scholarly journals BRAGINSKII EQUATIONS FOR HOT RELATIVISTIC PLASMAS: MIXED APPROACH

2020 ◽  
pp. 50-54
Author(s):  
I. Marushchenko ◽  
N.A. Azarenkov
Keyword(s):  
Transport Processes ◽  
Hot Electrons ◽  
Relativistic Electrons ◽  
Relativistic Hydrodynamics ◽  
Classical Representation ◽  
Fusion Plasma ◽  
Relativistic Plasmas ◽  
Astrophysical Objects ◽  
Relativistic Description ◽  
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.

scholarly journals Generation and transport of fast electrons inside cone targets irradiated by intense laser pulses

2006 ◽  
Vol 24 (1) ◽  
pp. 5-8 ◽  
Author(s):  
TATSUFUMI NAKAMURA ◽  
HITOSHI SAKAGAMI ◽  
TOMOYUKI JOHZAKI ◽  
HIDEO NAGATOMO ◽  
KUNIOKI MIMA
Keyword(s):  
Laser Pulses ◽  
Transport Processes ◽  
Hot Electrons ◽  
Intense Laser ◽  
Rear Side ◽  
Fast Electrons ◽  
Surface Magnetic Field ◽  
Particle In Cell ◽  
Intense Laser Pulses ◽  
Cone Target

Fast electrons are effectively generated from solid targets of cone-geometry by irradiating intense laser pulses, which is applied to fast ignition scheme. For realizing optimal core heating by those electrons, understanding the characteristics of electrons emitted from cone targets is crucial. In this paper, in order to understand the generation and transport processes of hot electrons inside the cone target, two-dimensional (2D) particle-in-cell (PIC) simulations were carried out. It is shown that hot electrons form current layers which are guided by self-generated surface magnetic field, which results in effective energy transfer from laser pulse to hot electrons. When the hot electrons propagate through the steep density gradient at the cone tip, electrostatic field is induced via Weibel instability. As a result, hot electrons are confined inside and emitted gradually from the target, as an electron beam of long duration. Energy spectrum and temporal profile of hot electrons are also evaluated at the rear side of the target, where the profile of rear side plasma is taken from the fluid code and the result is sent to Fokker-Planck code.

First solar electron events observed by EPD aboard Solar Orbiter

2021 ◽  
Author(s):  
Raúl Gómez-Herrero ◽  
Daniel Pacheco ◽  
Alexander Kollhoff ◽  
Francisco Espinosa Lara ◽  
Johan L. Freiherr von Forstner ◽  
...  
Keyword(s):  
Heavy Ions ◽  
Extreme Ultraviolet ◽  
Transport Processes ◽  
Relativistic Electrons ◽  
Radio Bursts ◽  
Solar Origin ◽  
Time Profiles ◽  
Field Environment ◽  
Multiple Spacecraft ◽  
Excellent Energy Resolution

<p>The first solar electron events detected by Solar Orbiter were observed by the Energetic Particle Detector (EPD) suite during July 11-23, 2020, when the spacecraft was at heliocentric distances between 0.61 and 0.69 au. We combined EPD electron observations from 4 keV to the relativistic range (few MeV), radio dynamic spectra and extreme ultraviolet (EUV) observations from multiple spacecraft in order to identify the solar origin of these electron events. Electron anisotropies and timing as well as the plasma and magnetic field environment were evaluated to characterize the interplanetary transport conditions. We found that all the electron events were clearly associated with type III radio bursts. EUV jets were also found in association with all of them except one. A diversity of time profiles and pitch-angle distributions (ranging from almost isotropic to beam-like) was observed. These observations indicate that different source locations and different magnetic connectivity and transport conditions were likely involved. The broad spectral range covered by EPD with excellent energy resolution and the high time cadence ensure that future observations close to the Sun will contribute to the understanding of the acceleration, release, and transport processes of energetic particles. EPD observations will play a key role in the identification of the sources of impulsive events and the links between the near-relativistic electrons and the ion populations enriched in <sup>3</sup>He and heavy ions</p><p> </p>

Generalization of the Harris current sheet model for non-relativistic, relativistic and pair plasmas

