Solitary potential structures observed in the magnetosheath by the Cluster spacecraft

Abstract. Bipolar pulses of ~ 25-100 µs in duration have been observed in the wave electric field data obtained by the Wideband plasma wave instrument on the Cluster spacecraft in the dayside magnetosheath. These pulses are similar in almost all respects to those observed on several spacecraft over the last few years. They represent solitary potential structures, and in this case, electron phase space holes. When the time series data containing the bipolar pulses on Cluster are transformed to the frequency domain by a windowed FFT, the pulses appear as typical broad-band features, extending from the low-frequency cutoff of the bandpass filter, ~ 1 kHz, up to as great as 20-40 kHz in some cases, with decreasing intensity as the frequency increases. The upper frequency cutoff of the broad band is an indication of the individual pulse durations (1/f). The solitary potential structures are detected when the local magnetic field is contained primarily in the spin plane, indicating that they propagate along the magnetic field. Their frequency extent and intensity seem to increase as the angle between the directions of the magnetic field and the plasma flow decreases from 90°. Of major significance is the finding that the overall profile of the broad-band features observed simultaneously by two Cluster spacecraft, separated by a distance of over 750 km, are strikingly similar in terms of onset times, frequency extent, intensity, and termination. This implies that the generation region of the solitary potential structures observed in the magnetosheath near the bow shock is very large and may be located at or near the bow shock, or be connected with the bow shock in some way.

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Statistical study of foreshock cavitons

Annales Geophysicae ◽

10.5194/angeo-31-2163-2013 ◽

2013 ◽

Vol 31 (12) ◽

pp. 2163-2178 ◽

Cited By ~ 14

Author(s):

P. Kajdič ◽

X. Blanco-Cano ◽

N. Omidi ◽

K. Meziane ◽

C. T. Russell ◽

...

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Statistical Study ◽

Low Frequency ◽

Bow Shock ◽

Occurrence Rate ◽

Time Intervals ◽

Distinct Structure ◽

Wide Range ◽

The Magnetic Field

Abstract. In this work we perform a statistical analysis of 92 foreshock cavitons observed with the Cluster spacecraft 1 during the period 2001–2006. We analyze time intervals during which the spacecraft was located in the Earth's foreshock with durations longer than 10 min. Together these amount to ~ 50 days. The cavitons are transient structures in the Earth's foreshock. Their main signatures in the data include simultaneous depletions of the magnetic field intensity and plasma density, which are surrounded by a rim of enhanced values of these two quantities. Cavitons form due to nonlinear interaction of transverse and compressive ultra-low frequency (ULF) waves and are therefore always surrounded by intense compressive ULF fluctuations. They are carried by the solar wind towards the bow shock. This work represents the first systematic study of a large sample of foreshock cavitons. We find that cavitons appear for a wide range of solar wind and interplanetary magnetic field conditions and are therefore a common feature upstream of Earth's quasi-parallel bow shock with an average occurrence rate of ~ 2 events per day. We also discuss their observational properties in the context of other known upstream phenomena and show that the cavitons are a distinct structure in the foreshock.

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On the generation of solitary waves observed by Cluster in the near-Earth magnetosheath

Nonlinear Processes in Geophysics ◽

10.5194/npg-12-181-2005 ◽

2005 ◽

Vol 12 (2) ◽

pp. 181-193 ◽

Cited By ~ 46

Author(s):

J. S. Pickett ◽

L.-J. Chen ◽

S. W. Kahler ◽

O. Santolík ◽

M. L. Goldstein ◽

...

Keyword(s):

