Theory of wave polarization of radio waves in magnetospheric cavities

1987 ◽  
Vol 412 (1842) ◽  
pp. 25-44 ◽  
Keyword(s):  
Magnetic Field ◽  
Low Frequency ◽  
Extraordinary Wave ◽  
Wave Polarization ◽  
Radio Waves ◽  
Full Wave ◽  
Magnetic Field Change ◽  
Planetary Magnetic Field ◽  
Wave Normal ◽  
The Magnetic Field

When interpreting observations of radio waves of low frequency in magnetospheric cavities, it is often assumed that the electron concentra­tion is small enough for the ray paths to be treated as straight, but great enough to ensure that a wave that starts as a pure ordinary (or extraordinary) wave has a wave polarization close to that of an ordinary (or extraordinary) wave at each point of the path. This polarization changes because the magnitude and direction of the planetary magnetic field change along the path. But the change of the magnetic field also introduces coupling between the ordinary and extraordinary waves. If the electron concentration is small or zero, this coupling may be cumulative so that it restricts or prevents the change of polarization. A full-wave integration of the governing differential equations is used to study this problem. It is similar to the problem of limiting polarization for a radio wave emerging from the ionosphere into free space. It is concluded that the polarization of an initially ordinary (or extraordinary) wave remains close to that of a locally produced ordinary (or extra­ordinary) wave with the same wave-normal direction, provided that the plasma frequency exceeds a minimum value. This value depends on the direction of the path. Some typical examples are given.

Theory of the reflexion of low-frequency radio waves obliquely incident on the ionosphere

1974 ◽  
Vol 336 (1607) ◽  
pp. 525-542 ◽  
Keyword(s):  
Low Frequency ◽  
Extraordinary Wave ◽  
Meridian Plane ◽  
Radio Waves ◽  
Quartic Equation ◽  
Obliquely Incident ◽  
Full Wave ◽  
Magnetic Meridian ◽  
Electron Gyrofrequency ◽  
Wave Normal

The properties of the two principal reflexions for radio waves obliquely incident on a horizontally stratified ionosphere in and near the magnetic meridian plane, for frequencies less than the electron gyrofrequency, are investigated using 'full wave’ numerical methods. When the wave normal of the incident wave is close to either of two directions, which are in the magnetic meridian plane, at particular angles θ b and θ e to the vertical, then for propagation from south to north (northern hemisphere), the polarizations of the two reflexions are found to take anomalous values. This behaviour is related to the properties of the Booker quartic equation. An extraordinary wave incident at an angle near θ e in the N–S direction generates some of the upgoing ‘whistler’ mode, an d this process is also investigated.

PEMANFAATAN RADIASI ENERGI TEGANGAN 150 KV UNTUK LAMPU LED PENERANGAN JALAN

Jurnal Teknik ◽  
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.

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

Symmetry ◽  
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.

scholarly journals Reversibility of the Magnetocaloric Effect in the Bean-Rodbell Model

2021 ◽  
Vol 7 (5) ◽  
pp. 60
Author(s):  
Luis M. Moreno-Ramírez ◽  
Victorino Franco
Keyword(s):  
Magnetic Field ◽  
Thermal Hysteresis ◽  
Entropy Change ◽  
Second Order ◽  
Zero Field ◽  
First Order ◽  
Magnetic Field Change ◽  
Magnetocaloric Materials ◽  
Moderate Magnetic Field ◽  
The Magnetic Field

The applicability of magnetocaloric materials is limited by irreversibility. In this work, we evaluate the reversible magnetocaloric response associated with magnetoelastic transitions in the framework of the Bean-Rodbell model. This model allows the description of both second- and first-order magnetoelastic transitions by the modification of the η parameter (η<1 for second-order and η>1 for first-order ones). The response is quantified via the Temperature-averaged Entropy Change (TEC), which has been shown to be an easy and effective figure of merit for magnetocaloric materials. A strong magnetic field dependence of TEC is found for first-order transitions, having a significant increase when the magnetic field is large enough to overcome the thermal hysteresis of the material observed at zero field. This field value, as well as the magnetic field evolution of the transition temperature, strongly depend on the atomic magnetic moment of the material. For a moderate magnetic field change of 2 T, first-order transitions with η≈1.3−1.8 have better TEC than those corresponding to stronger first-order transitions and even second-order ones.