2008 ◽  
Vol 74 (6) ◽  
pp. 749-763 ◽  
Author(s):  
M. BALIKHIN ◽  
M. GEDALIN
Keyword(s):  
Magnetic Field ◽  
Current Sheet ◽  
Plasma Acceleration ◽  
Relativistic Plasmas ◽  
Special Cases ◽  
Self Consistent ◽  
Astrophysical Objects ◽  
The Magnetic Field

AbstractReconnection is believed to be responsible for plasma acceleration in a large number of space and astrophysical objects. Onset of reconnection is usually related to instabilities of current sheet equilibria. Analytical self-consistent models of an equilibrium current sheet (Harris equilibrium) are known for non-relativistic plasmas and some special cases of relativistic plasmas. We develop a description of generalized Harris equilibria in collisionless non-relativistic and relativistic plasmas. Possible shapes of the magnetic field are analyzed.

scholarly journals The model of the influence of the electron refluxing on the electron transport and Kα emission

2017 ◽  
Vol 35 (3) ◽  
pp. 483-491 ◽  
Author(s):  
J.C. Zhao ◽  
L.H. Cao ◽  
J.H. Zheng ◽  
Z.Q. Zhao ◽  
Z.J. Liu ◽  
...  
Keyword(s):  
Electric Fields ◽  
Critical Thickness ◽  
Energy Conversion Efficiency ◽  
Target Thickness ◽  
Thick Target ◽  
Transport Processes ◽  
Hot Electrons ◽  
Monte Carlo Code ◽  
Photon Yield ◽  
X Ray

AbstractIn our previous research (Zhao et al., 2016), we focus on the transport processes from hot electrons to Kα X-ray emission in a copper foil and nanobrush target when the electron refluxing effect is not taken into account. In this work, considering the refluxing effect, the transport of hot electrons in a solid target is studied by adding the electric fields both at the front and rear surfaces of the target with Monte Carlo code Geant4. Simulation results show that the electron refluxing has an important influence on Kα photon yield and the size of Kα radiation source. Kα yield from the 10-μm-thick target with the electron refluxing effect is 2.7–3.7 times more than that without the refluxing for the electron temperatures from 0.4 to 1.4 MeV. The laser-to-Kα photon energy conversion efficiency ${\rm \eta} _{L \to K_{\rm \alpha}} $ with the refluxing effect is always higher than that without the refluxing, and both of them decrease gradually with laser strength Iλ2. Considering the electron refluxing effect or not, the variations of Kα yield with the target thickness d are very different. A critical thickness of the target dc (~30 μm) is achieved to confirm whether the refluxing effect is valid for the target. For the target with the thickness d less than dc, the refluxing effect can enhance Kα yield with several times, while for the target with the thickness d larger than dc, the refluxing effect is not so effective. The full-width at half-maximum increases from 23 to 56 µm after including the refluxing effect by the electron beam with the radius of 10 µm and the temperature of 400 keV.

Subsonic Potentials in Ultradense Plasmas

2019 ◽  
Vol 74 (3) ◽  
pp. 207-212 ◽  
Author(s):  
Arroj A. Khan ◽  
I. Zeba ◽  
M. Jamil
Keyword(s):  
Test Particle ◽  
Relativistic Electrons ◽  
Ion Acoustic Wave ◽  
Dense Plasmas ◽  
Relativistic Plasmas ◽  
Quantum Hydrodynamic Model ◽  
Fermi Temperature ◽  
Dynamic Potential ◽  
Test Charge ◽  
Particle Speed

AbstractThe existence of the subsonic dynamic potential for a test charge in extremely dense quantum plasmas is pointed out for the first time. The dispersion equation of ion acoustic wave in relativistic plasmas is derived by using the quantum hydrodynamic model. The relativistic electrons obey Fermi statistics, whereas the ions are taken classically. The standard model of wake potential is hereafter applied for the derivation of dynamic potential of the test particle. A usual supersonic potential is found suppressed. However, the oscillatory subsonic wake potential does exist in small length scales. The analytical results are applied in different regions by taking the range of magnetic field as well as the electron number density. It is found that the dynamic potential exists only when vt < Cs, showing the presence of subsonic wake potential contrary to the usual supersonic condition vt > Cs. Here vt is the test particle speed and Cs is the acoustic speed defined by the Fermi temperature of the electrons. This work is significant in order to describe the structure formation in the astrophysical environment and laboratory dense plasmas.

