scholarly journals Transport of thermal plasma above the auroral ionosphere in the presence of electrostatic ion-cyclotron turbulence

1999 ◽  
Vol 17 (1) ◽  
pp. 27-36 ◽  
Author(s):  
V. E. Zakharov ◽  
C.-V. Meister
Keyword(s):  
Electric Fields ◽  
Electromagnetic Waves ◽  
Large Scale ◽  
Momentum Balance ◽  
Turbulent Region ◽  
Magnetospheric Convection ◽  
Ion Cyclotron ◽  
Nonisothermal Plasma ◽  
Field Lines ◽  
Energy And Momentum

Abstract. The electron component of intensive electric currents flowing along the geomagnetic field lines excites turbulence in the thermal magnetospheric plasma. The protons are then scattered by the excited electromagnetic waves, and as a result the plasma is stable. As the electron and ion temperatures of the background plasma are approximately equal each other, here electrostatic ion-cyclotron (EIC) turbulence is considered. In the nonisothermal plasma the ion-acoustic turbulence may occur additionally. The anomalous resistivity of the plasma causes large-scale differences of the electrostatic potential along the magnetic field lines. The presence of these differences provides heating and acceleration of the thermal and energetic auroral plasma. The investigation of the energy and momentum balance of the plasma and waves in the turbulent region is performed numerically, taking the magnetospheric convection and thermal conductivity of the plasma into account. As shown for the quasi-steady state, EIC turbulence may provide differences of the electric potential of ΔV≈1–10 kV at altitudes of 500 < h < 10 000 km above the Earth's surface. In the turbulent region, the temperatures of the electrons and protons increase only a few times in comparison with the background values.Key words. Magnetospheric physics (electric fields; plasma waves and instabilities)  

scholarly journals The relationship between small-scale and large-scale ionospheric electron density irregularities generated by powerful HF electromagnetic waves at high latitudes

2006 ◽  
Vol 24 (11) ◽  
pp. 2901-2909 ◽  
Author(s):  
E. D. Tereshchenko ◽  
B. Z. Khudukon ◽  
M. T. Rietveld ◽  
B. Isham ◽  
T. Hagfors ◽  
...  
Keyword(s):  
Geomagnetic Field ◽  
Electromagnetic Waves ◽  
Large Scale ◽  
Small Scale ◽  
Direction Parallel ◽  
Model Calculations ◽  
Amplitude Fluctuations ◽  
Field Lines ◽  
Experimental Values ◽  
Magnetic Zenith

Abstract. Satellite radio beacons were used in June 2001 to probe the ionosphere modified by a radio beam produced by the EISCAT high-power, high-frequency (HF) transmitter located near Tromsø (Norway). Amplitude scintillations and variations of the phase of 150- and 400-MHz signals from Russian navigational satellites passing over the modified region were observed at three receiver sites. In several papers it has been stressed that in the polar ionosphere the thermal self-focusing on striations during ionospheric modification is the main mechanism resulting in the formation of large-scale (hundreds of meters to kilometers) nonlinear structures aligned along the geomagnetic field (magnetic zenith effect). It has also been claimed that the maximum effects caused by small-scale (tens of meters) irregularities detected in satellite signals are also observed in the direction parallel to the magnetic field. Contrary to those studies, the present paper shows that the maximum in amplitude scintillations does not correspond strictly to the magnetic zenith direction because high latitude drifts typically cause a considerable anisotropy of small-scale irregularities in a plane perpendicular to the geomagnetic field resulting in a deviation of the amplitude-scintillation peak relative to the minimum angle between the line-of-sight to the satellite and direction of the geomagnetic field lines. The variance of the logarithmic relative amplitude fluctuations is considered here, which is a useful quantity in such studies. The experimental values of the variance are compared with model calculations and good agreement has been found. It is also shown from the experimental data that in most of the satellite passes a variance maximum occurs at a minimum in the phase fluctuations indicating that the artificial excitation of large-scale irregularities is minimum when the excitation of small-scale irregularities is maximum.

