The time dependent electron velocity distribution in a fully ionized gas under the action of electric and magnetic field

1971 ◽  
Vol 21 (2) ◽  
pp. 153-160
Author(s):  
B. Šesták
Keyword(s):  
Magnetic Field ◽  
Velocity Distribution ◽  
Time Dependent ◽  
Electron Velocity ◽  
Ionized Gas ◽  
Electron Velocity Distribution ◽  
Electric And Magnetic Field

Particle-In-Cell simulations of resonant interactions between whistler waves and electrons in the near-Sun solar wind: scattering of the strahl into the halo and heat flux regulation.

2021 ◽  
Author(s):  
Alfredo Micera ◽  
Andrei Zhukov ◽  
Rodrigo A. López ◽  
Maria Elena Innocenti ◽  
Marian Lazar ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Heat Flux ◽  
Solar Wind ◽  
Velocity Distribution ◽  
Pitch Angle ◽  
Electron Velocity ◽  
Magnetic Field Direction ◽  
Whistler Waves ◽  
Electron Velocity Distribution ◽  
Particle In Cell

<p>Electron velocity distribution functions, initially composed of core and strahl populations as typically encountered in the near-Sun solar wind and as recently observed by Parker Solar Probe, have been modeled via fully kinetic Particle-In-Cell simulations. It has been demonstrated that, as a consequence of the evolution of the electron velocity distribution function, two branches of the whistler heat flux instability can be excited, which can drive whistler waves propagating in the direction parallel or oblique to the background magnetic field. First, the strahl undergoes pitch-angle scattering with oblique whistler waves, which provokes the reduction of the strahl drift velocity and the simultaneous broadening of its pitch angle distribution. Moreover, the interaction with the oblique whistler waves results in the scattering towards higher perpendicular velocities of resonant strahl electrons and in the appearance of a suprathermal halo population which, at higher energies, deviates from the Maxwellian distribution. Later on, the excited whistler waves shift towards smaller angles of propagation and secondary scattering processes with quasi-parallel whistler waves lead to a redistribution of the scattered particles into a more symmetric halo. All processes are accompanied by a significant decrease of the heat flux carried by the strahl population along the magnetic field direction, although the strongest heat flux rate decrease is simultaneous with the propagation of the oblique whistler waves.</p>

The effect of the orientations of electric and magnetic fields on the electron mean energy and drift velocity in a partially ionized gas

1961 ◽  
Vol 259 (1299) ◽  
pp. 518-530 ◽  
Keyword(s):  
Magnetic Field ◽  
Velocity Distribution ◽  
Electron Energy ◽  
Drift Velocity ◽  
Electron Velocity ◽  
Collision Time ◽  
Electron Velocity Distribution ◽  
Electron Velocity Distribution Function ◽  
The Mean ◽  
The Magnetic Field

The present investigation attempts to analyze the influence of the orientations of the imposed magnetic and electric fields on the mean electron energy and drift velocity. For this purpose, the electron velocity distribution function relating to the presence of the external fields with arbitrary orientations is first studied. The analysis is based on the Lorentz approximation and it is assumed that the electron velocity distribution is deter­mined essentially by the electron-atom collisions. The mean electron energy is discussed for two different cases: (1) contant mean free path and (2) constant collision time. In the case of constant collision time, the drift velocity as well as the electron current density is calculated. The Hall conductivity is expressed in a general form which depends upon the direction of the magnetic field with respect to the electrical field. Besides this, an additional com­ponent of the current is theoretically observed; in general, it vanishes if the magnetic field is either parallel or perpendicular to the electric field.

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