Diagnostics of vector magnetic fields
Stenflo, J. O.
1985-01-01
It is shown that the vector magnetic fields derived from observations with a filter magnetograph will be severely distorted if the spatially unresolved magnetic structure is not properly accounted for. Thus the apparent vector field will appear much more horizontal than it really is, but this distortion is strongly dependent on the area factor and the temperature line weakenings. As the available fluxtube models are not sufficiently well determined, it is not possible to correct the filter magnetograph observations for these effects in a reliable way, although a crude correction is of course much better than no correction at all. The solution to this diagnostic problem is to observe simultaneously in suitable combinations of spectral lines, and/or use Stokes line profiles recorded with very high spectral resolution. The diagnostic power of using a Fourier transform spectrometer for polarimetry is shown and some results from I and V spectra are illustrated. The line asymmetries caused by mass motions inside the fluxtubes adds an extra complication to the diagnostic problem, in particular as there are indications that the motions are nonstationary in nature. The temperature structure appears to be a function of fluxtube diameter, as a clear difference between plage and network fluxtubes was revealed. The divergence of the magnetic field with height plays an essential role in the explanation of the Stokes V asymmetries (in combination with the mass motions). A self consistent treatment of the subarcsec field geometry may be required to allow an accurate derivation of the spatially averaged vector magnetic field from spectrally resolved data.
Measurements of Solar Vector Magnetic Fields
Hagyard, M. J. (Editor)
1985-01-01
Various aspects of the measurement of solar magnetic fields are presented. The four major subdivisions of the study are: (1) theoretical understanding of solar vector magnetic fields; (3) techniques for interpretation of observational data; and (4) techniques for data display.
Measurements of Solar Vector Magnetic Fields
International Nuclear Information System (INIS)
Hagyard, M.J.
1985-05-01
Various aspects of the measurement of solar magnetic fields are presented. The four major subdivisions of the study are: (1) theoretical understanding of solar vector magnetic fields; (3) techniques for interpretation of observational data; and (4) techniques for data display
Magnetic vector field tag and seal
Johnston, Roger G.; Garcia, Anthony R.
2004-08-31
One or more magnets are placed in a container (preferably on objects inside the container) and the magnetic field strength and vector direction are measured with a magnetometer from at least one location near the container to provide the container with a magnetic vector field tag and seal. The location(s) of the magnetometer relative to the container are also noted. If the position of any magnet inside the container changes, then the measured vector fields at the these locations also change, indicating that the tag has been removed, the seal has broken, and therefore that the container and objects inside may have been tampered with. A hollow wheel with magnets inside may also provide a similar magnetic vector field tag and seal. As the wheel turns, the magnets tumble randomly inside, removing the tag and breaking the seal.
The significance of vector magnetic field measurements
Hagyard, M. J.
1990-01-01
Observations of four flaring solar active regions, obtained during 1980-1986 with the NASA Marshall vector magnetograph (Hagyard et al., 1982 and 1985), are presented graphically and characterized in detail, with reference to nearly simultaneous Big Bear Solar Observatory and USAF ASW H-alpha images. It is shown that the flares occurred where local photospheric magnetic fields differed most from the potential field, with initial brightening on either side of a magnetic-neutral line near the point of maximum angular shear (rather than that of maximum magnetic-field strength, typically 1 kG or greater). Particular emphasis is placed on the fact that these significant nonpotential features were detected only by measuring all three components of the vector magnetic field.
The vector structure of active magnetic fields
Parker, E. N.
1985-01-01
Observations are needed to show the form of the strains introduced into the fields above the surface of the Sun. The longitudinal component alone does not provide the basic information, so that it has been necessary in the past to use the filamentary structure observed in H sub alpha to supplement the longitudinal information. Vector measurements provide the additional essential information to determine the strains, with the filamentary structure available as a check for consistency. It is to be expected, then, that vector measurements will permit a direct mapping of the strains imposed on the magnetic fields of active regions. It will be interesting to study the relation of those strains to the emergence of magnetic flux, flares, eruptive prominences, etc. In particular we may hope to study the relaxation of the strains via the dynamical nonequilibrium.
Spectral Analysis of Vector Magnetic Field Profiles
Parker, Robert L.; OBrien, Michael S.
1997-01-01
We investigate the power spectra and cross spectra derived from the three components of the vector magnetic field measured on a straight horizontal path above a statistically stationary source. All of these spectra, which can be estimated from the recorded time series, are related to a single two-dimensional power spectral density via integrals that run in the across-track direction in the wavenumber domain. Thus the measured spectra must obey a number of strong constraints: for example, the sum of the two power spectral densities of the two horizontal field components equals the power spectral density of the vertical component at every wavenumber and the phase spectrum between the vertical and along-track components is always pi/2. These constraints provide powerful checks on the quality of the measured data; if they are violated, measurement or environmental noise should be suspected. The noise due to errors of orientation has a clear characteristic; both the power and phase spectra of the components differ from those of crustal signals, which makes orientation noise easy to detect and to quantify. The spectra of the crustal signals can be inverted to obtain information about the cross-track structure of the field. We illustrate these ideas using a high-altitude Project Magnet profile flown in the southeastern Pacific Ocean.
Measuring magnetic field vector by stimulated Raman transitions
International Nuclear Information System (INIS)
Wang, Wenli; Wei, Rong; Lin, Jinda; Wang, Yuzhu; Dong, Richang; Zou, Fan; Chen, Tingting
2016-01-01
We present a method for measuring the magnetic field vector in an atomic fountain by probing the line strength of stimulated Raman transitions. The relative line strength for a Λ-type level system with an existing magnetic field is theoretically analyzed. The magnetic field vector measured by our proposed method is consistent well with that by the traditional bias magnetic field method with an axial resolution of 6.1 mrad and a radial resolution of 0.16 rad. Dependences of the Raman transitions on laser polarization schemes are also analyzed. Our method offers the potential advantages for magnetic field measurement without requiring additional bias fields, beyond the limitation of magnetic field intensity, and extending the spatial measurement range. The proposed method can be widely used for measuring magnetic field vector in other precision measurement fields.
Inferring Lower Boundary Driving Conditions Using Vector Magnetic Field Observations
Schuck, Peter W.; Linton, Mark; Leake, James; MacNeice, Peter; Allred, Joel
2012-01-01
Low-beta coronal MHD simulations of realistic CME events require the detailed specification of the magnetic fields, velocities, densities, temperatures, etc., in the low corona. Presently, the most accurate estimates of solar vector magnetic fields are made in the high-beta photosphere. Several techniques have been developed that provide accurate estimates of the associated photospheric plasma velocities such as the Differential Affine Velocity Estimator for Vector Magnetograms and the Poloidal/Toroidal Decomposition. Nominally, these velocities are consistent with the evolution of the radial magnetic field. To evolve the tangential magnetic field radial gradients must be specified. In addition to estimating the photospheric vector magnetic and velocity fields, a further challenge involves incorporating these fields into an MHD simulation. The simulation boundary must be driven, consistent with the numerical boundary equations, with the goal of accurately reproducing the observed magnetic fields and estimated velocities at some height within the simulation. Even if this goal is achieved, many unanswered questions remain. How can the photospheric magnetic fields and velocities be propagated to the low corona through the transition region? At what cadence must we observe the photosphere to realistically simulate the corona? How do we model the magnetic fields and plasma velocities in the quiet Sun? How sensitive are the solutions to other unknowns that must be specified, such as the global solar magnetic field, and the photospheric temperature and density?
Improvement of vector compensation method for vehicle magnetic distortion field
Energy Technology Data Exchange (ETDEWEB)
Pang, Hongfeng, E-mail: panghongfeng@126.com; Zhang, Qi; Li, Ji; Luo, Shitu; Chen, Dixiang; Pan, Mengchun; Luo, Feilu
2014-03-15
Magnetic distortions such as eddy-current field and low frequency magnetic field have not been considered in vector compensation methods. A new compensation method is proposed to suppress these magnetic distortions and improve compensation performance, in which the magnetic distortions related to measurement vectors and time are considered. The experimental system mainly consists of a three-axis fluxgate magnetometer (DM-050), an underwater vehicle and a proton magnetometer, in which the scalar value of magnetic field is obtained with the proton magnetometer and considered to be the true value. Comparing with traditional compensation methods, experimental results show that the magnetic distortions can be further reduced by two times. After compensation, error intensity and RMS error are reduced from 11684.013 nT and 7794.604 nT to 16.219 nT and 5.907 nT respectively. It suggests an effective way to improve the compensation performance of magnetic distortions. - Highlights: • A new vector compensation method is proposed for vehicle magnetic distortion. • The proposed model not only includes magnetometer error but also considers magnetic distortion. • Compensation parameters are computed directly by solving nonlinear equations. • Compared with traditional methods, the proposed method is not related with rotation angle rate. • Error intensity and RMS error can be reduced to 1/2 of the error with traditional methods.
