Nonstationary radial-velocity distribution function for charged particles in a uniform magnetic field

1975 ◽  
Vol 18 (11) ◽  
pp. 1613-1615
Author(s):  
B. V. Kholomai
Keyword(s):  
Magnetic Field ◽  
Distribution Function ◽  
Velocity Distribution ◽  
Radial Velocity ◽  
Uniform Magnetic Field ◽  
Charged Particles ◽  
Velocity Distribution Function

Electromagnetic fluctuations from energetic particles in plasmas

1988 ◽  
Vol 40 (3) ◽  
pp. 407-417 ◽  
Author(s):  
Cheng Chu ◽  
J. L. Sperling
Keyword(s):  
Distribution Function ◽  
Velocity Distribution ◽  
Charged Particles ◽  
Velocity Distribution Function ◽  
Black Body ◽  
Black Body Radiation ◽  
Specific Model ◽  
Magnetized Plasma ◽  
Plasma Power ◽  
Correlation Techniques

Electromagnetic fluctuations, induced by energetic charged particles, are calculated using correlation techniques for a uniform magnetized plasma. Power emission in the ion-cyclotron range of frequencies (ICRF) is calculated for a specific model of velocity distribution function. The emissive spectra are distinct from that of the black-body radiation and have features that are consistent with experimental observation.

New kinetic cyclotron instability for electron beam in time-changing magnetic fields

2020 ◽  
Vol 86 (3) ◽  
Author(s):  
Irena Vorgul ◽  
M. Ayling ◽  
C. R. Straub ◽  
D. M. MacKay ◽  
J. D. Houghton ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Distribution Function ◽  
Velocity Distribution ◽  
Cyclotron Resonance ◽  
Cyclotron Frequency ◽  
Resonance Condition ◽  
Velocity Distribution Function ◽  
Spatial Gradient ◽  
Total Change ◽  
The Magnetic Field

This paper examines the velocity distribution function and cyclotron resonance conditions for a beam of electrons moving in a magnetic field which gradually changes with time. A spatial gradient of magnetic field is known to result in an unstable horseshoe distribution of electrons. The field gradient in time adds additional effects due to an induced electric field. The resultant anisotropic velocity distribution function, which we call a Luvdisk distribution, has some distinctive properties when compared to the horseshoe. Fitting the cyclotron resonance condition circle shows that the frequency of the resultant emission is under the local cyclotron frequency. While the spatial gradient results in the emission coming almost perpendicularly to the field, the direction of the radiation under a time-changing field has more variability. The Luvdisk distribution also arises when the magnetic field has a gradient both in space and time. The beam can be unstable if those gradients are added or subtracted from each other (if the gradients are of equal or different sign), which occurs even when the total change of magnetic field is negative. While the frequency of the emission is related to the final magnetic field value, its direction is indicative of the field’s history which produced the instability.

scholarly journals Challenges in the determination of the interstellar flow longitude from the pickup ion cutoff

2018 ◽  
Vol 611 ◽  
pp. A61 ◽  
Author(s):  
A. Taut ◽  
L. Berger ◽  
E. Möbius ◽  
C. Drews ◽  
V. Heidrich-Meisner ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Distribution Function ◽  
Interstellar Medium ◽  
Velocity Distribution ◽  
Interplanetary Magnetic Field ◽  
Velocity Distribution Function ◽  
Systematic Errors ◽  
Fundamental Parameter ◽  
Field Orientation ◽  
Selection Of

Context. The interstellar flow longitude corresponds to the Sun’s direction of movement relative to the local interstellar medium. Thus, it constitutes a fundamental parameter for our understanding of the heliosphere and, in particular, its interaction with its surroundings, which is currently investigated by the Interstellar Boundary EXplorer (IBEX). One possibility to derive this parameter is based on pickup ions (PUIs) that are former neutral ions that have been ionized in the inner heliosphere. The neutrals enter the heliosphere as an interstellar wind from the direction of the Sun’s movement against the partially ionized interstellar medium. PUIs carry information about the spatial variation of their neutral parent population (density and flow vector field) in their velocity distribution function. From the symmetry of the longitudinal flow velocity distribution, the interstellar flow longitude can be derived.Aim. The aim of this paper is to identify and eliminate systematic errors that are connected to this approach of measuring the interstellar flow longitude; we want to minimize any systematic influences on the result of this analysis and give a reasonable estimate for the uncertainty.Methods. We use He+ data measured by the PLAsma and SupraThermal Ion Composition (PLASTIC) sensor on the Solar TErrestrial RElations Observatory Ahead (STEREO A) spacecraft. We analyze a recent approach, identify sources of systematic errors, and propose solutions to eliminate them. Furthermore, a method is introduced to estimate the error associated with this approach. Additionally, we investigate how the selection of interplanetary magnetic field angles, which is closely connected to the pickup ion velocity distribution function, affects the result for the interstellar flow longitude.Results. We find that the revised analysis used to address part of the expected systematic effects obtains significantly different results than presented in the previous study. In particular, the derived uncertainties are considerably larger. Furthermore, an unexpected systematic trend of the resulting interstellar flow longitude with the selection of interplanetary magnetic field orientation is uncovered.

