Anomalous temperature relaxation and particle transport in a strongly non-unifrom, fully in ionized Plasma in a stromg mangnetic field

1995 ◽  
Vol 53 (1) ◽  
pp. 31-48 ◽  
Author(s):  
Alf H. Øien
Keyword(s):  
Magnetic Field ◽  
Particle Transport ◽  
Transport Theory ◽  
Debye Length ◽  
Larmor Radius ◽  
Collision Integrals ◽  
Ion Interactions ◽  
Electrons And Ions ◽  
Temperature Relaxation ◽  
The Magnetic Field

In classical kinetic and transport theory for a fully ionized plasma in a magnetic field, collision integrals from a uniform theory without fields are used. When the magnetic field is so strong that electrons may gyrate during electron—electron and electron—ion interactions, the form of the collision integrals will be modified. Another modification will stem from strong non-uniformities transverse to the magnetic field B. Using collision terms that explicitly incorporate these effects, we derive in particular the temperature relaxation between electrons and ions and the particle transport transverse to the magnetic field. In both cases collisions between gyrating electrons, which move along the magnetic field, and non-gyrating ions, which move in arbitrary directions at a distance transverse to B from the electrons larger than the electron Larmor radius but smaller than the Debye length, give rise to enhancement factors in the corresponding classical expressions of order In (mion/mel).

Effects of repeated interactions and correlational disintegration on kinetic and transport properties of a non-neutral plasma in strong fields

1990 ◽  
Vol 44 (1) ◽  
pp. 167-190 ◽  
Author(s):  
Alf H. Øien
Keyword(s):  
Magnetic Field ◽  
Particle Transport ◽  
Axial Magnetic Field ◽  
Debye Length ◽  
Electron Plasma ◽  
Larmor Radius ◽  
Equilibration Time ◽  
Cylindrically Symmetric ◽  
Electric Potentials ◽  
Good Agreement

Collisions in a cylindrically symmetric non-neutral (electron) plasma, where the Larmor radius is much smaller than the Debye length, and the consequent particle transport, are studied. The plasma is confined radially by a strong axial magnetic field and axially by electric potentials. Hence two particles may interact repeatedly. Eventually they drift too far away from each other poloidally to interact any more, owing to shear in the E × B drift. The consequent build-up of correlation is limited by correlational disintegration due to collisions with ‘third particles’ between the repeated interactions. A kinetic equation including these effects is derived, and the cross-field particle transport along the density gradient is found. An associated equilibration time is shown to scale as B and to be in good agreement with the experimentally obtained values of Briscoli, Malmberg and Fine.

ORBIT ANALYZER PROBES FOR THE MEASUREMENT OF PLASMA TEMPERATURES

1967 ◽  
Vol 45 (9) ◽  
pp. 3055-3064 ◽  
Author(s):  
D. J. Loughran ◽  
L. Schott ◽  
H. M. Skarsgard
Keyword(s):  
Magnetic Field ◽  
Debye Length ◽  
Current Collector ◽  
Boltzmann Distribution ◽  
Electron Velocity ◽  
Larmor Radius ◽  
Ion Temperature ◽  
Magnetic Analyzer ◽  
Current Characteristics ◽  
The Magnetic Field

An investigation is presented of two different probes, of the magnetic analyzer type, in which the magnetic field used for analysis of the particle orbits is also present in the plasma. Both probes employ a current collector whose distance from the aperture plane is adjustable. One probe (the charge-selective probe) collects charged particles of one sign, while theother (the charge-insensitive probe) collects particles of both signs. Assuming a Maxwell–Boltzmann distribution of electrons, the current collection characteristics are calculated for each probe. The use of these current characteristics for the measurement of the electron temperature is discussed. A procedure is also given for obtaining the mean electron velocity perpendicular to the magnetic field in the case of a non-Maxwellian velocity distribution. Finally, methods for measuring the ion temperature are presented for the special case of a small Debye length compared with the ion Larmor radius.