Improvement of vector compensation method for vehicle magnetic distortion field
International Nuclear Information System (INIS)
Pang, Hongfeng; Zhang, Qi; Li, Ji; Luo, Shitu; Chen, Dixiang; Pan, Mengchun; Luo, Feilu
2014-01-01
Magnetic distortions such as eddy-current field and low frequency magnetic field have not been considered in vector compensation methods. A new compensation method is proposed to suppress these magnetic distortions and improve compensation performance, in which the magnetic distortions related to measurement vectors and time are considered. The experimental system mainly consists of a three-axis fluxgate magnetometer (DM-050), an underwater vehicle and a proton magnetometer, in which the scalar value of magnetic field is obtained with the proton magnetometer and considered to be the true value. Comparing with traditional compensation methods, experimental results show that the magnetic distortions can be further reduced by two times. After compensation, error intensity and RMS error are reduced from 11684.013 nT and 7794.604 nT to 16.219 nT and 5.907 nT respectively. It suggests an effective way to improve the compensation performance of magnetic distortions. - Highlights: • A new vector compensation method is proposed for vehicle magnetic distortion. • The proposed model not only includes magnetometer error but also considers magnetic distortion. • Compensation parameters are computed directly by solving nonlinear equations. • Compared with traditional methods, the proposed method is not related with rotation angle rate. • Error intensity and RMS error can be reduced to 1/2 of the error with traditional methods
Determination of Coronal Magnetic Fields from Vector Magnetograms
Mikic, Zoran
1997-01-01
During the course of the present contract we developed an 'evolutionary technique' for the determination of force-free coronal magnetic fields from vector magnetograph observations. The method can successfully generate nonlinear force- free fields (with non-constant-a) that match vector magnetograms. We demonstrated that it is possible to determine coronal magnetic fields from photospheric measurements, and we applied it to vector magnetograms of active regions. We have also studied theoretical models of coronal fields that lead to disruptions. Specifically, we have demonstrated that the determination of force-free fields from exact boundary data is a well-posed mathematical problem, by verifying that the computed coronal field agrees with an analytic force-free field when boundary data for the analytic field are used; demonstrated that it is possible to determine active-region coronal magnetic fields from photospheric measurements, by computing the coronal field above active region 5747 on 20 October 1989, AR6919 on 15 November 1991, and AR7260 on 18 August 1992, from data taken with the Stokes Polarimeter at Mees Solar Observatory, University of Hawaii; started to analyze active region 7201 on 19 June 1992 using measurements made with the Advanced Stokes Polarimeter at NSO/Sac Peak; investigated the effects of imperfections in the photospheric data on the computed coronal magnetic field; documented the coronal field structure of AR5747 and compared it to the morphology of footpoint emission in a flare, showing that the 'high- pressure' H-alpha footpoints are connected by coronal field lines; shown that the variation of magnetic field strength along current-carrying field lines is significantly different from the variation in a potential field, and that the resulting near-constant area of elementary flux tubes is consistent with observations; begun to develop realistic models of coronal fields which can be used to study flare trigger mechanisms; demonstrated that
Magnetic monopole and vector field of the spin 0
International Nuclear Information System (INIS)
Pantyushin, A.A.
2001-01-01
The motion of electrically charged particles in uniform magnetic field by time is considered. It is found out that additional force acting on eclectically charged particle from the spin 0 vector field side is proportional to the magnetic field. Proportion coefficient is equal to eg/4π (g - unknown parameter, determining of the rate and character of source non-preservation) - the analogue of constant thin structure α=e 2 /4π. Obtained results give evidence to suppose that for explanation of indicated experiments the monopole introduction is not essential
Vector optical fields with polarization distributions similar to electric and magnetic field lines.
Pan, Yue; Li, Si-Min; Mao, Lei; Kong, Ling-Jun; Li, Yongnan; Tu, Chenghou; Wang, Pei; Wang, Hui-Tian
2013-07-01
We present, design and generate a new kind of vector optical fields with linear polarization distributions modeling to electric and magnetic field lines. The geometric configurations of "electric charges" and "magnetic charges" can engineer the spatial structure and symmetry of polarizations of vector optical field, providing additional degrees of freedom assisting in controlling the field symmetry at the focus and allowing engineering of the field distribution at the focus to the specific applications.
HEIGHT VARIATION OF THE VECTOR MAGNETIC FIELD IN SOLAR SPICULES
Energy Technology Data Exchange (ETDEWEB)
Suárez, D. Orozco; Ramos, A. Asensio; Bueno, J. Trujillo, E-mail: dorozco@iac.es [Instituto de Astrofísica de Canarias, E-38205 La Laguna, Tenerife (Spain)
2015-04-20
Proving the magnetic configuration of solar spicules has hitherto been difficult due to the lack of spatial resolution and image stability during off-limb ground-based observations. We report spectropolarimetric observations of spicules taken in the He i 1083 nm spectral region with the Tenerife Infrared Polarimeter II at the German Vacuum Tower Telescope of the Observatorio del Teide (Tenerife, Canary Islands, Spain). The data provide the variation with geometrical height of the Stokes I, Q, U, and V profiles, whose encoded information allows the determination of the magnetic field vector by means of the HAZEL inversion code. The inferred results show that the average magnetic field strength at the base of solar spicules is about 80 gauss, and then it decreases rapidly with height to about 30 gauss at a height of 3000 km above the visible solar surface. Moreover, the magnetic field vector is close to vertical at the base of the chromosphere and has mid-inclinations (about 50°) above 2 Mm height.
Vector magnetic field microscopy using nitrogen vacancy centers in diamond
Maertz, B.J.; Wijnheijmer, A.P.; Fuchs, G.D.; Nowakowski, M.E.; Awschalom, D.D.
2010-01-01
The localized spin triplet ground state of a nitrogen vacancy (NV) center in diamond can be used in atomic-scale detection of local magnetic fields. Here we present a technique using ensembles of these defects in diamond to image fields around magnetic structures. We extract the local magnetic field
International Nuclear Information System (INIS)
Dai, H.L.; Wang, X.
2006-01-01
In this paper, an analytical method is introduced to solve the problem for the dynamic stress-focusing and centred-effect of perturbation of the magnetic field vector in orthotropic cylinders under thermal and mechanical shock loads. Analytical expressions for the dynamic stresses and the perturbation of the magnetic field vector are obtained by means of finite Hankel transforms and Laplace transforms. The response histories of dynamic stresses and the perturbation of the field vector are also obtained. In practical examples, the dynamic focusing effect on both magnetoelastic stress and perturbation of the axial magnetic field vector in an orthotropic cylinder subjected to various shock loads is presented and discussed
VECTOR MAGNETIC FIELDS AND ELECTRIC CURRENTS FROM THE IMAGING VECTOR MAGNETOGRAPH
International Nuclear Information System (INIS)
Li Jing; Mickey, Don; Van Ballegooijen, A. A.
2009-01-01
First, we describe a general procedure to produce high-quality vector magnetograms using the Imaging Vector Magnetograph (IVM) at Mees Solar Observatory. Two IVM effects are newly discussed and taken into account: (1) the central wavelength of the Fabry-Perot is found to drift with time as a result of undiagnosed thermal or mechanical instabilities in the instrument; (2) the Stokes V-sign convention built into the IVM is found to be opposite to the conventional definition used in the study of radiative transfer of polarized radiation. At the spatial resolution 2'' x 2'', the Stokes Q, U, V uncertainty reaches ∼1 x 10 -3 to 5 x 10 -4 in time-averaged data over 1 hr in the quiet Sun. When vector magnetic fields are inferred from the time-averaged Stokes spectral images of FeI 6302.5 A, the resulting uncertainties are on the order of 10 G for the longitudinal fields (B || ), 40 G for the transverse field strength (B perpendicular ) and ∼9 0 for the magnetic azimuth (φ). The magnetic field inversion used in this work is the 'Triplet' code, which was developed and implemented in the IVM software package by the late B. J. LaBonte. The inversion code is described in detail in the Appendix. Second, we solve for the absolute value of the vertical electric current density, |J z |, accounting for the above IVM problems, for two different active regions. One is a single sunspot region (NOAA 10001 observed on 2002 June 20) while the other is a more complex, quadrupolar region (NOAA10030 observed on 2002 July 15). We use a calculation that does not require disambiguation of 180 0 in the transverse field directions. The |J z | uncertainty is on the order of ∼7.0 mA m -2 . The vertical current density increases with increasing vertical magnetic field. The rate of increase is about 1-2 times as large in the quadrupolar NOAA 10030 region as in the simple NOAA 10001, and it is more spatially variable over NOAA 10030 than over NOAA 10001.
Vector condensate and AdS soliton instability induced by a magnetic field
International Nuclear Information System (INIS)
Cai, Rong-Gen; Li, Li; Li, Li-Fang; Wu, You
2014-01-01
We continue to study the holographic p-wave superconductor model in the Einstein-Maxwell-complex vector field theory with a non-minimal coupling between the complex vector field and the Maxwell field. In this paper we work in the AdS soliton background which describes a conformal field theory in the confined phase and focus on the probe approximation. We find that an applied magnetic field can lead to the condensate of the vector field and the AdS soliton instability. As a result, a vortex lattice structure forms in the spatial directions perpendicular to the applied magnetic field. As a comparison, we also discuss the vector condensate in the Einstein-SU(2) Yang-Mills theory and find that in the setup of the present paper, the Einstein-Maxwell-complex vector field model is a generalization of the SU(2) model in the sense that the vector field has a general mass and gyromagnetic ratio
Vector magnetic field changes associated with X-class flares
Wang, Haimin; Ewell, M. W., Jr.; Zirin, H.; Ai, Guoxiang
1994-01-01
We present high-resolution transverse and longitudinal magnetic field measurements bracketing five X-class solar flares. We show that the magnetic shear, defined as the angular difference between the measured field and calculated potential field, actually increases after all of these flares. In each case, the shear is shown to increase along a substantial portion of the magnetic neutral line. For two of the cases, we have excellent time resolution, on the order of several minutes, and we demonstrate that the shear increase is impulsive. We briefly discuss the theoretical implications of our results.
Solar monochromatic images in magneto-sensitive spectral lines and maps of vector magnetic fields
Shihui, Y.; Jiehai, J.; Minhan, J.
1985-01-01
A new method which allows by use of the monochromatic images in some magneto-sensitive spectra line to derive both the magnetic field strength as well as the angle between magnetic field lines and line of sight for various places in solar active regions is described. In this way two dimensional maps of vector magnetic fields may be constructed. This method was applied to some observational material and reasonable results were obtained. In addition, a project for constructing the three dimensional maps of vector magnetic fields was worked out.
Metcalf, Thomas R.
1994-01-01
I present a robust algorithm that resolves the 180-deg ambiguity in measurements of the solar vector magnetic field. The technique simultaneously minimizes both the divergence of the magnetic field and the electric current density using a simulated annealing algorithm. This results in the field orientation with approximately minimum free energy. The technique is well-founded physically and is simple to implement.
Spherical cap modelling of Orsted magnetic field vectors over southern Africa
CSIR Research Space (South Africa)
Kotze, PB
2001-01-01
Full Text Available Vector magnetic field observations by the Orsted satellite during geomagnetic quiet conditions around January 1, 2000, have been employed to derive a spherical cap harmonic model (Haines, 1985) over the southern African region between 10 degrees...