Ion-acoustic double layers in magnetized plasma consisting of warm adiabatic ions and non-thermal electrons having vortex-like velocity distribution: existence and stability

2008 ◽  
Vol 74 (2) ◽  
pp. 163-186 ◽  
Author(s):  
JAYASREE DAS ◽  
ANUP BANDYOPADHYAY ◽  
K. P. DAS
Keyword(s):  
Magnetic Field ◽  
Distribution Function ◽  
Velocity Distribution ◽  
Double Layer ◽  
Static Magnetic Field ◽  
Velocity Distribution Function ◽  
Plasma Phys ◽  
Zk Equation ◽  
Ion Acoustic ◽  
Layer Solution

AbstractA combined Schamel's modified Korteweg–de Vries–Zakharov– Kuznetsov (S–KdV–ZK) equation efficiently describes the nonlinear behaviour of ion-acoustic waves in a plasma consisting of warm adiabatic ions and non-thermal electrons (due to the presence of fast energetic electrons) having vortex-like velocity distribution function (due to the presence of trapped electrons), immersed in a uniform (space-independent) and static (time-independent) magnetic field, when the vortex-like velocity distribution function of electrons approaches the non-thermal velocity distribution function of electrons as prescribed by Cairns et al. (1995 Electrostatic solitary structures in non-thermal plasmas. Geophys. Res. Lett. 22, 2709–2712), i.e. when the contribution of trapped electrons tends to zero. This combined S–KdV–ZK equation admits a double-layer solution propagating obliquely to the external uniform and static magnetic field. The condition for the existence of this double-layer solution has been derived. The three-dimensional stabilities of the double-layer solutions propagating obliquely to the external uniform and static magnetic field have been investigated by the multiple-scale perturbation expansion method of Allen and Rowlands (1993 Determination of growth rate for linearized Zakharov–Kuznetsov equation. J. Plasma Phys. 50, 413–424; 1995 Stability obliquely propagating plane solitons of the Zakharov–Kuznetsov equation. J. Plasma Phys. 53, 63–73). It is found that the double-layer solutions of the combined S–KdV–ZK equation are stable at the lowest order, i.e. up to the order k, where k is the wave number of perturbation.

Possible instrumental effects on moments computation of the solar wind proton velocity distribution function: Helios observations

2020 ◽  
Vol 639 ◽  
pp. A82 ◽  
Author(s):  
R. De Marco ◽  
R. Bruno ◽  
R. D’Amicis ◽  
D. Telloni ◽  
D. Perrone
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Distribution Function ◽  
Velocity Distribution ◽  
Field Data ◽  
Velocity Distribution Function ◽  
Instrumental Effects ◽  
Solar Wind Proton ◽  
Magnetic Field Data ◽  
Density Values

The solar wind is a highly turbulent medium in which most of the energy is carried by Alfvénic fluctuations. These fluctuations have a wide range of scales whose high-frequency tail can be relevant for the sampling techniques commonly used to detect the particle distribution in phase space in situ. We analyze the effect of Alfvénic fluctuations on moments computation of the solar wind proton velocity distribution for a plasma sensor, whose sampling time is comparable or even longer than the typical timescale of the velocity fluctuations induced by these perturbations. In particular, we numerically simulated the sampling procedure used on board Helios 2. We directly employed magnetic field data recorded by the Helios 2 magnetometer, when the s/c was immersed in fast wind during its primary mission to the Sun, to simulate Alfvénic fluctuations. More specifically, we used magnetic field data whose cadence of 4 Hz is considerably higher than that the plasma sensor needed to sample a full velocity distribution function, and we average these data to 1 Hz, which is the spin period of Helios. Density values, which are necessary to build Alfvénic fluctuations at these scales, are not available because the cadence of the Helios plasma data is 40.5 s. The adopted solution is based on the assumption that the available Helios plasma density power spectrum can be extended to the same frequencies as the magnetic field spectrum by extrapolating the power-law fit of the low-frequency range to the frequencies relevant for this study. Surrogate density values in the time domain are then obtained by inverse transforming this spectrum. We show that it cannot be excluded that relevant instrumental effects strongly contribute to generate interesting spectral and kinetic features that have been interpreted in the past literature as exclusively due to physical mechanisms.

scholarly journals The auroral O<sup>+</sup> non-Maxwellian velocity distribution function revisited

1997 ◽  
Vol 15 (2) ◽  
pp. 249-254 ◽  
Author(s):  
D. Hubert ◽  
F. Leblanc
Keyword(s):  
Magnetic Field ◽  
Distribution Function ◽  
Velocity Distribution ◽  
Polar Angle ◽  
Velocity Distribution Function ◽  
Distribution Functions ◽  
Field Direction ◽  
Magnetic Field Direction ◽  
Velocity Distribution Functions ◽  
The Magnetic Field

Abstract. New characteristics of O+ ion velocity distribution functions in a background of atomic oxygen neutrals subjected to intense external electromagnetic forces are presented. The one dimensional (1-D) distribution function along the magnetic field displays a core-halo shape which can be accurately fitted by a two Maxwellian model. The Maxwellian shape of the 1-D distribution function around a polar angle of 21 ± 1° from the magnetic field direction is confirmed, taking into account the accuracy of the Monte Carlo simulations. For the first time, the transition of the O+ 1-D distribution function from a core halo shape along the magnetic field direction to the well-known toroidal shape at large polar angles, through the Maxwellian shape at polar angle of 21 ± 1° is properly explained from a generic functional of the velocity moments at order 2 and 4.

scholarly journals Velocity distribution function of hydrogen atoms in ion source discharges

2021 ◽  
Author(s):  
Tatsuhiro Tokai ◽  
Yuji Shimabukuro ◽  
Hidenori Takahashi ◽  
Keita Bito ◽  
Motoi Wada
Keyword(s):  
Distribution Function ◽  
Velocity Distribution ◽  
Velocity Distribution Function ◽  
Ion Source ◽  
Hydrogen Atoms

scholarly journals Velocity distribution function of spontaneously evaporating atoms

2020 ◽  
Vol 5 (10) ◽  
Author(s):  
Sergiu Busuioc ◽  
Livio Gibelli ◽  
Duncan A. Lockerby ◽  
James E. Sprittles
Keyword(s):  
Distribution Function ◽  
Velocity Distribution ◽  
Velocity Distribution Function
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