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

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.

scholarly journals Solar Spike Suggests a More Active Sun

Eos ◽  
2019 ◽  
Vol 100 ◽  
Author(s):  
Nola Redd
Keyword(s):  
Magnetic Field ◽  
The Sun ◽  
Radio Waves ◽  
The Magnetic Field

Radio waves are providing a new way to probe the Sun and suggest that the magnetic field of its corona may be stronger than long thought.

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

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.

scholarly journals Radio Emission Model of a 'Typical' Pulsar

1987 ◽  
Vol 40 (6) ◽  
pp. 755 ◽  
Author(s):  
AZ Kazbegi ◽  
GZ Machabeli ◽  
G Melikidze
Keyword(s):  
Magnetic Field ◽  
Electromagnetic Waves ◽  
Emission Model ◽  
Radio Waves ◽  
Resonance Case ◽  
Pulsar Magnetosphere ◽  
Pulsar Emission ◽  
Dipole Magnetic Field ◽  
New Type ◽  
The Magnetic Field

The generation of radio waves in the plasma of the pulsar magnetosphere is considered taking into account the inhomogeneity of the dipole magnetic field. It is shown that the growth rate of the instability of the electromagnetic waves calculated in the non-resonance case turns out to be of the order of 1/ TO (where TO is the time of plasma escape from the light cylinder). However, the generation of electromagnetic waves from a new type Cherenkov resonance is possible, occurring when the particles have transverse velocities caused by the drift due to the inhomogeneity of the magnetic field. Estimates show that the development of this type of instability is possible only for pulsars with ages which exceed 104 yr. We make an attempt to explain some peculiarities of 'typical' pulsar emission on the basis of the model developed.

Low Frequency Measurements in Amorphous Wire for Studying GMI Effect

2011 ◽  
Vol 495 ◽  
pp. 201-204
Author(s):  
Polykseni Vourna
Keyword(s):  
Magnetic Field ◽  
Low Frequency ◽  
Major Change ◽  
Wheatstone Bridge ◽  
Amorphous Wire ◽  
Dc Voltage ◽  
Gmi Effect ◽  
Offset Voltage ◽  
Ac Current ◽  
The Magnetic Field

When a soft ferromagnetic material is flown by an ac current and a magnetic field is applied at the same time, a major change of its impedance is occurred. The aim of this paper is to investigate the influence of low frequency (1KHz-12KHz) ac current and the applied magnetic field on an amorphous magnetic wire (Co68Fe4.35Si12.5B15) without glass coating. For this purpose an experimental configuration has been setup, based on a Wheatstone bridge which receives an ac input signal from a frequency generator. The output is connected to the amorphous wire wrapped with a coil supplied by a dc voltage for the generation of the magnetic field. The output voltage pulse is measured for two cases a) The value of ac frequency is changing while the value of dc voltage applied to the coil remains constant (the magnetic field remains unchanged) and b) the magnetic field is changing while the ac frequency remains constant to a predefined value. Experimental results of the first scenario showed that when the frequency is altered a non-linear increase of the ac signal is observed at the output which shows an increase of the GMI effect and is related to the non-linearity of the wire’s permeability. For the second scenario the results showed an increase of the output signal offset (voltage) which also indicates an increase of the GMI effect.

Magnetocaloric Effect in Ni-Mn-Ga and Ni-Co-Mn-In Heusler Alloys

2009 ◽  
Vol 1200 ◽  
Author(s):  
Vasiliy Buchelnikov ◽  
Sergey Taskaev ◽  
Mikhail Drobosyuk ◽  
Vladimir Sokolovskiy ◽  
Viktor Koledov ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Magnetocaloric Effect ◽  
Curie Point ◽  
Direct Method ◽  
Heusler Alloys ◽  
Field Change ◽  
Adiabatic Temperature Change ◽  
Magnetic Field Change ◽  
A Direct Method ◽  
The Magnetic Field

AbstractThe positive magnetocaloric effect (MCE) in the vicinity of the Curie point in Ni2+xMn1-xGa (x=0.33, 0.36, 0.39) Heusler alloys and the negative and positive MCE near the metamagnetostructural (MMS) transition and the Curie point, respectively, in Ni45Co5Mn36.5In13.5 Heusler alloy has been measured by a direct method. For the magnetic field change ΔH = 2 T, the maximal adiabatic temperature change ΔTad at the Curie point in Ni2+xMn1-xGa alloys is larger than 0.6 K. For Ni45Co5Mn36.5In13.5 alloy, the maximal value of ΔTad = 1.68 K (for the same magnetic field change, ΔH = 2 T) is observed at the MMS phase transition temperature.

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