Observations of vector magnetic fields in flaring active regions
Chen, Jimin; Wang, Haimin; Zirin, Harold; Ai, Guoxiang
1994-01-01
We present vector magnetograph data of 6 active regions, all of which produced major flares. Of the 20 M-class (or above) flares, 7 satisfy the flare conditions prescribed by Hagyard (high shear and strong transverse fields). Strong photospheric shear, however, is not necessarily a condition for a flare. We find an increase in the shear for two flares, a 6-deg shear increase along the neutral line after a X-2 flare and a 13-deg increase after a M-1.9 flare. For other flares, we did not detect substantial shear changes.
VECTOR TOMOGRAPHY FOR THE CORONAL MAGNETIC FIELD. II. HANLE EFFECT MEASUREMENTS
International Nuclear Information System (INIS)
Kramar, M.; Inhester, B.; Lin, H.; Davila, J.
2013-01-01
In this paper, we investigate the feasibility of saturated coronal Hanle effect vector tomography or the application of vector tomographic inversion techniques to reconstruct the three-dimensional magnetic field configuration of the solar corona using linear polarization measurements of coronal emission lines. We applied Hanle effect vector tomographic inversion to artificial data produced from analytical coronal magnetic field models with equatorial and meridional currents and global coronal magnetic field models constructed by extrapolation of real photospheric magnetic field measurements. We tested tomographic inversion with only Stokes Q, U, electron density, and temperature inputs to simulate observations over large limb distances where the Stokes I parameters are difficult to obtain with ground-based coronagraphs. We synthesized the coronal linear polarization maps by inputting realistic noise appropriate for ground-based observations over a period of two weeks into the inversion algorithm. We found that our Hanle effect vector tomographic inversion can partially recover the coronal field with a poloidal field configuration, but that it is insensitive to a corona with a toroidal field. This result demonstrates that Hanle effect vector tomography is an effective tool for studying the solar corona and that it is complementary to Zeeman effect vector tomography for the reconstruction of the coronal magnetic field
Evolution of vector magnetic fields and the August 27 1990 X-3 flare
Wang, Haimin
1992-01-01
Vector magnetic fields in an active region of the sun are studied by means of continuous observations of magnetic-field evolution emphasizing magnetic shear build-up. The vector magnetograms are shown to measure magnetic fields correctly based on concurrent observations and a comparison of the transverse field with the H alpha fibril structure. The morphology and velocity pattern are examined, and these data and the shear build-up suggest that the active region's two major footprints are separated by a region with flows, new flux emergence, and several neutral lines. The magnetic shear appears to be caused by the collision and shear motion of two poles of opposite polarities. The transverse field is shown to turn from potential to sheared during the process of flux cancellation, and this effect can be incorporated into existing models of magnetic flux cancellation.
Cryogenic STM in 3D vector magnetic fields realized through a rotatable insert.
Trainer, C; Yim, C M; McLaren, M; Wahl, P
2017-09-01
Spin-polarized scanning tunneling microscopy (SP-STM) performed in vector magnetic fields promises atomic scale imaging of magnetic structure, providing complete information on the local spin texture of a sample in three dimensions. Here, we have designed and constructed a turntable system for a low temperature STM which in combination with a 2D vector magnet provides magnetic fields of up to 5 T in any direction relative to the tip-sample geometry. This enables STM imaging and spectroscopy to be performed at the same atomic-scale location and field-of-view on the sample, and most importantly, without experiencing any change on the tip apex before and after field switching. Combined with a ferromagnetic tip, this enables us to study the magnetization of complex magnetic orders in all three spatial directions.
Vector magnetic field observations with the Haleakala polarimeter
Mickey, D. L.
1985-01-01
Several enhancements were recently made to the Haleakala polarimeter. Linear array detectors provide simultaneous resolution over a 3-A wavelength range, with spectral resolution of 40 mA. Optical fibers are now used to carry the intensity-modulated light from the rotating quarter-wave plate polarimeter to the echelle spectrometer, permitting its removal from the spar to a more stable environment. These changes, together with improved quarter-wave plates, reduced systematic errors to a few parts in 10,000 for routine observations. Examples of Stokes profiles and derived magnetic field maps are presented.
Tadesse, T.; Wiegelmann, T.; Gosain, S.; MacNeice, P.; Pevtsov, A. A.
2014-01-01
Context. The magnetic field permeating the solar atmosphere is generally thought to provide the energy for much of the activity seen in the solar corona, such as flares, coronal mass ejections (CMEs), etc. To overcome the unavailability of coronal magnetic field measurements, photospheric magnetic field vector data can be used to reconstruct the coronal field. Currently, there are several modelling techniques being used to calculate three-dimensional field lines into the solar atmosphere. Aims. For the first time, synoptic maps of a photospheric-vector magnetic field synthesized from the vector spectromagnetograph (VSM) on Synoptic Optical Long-term Investigations of the Sun (SOLIS) are used to model the coronal magnetic field and estimate free magnetic energy in the global scale. The free energy (i.e., the energy in excess of the potential field energy) is one of the main indicators used in space weather forecasts to predict the eruptivity of active regions. Methods. We solve the nonlinear force-free field equations using an optimization principle in spherical geometry. The resulting threedimensional magnetic fields are used to estimate the magnetic free energy content E(sub free) = E(sub nlfff) - E(sub pot), which is the difference of the magnetic energies between the nonpotential field and the potential field in the global solar corona. For comparison, we overlay the extrapolated magnetic field lines with the extreme ultraviolet (EUV) observations by the atmospheric imaging assembly (AIA) on board the Solar Dynamics Observatory (SDO). Results. For a single Carrington rotation 2121, we find that the global nonlinear force-free field (NLFFF) magnetic energy density is 10.3% higher than the potential one. Most of this free energy is located in active regions.
In-Flight spacecraft magnetic field monitoring using scalar/vector gradiometry
DEFF Research Database (Denmark)
Primdahl, Fritz; Risbo, Torben; Merayo, José M.G.
2006-01-01
Earth magnetic field mapping from planetary orbiting satellites requires a spacecraft magnetic field environment control program combined with the deployment of the magnetic sensors on a boom in order to reduce the measurement error caused by the local spacecraft field. Magnetic mapping missions...... (Magsat, Oersted, CHAMP, SAC-C MMP and the planned ESA Swarm project) carry a vector magnetometer and an absolute scalar magnetometer for in-flight calibration of the vector magnetometer scale values and for monitoring of the inter-axes angles and offsets over time intervals from months to years...... sensors onboard the Oersted satellite. For Oersted, a large difference between the pre-flight determined spacecraft magnetic field and the in-flight estimate exists causing some concern about the general applicability of the dual sensors technique....
International Nuclear Information System (INIS)
Kramar, M.; Lin, H.; Tomczyk, S.
2016-01-01
We present the first direct “observation” of the global-scale, 3D coronal magnetic fields of Carrington Rotation (CR) Cycle 2112 using vector tomographic inversion techniques. The vector tomographic inversion uses measurements of the Fe xiii 10747 Å Hanle effect polarization signals by the Coronal Multichannel Polarimeter (CoMP) and 3D coronal density and temperature derived from scalar tomographic inversion of Solar Terrestrial Relations Observatory (STEREO)/Extreme Ultraviolet Imager (EUVI) coronal emission lines (CELs) intensity images as inputs to derive a coronal magnetic field model that best reproduces the observed polarization signals. While independent verifications of the vector tomography results cannot be performed, we compared the tomography inverted coronal magnetic fields with those constructed by magnetohydrodynamic (MHD) simulations based on observed photospheric magnetic fields of CR 2112 and 2113. We found that the MHD model for CR 2112 is qualitatively consistent with the tomography inverted result for most of the reconstruction domain except for several regions. Particularly, for one of the most noticeable regions, we found that the MHD simulation for CR 2113 predicted a model that more closely resembles the vector tomography inverted magnetic fields. In another case, our tomographic reconstruction predicted an open magnetic field at a region where a coronal hole can be seen directly from a STEREO-B/EUVI image. We discuss the utilities and limitations of the tomographic inversion technique, and present ideas for future developments
Migration transformation of two-dimensional magnetic vector and tensor fields
DEFF Research Database (Denmark)
Zhdanov, Michael; Cai, Hongzhu; Wilson, Glenn
2012-01-01
We introduce a new method of rapid interpretation of magnetic vector and tensor field data, based on ideas of potential field migration which extends the general principles of seismic and electromagnetic migration to potential fields. 2-D potential field migration represents a direct integral...... to the downward continuation of a well-behaved analytical function. We present case studies for imaging of SQUID-based magnetic tensor data acquired over a magnetite skarn at Tallawang, Australia. The results obtained from magnetic tensor field migration agree very well with both Euler deconvolution and the known...
International Nuclear Information System (INIS)
Gelinas, R.C.
1984-01-01
A system for transmission of information using a curl-free magnetic vector potential radiation field. The system includes current-carrying apparatus for generating a magnetic vector potential field with a curl-free component coupled to apparatus for modulating the current applied to the field generating apparatus. Receiving apparatus includes a detector with observable properties that vary with the application of an applied curl-free magnetic vector potential field. Analyzing apparatus for determining the information content of modulation imposed on the curl-free vector potential field can be established in materials that are not capable of transmitting more common electromagnetic radiation
Bommier, V.
1986-01-01
The Hanle effect is the modification of the linear polarization parameters of a spectral line due to the effect of the magnetic field. It has been successfully applied to the magnetic field vector diagnostic in solar prominences. The magnetic field vector is determined by comparing the measured polarization to the polarization computed, taking into account all the polarizing and depolarizing processes in line formation and the depolarizing effect of the magnetic field. The method was applied to simultaneous polarization measurements in the Helium D3 line and in the hydrogen beta line in 14 prominences. Four polarization parameters are measured, which lead to the determination of the three coordinates of the magnetic field vector and the electron density, owing to the sensitivity of the hydrogen beta line to the non-negligible effect of depolarizing collisions with electrons and protons of the medium. A mean value of 1.3 x 10 to the 10th power cu. cm. is derived in 14 prominences.
