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Plasma Physics

Plasma exists in a mixed form of electrons, positive ions and neutral atoms or molecules and plays an important role in many processes; from astrophysical solar flares to nuclear fusion devices for energy applications. There is a strong research interest both in theory and experiment to understand how the plasma energy is transferred into other forms and how plasma behaves in different environments. Investigating these processes under extreme conditions in a table-top setting has become feasible due to the availability of high-power lasers.

In this collection we highlight a selection of recent experimental and theoretical research papers published on this multidisciplinary topic in Nature Communications. These articles feature research on fundamental plasma processes that are relevant to astrophysical events, energy transfer from laser to the particles during their acceleration, material development for plasma confinement and nuclear reactions in plasma fusion devices. This collection showcases the variety of research that different communities can bring together to better understand the ubiquitous processes in plasma.

Fundamental properties of plasma

High intensity light with a non-zero orbital angular momentum could aid the development of laser-wakefield particle accelerators. Here, the authors theoretically show that stimulated Raman backscattering in plasmas can generate and amplify orbital angular momentum lasers to petawatt intensities.

Article | Open Access | | Nature Communications

Charge screening dominates the behaviour of high-energy plasmas, which exist in stars and possibly in future fusion technology. Here, the authors describe a theoretical framework for charge screening that goes beyond the conventional model and demonstrate its importance in analysing experimental data.

Article | Open Access | | Nature Communications

The effect of dense plasma environment on the energy levels of an ion is usually described in terms of a lowering of its continuum level. Here the authors present an isochoric-heating experiment to measure and compare continuum lowering in single-species and mixture plasmas to provide insights for models.

Article | Open Access | | Nature Communications

Particle accelerators

Intense laser pulses can induce the propagation of coherent waves through a plasma, which are useful for accelerating electrons. Here, the authors use a genetic algorithm and a deformable mirror to optimize the wavefront and improve electron beam intensity and divergence.

Article | | Nature Communications

Controlling and improving electron beam parameters are crucial for their application in free electron laser and X-ray sources. Here the authors generate quality electron beams with reduced energy spread from plasma accelerators by using a tailored escort electron bunch with the main accelerating bunch.

Article | Open Access | | Nature Communications

High power lasers can produce electron-positron pairs at GeV energies, but doing so through laser–laser collisions would require exceedingly high intensities. Here the authors present an all-optical scheme for pair production by irradiating near-critical-density plasmas with two counter-propagating lasers.

Article | Open Access | | Nature Communications

Experimental investigations of the response of matter to ionization would require extremely fast ion pump pulses. Here, the authors explore a different approach observing ionisation dynamics in SiO2glass by generating synchronized proton pulses from the interaction of high-power lasers on a solid target.

Article | Open Access | | Nature Communications

Neutron beams are useful studying fundamental physics problems, fusion process and material properties. Here the authors use intense laser irradiation of deuterated nanowire array targets to create high energy density plasmas capable of efficient generation of ultrafast neutron pulses.

Article | Open Access | | Nature Communications

Table-top laser-plasma ion accelerators have many potential applications, but achieving simultaneous narrow energy spread and high efficiency remains a challenge. Here, the authors produce ion beams with up to 18 MeV per nucleon whilst keeping the energy spread reduced through a self-organized process.

Article | Open Access | | Nature Communications

Recently, there has been significant progress on the application of laser-generated proton beams in material science. Here the authors demonstrate the benefit of employing such beams in stress testing different materials by examining their mechanical, optical, electrical, and morphological properties.

Article | Open Access | | Nature Communications

Electron beam quality in accelerators is crucial for light source application. Here the authors demonstrate beam conditioning of laser plasma electrons thanks to a specific transport line enabling the control of divergence, energy, steering and dispersion and the application to observe undulator radiation.

Article | Open Access | | Nature Communications

Fusion devices

Magnetic fusion reactors with higher ratio of plasma kinetic pressure to magnetic pressure are economically desirable. The authors demonstrate a path to such a reactor in a field reversed configuration that can attain microstability and reduced particle and thermal fluxes by manipulating the shear flow.

Article | Open Access | | Nature Communications

Early stellarator designs suffered from high particle losses, an issue that can be addressed by optimization of the coils. Here the authors measure the magnetic field lines in the Wendelstein 7-X stellarator, confirming that the complicated design of the superconducting coils has been realized successfully.

Article | Open Access | | Nature Communications

Understanding the transport of ions, electrons and heat in magnetized plasmas is important to the development of fusion power as well as our understanding of the behaviour of astrophysical objects. Ida et al.find that stochastization of magnetic field lines in a plasma damps plasma flow more strongly than expected.

Article | Open Access | | Nature Communications

Laboratory & astrophysical plasma

Understanding the role of magnetic turbulence in the atmosphere is difficult as direct access is limited, but latest laser technology can enable such studies in the lab. Here the authors probe the evolution of such turbulence in laser-generated plasma with its implications to astrophysical environments.

Article | Open Access | | Nature Communications

Since the 1970s space missions have observed `equatorial noise' — noise-like plasma waves closely confined to the magnetic equatorial region of Earth s magnetosphere. Here, the authors uncover their structured and periodic frequency pattern, revealing that they are generated by proton distributions.

Article | Open Access | | Nature Communications

Alfvén waves are fundamental plasma modes that provide a mechanism for the transfer of energy between particles and fields. Here the authors confirm experimentally the conservative energy exchange between Alfvén wave fields and plasma particles via high-resolution MMS observations of Earth’s magnetosphere.

Article | Open Access | | Nature Communications

Alfvénic waves are oscillations that occur in a plasma threaded by a magnetic field and their propagation, reflection and dissipation is believed to be partly responsible for the solar wind. Here, the authors observe the counter-propagating Alfvénic waves that most models require for solar-wind acceleration.

Article | Open Access | | Nature Communications

Although magnetic reconnection is recognized as the dominant mode for solar wind plasma to enter the magnetosphere, Kelvin–Helmholtz waves (KHW) have been suggested to also be involved. Here, the authors use 7 years of THEMIS data to show that KHW occur 19% of the time, and may be important for plasma transport.

Article | Open Access | | Nature Communications

Plasma releases magnetic energy by magnetic reconnection but the clear evidence of this phenomenon in relativistic regime is still lacking. Here the authors present a scheme for laboratory observation of the relativistic magnetic reconnection driven by laser-produced energetic electrons in the plasma.

Article | Open Access | | Nature Communications