Magnetic Field ◽

Solitary Waves ◽

Bow Shock ◽

Generation Mechanism ◽

Local Magnetic Field ◽

Magnetic Field Direction ◽

Waveform Data ◽

Background Magnetic Field ◽

Ion Velocity ◽

The Magnetic Field

Abstract. Through case studies involving Cluster waveform observations, solitary waves in the form of bipolar and tripolar pulses have recently been found to be quite abundant in the near-Earth dayside magnetosheath. We expand on the results of those previous studies by examining the distribution of solitary waves from the bow shock to the magnetopause using Cluster waveform data. Cluster's orbit allows for the measurement of solitary waves in the magnetosheath from about 10 RE to 19.5 RE. Our results clearly show that within the magnetosheath, solitary waves are likely to be observed at any distance from the bow shock and that this distance has no dependence on the time durations and amplitudes of the solitary waves. In addition we have found that these same two quantities show no dependence on either the ion velocity or the angle between the ion velocity and the local magnetic field direction. These results point to the conclusion that the solitary waves are probably created locally in the magnetosheath at multiple locations, and that the generation mechanism is most likely not solely related to ion dynamics, if at all. To gain insight into a possible local generation mechanism, we have examined the electron differential energy flux characteristics parallel and perpendicular to the magnetic field, as well as the local electron plasma and cyclotron frequencies and the type of bow shock that Cluster is behind, for several time intervals where solitary waves were observed in the magnetosheath. We have found that solitary waves are most likely to be observed when there are counterstreaming (~parallel and anti-parallel to the magnetic field) electrons at or below about 100eV. However, there are times when these counterstreaming electrons are present when solitary waves are not. During these times the background magnetic field strength is usually very low (<10nT), implying that the amplitudes of the solitary waves, if present, would be near or below those of other waves and electrostatic fluctuations in this region making it impossible to isolate or clearly distinguish them from these other emissions in the waveform data. Based on these results, we have concluded that some of the near-Earth magnetosheath solitary waves, perhaps in the form of electron phase-space holes, may be generated locally by a two-stream instability involving electrons based on the counterstreaming electrons that are often observed when solitary waves are present. We have not ruled out the possibility that the solitary waves could be generated as a result of the lower-hybrid Buneman instability in the presence of an electron beam, through the electron acoustic mode or through processes involving turbulence, which is almost always present in the magnetosheath, but these will be examined in a more comprehensive study in the future.

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PEMANFAATAN RADIASI ENERGI TEGANGAN 150 KV UNTUK LAMPU LED PENERANGAN JALAN

Jurnal Teknik ◽

10.31000/jt.v7i1.936 ◽

2018 ◽

Vol 7 (1) ◽

Author(s):

Mauludi Manfaluthy

Keyword(s):

Magnetic Field ◽

Electric Field ◽

High Voltage ◽

Low Frequency ◽

Energy Utilization ◽

World Health ◽

Electromagnetic Signals ◽

Health Organization ◽

The Magnetic Field ◽

Low Frequency Waves

WHO (World Health Organization) concludes that not much effect is caused by electric field up to 20 kV / m in humans. WHO standard also mentions that humans will not be affected by the magnetic field under 100 micro tesla and that the electric field will affect the human body with a maximum standard of 5,000 volts per meter. In this study did not discuss about the effect of high voltage radiation SUTT (High Voltage Air Channel) with human health. The research will focus on energy utilization of SUTT radiation. The combination of electric field and magnetic field on SUTT (70-150KV) can generate electromagnetic (EM) and radiation waves, which are expected to be converted to turn on street lights around the location of high voltage areas or into other forms. The design of this prototype works like an antenna in general that captures electromagnetic signals and converts them into AC waves. With a capacitor that can store the potential energy of AC and Schottky diode waves created specifically for low frequency waves, make the current into one direction (DC). From the research results obtained the current generated from the radiation is very small even though the voltage is big enough.Keywords : Radiance Energy, Joule Thief, and LED Module.

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Integral Equations for Problems on Wave Propagation in Near-Earth Plasma

Symmetry ◽

10.3390/sym13081395 ◽

2021 ◽

Vol 13 (8) ◽

pp. 1395

Author(s):

Danila Kostarev ◽

Dmitri Klimushkin ◽

Pavel Mager

Keyword(s):

Magnetic Field ◽

Integral Equations ◽

Field Potential ◽

Low Frequency ◽

Fredholm Equation ◽

Compression Waves ◽

Parallel Component ◽

Electric Field Potential ◽

The Magnetic Field ◽

Low Frequency Waves

We consider the solutions of two integrodifferential equations in this work. These equations describe the ultra-low frequency waves in the dipol-like model of the magnetosphere in the gyrokinetic framework. The first one is reduced to the homogeneous, second kind Fredholm equation. This equation describes the structure of the parallel component of the magnetic field of drift-compression waves along the Earth’s magnetic field. The second equation is reduced to the inhomogeneous, second kind Fredholm equation. This equation describes the field-aligned structure of the parallel electric field potential of Alfvén waves. Both integral equations are solved numerically.