The Evolution of Vector Magnetic Field Associated with Major Flares ...
Indian Academy of Sciences (India)
great enhancement in the non-potential field several hours before an .... conclusion is similar with that from daily evolution view – no sudden change happened. ... Jain, R., Hanaoka, Y., Sakurai, T. et al., Solar flares with remote brightening as ...
Nanoscale electric and magnetic optical vector fields: mapping & injection
le Feber, Boris
2015-01-01
Nanophotonic structures, which offer a sub-wavelength control over light and nearby emitters, promise to advance, for example, our ability to harvest light, process information and detect (bio-) chemical compounds. In general, the optical field distributions near nanophotonic structures are much
Combined tangential-normal vector elements for computing electric and magnetic fields
International Nuclear Information System (INIS)
Sachdev, S.; Cendes, Z.J.
1993-01-01
A direct method for computing electric and magnetic fields in two dimensions is developed. This method determines both the fields and fluxes directly from Maxwell's curl and divergence equations without introducing potential functions. This allows both the curl and the divergence of the field to be set independently in all elements. The technique is based on a new type of vector finite element that simultaneously interpolates to the tangential component of the electric or the magnetic field and the normal component of the electric or magnetic flux. Continuity conditions are imposed across element edges simply by setting like variables to be the same across element edges. This guarantees the continuity of the field and flux at the mid-point of each edge and that for all edges the average value of the tangential component of the field and of the normal component of the flux is identical
Ronan, R. S.; Mickey, D. L.; Orrall, F. Q.
1987-01-01
The results of two methods for deriving photospheric vector magnetic fields from the Zeeman effect, as observed in the Fe I line at 6302.5 A at high spectral resolution (45 mA), are compared. The first method does not take magnetooptical effects into account, but determines the vector magnetic field from the integral properties of the Stokes profiles. The second method is an iterative least-squares fitting technique which fits the observed Stokes profiles to the profiles predicted by the Unno-Rachkovsky solution to the radiative transfer equation. For sunspot fields above about 1500 gauss, the two methods are found to agree in derived azimuthal and inclination angles to within about + or - 20 deg.
Energy Technology Data Exchange (ETDEWEB)
Bagrov, V G; Dorofeev, O F; Sokolov, A A; Ternov, I M; Khalilov, V R [Moskovskij Gosudarstvennyj Univ. (USSR)
1975-03-11
When electrons move in a magnetic field, synchrotron radiation gives rise to transitions accompanied by the electron spin reorientation. In this case, it is essential that the transition probability depends on the spin orientation; as a result electron polarization takes place with the spin orientation being predominantly opposite to the direction of the magnetic field. This effect has been called ''radiative self-polarization of electrons''. The present work is concerned with the question how the choice of the spin operator will affect the self-polarization degree and relaxation time. The problem has been solved for a vector spin operator.
Infrared Dual-Line Hanle Diagnostic of the Coronal Vector Magnetic Field
Energy Technology Data Exchange (ETDEWEB)
Dima, Gabriel I.; Kuhn, Jeffrey R. [Institute for Astronomy, University of Hawaii, Pukalani, HI (United States); Berdyugina, Svetlana V., E-mail: gdima@hawaii.edu [Institute for Astronomy, University of Hawaii, Pukalani, HI (United States); Kiepenheuer Institut fuer Sonnenphysik, Freiburg (Germany); Predictive Science Inc., San Diego, CA (United States)
2016-04-20
Measuring the coronal vector magnetic field is still a major challenge in solar physics. This is due to the intrinsic weakness of the field (e.g., ~4G at a height of 0.1R⊙ above an active region) and the large thermal broadening of coronal emission lines. We propose using concurrent linear polarization measurements of near-infrared forbidden and permitted lines together with Hanle effect models to calculate the coronal vector magnetic field. In the unsaturated Hanle regime both the direction and strength of the magnetic field affect the linear polarization, while in the saturated regime the polarization is insensitive to the strength of the field. The relatively long radiative lifetimes of coronal forbidden atomic transitions implies that the emission lines are formed in the saturated Hanle regime and the linear polarization is insensitive to the strength of the field. By combining measurements of both forbidden and permitted lines, the direction and strength of the field can be obtained. For example, the SiX 1.4301 μm line shows strong linear polarization and has been observed in emission over a large field-of-view (out to elongations of 0.5 R⊙). Here we describe an algorithm that combines linear polarization measurements of the SiX 1.4301 μm forbidden line with linear polarization observations of the HeI 1.0830 μm permitted coronal line to obtain the vector magnetic field. To illustrate the concept we assume that the emitting gas for both atomic transitions is located in the plane of the sky. The further development of this method and associated tools will be a critical step toward interpreting the high spectral, spatial and temporal infrared spectro-polarimetric measurements that will be possible when the Daniel K. Inouye Solar Telescope (DKIST) is completed in 2019.
Stokes profile analysis and vector magnetic fields. I. Inversion of photospheric lines
International Nuclear Information System (INIS)
Skumanich, A.; Lites, B.W.
1987-01-01
Improvements are proposed for the Auer et al. (1977) method for the analytic inversion of Stokes profiles via nonlinear least squares. The introduction of additional physics into the Mueller absorption matrix (by including damping wings and magnetooptical birefringence, and by decoupling the intensity profile from the three-vector polarization profile in the analysis) is found to result in a more robust inversion method, providing more reliable and accurate estimates of sunspot vector magnetic fields without significant loss of economy. The method is applied to sunspot observations obtained with the High Altitude Observatory polarimeter. 29 references
On parasupersymmetric oscillators and relativistic vector mesons in constant magnetic fields
Debergh, Nathalie; Beckers, Jules
1995-01-01
Johnson-Lippmann considerations on oscillators and their connection with the minimal coupling schemes are visited in order to introduce a new Sakata-Taketani equation describing vector mesons in interaction with a constant magnetic field. This new proposal, based on a specific parasupersymmetric oscillator-like system, is characterized by real energies as opposed to previously pointed out relativistic equations corresponding to this interacting context.
Balasubramaniam, K. S.; West, E. A.
1991-01-01
The Marshall Space Flight Center (MSFC) vector magnetograph is a tunable filter magnetograph with a bandpass of 125 mA. Results are presented of the inversion of Stokes polarization profiles observed with the MSFC vector magnetograph centered on a sunspot to recover the vector magnetic field parameters and thermodynamic parameters of the spectral line forming region using the Fe I 5250.2 A spectral line using a nonlinear least-squares fitting technique. As a preliminary investigation, it is also shown that the recovered thermodynamic parameters could be better understood if the fitted parameters like Doppler width, opacity ratio, and damping constant were broken down into more basic quantities like temperature, microturbulent velocity, or density parameter.
3D vector distribution of the electro-magnetic fields on a random gold film
Canneson, Damien; Berini, Bruno; Buil, Stéphanie; Hermier, Jean-Pierre; Quélin, Xavier
2018-05-01
The 3D vector distribution of the electro-magnetic fields at the very close vicinity of the surface of a random gold film is studied. Such films are well known for their properties of light confinement and large fluctuations of local density of optical states. Using Finite-Difference Time-Domain simulations, we show that it is possible to determine the local orientation of the electro-magnetic fields. This allows us to obtain a complete characterization of the fields. Large fluctuations of their amplitude are observed as previously shown. Here, we demonstrate large variations of their direction depending both on the position on the random gold film, and on the distance to it. Such characterization could be useful for a better understanding of applications like the coupling of point-like dipoles to such films.
Changes in measured vector magnetic fields when transformed into heliographic coordinates
Hagyard, M. J.
1987-01-01
The changes that occur in measured magnetic fields when they are transformed into a heliographic coordinate system are investigated. To carry out this investigation, measurements of the vector magnetic field of an active region that was observed at 1/3 the solar radius from disk center are taken, and the observed field is transformed into heliographic coordinates. Differences in the calculated potential field that occur when the heliographic normal component of the field is used as the boundary condition rather than the observed line-of-sight component are also examined. The results of this analysis show: (1) that the observed fields of sunspots more closely resemble the generally accepted picture of the distribution of umbral fields if they are displayed in heliographic coordinates; (2) that the differences in the potential calculations are less than 200 G in field strength and 20 deg in field azimuth outside sunspots; and (3) that differences in the two potential calculations in the sunspot areas are no more than 400 G in field strength but range from 60 to 80 deg in field azimuth in localized umbral areas.
Lites, B. W.; Skumanich, A.
1985-01-01
A method is presented for recovery of the vector magnetic field and thermodynamic parameters from polarization measurement of photospheric line profiles measured with filtergraphs. The method includes magneto-optic effects and may be utilized on data sampled at arbitrary wavelengths within the line profile. The accuracy of this method is explored through inversion of synthetic Stokes profiles subjected to varying levels of random noise, instrumental wave-length resolution, and line profile sampling. The level of error introduced by the systematic effect of profile sampling over a finite fraction of the 5 minute oscillation cycle is also investigated. The results presented here are intended to guide instrumental design and observational procedure.
Z3 model of Saturns magnetic field and the Pioneer 11 vector helium magnetometer observations
International Nuclear Information System (INIS)
Connerney, J.E.P.; Acuna, M.H.; Ness, N.F.
1984-05-01
Magnetic field observations obtained by the Pioneer 11 vector helium magnetometer are compared with the Z(sub 3) model magnetic field. These Pioneer 11 observations, obtained at close-in radial distances, constitute an important and independent test of the Z(sub 3) zonal harmonic model, which was derived from Voyager 1 and Voyager 2 fluxgate magnetometer observations. Differences between the Pioneer 11 magnetometer and the Z(sub 3) model field are found to be small (approximately 1%) and quantitatively consistent with the expected instrumental accuracy. A detailed examination of these differences in spacecraft payload coordinates shows that they are uniquely associated with the instrument frame of reference and operation. A much improved fit to the Pioneer 11 observations is obtained by rotation of the instrument coordinate system about the spacecraft spin axis by 1.4 degree. With this adjustment, possibly associated with an instrumental phase lag or roll attitude error, the Pioneer 11 vector helium magnetometer observations are fully consistent with the Voyager Z(sub 3) model
Directory of Open Access Journals (Sweden)
Shi-Xiong Zhang
2014-02-01
Full Text Available Permanent Magnet Synchronous motor (PMSM has received widespread acceptance in recent years. In this paper, a new rotor and stator Magnetic Fields Direct-Orthogonalized Vector Control (MFDOVC scheme is proposed for PMSM servo system. This method simplified the complex calculation of traditional vector control, a part of the system resource is economized. At the same time, through the simulation illustration validation, the performance of PMSM servo system with the proposed MFDOVC scheme can achieve the same with the complex traditional vector control method, but much simpler calculation is implemented using the proposed method.
