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| Open AccessMicron-scale phenomena observed in a turbulent laser-produced plasma
Turbulence effects explored use macroscale systems in general. Here the authors generate a turbulent plasma using laser irradiation of a solid target and study the dynamics of the plasma flow at the micron-scale by using scattering of an XFEL beam.
- G. Rigon
- , B. Albertazzi
- & M. Koenig
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| Open AccessUltrafast multi-cycle terahertz measurements of the electrical conductivity in strongly excited solids
The electrical conductivity is critical to understand warm dense matter, but the accurate measurement is extremely challenging. Here the authors use multi-cycle THz pulses to measure the conductivity of gold foils strongly heated by free-electron laser, determining the individual contributions of electron-electron and electron-ion scattering.
- Z. Chen
- , C. B. Curry
- & S. H. Glenzer
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| Open AccessIntegration of full divertor detachment with improved core confinement for tokamak fusion plasmas
Plasma fusion devices like tokamaks are important for energy generation but there are many challenges for their steady state operation. Here, the authors show that full divertor detachment is compatible with high-confinement high-poloidal-beta core plasmas and this prevents the damage to the divertor target plates and the first wall.
- L. Wang
- , H. Q. Wang
- & J. B. Liu
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| Open AccessReal-time feedback control of the impurity emission front in tokamak divertor plasmas
The exhaust of heat and particles is an important challenge in future nuclear fusion devices. Here the authors report the use of carbon emission as indicator for plasma detachment in a tokamak and its real-time feedback control.
- T. Ravensbergen
- , M. van Berkel
- & M. R. de Baar
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| Open AccessElectrical conductivity of warm dense silica from double-shock experiments
Warm dense silica is a key component in rocky planets’ mantles, but reproducing the relevant conditions in experiments is challenging. Here the authors use a double-shock technique to achieve such conditions and measure the reflectivity in situ, providing insight into the conductivity and its possible impact on dynamo processes in super-Earths’ mantles.
- M. Guarguaglini
- , F. Soubiran
- & A. Ravasio
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| Open AccessLaboratory disruption of scaled astrophysical outflows by a misaligned magnetic field
Mass outflow is a common process in astrophysical objects. Here the authors investigate in which conditions an astrophysically-scaled laser-produced plasma flow can be collimated and evolves in the presence of a misaligned external magnetic field.
- G. Revet
- , B. Khiar
- & J. Fuchs
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| Open AccessUltrafast electron cooling in an expanding ultracold plasma
Here the authors report on the creation of ultracold plasma by photoionization of a Bose-Einstein condensate with a femtosecond laser pulse. The experimental setup grants direct access to the electron temperature and reveals ultrafast cooling of electrons in an initially strongly coupled plasma.
- Tobias Kroker
- , Mario Großmann
- & Juliette Simonet
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| Open AccessEffects of plasma turbulence on the nonlinear evolution of magnetic island in tokamak
Magnetic reconnection and plasma turbulence occur in atmospheric and magnetized laboratory plasmas. Here the authors report evolution of magnetic islands and plasma turbulence in tokamak plasmas using high resolution 2D electron cyclotron emission diagnostics.
- Minjun J. Choi
- , Lāszlo Bardōczi
- & George McKee
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| Open AccessObservations of pressure anisotropy effects within semi-collisional magnetized plasma bubbles
Magnetic fields can be reorganized by plasma flows and lead to effects such as magnetic reconnection. Here the authors explore the evolution of magnetized-plasma bubbles in a semi-collisional regime and the role of pressure anisotropy in influencing the flow of the laser-produced plasma.
- E. R. Tubman
- , A. S. Joglekar
- & N. C. Woolsey
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Article
| Open AccessAutomation and control of laser wakefield accelerators using Bayesian optimization
Laser wakefield accelerators are compact sources of ultra-relativistic electrons which are highly sensitive to many control parameters. Here the authors present an automated machine learning based method for the efficient multi-dimensional optimization of these plasma-based particle accelerators.
