Dispersion and damping rate of Langmuir wave in space plasma with regularized Kappa distributed electrons

2021 ◽  
Author(s):  
Yong Liu ◽  
Xu Chen
Keyword(s):  
Source Region ◽  
Collisionless Plasma ◽  
Langmuir Wave ◽  
Nonlinear Process ◽  
Cutoff Parameter ◽  
Linear Behavior ◽  
Damping Rate ◽  
Solar Type ◽  
The One ◽  
Kappa Distributed Electrons

Abstract The dispersion of Langmuir wave (LW) in an unmagnetized collisionless plasma with regularized Kappa distributed electrons is investigated from the kinetic theory. The frequency and damping rate of LW are analyzed for the parameters relating to the source region of a solar type III radio burst. It is found that the linear behavior of LW is greatly modified by the suprathermal index κ and the exponential cutoff parameter α. In the region κ<1.5, the damping rate of LW will be much larger than the one with Maxwellian distributed electrons. Hence, the nonlinear process of LW in low κ region may exhibit different properties in comparison with the one in large $\kappa$ region.

Heliograph Observations of both Fast Drift (Type III) and Continuum (Type IV) Solar Emission from the one Source high above the Solar Limb

1978 ◽  
Vol 3 (4) ◽  
pp. 253-256 ◽  
Author(s):  
R. A. Duncan
Keyword(s):  
Langmuir Wave ◽  
Solar Limb ◽  
Continuum Emission ◽  
Type Iii ◽  
Type Iv ◽  
Solar Type ◽  
Fast Drift ◽  
The One ◽  
Wave Conversion ◽  
Late Stages

Many authors (e.g. Magun et al. 1975) have debated the question ‘does solar type IV continuum emission arise through Langmuir wave conversion or through gyro-synchrotron emission?’ Culgoora radio spectrograph and heliograph observations of the late stages of a recent (7 September 1977) type II, IV event showed both type IV* (continuum) and transient type III (electron-beam) emission coming from the same source, high above the solar limb. These observations suggest that this particular type IV continuum arose through a mechanism similar to that of the type III, probably fundamental Langmuir-wave emission, in a corona with a tenfold enhancement of plasma density.

scholarly journals Full exploration of the giant planet population around β Pictoris

2018 ◽  
Vol 612 ◽  
pp. A108 ◽  
Author(s):  
A.-M. Lagrange ◽  
M. Keppler ◽  
N. Meunier ◽  
J. Lannier ◽  
H. Beust ◽  
...  
Keyword(s):  
Extrasolar Planets ◽  
Giant Planet ◽  
Young Stars ◽  
Giant Planets ◽  
Close Orbit ◽  
Wide Range ◽  
Detection Probabilities ◽  
Solar Type ◽  
Formation And Evolution ◽  
The One

Context. The search for extrasolar planets has been limited so far to close orbit (typ. ≤5 au) planets around mature solar-type stars on the one hand, and to planets on wide orbits (≥10 au) around young stars on the other hand. To get a better view of the full giant planet population, we have started a survey to search for giant planets around a sample of carefully selected young stars. Aims. This paper aims at exploring the giant planet population around one of our targets, β Pictoris, over a wide range of separations. With a disk and a planet already known, the β Pictoris system is indeed a very precious system for studies of planetary formation and evolution, as well as of planet–disk interactions. Methods. We analyse more than 2000 HARPS high-resolution spectra taken over 13 years as well as NaCo images recorded between 2003 and 2016. We combine these data to compute the detection probabilities of planets throughout the disk, from a fraction of au to a few dozen au. Results. We exclude the presence of planets more massive than 3 MJup closer than 1 au and further than 10 au, with a 90% probability. 15+ MJup companions are excluded throughout the disk except between 3 and 5 au with a 90% probability. In this region, we exclude companions with masses larger than 18 (resp. 30) MJup with probabilities of 60 (resp. 90) %.

A self-similar solution for expansion into a vacuum of a collisionless plasma bunch

1998 ◽  
Vol 59 (1) ◽  
pp. 83-90 ◽  
Author(s):  
A. V. BAITIN ◽  
K. M. KUZANYAN
Keyword(s):  
Electron Distribution Function ◽  
Collisionless Plasma ◽  
Electron Component ◽  
One Dimensional ◽  
Ultrarelativistic Electron ◽  
Plasma Bunch ◽  
Self Similar Solution ◽  
Self Similar ◽  
The One ◽  
Similar Solutions

The process of expansion into a vacuum of a collisionless plasma bunch with relativistic electron temperature is investigated for the one-dimensional case. Self-similar solutions for the evolution of the electron distribution function and ion acceleration are obtained, taking account of cooling of the electron component of plasma for the cases of non-relativistic and ultrarelativistic electron energies.

