Stark effect in three‐dimensional stochastic electric fields and a static magnetic field of a helium plasma

1977 ◽  
Vol 48 (9) ◽  
pp. 3651-3659 ◽  
Author(s):  
S. H. Kim
Keyword(s):  
Magnetic Field ◽  
Electric Fields ◽  
Static Magnetic Field ◽  
Stark Effect ◽  
Three Dimensional ◽  
Helium Plasma

scholarly journals Use of Magnetic Field for Mitigating Gyroscope Errors for Indoor Pedestrian Positioning

Sensors ◽  
2018 ◽  
Vol 18 (8) ◽  
pp. 2592 ◽  
Author(s):  
Ming Ma ◽  
Qian Song ◽  
Yang Gu ◽  
Zhimin Zhou
Keyword(s):  
Magnetic Field ◽  
Static Magnetic Field ◽  
Inertial Navigation System ◽  
Three Dimensional ◽  
Calibration Method ◽  
Rate Of Change ◽  
Superior Performance ◽  
Novel Approach ◽  
Straight Line ◽  
Magnetometer Calibration

In the field of indoor pedestrian positioning, the improved Quasi-Static magnetic Field (iQSF) method has been proposed to estimate gyroscope biases in magnetically perturbed environments. However, this method is only effective when a person walks along straight-line paths. For other curved or more complex path patterns, the iQSF method would fail to detect the quasi-static magnetic field. To address this issue, a novel approach is developed for quasi-static magnetic field detection in foot-mounted Inertial Navigation System. The proposed method detects the quasi-static magnetic field using the rate of change in differences between the magnetically derived heading and the heading derived from gyroscope. In addition, to eliminate the distortions caused by system platforms and shoes, a magnetometer calibration method is developed and the calibration is transformed from three-dimensional to two-dimensional coordinate according to the motion model of a pedestrian. The experimental results demonstrate that the proposed method can provide superior performance in suppressing the heading errors with the comparison to iQSF method.

scholarly journals Induced telluric currents play a major role in the interpretation of geomagnetic variations

2020 ◽  
Author(s):  
Liisa Juusola ◽  
Heikki Vanhamäki ◽  
Ari Viljanen ◽  
Maxim Smirnov
Keyword(s):  
Magnetic Field ◽  
Electric Fields ◽  
Time Derivative ◽  
Three Dimensional ◽  
Image Data ◽  
Geomagnetically Induced Currents ◽  
Ionospheric Currents ◽  
Geomagnetic Variations ◽  
Near Surface ◽  
Telluric Currents

Abstract. Geomagnetically induced currents (GIC) are directly described by ground electric fields, but estimating them is time-consuming and requires knowledge of the ionospheric currents as well as the three-dimensional distribution of the electrical conductivity of the Earth. The time derivative of the horizontal component of the ground magnetic field (dH/dt) is closely related to the electric field via Faraday's law, and provides a convenient proxy for the GIC risk. However, forecasting dH/dt still remains a challenge. We use 25 years of 10 s data from the North European International Monitor for Auroral Geomagnetic Effects (IMAGE) magnetometer network to show that part of this problem stems from the fact that instead of the primary ionospheric currents, the measured dH/dt is dominated by the signature from the secondary induced telluric currents nearly at all IMAGE stations. The largest effects due to telluric currents occur at coastal sites close to highly-conducting ocean water and close to near-surface conductivity anomalies. The secondary magnetic field contribution to the total field is a few tens of percent, in accordance with earlier studies. Our results have been derived using IMAGE data and are thus only valid for the involved stations. However, it is likely that the main principle also applies to other areas. Consequently, it is recommended that the field separation into internal (telluric) and external (ionospheric and magnetospheric) parts is performed whenever feasible, i.e., a dense observation network is available.

scholarly journals Induced currents due to 3D ground conductivity play a major role in the interpretation of geomagnetic variations

2020 ◽  
Vol 38 (5) ◽  
pp. 983-998
Author(s):  
Liisa Juusola ◽  
Heikki Vanhamäki ◽  
Ari Viljanen ◽  
Maxim Smirnov
Keyword(s):  
Magnetic Field ◽  
Electric Fields ◽  
Time Derivative ◽  
Three Dimensional ◽  
Geomagnetically Induced Currents ◽  
Ionospheric Currents ◽  
Geomagnetic Variations ◽  
Near Surface ◽  
Induced Currents ◽  
Telluric Currents

Abstract. Geomagnetically induced currents (GICs) are directly described by ground electric fields, but estimating them is time-consuming and requires knowledge of the ionospheric currents and the three-dimensional (3D) distribution of the electrical conductivity of the Earth. The time derivative of the horizontal component of the ground magnetic field (dH∕dt) is closely related to the electric field via Faraday's law and provides a convenient proxy for the GIC risk. However, forecasting dH∕dt still remains a challenge. We use 25 years of 10 s data from the northern European International Monitor for Auroral Geomagnetic Effects (IMAGE) magnetometer network to show that part of this problem stems from the fact that, instead of the primary ionospheric currents, the measured dH∕dt is dominated by the signature from the secondary induced telluric currents at nearly all IMAGE stations. The largest effects due to telluric currents occur at coastal sites close to high-conducting ocean water and close to near-surface conductivity anomalies. The secondary magnetic field contribution to the total field is a few tens of percent, in accordance with earlier studies. Our results have been derived using IMAGE data and are thus only valid for the stations involved. However, it is likely that the main principle also applies to other areas. Consequently, it is recommended that the field separation into internal (telluric) and external (ionospheric and magnetospheric) parts is performed whenever feasible (i.e., a dense observation network is available).