- R. J. Shalloo
- , S. J. D. Dann
- & M. J. V. Streeter
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Article
| Open AccessLaser-driven x-ray and proton micro-source and application to simultaneous single-shot bi-modal radiographic imaging
Here the authors show a synchronized single-shot bi-modal x-ray and proton source based on laser-generated plasma. This source can be useful for radiographic and tomographic imaging.
- T. M. Ostermayr
- , C. Kreuzer
- & J. Schreiber
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Article
| Open AccessHigh-resolution sampling of beam-driven plasma wakefields
Controlled particle acceleration in plasmas requires precise measurements of the excited wakefield. Here the authors report and demonstrate a high-resolution method to measure the effective longitudinal electric field of a beam-driven plasma-wakefield accelerator.
- S. Schröder
- , C. A. Lindstrøm
- & J. Osterhoff
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| Open AccessSelf-consistent kinetic model of nested electron- and ion-scale magnetic cavities in space plasmas
Magnetic cavities play important roles in the energy cascade, conversion and dissipation in turbulent plasmas. Here, the authors show a theoretical insight into magnetic cavities by deriving a self-consistent, kinetic theory of these coherent structures.
- Jing-Huan Li
- , Fan Yang
- & James L. Burch
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Article
| Open AccessObservation of a high degree of stopping for laser-accelerated intense proton beams in dense ionized matter
A detailed understanding of particle stopping in matter is essential for nuclear fusion and high energy density science. Here, the authors report one order of magnitude enhancement of intense laser-accelerated proton beam stopping in dense ionized matter in comparison with currently used models describing ion stopping in matter.
- Jieru Ren
- , Zhigang Deng
- & Yongtao Zhao
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| Open AccessMagnetotail reconnection onset caused by electron kinetics with a strong external driver
Magnetotail reconnection plays a crucial role in explosive energy conversion in geospace. Here, the authors show that magnetotail reconnection starts from electron reconnection in the presence of a strong external driver, which then develops into ion reconnection.
- San Lu
- , Rongsheng Wang
- & Shui Wang
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Article
| Open AccessVery-Low-Frequency transmitters bifurcate energetic electron belt in near-earth space
Very-Low-Frequency (VLF) communication transmitters, operate worldwide, radiate emissions at particular frequencies 10-30 kHz. Here, the authors show VLF transmitter emissions that leak from the Earth’s ground are primarily responsible for bifurcating the energetic electron belt over 20–100 keV.
- Man Hua
- , Wen Li
- & Geoffrey D. Reeves
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| Open AccessDissipation of electron-beam-driven plasma wakes
Plasma wakefield accelerators promise compact, affordable future particle accelerators, but require deposition of enormous energy into a small volume. Here, the authors measure and simulate how this energy transfers from the wake into surrounding plasma, a process that ultimately governs the accelerator’s repetition rate.
- Rafal Zgadzaj
- , T. Silva
- & M. C. Downer
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| Open AccessLocal heating of radiation belt electrons to ultra-relativistic energies
Electrons in the Van Allen radiation belts can have energies in excess of 7 MeV, however, the energization mechanism is debated. Here, the authors show phase space density peaks in magnetic coordinate space as a way of analyzing satellite observations which demonstrates that local acceleration is capable of heating electrons up to 7 MeV.
- Hayley J. Allison
- & Yuri Y. Shprits
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| Open AccessTransient lensing from a photoemitted electron gas imaged by ultrafast electron microscopy
Excited charge carriers, such as photoelectrons, play an important role in fundamental and technological fields. Here the authors employ an ultrafast electron microscope to directly visualize the cyclotron oscillations and oblate-to-prolate shape change of a photoemitted electron gas from a laser-excited copper surface.
- Omid Zandi
- , Allan E. Sykes
- & Renske M. van der Veen
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| Open AccessMagnetic pumping model for energizing superthermal particles applied to observations of the Earth's bow shock
Energetic particle generation is an important component of a variety of astrophysical systems. Here, the authors show when magnetic pumping is extended to a spatially-varying magnetic flux tube, magnetic trapping of superthermal particles renders pumping an effective energization method for particles moving faster than the speed of the waves.
