Plasma physics

  • Article
    | Open Access

    Magnetized plasma can be regarded as topological matter. Here the authors identify a necessary and sufficient condition for the existence of topological edge mode and find that cold magnetized plasma has ten topological phases in the plasma frequency, cyclotron frequency and wave-vector space.

    • Yichen Fu
    •  & Hong Qin
  • Article
    | Open Access

    It was predicted that Alfvén waves can account for the acceleration of precipitating auroral electrons. Here, the authors show laboratory measurements of the resonant transfer of energy from Alfvén waves to electrons under conditions relevant to the auroral zone as a direct test.

    • J. W. R. Schroeder
    • , G. G. Howes
    •  & S. Dorfman
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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
  • Article
    | Open Access

    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