scholarly journals On the kinetic foundations of Kaluza's magnetohydrodynamics

2015 ◽  
Vol 40 (2) ◽  
Author(s):  
Alfredo Sandoval-Villalbazo ◽  
Alma R. Sagaceta-Mejía ◽  
Ana L. García-Perciante
Keyword(s):  
Heat Flux ◽  
Kinetic Theory ◽  
Relativistic Effect ◽  
Transport Processes ◽  
Minkowski Space Time ◽  
Dimensional Minkowski Space ◽  
Relativistic Approach ◽  
Relativistic Description ◽  
Thermodynamic Forces ◽  
Complete Framework

AbstractRecent work has shown the existence of a relativistic effect present in a single component non-equilibrium fluid, corresponding to a heat flux due to an electric field [J. Non-Equilib. Thermodyn. 38 (2013), 141–151]. The treatment in that work was limited to a four-dimensional Minkowski space-time in which the Boltzmann equation was treated in a special relativistic approach. The more complete framework of general relativity can be introduced to kinetic theory in order to describe transport processes associated to electromagnetic fields. In this context, the original Kaluza's formalism is a promising approach [Sitz. Ber. Preuss. Akad. Wiss. (1921), 966–972; Gen. Rel. Grav. 39 (2007), 1287–1296; Phys. Plasmas 7 (2000), 4823–4830]. The present work contains a kinetic theory basis for Kaluza's magnetohydrodynamics and gives a novel description for the establishment of thermodynamic forces beyond the special relativistic description.

Turbulence acceleration by strong Langmuir plasmons in a laser-plasma

2007 ◽  
Vol 73 (5) ◽  
pp. 619-625 ◽  
Author(s):  
XIAO-SONG YANG ◽  
SAN-QIU LIU
Keyword(s):  
Laser Plasma ◽  
Planck Equation ◽  
Hot Electrons ◽  
Experimental Result ◽  
Relativistic Electrons ◽  
Critical Surface ◽  
Exponential Form ◽  
Strong Turbulence ◽  
Fokker Planck Equation ◽  
Fokker Planck

AbstractThe turbulence acceleration of ultra-relativistic electrons by strong Langmuir plasmons is analytically studied in a laser-plasma. Based on the Fokker–Planck equation in the frame of strong turbulence, the exponential form of the spectra of hot electrons is obtained theoretically, which is consistent with the experimental result near the critical surface in a laser-plasma.

scholarly journals X-ray emission from hot accretion flows

2013 ◽  
Vol 9 (S304) ◽  
pp. 266-269
Author(s):  
Andrzej Niedźwiecki ◽  
Fu-Guo Xie ◽  
Agnieszka Stȩpnik
Keyword(s):  
Magnetic Field ◽  
Synchrotron Radiation ◽  
Strong Magnetic Field ◽  
Relativistic Electrons ◽  
Refined Model ◽  
X Ray ◽  
Accretion Flows ◽  
Hydrodynamic Processes ◽  
General Relativistic ◽  
Relativistic Description

AbstractRadiatively inefficient, hot accretion flows are widely considered as a relevant accretion mode in low-luminosity AGNs. We study spectral formation in such flows using a refined model with a fully general relativistic description of both the radiative (leptonic and hadronic) and hydrodynamic processes, as well as with an exact treatment of global Comptonization. We find that the X-ray spectral index–Eddington ratio anticorrelation as well as the cut-off energy measured in the best-studied objects favor accretion flows with rather strong magnetic field and with a weak direct heating of electrons. Furthermore, they require a much stronger source of seed photons than considered in previous studies. The nonthermal synchrotron radiation of relativistic electrons seems to be the most likely process capable of providing a sufficient flux of seed photons. Hadronic processes, which should occur due to basic properties of hot flows, provide an attractive explanation for the origin of such electrons.

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