- E. Lichko
- & J. Egedal
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| Open AccessPhoton deceleration in plasma wakes generates single-cycle relativistic tunable infrared pulses
Plasma can act as strong nonlinear refractive index medium that can be exploited to downshift the frequency of a laser pulse. Here, the authors show the generation of single-cycle tunable infrared pulses using strong density gradients associated with laser-produced wakes in plasmas.
- Zan Nie
- , Chih-Hao Pai
- & Chan Joshi
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| Open AccessDemonstration of X-ray Thomson scattering as diagnostics for miscibility in warm dense matter
It is challenging to reliably probe the miscibility behavior of elements in extreme conditions. Here, the authors use X-ray Thomson scattering and compare to the X-ray diffraction method in order to determine mixing of different atomic species in warm dense matter conditions.
- S. Frydrych
- , J. Vorberger
- & D. Kraus
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| Open AccessProminent radiative contributions from multiply-excited states in laser-produced tin plasma for nanolithography
Extreme ultraviolet (EUV) light is entering use in nanolithography. Here the authors discuss experimental and theoretical results about the prominent role of multiply-excited states in highly charged tin ions in the mechanism of EUV light emission from laser-produced plasma.
- F. Torretti
- , J. Sheil
- & J. Colgan
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| Open AccessInterspecies radiative transition in warm and superdense plasma mixtures
Matter at extremely high density and pressure behaves differently than at ambient conditions. Here the authors use first-principles calculations to show the existence of interspecies radiative and dipole-forbidden transitions in warm and superdense plasma mixture of iron and zinc.
- S. X. Hu
- , V. V. Karasiev
- & M. Torrent
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| Open AccessStructural dynamics in proteins induced by and probed with X-ray free-electron laser pulses
The local X-ray-induced dynamics that occur in protein crystals during serial femtosecond crystallography (SFX) measurements at XFELs are not well understood. Here the authors performed a time-resolved X-ray pump X-ray probe SFX experiment, and they observe distinct structural changes in the disulfide bridges and peptide backbone of proteins; complementing theoretical approaches allow them to further characterize the details of the X-ray induced ionization and local structural dynamics.
- Karol Nass
- , Alexander Gorel
- & Ilme Schlichting
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| Open AccessObservation of persistent species temperature separation in inertial confinement fusion mixtures
The influence of contaminants is one of the factors hindering self-sustained thermonuclear burn in inertial confinement fusion. Here, the authors present evidence, through simulations and experiments, that contaminants do not fully reach thermal equilibrium, and thus their amount is usually underestimated.
- Brian M. Haines
- , R. C. Shah
- & D. W. Schmidt
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| Open AccessDirect observation of imploded core heating via fast electrons with super-penetration scheme
Fast ignition is an interesting scheme for nuclear fusion reaction. Here the authors show electron generation using intense short laser pulses and energy transport by coupling the laser energy to the imploded plasma core as in the ICF conditions.
- T. Gong
- , H. Habara
- & K. A. Tanaka
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| Open AccessIntense attosecond pulses carrying orbital angular momentum using laser plasma interactions
Vortices in light fields are of growing importance in the XUV and X-ray ranges. Here the authors show by simulations that high harmonics and attosecond pulses, generated while irradiating a deformed thin foil with circularly-polarized Gaussian laser pulses, carry a well-defined orbital angular momentum.
- J. W. Wang
- , M. Zepf
- & S. G. Rykovanov
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| Open AccessOrigin of two-band chorus in the radiation belt of Earth
Chorus waves are crucial on radiation belt dynamics in the space of magnetized planets. Here, the authors show that initially excited single-band chorus waves can quickly accelerate medium energy electrons, and divide the anisotropic electrons into low and high energy components, which subsequently excite two-band chorus waves.
- Jinxing Li
- , Jacob Bortnik
- & Daniel N. Baker
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| Open AccessCharacterization of suprathermal electrons inside a laser accelerated plasma via highly-resolved K⍺-emission
Suprathermal electrons in laser-generated plasmas are potentially useful in many plasma environments. Here the authors show the characterization of suprathermal electrons in laser-generated Cu plasma using a high-resolution X-ray spectroscopy combined with hydrodynamic and atomic modeling.