Layeghi, Azam; Latifi, Hamid
2018-06-01
A magnetic field vector sensor based on super-paramagnetic fluid and tapered Hi-Bi fiber (THB) in fiber loop mirror (FLM) is proposed. A two-dimensional detection of external magnetic field (EMF) is experimentally demonstrated and theoretically simulated by Jones matrix to analyze the physical operation in detail. A birefringence is obtained due to magnetic fluid (MF) in applied EMF. By surrounding the THB with MF, a tunable birefringence of MF affect the transmission of the sensor. Slow and fast axes of this obtained birefringence are determined by the direction of applied EMF. In this way, the transmission response of the sensor is depended on the angle between the EMF orientation and the main axes of polarization maintaining fiber (PMF) in FLM. The wavelength shift and intensity shift versus EMF orientation show a sinusoidal behavior, while the applied EMF is constant. Also, the changes in the intensity of EMF in a certain direction results in wavelength shift in the sensor spectrum. The maximum wavelength sensitivity of 214 pm/mT is observed.
SOLAR FLARE PREDICTION USING SDO/HMI VECTOR MAGNETIC FIELD DATA WITH A MACHINE-LEARNING ALGORITHM
International Nuclear Information System (INIS)
Bobra, M. G.; Couvidat, S.
2015-01-01
We attempt to forecast M- and X-class solar flares using a machine-learning algorithm, called support vector machine (SVM), and four years of data from the Solar Dynamics Observatory's Helioseismic and Magnetic Imager, the first instrument to continuously map the full-disk photospheric vector magnetic field from space. Most flare forecasting efforts described in the literature use either line-of-sight magnetograms or a relatively small number of ground-based vector magnetograms. This is the first time a large data set of vector magnetograms has been used to forecast solar flares. We build a catalog of flaring and non-flaring active regions sampled from a database of 2071 active regions, comprised of 1.5 million active region patches of vector magnetic field data, and characterize each active region by 25 parameters. We then train and test the machine-learning algorithm and we estimate its performances using forecast verification metrics with an emphasis on the true skill statistic (TSS). We obtain relatively high TSS scores and overall predictive abilities. We surmise that this is partly due to fine-tuning the SVM for this purpose and also to an advantageous set of features that can only be calculated from vector magnetic field data. We also apply a feature selection algorithm to determine which of our 25 features are useful for discriminating between flaring and non-flaring active regions and conclude that only a handful are needed for good predictive abilities
Transient rotation of photospheric vector magnetic fields associated with a solar flare.
Xu, Yan; Cao, Wenda; Ahn, Kwangsu; Jing, Ju; Liu, Chang; Chae, Jongchul; Huang, Nengyi; Deng, Na; Gary, Dale E; Wang, Haimin
2018-01-03
As one of the most violent eruptions on the Sun, flares are believed to be powered by magnetic reconnection. The fundamental physics involving the release, transfer, and deposition of energy have been studied extensively. Taking advantage of the unprecedented resolution provided by the 1.6 m Goode Solar Telescope, here, we show a sudden rotation of vector magnetic fields, about 12-20° counterclockwise, associated with a flare. Unlike the permanent changes reported previously, the azimuth-angle change is transient and cospatial/temporal with Hα emission. The measured azimuth angle becomes closer to that in potential fields suggesting untwist of flare loops. The magnetograms were obtained in the near infrared at 1.56 μm, which is minimally affected by flare emission and no intensity profile change was detected. We believe that these transient changes are real and discuss the possible explanations in which the high-energy electron beams or Alfve'n waves play a crucial role.
Observations of vector magnetic fields with a magneto-optic filter
Cacciani, Alessandro; Varsik, John; Zirin, Harold
1990-01-01
The use of the magnetooptic filter to observe solar magnetic fields in the potassium line at 7699 A is described. The filter has been used in the Big Bear videomagnetograph since October 23. It gives a high sensitivity and dynamic range for longitudnal magnetic fields and enables measurement of transverse magnetic fields using the sigma component. Examples of the observations are presented.
International Nuclear Information System (INIS)
Velasco-Martínez, D; Kunold, A; Cardoso, J L; Ibarra-Sierra, V G; Sandoval-Santana, J C
2014-01-01
In this paper we introduce an alternative approach to studying the motion of a planar charged particle subject to a static uniform magnetic field. It is well known that an electric charge under a uniform magnetic field has a planar motion if its initial velocity is perpendicular to the magnetic field. Although some constants of motion (CsM), as the energy and the angular momentum, have been widely discussed for this system, others have been neglected. We find that the angular momentum, the generator of the magnetic translations and the magnetic Laplace–Runge–Lenz vector are CsM for this particular system. We show also that these three quantities form an orthogonal basis of vectors. The present work addresses many aspects of the motion of a charged particle in a magnetic field that should be useful for students and tutors of the classical mechanics courses at the senior undergraduate level. (paper)
Vector (two-dimensional) magnetic phenomena
International Nuclear Information System (INIS)
Enokizono, Masato
2002-01-01
In this paper, some interesting phenomena were described from the viewpoint of two-dimensional magnetic property, which is reworded with the vector magnetic property. It shows imperfection of conventional magnetic property and some interested phenomena were discovered, too. We found magnetic materials had the strong nonlinearity both magnitude and spatial phase due to the relationship between the magnetic field strength H-vector and the magnetic flux density B-vector. Therefore, magnetic properties should be defined as the vector relationship. Furthermore, the new Barukhausen signal was observed under rotating flux. (Author)
Belinsky, Moisey I
2016-05-02
The rotation behavior of the vector chirality κ, scalar chirality χ, and magnetization M in the rotating magnetic field H1 is considered for the V3 and Cu3 nanomagnets, in which the Dzialoshinsky-Moriya coupling is active. The polar rotation of the field H1 of the given strength H1 results in the energy spectrum characterized by different vector and scalar chiralities in the ground and excited states. The magnetochiral correlations between the vector and scalar chiralities, energy, and magnetization in the rotating field were considered. Under the uniform polar rotation of the field H1, the ground-state chirality vector κI performs sawtooth oscillations and the magnetization vector MI performs the sawtooth oscillating rotation that is accompanied by the correlated transformation of the scalar chirality χI. This demonstrates the magnetochiral effect of the joint rotation behavior and simultaneous frustrations of the spin chiralities and magnetization in the rotating field, which are governed by the correlation between the chiralities and magnetization.
International Nuclear Information System (INIS)
Meyer, R.-L.
1975-01-01
The evolution of the scattering cross section maximas of an electromagnetic wave by a magnetoplasma, the angle between the wave vector and the confining magnetic field approaching π/2 were computed. It is shown that the maximas are shifted toward the roots of the electrostatic dispersion relation in perpendicular propagation. These roots are not exactly the electron cyclotron harmonics [fr
International Nuclear Information System (INIS)
Anderson, D.V.; Breazeal, J.; Finan, C.H.; Johnston, B.M.
1976-01-01
ABCXYZ is a computer code for obtaining the Cartesian components of the vector potential and the magnetic field on an observed grid from an arrangement of current-carrying wires. Arbitrary combinations of straight line segments, arcs, and loops are allowed in the specification of the currents. Arbitrary positions and orientations of the current-carrying elements are also allowed. Specification of the wire diameter permits the computation of well-defined fields, even in the interiors of the conductors. An optical feature generates magnetic field lines. Extensive graphical and printed output is available to the user including contour, grid-line, and field-line plots. 12 figures, 1 table
Flare activity, sunspot motions, and the evolution of vector magnetic fields in Hale region 17244
Neidig, Donald F.; Hagyard, Mona J.; Machado, Marcos E.; Smith, Jesse B., Jr.
1986-01-01
The magnetic and dynamical circumstances leading to the 1B/M4 flare of November 5, 1980 are studied, and a strong association is found between the buildup of magnetic shear and the onset of flare activity within the active region. The development of shear, as observed directly in vector magnetograms, is consistent in detail with the dynamical history of the active region and identifies the precise location of the optical and hard-X-ray kernels of the flare emission.
Fractal vector optical fields.
Pan, Yue; Gao, Xu-Zhen; Cai, Meng-Qiang; Zhang, Guan-Lin; Li, Yongnan; Tu, Chenghou; Wang, Hui-Tian
2016-07-15
We introduce the concept of a fractal, which provides an alternative approach for flexibly engineering the optical fields and their focal fields. We propose, design, and create a new family of optical fields-fractal vector optical fields, which build a bridge between the fractal and vector optical fields. The fractal vector optical fields have polarization states exhibiting fractal geometry, and may also involve the phase and/or amplitude simultaneously. The results reveal that the focal fields exhibit self-similarity, and the hierarchy of the fractal has the "weeding" role. The fractal can be used to engineer the focal field.
Curjel, C. R.
1990-01-01
Presented are activities that help students understand the idea of a vector field. Included are definitions, flow lines, tangential and normal components along curves, flux and work, field conservation, and differential equations. (KR)
Complex Polynomial Vector Fields
DEFF Research Database (Denmark)
The two branches of dynamical systems, continuous and discrete, correspond to the study of differential equations (vector fields) and iteration of mappings respectively. In holomorphic dynamics, the systems studied are restricted to those described by holomorphic (complex analytic) functions...... or meromorphic (allowing poles as singularities) functions. There already exists a well-developed theory for iterative holomorphic dynamical systems, and successful relations found between iteration theory and flows of vector fields have been one of the main motivations for the recent interest in holomorphic...... vector fields. Since the class of complex polynomial vector fields in the plane is natural to consider, it is remarkable that its study has only begun very recently. There are numerous fundamental questions that are still open, both in the general classification of these vector fields, the decomposition...