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Experimental and numerical investigation of plasma parameters in the magnetosheath

MATEC Web of Conferences ◽

10.1051/matecconf/201814503003 ◽

2018 ◽

Vol 145 ◽

pp. 03003

Author(s):

Polya Dobreva ◽

Monio Kartalev ◽

Olga Nitcheva ◽

Natalia Borodkova ◽

Georgy Zastenker

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Numerical Investigation ◽

Euler Equations ◽

Ideal Gas ◽

Bow Shock ◽

Plasma Parameters ◽

Wind Spacecraft ◽

The Magnetic Field ◽

Good Agreement

We investigate the behaviour of the plasma parameters in the magnetosheath in a case when Interball-1 satellite stayed in the magnetosheath, crossing the tail magnetopause. In our analysis we apply the numerical magnetosheath-magnetosphere model as a theoretical tool. The bow shock and the magnetopause are self-consistently determined in the process of the solution. The flow in the magnetosheath is governed by the Euler equations of compressible ideal gas. The magnetic field in the magnetosphere is calculated by a variant of the Tsyganenko model, modified to account for an asymmetric magnetopause. Also, the magnetopause currents in Tsyganenko model are replaced by numericaly calulated ones. Measurements from WIND spacecraft are used as a solar wind monitor. The results demonstrate a good agreement between the model-calculated and measured values of the parameters under investigation.

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Scattering of field-aligned beam ions upstream of Earth's bow shock

Annales Geophysicae ◽

10.5194/angeo-25-785-2007 ◽

2007 ◽

Vol 25 (3) ◽

pp. 785-799 ◽

Cited By ~ 24

Author(s):

A. Kis ◽

M. Scholer ◽

B. Klecker ◽

H. Kucharek ◽

E. A. Lucek ◽

...

Keyword(s):

Magnetic Field ◽

Solar Wind ◽

Field Measurements ◽

Bow Shock ◽

Ion Distribution ◽

Parallel Side ◽

Earth’S Bow Shock ◽

High Mach ◽

The Magnetic Field

Abstract. Field-aligned beams are known to originate from the quasi-perpendicular side of the Earth's bow shock, while the diffuse ion population consists of accelerated ions at the quasi-parallel side of the bow shock. The two distinct ion populations show typical characteristics in their velocity space distributions. By using particle and magnetic field measurements from one Cluster spacecraft we present a case study when the two ion populations are observed simultaneously in the foreshock region during a high Mach number, high solar wind velocity event. We present the spatial-temporal evolution of the field-aligned beam ion distribution in front of the Earth's bow shock, focusing on the processes in the deep foreshock region, i.e. on the quasi-parallel side. Our analysis demonstrates that the scattering of field-aligned beam (FAB) ions combined with convection by the solar wind results in the presence of lower-energy, toroidal gyrating ions at positions deeper in the foreshock region which are magnetically connected to the quasi-parallel bow shock. The gyrating ions are superposed onto a higher energy diffuse ion population. It is suggested that the toroidal gyrating ion population observed deep in the foreshock region has its origins in the FAB and that its characteristics are correlated with its distance from the FAB, but is independent on distance to the bow shock along the magnetic field.

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Spacecraft and interplanetary contributions to the magnetic environment on-board LISA Pathfinder

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa830 ◽

2020 ◽

Vol 494 (2) ◽

pp. 3014-3027

Author(s):

M Armano ◽

H Audley ◽

J Baird ◽

P Binetruy ◽

M Born ◽

...

Keyword(s):

Magnetic Field ◽

New Technologies ◽

Magnetic Measurements ◽

Magnetic Measurement ◽

Low Frequency ◽

Lisa Pathfinder ◽

Frequency Regime ◽

The Magnetic Field ◽

Instrument Sensitivity ◽

Stationary Component

ABSTRACT LISA Pathfinder (LPF) has been a space-based mission designed to test new technologies that will be required for a gravitational wave observatory in space. Magnetically driven forces play a key role in the instrument sensitivity in the low-frequency regime (mHz and below), the measurement band of interest for a space-based observatory. The magnetic field can couple to the magnetic susceptibility and remanent magnetic moment from the test masses and disturb them from their geodesic movement. LPF carried on-board a dedicated magnetic measurement subsystem with noise levels of 10 $\rm nT \ Hz^{-1/2}$ from 1 Hz down to 1 mHz. In this paper we report on the magnetic measurements throughout LPF operations. We characterize the magnetic environment within the spacecraft, study the time evolution of the magnetic field and its stability down to 20 μHz, where we measure values around 200 $\rm nT \ Hz^{-1/2}$, and identify two different frequency regimes, one related to the interplanetary magnetic field and the other to the magnetic field originating inside the spacecraft. Finally, we characterize the non-stationary component of the fluctuations of the magnetic field below the mHz and relate them to the dynamics of the solar wind.