scholarly journals Behavior of compressed plasmas in magnetic fields

2020 ◽  
Vol 4 (1) ◽  
Author(s):  
Gurudas Ganguli ◽  
Chris Crabtree ◽  
Alex Fletcher ◽  
Bill Amatucci
Keyword(s):  
Electric Fields ◽  
Large Scale ◽  
Global Scale ◽  
Small Scale ◽  
Kinetic Regime ◽  
Plasma Dynamics ◽  
Formidable Challenge ◽  
Energy And Momentum ◽  
Intense Activity ◽  
Different Characteristics

AbstractPlasma in the earth’s magnetosphere is subjected to compression during geomagnetically active periods and relaxation in subsequent quiet times. Repeated compression and relaxation is the origin of much of the plasma dynamics and intermittency in the near-earth environment. An observable manifestation of compression is the thinning of the plasma sheet resulting in magnetic reconnection when the solar wind mass, energy, and momentum floods into the magnetosphere culminating in the spectacular auroral display. This phenomenon is rich in physics at all scale sizes, which are causally interconnected. This poses a formidable challenge in accurately modeling the physics. The large-scale processes are fluid-like and are reasonably well captured in the global magnetohydrodynamic (MHD) models, but those in the smaller scales responsible for dissipation and relaxation that feed back to the larger scale dynamics are often in the kinetic regime. The self-consistent generation of the small-scale processes and their feedback to the global plasma dynamics remains to be fully explored. Plasma compression can lead to the generation of electromagnetic fields that distort the particle orbits and introduce new features beyond the purview of the MHD framework, such as ambipolar electric fields, unequal plasma drifts and currents among species, strong spatial and velocity gradients in gyroscale layers separating plasmas of different characteristics, etc. These boundary layers are regions of intense activity characterized by emissions that are measurable. We study the behavior of such compressed plasmas and discuss the relaxation mechanisms to understand their measurable signatures as well as their feedback to influence the global scale plasma evolution.

Impacts of global re-/afforestation and deforestation on large scale atmospheric circulation

2020 ◽  
Author(s):  
Iris Manola ◽  
Dim Coumou ◽  
Andrea Alessandri ◽  
Edouard Davin ◽  
Suqi Guo ◽  
...  
Keyword(s):  
Atmospheric Circulation ◽  
Large Scale ◽  
Crop Yields ◽  
Dominant Role ◽  
Momentum Balance ◽  
Boreal Summer ◽  
Earth System ◽  
Model Experiments ◽  
Non Local ◽  
Energy And Momentum

&lt;p&gt;Land cover and land management (LCLM) changes have a high potential to influence the biogeophysical and biogeochemical earth system processes. The interaction of soil and vegetation with the atmosphere alternates the water, energy and momentum balance, in turn affecting the climate locally, as well as the climate of distant regions through teleconnection pathways. This, among others, might benefit or oppose risks to local and global breadbasket regions, impacting the crop yields.&lt;/p&gt; &lt;p&gt;In this study, we conduct model experiments to assess the local and remote impact of LCLM changes, in particular global re-/afforestation and deforestation, with a focus on the large-scale boreal summer atmospheric circulation. We hypothesize that due to the dominant role of land-atmosphere feedbacks in this season, robust dynamical transformations take place due to the LCLM changes. The idealized model experiments consist of three fully coupled Earth System Models (EC-EARTH, MPI-ESM and CESM) that run under constant 2015 greenhouse forcing for 150 years. Globally the LCLM changes go through a sequence of unchanged grid boxes in a checkerboard approach as recent studies have done, in order to accurately separate the local from the non-local effects.&lt;/p&gt;

Planar channel flow in Braginskii magnetohydrodynamics

2011 ◽  
Vol 667 ◽  
pp. 520-543 ◽  
Author(s):  
PAUL J. DELLAR
Keyword(s):  
Magnetic Field ◽  
Small Parameter ◽  
Boundary Layers ◽  
Large Scale ◽  
Viscosity Ratio ◽  
Maximum Velocity ◽  
Momentum Balance ◽  
Larmor Radius ◽  
Viscous Stress ◽  
Field Lines

