scholarly journals Numerical simulation of the ground distribution of the field strength of an on-board low-frequency transmitter located in the ionosphere.

2021 ◽  
Author(s):  
A.V. Moshkov ◽  
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Geomagnetic Latitude ◽  
Vertical Component ◽  
Low Frequency ◽  
Lower Ionosphere ◽  
Loop Current ◽  
The Earth ◽  
Transmitting Antenna ◽  
The Magnetic Field

Projects of active experiments in the ionosphere and the magnetosphere of the Earth and planets often include powerful low-frequency transmitters installed on-board of a spacecraft. Such sources are very effective, but their radiation is extremely heterogeneous in space because of the anisotropy of the ionospheric plasma due to the presence of the magnetic field of the Earth. This paper is devoted to numerical modeling of a distribution of the wave field strength near the Earth surface. The work examines a specific active wave experiment with a 20 m loop as a transmitting antenna. The satellite is assumed to orbit with an inclination of 82.5 degrees at an average altitude of 1000 km. All calculations are performed in linear approximation using the cold magneto-active plasma model. The computation model uses ray approximation everywhere except for the highly heterogeneous lower ionosphere, where a full wave equations set is applied. It is shown that the maximum magnetic field value is decreased with increasing of the geomagnetic latitude value and the strength range is 1… 2 nA/m for frequency 10 kHz and loop current 100 A. The magnitude of the vertical component of the electric field lies in the range of 0.4 ... 0.8 μV/m. An average Doppler frequency shift is equal to ~0.4 Hz. A comparison is made between the data of the numerical experiment and the results of simple estimations of the values of the magnetic field strength at the maximum of the ground distribution.

THE INFLUENCE OF THE IONOSPHERE ON THE VERTICAL FORCE EXCITED BY A HORIZONTAL ELECTRIC DIPOLE

2020 ◽  
pp. 68-76
Author(s):  
P. E. Tereshchenko
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Vertical Component ◽  
Low Frequency ◽  
Vertical Force ◽  
Frequency Range ◽  
The Earth ◽  
Horizontal Electric Dipole ◽  
Lower Frequency Range ◽  
The Magnetic Field

An analytical expression for the vertical component of the magnetic field has been obtained, with the help of which calculations have been made showing the effect of the ionosphere on the low-frequency field in the Earth-ionosphere waveguide. At distances from the source that are less than the doubled waveguide height, in ELF, and a lower frequency range, noticeable changes in the field strength caused by the state of the ionosphere are found.

scholarly journals Independent estimates of energies of steep-spectrum radio sources

2013 ◽  
Vol 9 (S304) ◽  
pp. 96-99
Author(s):  
Alla Miroshnichenko
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Low Frequency ◽  
Relativistic Electrons ◽  
Frequency Spectra ◽  
Inverse Compton Scattering ◽  
Spectrum Radio ◽  
The Magnetic Field ◽  
Relativistic Particles

AbstractWe examine properties of galaxies and quasars with steep low-frequency spectra from the UTR-2 catalogue. The number of the objects have the non-thermal X-ray emission due to the inverse Compton scattering of radio photons of the microwave background by relativistic electrons. So, it is possible to estimate the magnetic field strength and the ratio of energies of the magnetic field and relativistic particles, independently. As we have received the determined values of magnetic field strength are near to one order less than those at the well-known energy equipartition condition. We conclude from the obtained energy ratio that the energy of relativistic particles prevails over the energy of magnetic field in the galaxies and quasars with steep radio spectra.

scholarly journals THE MAGNETIC PROPERTIES MEASUREMENT OF COIL FOR GRAVITATIONAL ACCELERATION DETERMINATION

2020 ◽  
Vol 5 (2) ◽  
pp. 119-128
Author(s):  
Cherly Salawane ◽  
Supriyadi Supriyadi ◽  
Ronaldo Talapessy ◽  
Mirtha Yunitha Sari Risakotta
Keyword(s):  
Magnetic Field ◽  
Magnetic Properties ◽  
Field Strength ◽  
Electric Current ◽  
Graphical Method ◽  
Current Strength ◽  
Gravitational Acceleration ◽  
The Earth ◽  
The Magnetic Field ◽  
A Current