scholarly journals Diffusion at the Earth magnetopause: enhancement by Kelvin-Helmholtz instability

2007 ◽  
Vol 25 (1) ◽  
pp. 271-282 ◽  
Author(s):  
R. Smets ◽  
G. Belmont ◽  
D. Delcourt ◽  
L. Rezeau
Keyword(s):  
Magnetic Field ◽  
Distribution Functions ◽  
Larmor Radius ◽  
Simple Analytical Model ◽  
Helmholtz Instability ◽  
Field Reversal ◽  
Finite Larmor Radius ◽  
The Earth ◽  
Specific Distribution ◽  
The Magnetic Field

Abstract. Using hybrid simulations, we examine how particles can diffuse across the Earth's magnetopause because of finite Larmor radius effects. We focus on tangential discontinuities and consider a reversal of the magnetic field that closely models the magnetopause under southward interplanetary magnetic field. When the Larmor radius is on the order of the field reversal thickness, we show that particles can cross the discontinuity. We also show that with a realistic initial shear flow, a Kelvin-Helmholtz instability develops that increases the efficiency of the crossing process. We investigate the distribution functions of the transmitted ions and demonstrate that they are structured according to a D-shape. It accordingly appears that magnetic reconnection at the magnetopause is not the only process that leads to such specific distribution functions. A simple analytical model that describes the built-up of these functions is proposed.

Influence of time-variable solar wind on the response of Mercury’s magnetosphere

2021 ◽  
Author(s):  
Sae Aizawa ◽  
Nicolas André ◽  
Ronan Modolo ◽  
Elisabeth Werner ◽  
Jim Slavin ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Charged Particles ◽  
Time Variable ◽  
Low Energy ◽  
Field Of View ◽  
Plasma Measurement ◽  
Electrons And Ions ◽  
Low Energy Electrons ◽  
The Magnetic Field

<p><span lang="EN-GB">BepiColombo is going to conduct its first Mercury flyby in October 2021. During this flyby,  plasma measurement will be obtained and bring new insights on the Hermean magnetosphere and its interaction with the Sun despite the limited field of view of the instruments during the cruise phase. Unlike Mariner-10 ion measurements will be obtained, and unlike MESSENGER, low energy electrons and ions will be measured simultaneously. In this study, we have revisited Mariner 10 and MESSENGER observations with the help of the global hybrid model LatHyS in order to understand the influence of time-variable solar wind and to constraint the plasma environment. We are able to reproduce the magnetic field observations of Mariner 10 along its trajectory with in particular two distinct signatures consisting of a quiet and disturbed state of the magnetosphere. In addition, the plasma spectrogram is also collected in the model and this enables us to detail the properties of the charged particles observed during the flyby. We will discuss all these signatures both in term of an interaction with a time-variable solar wind and localized processes occurring in the magnetosphere. We will then present the virtual sampling of both the magnetic field and plasma spectrogram along BepiColombo’s first Mercury flyby trajectory and discuss the possible signatures to be observed at that time.</span></p>

Transport of energetic particles from reconnecting current sheets in flaring corona to the heliosphere

2021 ◽  
Author(s):  
Philippa Browning ◽  
Mykola Gordovskyy ◽  
Satashi Inoue ◽  
Eduard Kontar ◽  
Kanya Kusano ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Energetic Particles ◽  
Transport Processes ◽  
Data Driven ◽  
Current Sheets ◽  
Electrons And Ions ◽  
Data Driven Approach ◽  
Particle Simulations ◽  
The Magnetic Field

