Generation of Cold Magnetized Relativistic Plasmas at the Rear of Thin Foils Irradiated by Ultra-High-Intensity Laser Pulses

A scheme to generate magnetized relativistic plasmas in a laboratory setting is proposed. It is based on the interaction of ultra-high-intensity sub-picosecond laser pulses with few-micron-thick foils or films. By means of Particle-In-Cell simulations, it is shown that energetic electrons produced by the laser and evacuated at the rear of the target trigger an expansion of the target, building up a strong azimuthal magnetic field. It is shown that in the expanding plasma sheath, a ratio of the magnetic pressure and the electron rest-mass energy density exceeds unity, whereas the plasma pressure is lower than the magnetic pressure and the electron gyroradius is lower than the plasma dimension. This scheme can be utilized to study astrophysical extreme phenomena such as relativistic magnetic reconnection in laboratory.

The spectral line asymmetry of the Doppler effect in relativistic plasmas

{In this work, we present a comparative study between the relativistic and non- relativistic Doppler effects on spectral line profiles in ultra-hot plasmas at the laboratory system. We have established an exact formula of the relativistic Doppler profile in ultra-high-temperature plasma that is not a Gaussian one (unlike the nonrelativistic Doppler profile that is Gaussian). We have also derived a new FWHM (Full Width at Half Maximum) formula of the corresponding profile that is different from the non-relativistic FWHM (sqrtlog(T=M)). We have also shown that, in the relativistic case, Doppler broadening exhibits an asymmetry of spectral line profile (non- gaussian profile). To ensure the validity of our investigation, we have compared our theoretical calculation with the experimental results that shows a good agreement.

Self-organized multiscale structures in thermally relativistic electron-positron-ion plasmas

The self-organization of a thermally relativistic magnetized plasma comprising of electrons, positrons and static ions is investigated. The self-organized state is found to be the superposition of three distinct Beltrami fields known as triple Beltrami (TB) state. In general, the eigenvalues associated with the multiscale self-organized vortices may be a pair of complex conjugate and real one. It is shown that all the eigenvalues become real when thermal energy increases or the positron density decreases. The impact of relativistic temperature and positron density on the formation of self-organized structures is investigated. The self-organized field and flow vortices may vary simultaneously on vastly different length scales. The disparate variation of self-organized vortices is important in the context of dynamo theory. The present work is useful to study the formation of multiscale vortices and dynamo mechanisms in multi-species thermally relativistic plasmas.

BRAGINSKII EQUATIONS FOR HOT RELATIVISTIC PLASMAS: MIXED APPROACH

In the paper, the Braginskii equations for relativistic electrons in hot plasmas with slow macroscopic fluxes are derived. This consideration is suitable for description of the typical fusion plasma with the temperatures of about several tens of kiloelectronvolt, when the plasma rotation and the longitudinal currents should be taken into account. Contrary to other papers devoted to classical description of transport processes in fusion devices, as well as to fully relativistic description of the astrophysical objects, we propose the mixed approach with fully relativistic kinetics for the hot electrons and non-relativistic macroscopic fluxes. The obtained form of the Braginskii equations includes all important features of relativistic hydrodynamics, has the same form as the classical representation, which is currently implemented into modern transport codes, and can easily replace the latter.