The value of the gravitational acceleration of the earth above the earth’s surface depends on the position of the latitude and longitude of the earth’s surface, in other words, because the shape of the earth’s surface is not round like a ball. The magnitude of gravity is not the same everywhere on the surface of the earth. The purpose of this study is to analyze the value of the earth’s gravitational acceleration in a laboratory using a current balance with a graphical method. Fluctuations in the value of the magnetic field strength (B) and the value of the electric current strength (i) on the current balance cause the value of laboratory gravitational acceleration (glab) to vary in the transfer of electric charge (q) according to coil type. The magnitude of the earth’s gravitational acceleration value obtained in a laboratory with a current balance for each type of coil is as follows: SF-37 glab-nr=9.89 m/s2, SF-38 glab-nr=9.90 m/s2, SF-39 glab-nr=9.76 m/s2, SF-40 glab-nr=9.95 m/s2, SF-41 glab-nr=9.75 m/s2 dan SF-42 glab-nr=9.93 m/s2. The results obtained indicate that the value of the earth’s gravitational acceleration in a laboratory close to the literature value is the value of the glab-nr in the SF-37 coil type of 9.89 m/s2.

scholarly journals Stretching of the Super-Elastic Double-Helix Geon. Wheeler´s Thermal Geons as Quanta of Heat and Momentum. Bohm´s Diffusion and the Heating of the Solar Corona and Heating of the Earth - Geon Engineering. Milgrom-Verlinde Constant. Mareš - Šesták constant

2020 ◽  
Vol 12 (2) ◽  
pp. 12
Author(s):  
Jiri Stavek
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Solar Corona ◽  
Magnetic Field Strength ◽  
Double Helix ◽  
David Bohm ◽  
The Earth ◽  
Highly Sensitive ◽  
Low Magnetic Field ◽  
The Magnetic Field

In our approach we have combined knowledge of Old Masters (working in this field before the year 1905), New Masters (working in this field after the year 1905) and Dissidents under the guidance of Louis de Broglie and David Bohm. Based on the great works of Julian Schwinger and John Archibald Wheeler we will study properties of geons formed by fusion of two soft x-ray particles (dyons) in the Schwarzschild gravitation core in our Sun at temperature 16 * 106 K. There are now several Teams that are able to achieve this fusion temperature in their special instruments (Tokamak, HL-2M Tokamak, Wendelstein 7-X, NIF, etc.) and to study properties of those formed geons. Thermal geons are with us all the time but they are very deeply hidden in our experiments. We have newly introduced Mareš - Šesták constant as the ratio of geon momentum to heat quantum of geon. The key information to enter into the World of geons was the empirical formula of David Bohm - the very well-known Bohm diffusion. From this formula we have extracted the amplitude, wavelength, frequency, quantum of the geon action, displacement law for geons, etc. It was found that geons are highly sensitive to the magnetic field strength. At a low magnetic field strength, the “inflation of geons” can occur. This effect could explain the Superheating of the Solar corona and the observed Heating of the Earth during two last centuries influenced by the changes in the Earth´s magnetic field. Geon engineering might modify the geon volume through the magnetic field strength. On the other hand, we were stimulated by the works of Mordehai Milgrom and Eric Verlinde and derived the Milgrom-Verlinde constant describing the gravitational field strength leading to the Newtonian gravitational constant on thermodynamic principles. The quantum of the geon momentum might open a new way how to understand gravitational phenomena. Can it be that Nature cleverly inserted geons into our experimental apparatuses and into our very-well known Old Formulae? We want to pass this concept into the hands of Readers of this Journal better educated in the Mathematics, Physics, and Thermodynamics.

scholarly journals Implications of the Low-frequency Turnover in the Spectrum of Radio Knot C in DG Tau

2021 ◽  
Vol 923 (1) ◽  
pp. 61
Author(s):  
C.-I. Björnsson
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Radio Emission ◽  
Magnetic Field Strength ◽  
Spectral Index ◽  
Low Frequency ◽  
Relativistic Electrons ◽  
Fermi Acceleration ◽  
Emission Volume ◽  
The Magnetic Field

Abstract The synchrotron spectrum of radio knot C in the protostellar object DG Tau has a low-frequency turnover. This is used to show that its magnetic field strength is likely to be at least 10 mG, which is roughly two orders of magnitude larger than previously estimated. The earlier, lower value is due to an overestimate of the emission volume together with an omission of the dependence of the minimum magnetic field on the synchrotron spectral index. Since the source is partially resolved, this implies a low volume-filling factor for the synchrotron emission. It is argued that the high pressure needed to account for the observations is due to shocks. In addition, cooling of the thermal gas is probably necessary in order to further enhance the magnetic field strength as well as the density of relativistic electrons. It is suggested that the observed spectral index implies that the energy of the radio-emitting electrons is below that needed to take part in first-order Fermi acceleration. Hence, the radio emission gives insights to the properties of its pre-acceleration phase. Attention is also drawn to the similarities between the properties of radio knot C and the shock-induced radio emission in supernovae.