Braginskii magnetohydrodynamics (MHD) is a single-fluid description of large-scale motions in strongly magnetised plasmas. The ion Larmor radius in these plasmas is much shorter than the mean free path between collisions, so momentum transport across magnetic field lines is strongly suppressed. The relation between the strain rate and the viscous stress becomes highly anisotropic, with the viscous stress being predominantly aligned parallel to the magnetic field. We present an analytical study of the steady planar flow across an imposed uniform magnetic field driven by a uniform pressure gradient along a straight channel, the configuration known as Hartmann flow, in Braginskii MHD. The global momentum balance cannot be satisfied by just the parallel viscous stress, so we include the viscous stress perpendicular to magnetic field lines as well. The ratio of perpendicular to parallel viscosities is the key small parameter in our analysis. When another parameter, the Hartmann number, is large the flow is uniform across most of the channel, with boundary layers on either wall that are modifications of the Hartmann layers in standard isotropic MHD. However, the Hartmann layer solution predicts an infinite current and infinite shear at the wall, consistent with a local series solution of the underlying differential equation that is valid for all Hartmann numbers. These singularities are resolved by inner boundary layers whose width scales as the three-quarters power of the viscosity ratio, while the maximum velocity scales as the inverse one-quarter power of the viscosity ratio. The inner wall layers fit between the Hartmann layers, if present, and the walls. The solution thus does not approach a limit as the viscosity ratio tends to zero. Essential features of the solution, such as the maximum current and maximum velocity, are determined by the size of the viscosity ratio, which is the regularising small parameter.

On Microfaceting Instability of Pt(110) Under Catalytic Oxidation of Adsorbed Co

1992 ◽  
Vol 263 ◽  
Author(s):  
M. Papoular
Keyword(s):  
Catalytic Oxidation ◽  
Oxidation Reaction ◽  
Nucleation And Growth ◽  
Point Of View ◽  
Momentum Balance ◽  
Layer By Layer ◽  
Adsorption Of Co ◽  
Specific Temperature ◽  
Energy And Momentum ◽  
Sawtooth Profile

ABSTRACTAs demonstrated by recent STM [1] and LEED [2] experiments the platinum (110) surface undergoes, at carbon monoxide submonolayer coverages, a phase transition from the 1 x 2 “missing-row” (reconstructed) state to the 1 x 1(bulk-like) state under specific temperature and partial-pressure conditions. The catalytic oxidation reaction CO + 1/2 → CO2 drives a microfaceting instability [3] [4] of the Pt(110) surface which ends up in a regular sawtooth profile with a period ≈ 200 Å, along the [110] direction.We introduce the idea that the rather extensive Pt mass transport, as involved in the process, could be energetically assisted by the reaction itself. Energy and momentum-balance considerations lead us to expect an energy ≲ 0.5 eV to be transferrable to thesubstrate. This should efficiently contribute to initiating the “scraping”process that leads to the microfaceted pattern.A simple model for nucleation and growth of facets is presented (see ref. 5), yielding characteristic times of order minutes (at T = 500 K), in fair agreement with experiment.Independently of the structural/catalytic problem, adsorption of CO at submonolayer coverages on, e.g., Pt(110) might be of interest from a surfactantphysics point of view (see ref. 6 for a very recent study on layer-by-layer homoepitaxial metal growth).

MUTUAL NONLINEAR INTERACTION OF A NUMBER OF ELECTROMAGNETIC WAVES IN A PLASMA

1963 ◽  
Vol 41 (10) ◽  
pp. 1702-1711 ◽  
Author(s):  
Mahendra Singh Sodha ◽  
Carl J. Palumbo
Keyword(s):  
Wave Equation ◽  
Electric Fields ◽  
Current Density ◽  
Nonlinear Interaction ◽  
Electromagnetic Waves ◽  
Physical Significance ◽  
Mutual Interaction ◽  
Modulated Waves ◽  
Boltzmann's Equation ◽  
Uniform Plasma