Complex Polynomial Vector Fields
DEFF Research Database (Denmark)
Dias, Kealey
vector fields. Since the class of complex polynomial vector fields in the plane is natural to consider, it is remarkable that its study has only begun very recently. There are numerous fundamental questions that are still open, both in the general classification of these vector fields, the decomposition...... of parameter spaces into structurally stable domains, and a description of the bifurcations. For this reason, the talk will focus on these questions for complex polynomial vector fields.......The two branches of dynamical systems, continuous and discrete, correspond to the study of differential equations (vector fields) and iteration of mappings respectively. In holomorphic dynamics, the systems studied are restricted to those described by holomorphic (complex analytic) functions...
Hewagama, Tilak; Deming, Drake; Jennings, Donald E.; Osherovich, Vladimir; Wiedemann, Gunter; Zipoy, David; Mickey, Donald L.; Garcia, Howard
1993-01-01
Polarimetric observations at 12 microns of two sunpots are reported. The horizontal distribution of parameters such as magnetic field strength, inclination, azimuth, and magnetic field filling factors are presented along with information about the height dependence of the magnetic field strength. Comparisons with contemporary magnetostatic sunspot models are made. The magnetic data are used to estimate the height of 12 micron line formation. From the data, it is concluded that within a stable sunspot there are no regions that are magnetically filamentary, in the sense of containing both strong-field and field-free regions.
International Nuclear Information System (INIS)
Kovalevskij, I.V.; Levitin, A.E.; Fedoseeva, M.K.
1984-01-01
A relation between the index Dsub(st) and azimuthal component Bsub(y) of interplanetary magnetic field (IMF) vector during several magnetic storms with Dsub(st) > 100nT is discussed. It is established that the relation between Dsub(st) index and Bsub(y) and Esub(z) component of electric interplanetary field (EIF) is closed than the relation between Dsub(st) and Bsub(z) component of IMF and Esub(y) component of EIF. Correlation coefficients of Dsub(st) and Bsub(y) and Esub(z) differ but slightly from each other
Ainsbury, Elizabeth A.; Conein, Emma; Henshaw, Denis L.
2005-07-01
Elliptically polarized magnetic fields induce higher currents in the body compared with their plane polarized counterparts. This investigation examines the degree of vector ellipticity of extremely low frequency magnetic fields (ELF-MFs) in the home, with regard to the adverse health effects reportedly associated with ELF-MFs, for instance childhood leukaemia. Tri-axial measurements of the magnitude and phase of the 0-3000 Hz magnetic fields, produced by 226 domestic mains-fed appliances of 32 different types, were carried out in 16 homes in Worcestershire in the summer of 2004. Magnetic field strengths were low, with average (RMS) values of 0.03 ± 0.02 µT across all residences. In contrast, background field ellipticities were high, on average 47 ± 11%. Microwave and electric ovens produced the highest ellipticities: mean respective values of 21 ± 21% and 21 ± 17% were observed 20 cm away from these appliances. There was a negative correlation between field strength and field polarization, which we attribute to the higher relative field contribution close to each individual (single-phase) appliance. The measurements demonstrate that domestic magnetic fields are extremely complex and cannot simply be characterized by traditional measurements such as time-weighted average or peak exposure levels. We conclude that ellipticity should become a relevant metric for future epidemiological studies of health and ELF-MF exposure. This work is supported by the charity CHILDREN with LEUKAEMIA, registered charity number 298405.
International Nuclear Information System (INIS)
Ainsbury, Elizabeth A; Conein, Emma; Henshaw, Denis L
2005-01-01
Elliptically polarized magnetic fields induce higher currents in the body compared with their plane polarized counterparts. This investigation examines the degree of vector ellipticity of extremely low frequency magnetic fields (ELF-MFs) in the home, with regard to the adverse health effects reportedly associated with ELF-MFs, for instance childhood leukaemia. Tri-axial measurements of the magnitude and phase of the 0-3000 Hz magnetic fields, produced by 226 domestic mains-fed appliances of 32 different types, were carried out in 16 homes in Worcestershire in the summer of 2004. Magnetic field strengths were low, with average (RMS) values of 0.03 ± 0.02 μT across all residences. In contrast, background field ellipticities were high, on average 47 ± 11%. Microwave and electric ovens produced the highest ellipticities: mean respective values of 21 ± 21% and 21 ± 17% were observed 20 cm away from these appliances. There was a negative correlation between field strength and field polarization, which we attribute to the higher relative field contribution close to each individual (single-phase) appliance. The measurements demonstrate that domestic magnetic fields are extremely complex and cannot simply be characterized by traditional measurements such as time-weighted average or peak exposure levels. We conclude that ellipticity should become a relevant metric for future epidemiological studies of health and ELF-MF exposure
The photospheric vector magnetic field of a sunspot and its vertical gradient
Hagyard, M. J.; West, E. A.; Tandberg-Hanssen, E.; Smith, J. E.; Henze, W., Jr.; Beckers, J. M.; Bruner, E. C.; Hyder, C. L.; Gurman, J. B.; Shine, R. A.
1981-01-01
The results of direct comparisons of photospheric and transition region line-of-sight field observations of sunspots using the SMM UV spectrometer and polarimeter are reported. The analysis accompanying the data is concentrated on demonstrating that the sunspot concentrated magnetic field extends into the transition region. An observation of a sunspot on Oct. 23, 1980 at the S 18 E 03 location is used as an example. Maximum field strengths ranged from 2030-2240 gauss for large and small umbrae viewed and inclination of the field to the line-of-sight was determined for the photosphere and transition region. The distribution of the magnetic field over the sunspot and variation of the line-of-sight gradient are discussed, as are the magnitudes and gradients of the photospheric field across the penumbral-photospheric boundaries.
Hayashi, Keiji; Feng, Xueshang; Xiong, Ming; Jiang, Chaowei
2018-03-01
For realistic magnetohydrodynamics (MHD) simulation of the solar active region (AR), two types of capabilities are required. The first is the capability to calculate the bottom-boundary electric field vector, with which the observed magnetic field can be reconstructed through the induction equation. The second is a proper boundary treatment to limit the size of the sub-Alfvénic simulation region. We developed (1) a practical inversion method to yield the solar-surface electric field vector from the temporal evolution of the three components of magnetic field data maps, and (2) a characteristic-based free boundary treatment for the top and side sub-Alfvénic boundary surfaces. We simulate the temporal evolution of AR 11158 over 16 hr for testing, using Solar Dynamics Observatory/Helioseismic Magnetic Imager vector magnetic field observation data and our time-dependent three-dimensional MHD simulation with these two features. Despite several assumptions in calculating the electric field and compromises for mitigating computational difficulties at the very low beta regime, several features of the AR were reasonably retrieved, such as twisting field structures, energy accumulation comparable to an X-class flare, and sudden changes at the time of the X-flare. The present MHD model can be a first step toward more realistic modeling of AR in the future.
Demerdash, N. A.; Wang, R.; Secunde, R.
1992-01-01
A 3D finite element (FE) approach was developed and implemented for computation of global magnetic fields in a 14.3 kVA modified Lundell alternator. The essence of the new method is the combined use of magnetic vector and scalar potential formulations in 3D FEs. This approach makes it practical, using state of the art supercomputer resources, to globally analyze magnetic fields and operating performances of rotating machines which have truly 3D magnetic flux patterns. The 3D FE-computed fields and machine inductances as well as various machine performance simulations of the 14.3 kVA machine are presented in this paper and its two companion papers.
Energy Technology Data Exchange (ETDEWEB)
Nouri, N.; Plaster, B.
2014-12-11
An experiment may face the challenge of real-time determination of the magnetic field vector components present within some interior region of the experimental apparatus over which it is impossible to directly measure the field components during the operation of the experiment. As a solution to this problem, we propose a general concept which provides for a unique determination of the field components within such an interior region solely from exterior measurements at fixed discrete locations. The method is general and does not require the field to possess any type of symmetry. We describe our systematic approach for optimizing the locations of these exterior measurements which maximizes their sensitivity to successive terms in a multipole expansion of the field.
Vector Fields on Product Manifolds
Kurz, Stefan
2011-01-01
This short report establishes some basic properties of smooth vector fields on product manifolds. The main results are: (i) On a product manifold there always exists a direct sum decomposition into horizontal and vertical vector fields. (ii) Horizontal and vertical vector fields are naturally isomorphic to smooth families of vector fields defined on the factors. Vector fields are regarded as derivations of the algebra of smooth functions.
Moore, R. L.; Hagyard, M. J.; Davis, J. M.
1987-01-01
The present MSFC Vector Magnetograph has sufficient spatial resolution (2.7 arcsec pixels) and sensitivity to the transverse field (the noise level is about 100 gauss) to map the transverse field in active regions accurately enough to reveal key aspects of the sheared magnetic fields commonly found at flare sites. From the measured shear angle along the polarity inversion line in sites that flared and in other shear sites that didn't flare, evidence is found that a sufficient condition for a flare to occur in 1000 gauss fields in and near sunspots is that both: (1) the maximum shear angle exceed 85 degrees; and (2) the extent of strong shear (shear angle of greater than 80 degrees) exceed 10,000 km.
Wang, R.; Demerdash, N. A.
1991-01-01
A method of combined use of magnetic vector potential based finite-element (FE) formulations and magnetic scalar potential (MSP) based formulations for computation of three-dimensional magnetostatic fields is introduced. In this method, the curl-component of the magnetic field intensity is computed by a reduced magnetic vector potential. This field intensity forms the basic of a forcing function for a global magnetic scalar potential solution over the entire volume of the region. This method allows one to include iron portions sandwiched in between conductors within partitioned current-carrying subregions. The method is most suited for large-scale global-type 3-D magnetostatic field computations in electrical devices, and in particular rotating electric machinery.
Hagyard, Mona J.; Stark, B. A.; Venkatakrishnan, P.
