelerated or to avoid being decelerated. Conclusions. The findings of our laboratory investigation are relevant for our understanding of the energy distribution of high-energy particles that populate the interplanetary space in our solar system and the very local interstellar medium around the heliopause, where the observations have found evidence of subcritical collisionless shocks that may, eventually, collide with each other.

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Section: Resultsmentioning

confidence: 60%

Section: Resultsmentioning

confidence: 99%

Section: Mhd Simulationsmentioning

confidence: 97%

Section: Setup and Diagnosticsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Particle energization in colliding subcritical collisionless shocks investigated in the laboratory

Fazzini¹,

Yao²,

K.³

et al. 2022

Preprint

Self Cite

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Investigating particle acceleration dynamics in interpenetrating magnetized collisionless super-critical shocks

et al. 2023

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Colliding collisionless shocks appear in a great variety of astrophysical phenomena and are thought to be possible sources of particle acceleration in the Universe. We have previously investigated particle acceleration induced by single super-critical shocks (whose magnetosonic Mach number is higher than the critical value of 2.7) (Yao et al., Nat. Phys., vol. 17, issue 10, 2021, pp. 1177–1182; Yao et al., Matter Radiat. Extrem., vol. 7, issue 1, 2022, 014402), as well as the collision of two sub-critical shocks (Fazzini et al., Astron. Astrophys., vol. 665, 2022, A87). Here, we propose to make measurements of accelerated particles from interpenetrating super-critical shocks to observe the ‘phase-locking effect’ (Fazzini et al., Astron. Astrophys., vol. 665, 2022, A87) from such an event. This effect is predicted to significantly boost the energy spectrum of the energized ions compared with a single super-critical collisionless shock. We thus anticipate that the results obtained in the proposed experiment could have a significant impact on our understanding of one type of primary source (acceleration of thermal ions as opposed to secondary acceleration mechanisms of already energetic ions) of ion energization of particles in the Universe.

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Electron stochastic acceleration in laboratory-produced kinetic turbulent plasmas

Yuan,

Lei,

Wei

et al. 2024

Nat Commun

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The origin of energetic charged particles in universe remains an unresolved issue. Astronomical observations combined with simulations have provided insights into particle acceleration mechanisms, including magnetic reconnection acceleration, shock acceleration, and stochastic acceleration. Recent experiments have also confirmed that electrons can be accelerated through processes such as magnetic reconnection and collisionless shock formation. However, laboratory identifying stochastic acceleration as a feasible mechanism is still a challenge, particularly in the creation of collision-free turbulent plasmas. Here, we present experimental results demonstrating kinetic turbulence with a typical spectrum k−2.9 originating from Weibel instability. Energetic electrons exhibiting a power-law distribution are clearly observed. Simulations further reveal that thermal electrons undergo stochastic acceleration through collisions with multiple magnetic islands-like structures within the turbulent region. This study sheds light on a critical transition period during supernova explosion, where kinetic turbulences originating from Weibel instability emerge prior to collisionless shock formation. Our results suggest that electrons undergo stochastic acceleration during this transition phase.

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Laboratory evidence for proton energization by collisionless shock surfing

Cited by 15 publications

References 78 publications

Particle energization in colliding subcritical collisionless shocks investigated in the laboratory

Particle energization in colliding subcritical collisionless shocks investigated in the laboratory

Investigating particle acceleration dynamics in interpenetrating magnetized collisionless super-critical shocks

Electron stochastic acceleration in laboratory-produced kinetic turbulent plasmas

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