<p>In this study, we inverstigate the acceleration of electrons and ions at current sheets in the flaring solar corona, and their transport into the heliosphere. We consider both generic solar flare models and specific flaring events with a data-driven approach. The aim is to answer two questions: (a) what fraction of particles accelerated in different flares can escape into the heliosphere?; and (b) what are the characteristics of the particle populations propagating towards the chromosphere and into the heliosphere?</p><p>We use a combination of data-driven 3D magnetohydrodynamics simulations with drift-kinetic particle simulations to model the evolution of the magnetic field and both thermal and non-thermal plasma and to forward-model observable characteristics. Particles are accelerated in current sheets associated with flaring reconnection. When applied to a specific flare, the model successfully predicts observed features such as the location and relative intensity of hard X-ray sources and helioseismic source locations. This confirms the viability of the approach.</p><p>Using these MHD-particle models, we will show how the magnetic field evolution and particle transport processes affect the characteristics of both energetic electrons and ions in the the inner corona and the heliosphere. The implications for interpretation of in situ measurements of energetic particles by Solar Orbiter and Parker Solar Probe will be discussed.</p><p> </p><p> </p>

Particle Transport in a Turbulent Square Duct Flow With an Imposed Magnetic Field

2013 ◽  
Author(s):  
Rui Liu ◽  
Surya P. Vanka ◽  
Brian G. Thomas
Keyword(s):  
Magnetic Field ◽  
Particle Transport ◽  
Continuous Flow ◽  
Duct Flow ◽  
Deposition Rates ◽  
Square Duct ◽  
Side Walls ◽  
Volume Method ◽  
The Magnetic Field ◽  
A Current

In this paper we study the particle transport and deposition in a turbulent square duct flow with an imposed magnetic field using Direct Numerical Simulations (DNS) of the continuous flow. A magnetic field induces a current and the interaction of this current with the magnetic field generates a Lorentz force which brakes the flow and modifies the flow structure. A second-order accurate finite volume method in time and space is used and implemented on a GPU. Particles are injected at the entrance to the duct continuously and their rates of deposition on the duct walls are computed for different magnetic field strengths. Because of the changes to the flow due to the magnetic field, the deposition rates are different on the top and bottom walls compared to the side walls. This is different than in a non-MHD square duct flow, where quadrant (and octant) symmetry is obtained.

Rayleigh-Taylor Instability of a Stratified Plasma

1974 ◽  
Vol 29 (3) ◽  
pp. 518-523 ◽  
Author(s):  
K. M. Srivastava
Keyword(s):  
Magnetic Field ◽  
Boussinesq Approximation ◽  
Short Wave ◽  
Taylor Instability ◽  
Larmor Radius ◽  
Finite Larmor Radius ◽  
Wave Disturbances ◽  
Magnetic Field Gradients ◽  
Rayleigh Taylor Instability ◽  
The Magnetic Field

We have investigated the effect of finite Larmor radius on the Rayleigh-Taylor instability of a semi-infinite, compressible, stratified and infinitely conducting plasma. The plasma is assumed to have a one dimensional density and magnetic field gradients. The eigenvalue problem has been solved under Boussinesq approximation for disturbances parallel to the magnetic field. It has been established that for perturbation parallel to the magnetic field, the system is stable for both stable and unstable stratification. For perturbation perpendicular to the magnetic field, the problem has been solved without Boussinesq approximation. The dispersion relation has been discussed in the two limiting cases, the short and long wave disturbances. It has been observed that the gyroviscosity has a destabilizing influence from k = 0 to k = 4.5 for ß* = 0.1 and for ß* = 0.1 up to k* = 2.85 and then onwards it acts as a stabilizing agent. It has a damping effect on the short wave disturbances. For some parameters, the largets imaginary part has been shown in Figs. 1 and 2

The Deflection Magnet Design for PKU Energetic Particle Instrument

2020 ◽  
Author(s):  
Weihong Shi ◽  
Xiangqian Yu ◽  
Yongfu Wang ◽  
Linghua Wang ◽  
Xin Huang ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Energetic Particle ◽  
Permanent Magnets ◽  
Interplanetary Space ◽  
Three Dimensional ◽  
Good Time ◽  
Electrons And Ions ◽  
Peking University ◽  
Dimensional Distribution ◽  
The Magnetic Field