In this communication the authors have obtained an expression for current density in a slightly ionized uniform plasma in the presence of a number of electric fields of different frequencies by solving the appropriate Boltzmann's equation. This expression along with the wave equation has been used to investigate the nonlinear mutual interaction of a number of electromagnetic waves, propagating in a plasma. Limitations of the present analysis have also been indicated and the physical significance of the results has been discussed. The technique has also been applied to investigate the mutual interaction of amplitude-modulated waves, and the results express a generalization of Luxembourg effect to a number of strong modulated waves.

scholarly journals RF-Carpets that Compress Ions to High Density Beams

2015 ◽  
Vol 21 (S4) ◽  
pp. 84-89
Author(s):  
H. Wollnik ◽  
F. Arai ◽  
Y. Ito ◽  
P. Schury ◽  
M. Wada
Keyword(s):  
Phase Space ◽  
Electric Field ◽  
Electric Fields ◽  
Ion Beams ◽  
High Density ◽  
Ion Density ◽  
Field Lines

AbstractIons that are moved by electric fields in gases follow quite exactly the electric field lines since these ions have substantially lost their kinetic energies in collisions with gas atoms or molecules and so carry no momenta. Shaping the electric fields appropriately the phase space such ion beams occupy can be reduced and correspondingly the ion density of beams be increased.

Using three elementary particles to construct the physical world

2021 ◽  
Vol 34 (2) ◽  
pp. 236-247
Author(s):  
Huawang Li
Keyword(s):  
Electromagnetic Waves ◽  
Physical World ◽  
Elementary Particles ◽  
Average Kinetic Energy ◽  
Particle Collisions ◽  
Conservation Of Energy ◽  
Fundamental Particles ◽  
Energy And Momentum ◽  
Physical Phenomena ◽  
The Universe

In this paper, we conjecture that gravitation, electromagnetism, and strong nuclear interactions are all produced by particle collisions by determining the essential concept of force in physics (that is, the magnitude of change in momentum per unit time for a group of particles traveling in one direction), and further speculate the existence of a new particle, Yizi. The average kinetic energy of Yizi is considered to be equal to Planck’s constant, so the mass of Yizi is calculated to be <mml:math display="inline"> <mml:mrow> <mml:mn>7.37</mml:mn> <mml:mo>×</mml:mo> <mml:msup> <mml:mrow> <mml:mn>10</mml:mn> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>51</mml:mn> </mml:mrow> </mml:msup> </mml:mrow> </mml:math> kg and the average velocity of Yizi is <mml:math display="inline"> <mml:mrow> <mml:mn>4.24</mml:mn> <mml:mo>×</mml:mo> <mml:msup> <mml:mrow> <mml:mn>10</mml:mn> </mml:mrow> <mml:mn>8</mml:mn> </mml:msup> </mml:mrow> </mml:math> m/s. The universe is filled with Yizi gas, the number density of Yizi can reach <mml:math display="inline"> <mml:mrow> <mml:mn>1.61</mml:mn> <mml:mo>×</mml:mo> <mml:msup> <mml:mrow> <mml:mn>10</mml:mn> </mml:mrow> <mml:mrow> <mml:mn>64</mml:mn> </mml:mrow> </mml:msup> </mml:mrow> </mml:math> /m3, and Yizi has no charge. After abandoning the idealism of physics, I try to construct a physical framework from three elementary particles: Protons, electrons, and Yizis. (The elementary particles mentioned here generally refer to the indivisible particles that constitute objects.) The effects of Yizi on the conversion of light, electricity, magnetism, mass, and energy as well as the strong nuclear and electromagnetic forces are emphasized. The gravitation of electromagnetic waves is measured using a Cavendish torsion balance. It is shown experimentally that electromagnetic waves not only produce pressure (repulsion) but also gravitational forces upon objects. The universe is a combination of three fundamental particles. Motion is eternal and follows the laws of conservation of energy and momentum. There is only one force: The magnitude of change in momentum per unit time for a group of particles traveling in one direction. Furthermore, this corresponds to the magnitude of the force that the group of particles exerts in that direction. From this perspective, all physical phenomena are relatively easy to explain.

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