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ANALYSIS OF HIGH-FREQUENCY C-CORE MAGNETIC FLUX LEAKAGES FOR BONE TUMOR WITH INDUCTION HEATING BY USING MULTI-COIL

Proceedings 17th International Conference on Microwave and High Frequency Heating ◽

10.4995/ampere2019.2019.9900 ◽

2019 ◽

Author(s):

Metharak Jokpudsa ◽

Supawat Kotchapradit ◽

Chanchai Thongsopa ◽

Thanaset Thosdeekoraphat

Keyword(s):

Magnetic Field ◽

High Frequency ◽

Tumor Tissue ◽

Low Frequency ◽

Heat Energy ◽

High Frequencies ◽

Frequency Magnetic Field ◽

High Frequency Magnetic Field ◽

The Magnetic Field ◽

Flux Leakage

High-frequency magnetic field has been developed pervasively. The induction of heat from the magnetic field can help to treat tumor tissue to a certain extent. Normally, treatment by the low-frequency magnetic field needed to be combined with magnetic substances. To assist in the induction of magnetic fields and reduce flux leakage. However, there are studies that have found that high frequencies can cause heat to tumor tissue. In this paper present, a new magnetic application will focus on the analysis of the high-frequency magnetic nickel core with multi-coil. In order to focus the heat energy using a high-frequency magnetic field into the tumor tissue. The magnetic coil was excited by 915 MHz signal and the combination of tissues used are muscle, bone, and tumor. The magnetic power on the heating predicted by the analytical model, the power loss density (2.98e-6 w/m3) was analyzed using the CST microwave studio.

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The relative orientation between the magnetic field and gas density structures in non-gravitating turbulent media

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3078 ◽

2020 ◽

Vol 499 (4) ◽

pp. 4785-4792

Author(s):

Bastian Körtgen ◽

Juan D Soler

Keyword(s):

Magnetic Field ◽

Molecular Clouds ◽

Relative Orientation ◽

Local Magnetic Field ◽

Gas Formation ◽

Initial Magnetization ◽

The Galaxy ◽

Dynamical Time ◽

Isothermal Gas ◽

The Magnetic Field

ABSTRACT Magnetic fields are a dynamically important agent for regulating structure formation in the interstellar medium. The study of the relative orientation between the local magnetic field and gas (column-) density gradient has become a powerful tool to analyse the magnetic field’s impact on the dense gas formation in the Galaxy. In this study, we perform numerical simulations of a non-gravitating, isothermal gas, where the turbulence is driven either solenoidally or compressively. We find that only simulations with an initially strong magnetic field (plasma-β < 1) show a change in the preferential orientation between the magnetic field and isodensity contours, from mostly parallel at low densities to mostly perpendicular at higher densities. Hence, compressive turbulence alone is not capable of inducing the transition observed towards nearby molecular clouds. At the same high initial magnetization, we find that solenoidal modes produce a sharper transition in the relative orientation with increasing density than compressive modes. We further study the time evolution of the relative orientation and find that it remains unchanged by the turbulent forcing after one dynamical time-scale.

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ANALYTICAL MODEL OF THE PLANETARY BOW SHOCK FOR VARIOUS MAGNETIC FIELD DIRECTIONS BASED ON MHD CALCULATIONS

Solnechno-Zemnaya Fizika ◽

10.12737/szf-64202007 ◽

2020 ◽

Vol 6 (4) ◽

pp. 51-58

Author(s):

Galina Kotova ◽

Mikhail Verigin ◽

Tamash Gomboshi ◽

Konstantin Kabin

Keyword(s):

Magnetic Field ◽

Computer Time ◽

Bow Shock ◽

Radius Of Curvature ◽

Dynamic Flow ◽

Physical Processes ◽

Downstream Slope ◽

Mach Numbers ◽

Semi Empirical ◽

The Magnetic Field

Study of physical processes in plasma near planets often requires knowledge of the position and shape of the planetary bow shock. Empirical models are usually used since theoretical MHD and kinetic models consume too much computer time and cannot be used to track fast processes. M.I. Verigin proposed a semi-empirical approach based on the use of exact theoretical expressions with a small number of parameters, which have a clear physical meaning. These parameters are estimated by fitting experimental data or detailed MHD calculations. A model of the bow shock near an arbitrary-shaped obstacle has previously been developed for a gas-dynamic flow. This model can be applied to any sonic Mach numbers and large values of the Alfven Mach number. In addition, the asymptotic Mach cone — the angle of inclination of the shock wave at an infinite distance from the planet — has been calculated analytically in the MHD approximation. In this paper, we propose a model of the bow shock for any direction of the magnetic field with respect to the upcoming flow and for any Mach numbers. Parameters of the model are the distance of the nose point from the obstacle, radius of curvature and bluntness of the bow shock at the nose point, a parameter related to the transition to the asymptotic downstream slope of the shock, and a skewing angle appearing when the interplanetary magnetic field is directed at an angle to the solar wind velocity.

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