<p>The Energetic Particle Instrument (EPI), proposed by Peking University for a L1 mission, is designed to provide the three-dimensional distribution of suprathermal electrons and ions with good time, energy and angular resolutions in the interplanetary space, respectively, at energies from 20 keV to 1 MeV and from 20 keV to 11 MeV.  The EPI consists of four dual-double-ended foil/magnet semi-conductor telescopes, which cleanly separate electrons in the energy range from 20 to 400 keV and ions from 20 keV to 6 MeV.</p><p>The magnet of semi-conductor telescopes consists of four type 677H rare earth permanent magnets and a soft iron frame. Due to the high saturation polarization and high magnetic anisotropy of the Nd<sub>2</sub>Fe<sub>14</sub>B strongly magnetic matrix phase, this system can make the magnetic field strong enough to make the electrons deflected.</p><p>A frame made of iron-cobalt alloy VACOFLUX 50 will be able to combine two pairs of magnets and cause the magnetic field to decay rapidly in the far field. In this way, the two air gaps in the system can simultaneously provide a deflecting magnetic field for a pair of anti-parallel sensor systems.</p>

Kinetic and transport theory for a non-neutral plasma taking account of strong gyration and non-uniformities on the collisional scale

1987 ◽  
Vol 38 (3) ◽  
pp. 351-371 ◽  
Author(s):  
Alf H. Øien
Keyword(s):  
Magnetic Field ◽  
Distribution Function ◽  
Electric Field ◽  
Strong Magnetic Field ◽  
Transport Theory ◽  
Collision Integral ◽  
Collision Term ◽  
Third Order ◽  
Derivatives Of ◽  
The Magnetic Field

From the BBGKY equations for a pure electron plasma a derivation is made of a collision integral that includes the combined effects of particle gyration in a strong magnetic field and non-uniformities of both the distribution function and the self-consistent electric field on the collisional scale. A series expansion of the collision integral through the distribution function and the electric field on the collisional scale is carried out to third order in derivatives of the distribution function and to second order in derivatives of the electric field. For the strong-magnetic-field case when collision-term contributions to only first order in 1/B are included, a particle flux transverse to the magnetic field proportional to l/B2 is derived. The importance of long-range collective collisions in this process is shown. The result is in contrast with the classical l/B4 proportionality, and is in accordance with earlier studies.

scholarly journals Ion energy increase in laser-generated plasma expanding through axial magnetic field trap

2007 ◽  
Vol 25 (3) ◽  
pp. 453-464 ◽  
Author(s):  
L. Torrisi ◽  
D. Margarone ◽  
S. Gammino ◽  
L. Andò
Keyword(s):  
Magnetic Field ◽  
Electric Field ◽  
Electric Fields ◽  
Axial Magnetic Field ◽  
Ion Beam ◽  
High Vacuum ◽  
Target Surface ◽  
Axial Direction ◽  
Ion Interactions ◽  
The Magnetic Field

Laser-generated plasma is obtained in high vacuum (10−7 mbar) by irradiation of metallic targets (Al, Cu, Ta) with laser beam with intensities of the order of 1010 W/cm2. An Nd:Yag laser operating at 1064 nm wavelength, 9 ns pulse width, and 500 mJ maximum pulse energy is used. Time of flight measurements of ion emission along the direction normal to the target surface were performed with an ion collector. Measurements with and without a 0.1 Tesla magnetic field, directed along the normal to the target surface, have been taken for different target-detector distances and for increasing laser pulse intensity. Results have demonstrated that the magnetic field configuration creates an electron trap in front of the target surface along the axial direction. Electric fields inside the trap induce ion acceleration; the presence of electron bundles not only focuses the ion beam but also increases its energy, mean charge state and current. The explanation of this phenomenon can be found in the electric field modification inside the non-equilibrium plasma because of an electron bunching that increases the number of electron-ion interactions. The magnetic field, in fact, modifies the electric field due to the charge separation between the clouds of fast electrons, many of which remain trapped in the magnetic hole, and slow ions, ejected from the ablated target; moreover it increases the number of electron-ion interactions producing higher charge states.

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