scholarly journals CHANG-ES

2019 ◽  
Vol 632 ◽  
pp. A13 ◽  
Author(s):  
Y. Stein ◽  
R.-J. Dettmar ◽  
M. Weżgowiec ◽  
J. Irwin ◽  
R. Beck ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Flux Density ◽  
Magnetic Field Strength ◽  
Low Frequency ◽  
Transport Processes ◽  
Radio Continuum ◽  
Continuum Emission ◽  
X Ray ◽  
The Magnetic Field

Context. The radio continuum halos of edge-on spiral galaxies have diverse morphologies, with different magnetic field properties and cosmic ray (CR) transport processes into the halo. Aims. Using the Continuum HAloes in Nearby Galaxies – an EVLA Survey (CHANG-ES) radio continuum data from the Karl G. Jansky Very Large Array (VLA) in two frequency bands, 6 GHz (C-band) and 1.5 GHz (L-band), we analyzed the radio properties, including polarization and the transport processes of the CR electrons (CREs), in the edge-on spiral galaxy NGC 4013. Supplementary LOw-Frequency ARray (LOFAR) data at 150 MHz are used to study the low-frequency properties of this galaxy and X-ray data are used to investigate the central region. Methods. We determined the total radio flux densities (central source, disk, halo and total) as well as the radio scale heights of the radio continuum emission at both CHANG-ES frequencies and at the LOFAR frequency. We derived the magnetic field orientation from CHANG-ES polarization data and rotation measure synthesis (RM synthesis). Furthermore, we used the revised equipartition formula to calculate the magnetic field strength. Lastly, we modeled the processes of CR transport into the halo with the 1D SPINNAKER model. Results. The central point source dominates the radio continuum emission with a mean of ∼35% of the total flux density emerging from the central source in both CHANG-ES bands. Complementary X-ray data from Chandra show one dominant point source in the central part. The XMM-Newton spectrum shows hard X-rays, but no clear AGN classification is possible at this time. The radio continuum halo of NGC 4013 in C-band is rather small, while the low-frequency LOFAR data reveal a large halo. The scale height analysis shows that Gaussian fits, with halo scale heights of 1.2 kpc in C-band, 2.0 kpc in L-band, and 3.1 kpc at 150 MHz, better represent the intensity profiles than do exponential fits. The frequency dependence gives clear preference to diffusive CRE transport. The radio halo of NGC 4013 is relatively faint and contributes only 40% and 56% of the total flux density in C-band and L-band, respectively. This is less than in galaxies with wind-driven halos. While the SPINNAKER models of the radio profiles show that advection with a launching velocity of ∼20 km s−1 (increasing to ∼50 km s−1 at 4 kpc height) fits the data equally well or slightly better, diffusion is the dominating transport process up to heights of 1–2 kpc. The polarization data reveal plane-parallel, regular magnetic fields within the entire disk and vertical halo components indicating the presence of an axisymmetric field having a radial component pointing outwards. The mean magnetic field strength of the disk of NGC 4013 of 6.6 μG is rather small. Large-scale vertical fields are observed in the halo out to heights of about 6 kpc. Conclusions. The interaction and the low star formation rate (SFR) across the disk of NGC 4013 probably influence the appearance of its radio continuum halo and are correlated with the low total magnetic field strength. Several observable quantities give consistent evidence that the CR transport in the halo of NGC 4013 is diffusive: the frequency dependence of the synchrotron scale height, the disk/halo flux density ratio, the vertical profile of the synchrotron spectral index, the small propagation speed measured modeled with SPINNAKER, and the low temperature of the X-ray emitting hot gas.

scholarly journals The magnetic nature of umbra–penumbra boundary in sunspots

2018 ◽  
Vol 611 ◽  
pp. L4 ◽  
Author(s):  
J. Jurčák ◽  
R. Rezaei ◽  
N. Bello González ◽  
R. Schlichenmaier ◽  
J. Vomlel
Keyword(s):  
Magnetic Field ◽  
Solar Cycle ◽  
Field Strength ◽  
Magnetic Field Strength ◽  
Field Component ◽  
Vertical Component ◽  
Vertical Magnetic Field ◽  
Intensity Threshold ◽  
The Magnetic Field ◽  
Magnetic Nature