1998-01-01
A careful analysis of a 6-hour time sequence of vector magnetograms of AR 6659, observed on 1991 June 10 with the MSFC vector magnetograph, has revealed only minor changes in the vector magnetic field azimuths in the vicinity of two M-class flares, and the association of these changes with the flares is not unambiguous. In this paper we present our analysis of the data which includes comparison of vector magnetograms prior to and during the flares, calculation of distributions of the rms variation of the azimuth at each pixel in the field of view of the active region, and examination of the variation with time of the azimuths at every pixel covered by the main flare emissions as observed with the H-alpha telescope coaligned with the vector magnetograph. We also present results of an analysis of evolutionary changes in the azimuth over the field of view of the active region.
Energy Technology Data Exchange (ETDEWEB)
Walstrom, Peter Lowell [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2017-08-07
A numerical algorithm for computing the field components B_{r} and B_{z} and their r and z derivatives with open boundaries in cylindrical coordinates for radially thin solenoids with uniform current density is described in this note. An algorithm for computing the vector potential A_{θ} is also described. For the convenience of the reader, derivations of the final expressions from their defining integrals are given in detail, since their derivations are not all easily found in textbooks. Numerical calculations are based on evaluation of complete elliptic integrals using the Bulirsch algorithm cel. The (apparently) new feature of the algorithms described in this note applies to cases where the field point is outside of the bore of the solenoid and the field-point radius approaches the solenoid radius. Since the elliptic integrals of the third kind normally used in computing B_{z} and A_{θ} become infinite in this region of parameter space, fields for points with the axial coordinate z outside of the ends of the solenoid and near the solenoid radius are treated by use of elliptic integrals of the third kind of modified argument, derived by use of an addition theorem. Also, the algorithms also avoid the numerical difficulties the textbook solutions have for points near the axis arising from explicit factors of 1/r or 1/r^{2} in the some of the expressions.
Weaving Knotted Vector Fields with Tunable Helicity.
Kedia, Hridesh; Foster, David; Dennis, Mark R; Irvine, William T M
2016-12-30
We present a general construction of divergence-free knotted vector fields from complex scalar fields, whose closed field lines encode many kinds of knots and links, including torus knots, their cables, the figure-8 knot, and its generalizations. As finite-energy physical fields, they represent initial states for fields such as the magnetic field in a plasma, or the vorticity field in a fluid. We give a systematic procedure for calculating the vector potential, starting from complex scalar functions with knotted zero filaments, thus enabling an explicit computation of the helicity of these knotted fields. The construction can be used to generate isolated knotted flux tubes, filled by knots encoded in the lines of the vector field. Lastly, we give examples of manifestly knotted vector fields with vanishing helicity. Our results provide building blocks for analytical models and simulations alike.
Wang, Ren H.
1991-01-01
A method of combined use of magnetic vector potential (MVP) based finite element (FE) formulations and magnetic scalar potential (MSP) based FE formulations for computation of three-dimensional (3D) magnetostatic fields is developed. This combined MVP-MSP 3D-FE method leads to considerable reduction by nearly a factor of 3 in the number of unknowns in comparison to the number of unknowns which must be computed in global MVP based FE solutions. This method allows one to incorporate portions of iron cores sandwiched in between coils (conductors) in current-carrying regions. Thus, it greatly simplifies the geometries of current carrying regions (in comparison with the exclusive MSP based methods) in electric machinery applications. A unique feature of this approach is that the global MSP solution is single valued in nature, that is, no branch cut is needed. This is again a superiority over the exclusive MSP based methods. A Newton-Raphson procedure with a concept of an adaptive relaxation factor was developed and successfully used in solving the 3D-FE problem with magnetic material anisotropy and nonlinearity. Accordingly, this combined MVP-MSP 3D-FE method is most suited for solution of large scale global type magnetic field computations in rotating electric machinery with very complex magnetic circuit geometries, as well as nonlinear and anisotropic material properties.
DEFF Research Database (Denmark)
Olsen, Nils
2015-01-01
he Earth has a large and complicated magnetic field, the major part of which is produced by a self-sustaining dynamo operating in the fluid outer core. Magnetic field observations provide one of the few tools for remote sensing the Earth’s deep interior, especially regarding the dynamics...... of the fluid flow at the top of the core. However, what is measured at or near the surface of the Earth is the superposition of the core field and fields caused by magnetized rocks in the Earth’s crust, by electric currents flowing in the ionosphere, magnetosphere, and oceans, and by currents induced...... in the Earth by time-varying external fields. These sources have their specific characteristics in terms of spatial and temporal variations, and their proper separation, based on magnetic measurements, is a major challenge. Such a separation is a prerequisite for remote sensing by means of magnetic field...
Energy Technology Data Exchange (ETDEWEB)
Walstrom, Peter Lowell [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2017-08-24
A numerical algorithm for computing the field components B_{r} and B_{z} and their r and z derivatives with open boundaries in cylindrical coordinates for circular current loops is described. An algorithm for computing the vector potential is also described. For the convenience of the reader, derivations of the final expressions from their defining integrals are given in detail, since their derivations (especially for the field derivatives) are not all easily found in textbooks. Numerical calculations are based on evaluation of complete elliptic integrals using the Bulirsch algorithm cel. Since cel can evaluate complete elliptic integrals of a fairly general type, in some cases the elliptic integrals can be evaluated without first reducing them to forms containing standard Legendre forms. The algorithms avoid the numerical difficulties that many of the textbook solutions have for points near the axis because of explicit factors of 1=r or 1=r^{2} in the some of the expressions.
Hyperbolic-symmetry vector fields.
Gao, Xu-Zhen; Pan, Yue; Cai, Meng-Qiang; Li, Yongnan; Tu, Chenghou; Wang, Hui-Tian
2015-12-14
We present and construct a new kind of orthogonal coordinate system, hyperbolic coordinate system. We present and design a new kind of local linearly polarized vector fields, which is defined as the hyperbolic-symmetry vector fields because the points with the same polarization form a series of hyperbolae. We experimentally demonstrate the generation of such a kind of hyperbolic-symmetry vector optical fields. In particular, we also study the modified hyperbolic-symmetry vector optical fields with the twofold and fourfold symmetric states of polarization when introducing the mirror symmetry. The tight focusing behaviors of these vector fields are also investigated. In addition, we also fabricate micro-structures on the K9 glass surfaces by several tightly focused (modified) hyperbolic-symmetry vector fields patterns, which demonstrate that the simulated tightly focused fields are in good agreement with the fabricated micro-structures.
Bommier, V.; Leroy, J. L.; Sahal-Brechot, S.
1985-01-01
The Hanle effect method for magnetic field vector diagnostics has now provided results on the magnetic field strength and direction in quiescent prominences, from linear polarization measurements in the He I E sub 3 line, performed at the Pic-du-Midi and at Sacramento Peak. However, there is an inescapable ambiguity in the field vector determination: each polarization measurement provides two field vector solutions symmetrical with respect to the line-of-sight. A statistical analysis capable of solving this ambiguity was applied to the large sample of prominences observed at the Pic-du-Midi (Leroy, et al., 1984); the same method of analysis applied to the prominences observed at Sacramento Peak (Athay, et al., 1983) provides results in agreement on the most probable magnetic structure of prominences; these results are detailed. The statistical results were confirmed on favorable individual cases: for 15 prominences observed at Pic-du-Midi, the two-field vectors are pointing on the same side of the prominence, and the alpha angles are large enough with respect to the measurements and interpretation inaccuracies, so that the field polarity is derived without any ambiguity.
Estimation of Motion Vector Fields
DEFF Research Database (Denmark)
Larsen, Rasmus
1993-01-01
This paper presents an approach to the estimation of 2-D motion vector fields from time varying image sequences. We use a piecewise smooth model based on coupled vector/binary Markov random fields. We find the maximum a posteriori solution by simulated annealing. The algorithm generate sample...... fields by means of stochastic relaxation implemented via the Gibbs sampler....
Skumanich, A.; Lites, B. W.
1985-01-01
The least square fitting of Stokes observations of sunspots using a Milne-Eddington-Unno model appears to lead, in many circumstances, to various inconsistencies such as anomalously large doppler widths and, hence, small magnetic fields which are significantly below those inferred solely from the Zeeman splitting in the intensity profile. It is found that the introduction of additional physics into the model such as the inclusion of damping wings and magneto-optic birefrigence significantly improves the fit to Stokes parameters. Model fits excluding the intensity profile, i.e., of both magnitude as well as spectral shape of the polarization parameters alone, suggest that parasitic light in the intensity profile may also be a source of inconsistencies. The consequences of the physical changes on the vector properties of the field derived from the Fe I lambda 6173 line for the 17 November 1975 spot as well as on the thermodynamic state are discussed. A Doppler width delta lambda (D) - 25mA is bound to be consistent with a low spot temperature and microturbulence, and a damping constant of a = 0.2.
Simplified Representation of Vector Fields
Telea, Alexandru; Wijk, Jarke J. van
1999-01-01
Vector field visualization remains a difficult task. Although many local and global visualization methods for vector fields such as flow data exist, they usually require extensive user experience on setting the visualization parameters in order to produce images communicating the desired insight. We
Jiang, Chaowei; Wu, S. T.; Feng, Xueshang; Hu, Qiang
2014-05-01
Solar filaments are commonly thought to be supported in magnetic dips, in particular, in those of magnetic flux ropes (FRs). In this Letter, based on the observed photospheric vector magnetogram, we implement a nonlinear force-free field (NLFFF) extrapolation of a coronal magnetic FR that supports a large-scale intermediate filament between an active region and a weak polarity region. This result is a first, in the sense that current NLFFF extrapolations including the presence of FRs are limited to relatively small-scale filaments that are close to sunspots and along main polarity inversion lines (PILs) with strong transverse field and magnetic shear, and the existence of an FR is usually predictable. In contrast, the present filament lies along the weak-field region (photospheric field strength barbs very well, which strongly supports the FR-dip model for filaments. The filament is stably sustained because the FR is weakly twisted and strongly confined by the overlying closed arcades.