- M. Šmíd
- , O. Renner
- & F. B. Rosmej
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| Open AccessGenerating keV ion distributions for nuclear reactions at near solid-density using intense short-pulse lasers
Studying nuclear reactions in an astrophysical plasma environment is challenging but laboratory experiments can mimic such extreme conditions. Here the authors discuss the potential use of intense laser-produced dense plasma to find the rates of nuclear reactions in plasma-screened conditions.
- A. J. Kemp
- , S. C. Wilks
- & G. Grim
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| Open AccessEvidence of ubiquitous Alfvén pulses transporting energy from the photosphere to the upper chromosphere
Heating of the upper solar atmospheric layers is an open question. Here, the authors show observational evidence that ubiquitous Alfven pulses are excited by prevalent photospheric swirls, which are found to propagate upwards and carry enough energy flux needed to balance the local upper chromospheric energy loss.
- Jiajia Liu
- , Chris J. Nelson
- & Robert Erdélyi
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| Open AccessEnhancing laser beam performance by interfering intense laser beamlets
Enhanced coupling of laser energy to the target particles is a fundamental issue in laser-plasma interactions. Here the authors demonstrate increased photon absorption leading into higher laser to electron and proton energy transfer through the interference of multiple coherent beamlets.
- A. Morace
- , N. Iwata
- & R. Kodama
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| Open AccessLoss-cone instability modulation due to a magnetohydrodynamic sausage mode oscillation in the solar corona
Magnetohydrodynamic (MHD) waves and plasma instabilities can be studied during solar flares. Here the authors show evidence for an MHD sausage mode oscillation periodically triggering electron acceleration at a magnetic null point in the solar corona, indicating MHD oscillations in plasma can indirectly lead to loss-cone instability modulation.
- Eoin P. Carley
- , Laura A. Hayes
- & Peter T. Gallagher
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| Open AccessSupersonic plasma turbulence in the laboratory
Supersonic turbulence is relevant to astrophysical plasmas with their study mostly limited to numerical simulations. Here the authors demonstrate supersonic turbulence in collisional high Mach number plasma jets generated in laboratory by using high power lasers.
- T. G. White
- , M. T. Oliver
- & G. Gregori
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| Open AccessEvidence for electron Landau damping in space plasma turbulence
Various physical mechanisms are proposed to explain the heating observed in turbulent astrophysical plasmas. Here, Chen et al. find a signature consistent with one of these mechanisms, electron Landau damping, by applying a field-particle correlation technique to in situ spacecraft data of turbulence in the Earth’s magnetosheath.
- C. H. K. Chen
- , K. G. Klein
- & G. G. Howes
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| Open AccessDirect observations of a surface eigenmode of the dayside magnetopause
Surface waves on the boundary between a magnetosphere and the surrounding plasma might get trapped by the ionosphere forming an eigenmode. Here, Archer et al. show direct observations of this proposed mechanism at Earth’s magnetosphere by analyzing the response to an isolated fast plasma jet detected by the THEMIS satellites.
- M. O. Archer
- , H. Hietala
- & V. Angelopoulos
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| Open AccessAb initio predictions for polarized deuterium-tritium thermonuclear fusion
Thermonuclear fusion of nuclei of deuterium and tritium may provide the energy for the future and spin polarization is a potential mechanism for enhancing the nuclear reaction. Here the authors predict the enhanced DT fusion rate using chiral effective field theory and ab initio calculations.
- Guillaume Hupin
- , Sofia Quaglioni
- & Petr Navrátil
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| Open AccessVisualization of rapid electron precipitation via chorus element wave–particle interactions
Electron precipitation plays major role in magnetospheric physics and space weather. Here the authors show nonlinear behavior of the wave–particle interaction in the magnetosphere as the evolution of chorus electromagnetic waves detected by the Arase satellite and PWING observatory.