Context. Sunspots are the longest-known manifestation of solar activity, and their magnetic nature has been known for more than a century. Despite this, the boundary between umbrae and penumbrae, the two fundamental sunspot regions, has hitherto been solely defined by an intensity threshold. Aim. Here, we aim at studying the magnetic nature of umbra–penumbra boundaries in sunspots of different sizes, morphologies, evolutionary stages, and phases of the solar cycle. Methods. We used a sample of 88 scans of the Hinode/SOT spectropolarimeter to infer the magnetic field properties in at the umbral boundaries. We defined these umbra–penumbra boundaries by an intensity threshold and performed a statistical analysis of the magnetic field properties on these boundaries. Results. We statistically prove that the umbra–penumbra boundary in stable sunspots is characterised by an invariant value of the vertical magnetic field component: the vertical component of the magnetic field strength does not depend on the umbra size, its morphology, and phase of the solar cycle. With the statistical Bayesian inference, we find that the strength of the vertical magnetic field component is, with a likelihood of 99%, in the range of 1849–1885 G with the most probable value of 1867 G. In contrast, the magnetic field strength and inclination averaged along individual boundaries are found to be dependent on the umbral size: the larger the umbra, the stronger and more horizontal the magnetic field at its boundary. Conclusions. The umbra and penumbra of sunspots are separated by a boundary that has hitherto been defined by an intensity threshold. We now unveil the empirical law of the magnetic nature of the umbra–penumbra boundary in stable sunspots: it is an invariant vertical component of the magnetic field.

An Electromagnetic Survey Method for Directionally Drilling a Relief Well Into a Blown Out Oil or Gas Well

1984 ◽  
Vol 24 (03) ◽  
pp. 269-274 ◽  
Author(s):  
Arthur F. Kuckes ◽  
T. Lautzenhiser ◽  
A.G. Nekut ◽  
R. Sigal
Keyword(s):  
Magnetic Field ◽  
Current Flow ◽  
Unit Length ◽  
Low Frequency ◽  
Gas Wells ◽  
Surface Electrodes ◽  
The Earth ◽  
Large Enhancement ◽  
The Magnetic Field ◽  
A Current

Abstract This paper describes an electromagnetic method to facilitate drilling a well to intersect a target well casing. It has an important application in control of blown out oil and gas wells. By this method, a relief well was directionally drilled to intersect the casing of a blowout at 8,000 ft [2700 m]. The relative distance and azimuthal direction to the target casing can be determined when the relief well is up to more than 100 ft [30 m] from the blowout. Introduction There is a need, particularly in the control of runaway oil or gas wells, for the ability to drill a relief well to intersect a target well casing at a specified subsurface depth. Our method consists of detecting and analyzing the magnetic field generated by alternating electric current flow on a target well casing, drillstem, or fish. By comparison to the earth, steel is a very good electrical conductor; a steel well casing has a strong "short-circuiting" effect on the parallel component of electric current now in its vicinity, The magnetic field generated by current flow on the target casing and measured in the relief well can be used to determine the relative distance and direction from the relief well to the target. In this paper, we present the principles of operation along with the results of some field tests. An alternative scheme using a wireline current source is described in the Appendix. Principle of the Method Principle of the Method Consider the apparatus shown in Fig. 1. The dimensions shown can vary greatly: those given are for reference. A low-frequency AC is injected into the ground by use of surface electrodes near the blowout. The return current is collected by remote surface electrodes. If the blowout casing were not present, this arrangement would produce a very small magnetic field response on or near the blowout axis. With the blowout casing in place, there is a large enhancement of the current flowing down the blowout axis, which results in a large enhancement of the magnetic field as indicated by Ampere's law. Considering the geometry of the magnetic field resulting from a current-carrying conductor, the apparent direction to the conductor can be deduced. It is useful to introduce a parameter re that is the radius of a circular column of earth having the same resistance per unit length as the blown out well casing. If the conductivity of the earth is given by sigma e, that of the casing by sigma c, and the well casing has a radius rc and wall thickness hc, then re is given by (1) The electrical conductivity of steel is about 107 (omega.m)-1, whereas that of country rock in a petroleum environment is within an order of magnitude of 0.1 (omega.m)-1. Thus, a well casing with a 1/2-in. [1.3-cm] wall, 10 in. [25 cm] in diameter, has the same electrical resistance per unit length as a column of earth [sigma c = 1(omegam)-1] about 1,000 ft [300 m] in diameter. Such well casing has a short-circuiting effect to vertical current flow on a column of earth approximately this diameter. The sensitivity of standard magnetometers is such that after 100 seconds of signal averaging, an AC magnetic induction of less than 10–2 gammas or alternatively a magnetic field of 10–5 A/m can be detected. This corresponds to the magnetic field generated by a current of 2 mA on well casing 100 ft [30 m] away. The parameter re also indicates the scale length over which current builds up on a casing. Thus, for a semi-infinite casing surrounded by a uniform conductor of much lower conductivity, the current on the casing will build up to its asymptotic value within re of the end of the casing. Consequently, it is a valid approximation to calculate the current on the casing, Ic, by (2) when the electric field, E, parallel to the casing varies slowly on the scale re. This is the situation far from the surface injection electrodes. When a distance on the order of re from the blowout casing, the low-frequency magnetic field signal is caused predominantly by current flow on the blowout: predominantly by current flow on the blowout: (3) SPEJ P. 269