scholarly journals Controlled Phase Interactions Between Pulsed Electric Fields, Ultrasonic Motion, and Magnetic Fields in an Anodic Dissolution Cell

2018 ◽  
Vol 140 (4) ◽  
Author(s):  
Curtis Bradley ◽  
Johnson Samuel
Keyword(s):  
Magnetic Field ◽  
Anodic Dissolution ◽  
Electric Fields ◽  
High Frequency ◽  
Performance Metrics ◽  
Removal Rate ◽  
Ultrasonic Transducer ◽  
Three Dimensional ◽  
Electrochemical Machining ◽  
3D Printed

This paper presents the design of a novel testbed that effectively combines pulsed electric field waveforms, ultrasonic velocity, and magnetic field waveforms in an anodic dissolution electrochemical machining (ECM) cell. The testbed consists of a custom three-dimensional (3D)-printed flow cell that is integrated with (i) a bipolar-pulsed ECM circuit, (ii) an ultrasonic transducer, and (iii) a custom-built high-frequency electromagnet. The driving voltages of the ultrasonic transducer and electromagnet are calibrated to achieve a timed workpiece velocity and magnetic field, respectively, in the machining area. The ECM studies conducted using this testbed reveal that phase-controlled waveform interactions between the three assistances affect both the material removal rate (MRR) and surface roughness (Ra) performance metrics. The triad-assisted ECM case involving phase-specific combinations of all three high-frequency (15.625 kHz) assistance waveforms is found to be capable of achieving a 52% increase in MRR while also simultaneously yielding a 78% improvement in the Ra value over the baseline pulsed-ECM case. This result is encouraging because assisted ECM processes reported in the literature typically improve only one of these performance metrics at the expense of the other. In general, the findings reported in this paper are expected to enable the realization of multifield assisted ECM testbeds using phase-specific input waveforms that change on-the-fly to yield preferential combinations of MRR and surface finish.

Energy conversion by electron beam-driven waves in a compressed reconnection separatrix

2020 ◽  
Author(s):  
Justin Holmes ◽  
Rumi Nakamura ◽  
Owen Roberts ◽  
Daniel Schmid ◽  
Takuma Nakamura ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Electron Beam ◽  
Energy Conversion ◽  
Electric Fields ◽  
Spatial Configuration ◽  
Three Dimensional ◽  
Lower Hybrid ◽  
Magnetic Compression ◽  
Rotational Discontinuity ◽  
Highly Correlated

<p>We investigate magnetic compression near the reconnection separatrix observed by Magnetospheric MultiScale (MMS) on July 11<sup>th</sup> 2017. A clear transition between inflow and outflow in both ions and electrons is observed across an ion gyro-scale region of enhanced magnetic field. Multispacecraft techniques for magnetic curvature and local gradients along with timing of highly-correlated wave packets are used to determine the spatial configuration of the compressed region. Structure of the system is found to be inherently three dimensional; electron beam-driven modes propagating parallel to the magnetic field are observed concurrent with perpendicular-propagating lower hybrid waves. Larger scale surface waves are also present behind the compression front. Transforming to a deHoffmann-Teller frame across the boundary results in a distinctly non-rotational discontinuity with structure similar to a quasi-2D, Petschek-like slow shock. However, MHD jump conditions are not satisfied, indicating kinetic dissipation may occur within the thin layer. The largest amplitude measurements of $\mathbf{J}\cdot\mathbf{E}$ energy conversion are associated with an inflowing electron beam and parallel electric fields near the magnetic peak. Spikes in $\mathbf{J}\cdot\mathbf{E}$ are predominantly negative, suggesting electron-scale mixing between the reconnection inflow and outflow is partially responsible for the observed magnetic compression.</p>

Proton acceleration in three-dimensional non-null magnetic reconnection

2016 ◽  
Vol 82 (5) ◽  
Author(s):  
Z. Akbari ◽  
M. Hosseinpour ◽  
M. A. Mohammadi
Keyword(s):  
Magnetic Field ◽  
Energy Distribution ◽  
Magnetic Reconnection ◽  
Electric Fields ◽  
Three Dimensional ◽  
Null Point ◽  
Proton Acceleration ◽  
Electric And Magnetic Fields ◽  
Field Lines ◽  
The Magnetic Field

In a three-dimensional non-null magnetic reconnection, the process of magnetic reconnection takes place in the absence of a null point where the magnetic field vanishes. By randomly injecting a population of 10 000 protons, the trajectory and energy distribution of accelerated protons are investigated in the presence of magnetic and electric fields of a particular model of non-null magnetic reconnection with the typical parameters for the solar corona. The results show that protons are accelerated along the magnetic field lines away from the non-null point only at azimuthal angles where the magnitude of the electric field is strongest and therefore particles obtain kinetic energies of the order of thousands of MeV and even higher. Moreover, the energy distribution of the population depends strongly on the amplitude of the electric and magnetic fields. Comparison shows that a non-null magnetic reconnection is more efficient in accelerating protons to very high GeV energies than a null-point reconnection.

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