scholarly journals Optimal control of the two-dimensional Vlasov-Maxwell system

2020 ◽  
Author(s):  
Jörg Weber
Keyword(s):  
Adjoint Equation ◽  
Collisionless Plasma ◽  
Three Dimensional ◽  
Classical Solutions ◽  
Two Dimensional ◽  
Maxwell System ◽  
Global Classical Solutions ◽  
Global Existence Of Solutions ◽  
Dimensional Version ◽  
The One

The time evolution of a collisionless plasma is modeled by the Vlasov-Maxwell system which couples the Vlasov equation (the transport equation) with the Maxwell equations of electrodynamics. We only consider a two-dimensional version of the problem since existence of global, classical solutions of the full three-dimensional problem is not known. We add external currents to the system, in applications generated by coils, to control the plasma properly. After considering global existence of solutions to this system, differentiability of the control-to-state operator is proved. In applications, on the one hand, we want the shape of the plasma to be close to some desired shape. On the other hand, a cost term penalizing the external currents shall be as small as possible. These two aims lead to minimizing some objective function. We restrict ourselves to only such control currents that are realizable in applications. After that, we prove existence of a minimizer and deduce first order optimality conditions and the adjoint equation.

Ulysses Observations of Nonlinear Wave-wave Interactions in the Source Regions of Type III Solar Radio Bursts

2000 ◽  
Vol 179 ◽  
pp. 447-450
Author(s):  
G. Thejappa ◽  
R. J. MacDowall
Keyword(s):  
Acoustic Waves ◽  
Modulational Instability ◽  
Langmuir Wave ◽  
Wave Interactions ◽  
Burst Source ◽  
Langmuir Waves ◽  
Type Iii ◽  
Source Regions ◽  
Ion Acoustic ◽  
Solar Type

AbstractThe Ulysses Unified Radio and Plasma Wave Experiment (URAP) has observed Langmuir, ion-acoustic and associated solar type III radio emissions in the interplanetary medium. Bursts of 50–300 Hz (in the spacecraft frame) electric field signals, corresponding to long-wavelength ion-acoustic waves are often observed coincident in time with the most intense Langmuir wave spikes, providing evidence for the electrostatic decay instability. Langmuir waves often occur as envelope solitons, suggesting that strong turbulence processes, such as modulational instability and soliton formation, often coexist with weak turbulence processes, such as electrostatic decay, in a few type III burst source regions.

Modulational instability of obliquely modulated ionacoustic waves in a two-electron-temperature plasma

1985 ◽  
Vol 33 (2) ◽  
pp. 209-217 ◽  
Author(s):  
Yashvir ◽  
T. N. Bhatnagar ◽  
S. R. Sharma
Keyword(s):  
Electron Temperature ◽  
Acoustic Waves ◽  
Modulational Instability ◽  
Perturbation Technique ◽  
Collisionless Plasma ◽  
Maximum Growth ◽  
Maximum Growth Rate ◽  
Ion Acoustic Waves ◽  
Temperature Plasma ◽  
Damping Rate

The unstable domain in the (k, Ø) plane for oblique modulation of ion-acoustic waves, in a two-electron-temperature plasma, is investigated using the KBM perturbation technique. It is shown that, in a collisionless plasma, the maximum growth rate for the modulational instability, for large carrier-wave amplitudes (a0 ≳ 0·1), exceeds the electron Landau damping rate for sufficiently oblique modulation.

A Theoretical and Experimental Investigation of Mildly Nonlinear Consolidation Behavior in Saturated Soil

1971 ◽  
Vol 8 (2) ◽  
pp. 182-216 ◽  
Author(s):  
T. J. Poskitt ◽  
R. O. Birdsall
Keyword(s):  
Pore Pressure ◽  
Large Strain ◽  
Saturated Soil ◽  
Soil Parameters ◽  
Viscous Effects ◽  
Variable Permeability ◽  
Linear Behavior ◽  
Soil Skeleton ◽  
The One ◽  
Physical Laws

A theory is given which enables variable permeability and compressibility, large strain, and non-Newtonian viscous effects in the soil skeleton to be considered in the one-dimensional consolidation of saturated soil. The first three of these are fairly well understood phenomena and their influence on field behavior is predictable. The last, however, is much more open to interpretation and has been included to cover laboratory testing of thin samples where viscous effects are often known to be important. The rheological model used for the soil skeleton is of the same general form as that used by Gibson and Lo in their investigation of linear behavior in clays. However, in the present case nonlinear physical laws of a form known to fit the experimental data more closely have been used. This makes the governing equations nonlinear and they are correspondingly more difficult to solve. The principal theoretical results for settlement and pore pressure are given in a form convenient for practical use and a procedure is given whereby the basic soil parameters can be determined from a laboratory settlement curve. By using the parameters so obtained the theoretical midplane pore pressure can be computed and when compared with the experimental curve this gives a stringent test of the adequacy of the theory. Experimental results for three different clays are given, and the theory shows encouraging agreement with these.

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