scholarly journals How to determine the thermal electron density and the magnetic field strength from the Cluster/Whisper observations around the Earth

2001 ◽  
Vol 19 (10/12) ◽  
pp. 1711-1720 ◽  
Author(s):  
J. G. Trotignon ◽  
P. M. E. Décréau ◽  
J. L. Rauch ◽  
O. Randriamboarison ◽  
V. Krasnoselskikh ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Electron Density ◽  
Magnetic Field Strength ◽  
Density Ratio ◽  
Electron Velocity ◽  
Thermal Electron ◽  
The Earth ◽  
The Waves ◽  
The Magnetic Field

Abstract. The Wave Experiment Consortium, WEC, is a highly integrated package of five instruments used to study the plasma environment around the Earth. One of these instruments, the Waves of HIgh frequency and Sounder for Probing of Electron density by Relaxation, Whisper, aims at the thermal electron density evaluation and natural wave monitoring in the 4–83 kHz frequency range. In its active working mode, which is our primarily concern here, the Whisper instrument transmits a short wave train at a swept frequency and receives echoes after a delay. Incidentally, it behaves like a classical ground-based ionosonde. Natural modes of oscillations may thus be excited in the surrounding medium. This means that with suitable interpretations, the Whisper sounding technique becomes a powerful tool for plasma diagnosis. By taking into account the characteristic frequencies of the magnetoplasmas encountered by the Cluster spacecraft, it is indeed possible to reliably and accurately determine the electron density and, to a lesser degree, the magnetic field strength from the Whisper electric field measurements. Due to the predominantly electrostatic nature of the waves that are excited, observations of resonances may also lead to information on the electron velocity distribution functions. The existence of a hot population may indeed be revealed and the hot to cold density ratio can be estimated.Key words. Magnetospheric physics (plasma waves and instabilities). Space plasma physics (active perturbation experiments; instruments and techniques)

Extracting geoelectrical maps from vintage very-low-frequency airborne data, tipper inversion, and interpretation: A case study from northern Sweden

Geophysics ◽  
2016 ◽  
Vol 81 (5) ◽  
pp. B135-B147 ◽  
Author(s):  
Sayyed Mohammad Abtahi ◽  
Laust Börsting Pedersen ◽  
Jochen Kamm ◽  
Thomas Kalscheuer
Keyword(s):  
Magnetic Field ◽  
Apparent Resistivity ◽  
Vertical Component ◽  
Low Frequency ◽  
High Resistivity ◽  
Clear Correlation ◽  
Northern Sweden ◽  
Very Low Frequency ◽  
Basaltic Composition ◽  
The Magnetic Field

In 1985, the mining company Luossavaara-Kiirunavaara Aktiebolag collected airborne very-low-frequency (VLF) data in northern Sweden. The operators stored only the vertical component and the total magnetic field, which at that time were believed to be sufficient for qualitative interpretation. Therefore, the data could not be directly used for quantitative tensor VLF processing and inversion. To avoid the costs of resurveying, we have developed a novel technique to estimate the tippers from the measured VLF data by computing anomalous and normal parts of the horizontal components of the magnetic field from two transmitters separately. Retrieval of the normal horizontal components was possible because one component of the horizontal magnetic field was used as the phase reference during the measurements. Additionally, we have determined how the approximate apparent resistivity suitable for data visualization can be computed from the components of the magnetic field assuming an average normal resistivity of the subsurface. Maps of apparent resistivity combined with topography show a clear correlation between high topography and high resistivity, whereas conductive zones are found in valleys in between. More importantly, the 3D model inverted from the calculated tippers shows excellent agreement with a map of the surface geology. Based on this comparison, some less resistive zones can be related to fluids in fractures and others can be related to mineralized contact zones. We suggest to focus further exploration on conductive zones surrounding areas with basaltic composition.

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