- Mitsunori Ozaki
- , Yoshizumi Miyoshi
- & Iku Shinohara
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| Open AccessAll-optical structuring of laser-driven proton beam profiles
Shaping particle beams generated from laser-plasma accelerators is challenging. Here the authors demonstrate an all-optical method to structure the accelerated proton beam by modulating and imprinting the spatial laser profile onto the proton beam.
- Lieselotte Obst-Huebl
- , Tim Ziegler
- & Karl Zeil
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| Open AccessThe two-fluid dynamics and energetics of the asymmetric magnetic reconnection in laboratory and space plasmas
Magnetic energy in the plasma is transferred into particle energy by magnetic reconnection. Here the authors show the two-fluid dynamics of asymmetric magnetic reconnection in two different spatial scales of plasma, namely laboratory and astrophysical plasma.
- M. Yamada
- , L.-J. Chen
- & R. Torbert
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| Open AccessMagnetic reconnection driven by electron dynamics
Magnetic reconnection is the process of releasing energy by magnetized and space plasma. Here the authors report experimental observation of magnetic reconnection in laser-produced plasma and the role of electron scaling on reconnection.
- Y. Kuramitsu
- , T. Moritaka
- & M. Hoshino
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Article
| Open AccessFormation of electron radiation belts at Saturn by Z-mode wave acceleration
Radial diffusion is the only mechanism considered to accelerate trapped electrons to relativistic energies in Saturn’s magnetic field, forming radiation belts. Here the authors show another mechanism, electron acceleration via Doppler shifted cyclotron resonant interaction with Z-mode waves, which can form radiation belts inside the orbit of Enceladus.
- E. E. Woodfield
- , R. B. Horne
- & W. S. Kurth
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Article
| Open AccessSpectral interferometry with waveform-dependent relativistic high-order harmonics from plasma surfaces
High-order harmonic generation is explored in gases, solids and plasmas with moderate to high intensity lasers. Here the authors show spectral interferometry of HHG from relativistic plasma and its potential as a source of intense isolated attosecond pulses.
- Dmitrii Kormin
- , Antonin Borot
- & Laszlo Veisz
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Article
| Open AccessA diagnosis of the plasma waves responsible for the explosive energy release of substorm onset
The origin of geomagnetic substorms is still uncertain due to lack of comprehensive quantitative analyses. Here, the authors construct an observational dispersion relation of auroral forms that correspond to the explosive energy release from substorm onset.
- N. M. E. Kalmoni
- , I. J. Rae
- & C. Forsyth
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Article
| Open AccessMagnetized fast isochoric laser heating for efficient creation of ultra-high-energy-density states
It is desirable to deposit more energy in the dense plasma core to trigger the fusion ignition. Here the authors demonstrate enhanced energy coupling from laser to plasma core by using solid targets and guiding the transport of relativistic electron beam with external magnetic field.
- Shohei Sakata
- , Seungho Lee
- & Shinsuke Fujioka
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Article
| Open AccessEvidence of a turbulent ExB mixing avalanche mechanism of gas breakdown in strongly magnetized systems
Gas breakdown mechanism in plasma under the influence of complex electromagnetic field topology is still debatable. Here the authors present the evidence of the E×B mixing avalanche for gas breakdown in magnetized plasmas in fusion devices as tokamak.
- Min-Gu Yoo
- , Jeongwon Lee
- & Yong-Su Na
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| Open AccessProbing warm dense matter using femtosecond X-ray absorption spectroscopy with a laser-produced betatron source
Understanding the ultrafast dynamics of materials under extreme conditions is challenging. Here the authors use a femtosecond betatron X-ray source to investigate the solid to dense plasma phase transition in copper using XAS with unprecedented time resolution.
- B. Mahieu
- , N. Jourdain
- & L. Lecherbourg
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| Open AccessSimulations tackle abrupt massive migrations of energetic beam ions in a tokamak plasma
Understanding the occurrence of sudden changes in plasma parameters is important for the operation of magnetically confined fusion devices. Here the authors use simulation to shed light on the formation of abrupt large-amplitude events and the associated redistribution of energetic ions in a tokamak.
- Andreas Bierwage
- , Kouji Shinohara
- & Masatoshi Yagi