Jiang, Feng-Jian; Ye, Jian-Feng; Jiao, Zheng; Jiang, Jun; Ma, Kun; Yan, Xin-Hu; Lv, Hai-Jiang
2018-05-01
We perform a proof-of-principle experiment that uses a single negatively charged nitrogen–vacancy (NV) color center with a nearest neighbor 13C nuclear spin in diamond to detect the strength and direction (including both polar and azimuth angles) of a static vector magnetic field by optical detection magnetic resonance (ODMR) technique. With the known hyperfine coupling tensor between an NV center and a nearest neighbor 13C nuclear spin, we show that the information of static vector magnetic field could be extracted by observing the pulsed continuous wave (CW) spectrum. Project supported by the National Natural Science Foundation of China (Grant Nos. 11305074, 11135002, and 11275083), the Key Program of the Education Department Outstanding Youth Foundation of Anhui Province, China (Grant No. gxyqZD2017080), and the Education Department Natural Science Foundation of Anhui Province, China (Grant No. KJHS2015B09).
Stable piecewise polynomial vector fields
Directory of Open Access Journals (Sweden)
Claudio Pessoa
2012-09-01
Full Text Available Let $N={y>0}$ and $S={y<0}$ be the semi-planes of $mathbb{R}^2$ having as common boundary the line $D={y=0}$. Let $X$ and $Y$ be polynomial vector fields defined in $N$ and $S$, respectively, leading to a discontinuous piecewise polynomial vector field $Z=(X,Y$. This work pursues the stability and the transition analysis of solutions of $Z$ between $N$ and $S$, started by Filippov (1988 and Kozlova (1984 and reformulated by Sotomayor-Teixeira (1995 in terms of the regularization method. This method consists in analyzing a one parameter family of continuous vector fields $Z_{epsilon}$, defined by averaging $X$ and $Y$. This family approaches $Z$ when the parameter goes to zero. The results of Sotomayor-Teixeira and Sotomayor-Machado (2002 providing conditions on $(X,Y$ for the regularized vector fields to be structurally stable on planar compact connected regions are extended to discontinuous piecewise polynomial vector fields on $mathbb{R}^2$. Pertinent genericity results for vector fields satisfying the above stability conditions are also extended to the present case. A procedure for the study of discontinuous piecewise vector fields at infinity through a compactification is proposed here.
In situ vector calibration of magnetic observatories
Directory of Open Access Journals (Sweden)
A. Gonsette
2017-09-01
Full Text Available The goal of magnetic observatories is to measure and provide a vector magnetic field in a geodetic coordinate system. For that purpose, instrument set-up and calibration are crucial. In particular, the scale factor and orientation of a vector magnetometer may affect the magnetic field measurement. Here, we highlight the baseline concept and demonstrate that it is essential for data quality control. We show how the baselines can highlight a possible calibration error. We also provide a calibration method based on high-frequency absolute measurements. This method determines a transformation matrix for correcting variometer data suffering from scale factor and orientation errors. We finally present a practical case where recovered data have been successfully compared to those coming from a reference magnetometer.
Lee, Dukhyung; Kim, Dai-Sik
2016-01-01
We study light scattering off rectangular slot nano antennas on a metal film varying incident polarization and incident angle, to examine which field vector of light is more important: electric vector perpendicular to, versus magnetic vector parallel to the long axis of the rectangle. While vector Babinet’s principle would prefer magnetic field along the long axis for optimizing slot antenna function, convention and intuition most often refer to the electric field perpendicular to it. Here, we demonstrate experimentally that in accordance with vector Babinet’s principle, the incident magnetic vector parallel to the long axis is the dominant component, with the perpendicular incident electric field making a small contribution of the factor of 1/|ε|, the reciprocal of the absolute value of the dielectric constant of the metal, owing to the non-perfectness of metals at optical frequencies.
Vector Fields European user group meeting
2007-01-01
The "Vector Fields European user group meeting" will take place at CERN on 26 and 27 September 2007. Within this framework two workshops are organized at the CERN Training Centre: 24 September 2007 Modelling Magnets with Opera 25 September 2007 Modelling of Charged Particle Beam Devices with Opera If you are interested in attending the workshop or the user group meeting please contact Julie Shepherd (Vector Fields) or Pierre Baehler (CERN) directly at: Julie.Shepherd@vectorfields.co.uk, +44 (0) 1865 854933 or +44 (0) 1865 370151 Pierre.Baehler@cern.ch, 75016 / 160156.
von Allwörden, Henning; Eich, Andreas; Knol, Elze J; Hermenau, Jan; Sonntag, Andreas; Gerritsen, Jan W; Wegner, Daniel; Khajetoorians, Alexander A
2018-03-01
We describe the design and performance of a scanning tunneling microscope (STM) that operates at a base temperature of 30 mK in a vector magnetic field. The cryogenics is based on an ultra-high vacuum (UHV) top-loading wet dilution refrigerator that contains a vector magnet allowing for fields up to 9 T perpendicular and 4 T parallel to the sample. The STM is placed in a multi-chamber UHV system, which allows in situ preparation and exchange of samples and tips. The entire system rests on a 150-ton concrete block suspended by pneumatic isolators, which is housed in an acoustically isolated and electromagnetically shielded laboratory optimized for extremely low noise scanning probe measurements. We demonstrate the overall performance by illustrating atomic resolution and quasiparticle interference imaging and detail the vibrational noise of both the laboratory and microscope. We also determine the electron temperature via measurement of the superconducting gap of Re(0001) and illustrate magnetic field-dependent measurements of the spin excitations of individual Fe atoms on Pt(111). Finally, we demonstrate spin resolution by imaging the magnetic structure of the Fe double layer on W(110).
von Allwörden, Henning; Eich, Andreas; Knol, Elze J.; Hermenau, Jan; Sonntag, Andreas; Gerritsen, Jan W.; Wegner, Daniel; Khajetoorians, Alexander A.
2018-03-01
We describe the design and performance of a scanning tunneling microscope (STM) that operates at a base temperature of 30 mK in a vector magnetic field. The cryogenics is based on an ultra-high vacuum (UHV) top-loading wet dilution refrigerator that contains a vector magnet allowing for fields up to 9 T perpendicular and 4 T parallel to the sample. The STM is placed in a multi-chamber UHV system, which allows in situ preparation and exchange of samples and tips. The entire system rests on a 150-ton concrete block suspended by pneumatic isolators, which is housed in an acoustically isolated and electromagnetically shielded laboratory optimized for extremely low noise scanning probe measurements. We demonstrate the overall performance by illustrating atomic resolution and quasiparticle interference imaging and detail the vibrational noise of both the laboratory and microscope. We also determine the electron temperature via measurement of the superconducting gap of Re(0001) and illustrate magnetic field-dependent measurements of the spin excitations of individual Fe atoms on Pt(111). Finally, we demonstrate spin resolution by imaging the magnetic structure of the Fe double layer on W(110).
Energy Technology Data Exchange (ETDEWEB)
Jiang, Chaowei; Wu, S. T.; Hu, Qiang [Center for Space Plasma and Aeronomic Research, The University of Alabama in Huntsville, Huntsville, AL 35899 (United States); Feng, Xueshang, E-mail: cwjiang@spaceweather.ac.cn, E-mail: wus@uah.edu, E-mail: qh0001@uah.edu, E-mail: fengx@spaceweather.ac.cn [SIGMA Weather Group, State Key Laboratory for Space Weather, Center for Space Science and Applied Research, Chinese Academy of Sciences, Beijing 100190 (China)
2014-05-10
Solar filaments are commonly thought to be supported in magnetic dips, in particular, in those of magnetic flux ropes (FRs). In this Letter, based on the observed photospheric vector magnetogram, we implement a nonlinear force-free field (NLFFF) extrapolation of a coronal magnetic FR that supports a large-scale intermediate filament between an active region and a weak polarity region. This result is a first, in the sense that current NLFFF extrapolations including the presence of FRs are limited to relatively small-scale filaments that are close to sunspots and along main polarity inversion lines (PILs) with strong transverse field and magnetic shear, and the existence of an FR is usually predictable. In contrast, the present filament lies along the weak-field region (photospheric field strength ≲ 100 G), where the PIL is very fragmented due to small parasitic polarities on both sides of the PIL and the transverse field has a low signal-to-noise ratio. Thus, extrapolating a large-scale FR in such a case represents a far more difficult challenge. We demonstrate that our CESE-MHD-NLFFF code is sufficient for the challenge. The numerically reproduced magnetic dips of the extrapolated FR match observations of the filament and its barbs very well, which strongly supports the FR-dip model for filaments. The filament is stably sustained because the FR is weakly twisted and strongly confined by the overlying closed arcades.
Elliptic-symmetry vector optical fields.
Pan, Yue; Li, Yongnan; Li, Si-Min; Ren, Zhi-Cheng; Kong, Ling-Jun; Tu, Chenghou; Wang, Hui-Tian
2014-08-11
We present in principle and demonstrate experimentally a new kind of vector fields: elliptic-symmetry vector optical fields. This is a significant development in vector fields, as this breaks the cylindrical symmetry and enriches the family of vector fields. Due to the presence of an additional degrees of freedom, which is the interval between the foci in the elliptic coordinate system, the elliptic-symmetry vector fields are more flexible than the cylindrical vector fields for controlling the spatial structure of polarization and for engineering the focusing fields. The elliptic-symmetry vector fields can find many specific applications from optical trapping to optical machining and so on.
Satellite to study earth's magnetic field
1979-01-01
The Magnetic Field Satellite (Magsat) designed to measure the near earth magnetic field and crustal anomalies is briefly described. A scalar magnetometer to measure the magnitude of the earth's crustal magnetic field and a vector magnetometer to measure magnetic field direction as well as magnitude are included. The mission and its objectives are summarized along with the data collection and processing system.
Vector fields on nonorientable surfaces
Directory of Open Access Journals (Sweden)
Ilie Barza
2003-01-01
X, and the space of vector fields on X are proved by using a symmetrisation process. An example related to the normal derivative on the border of the Möbius strip supports the nontriviality of the concepts introduced in this paper.
International Nuclear Information System (INIS)
Lites, B.W.; Skumanich, A.; Rees, D.E.; Murphy, G.A.; Carlsson, M.; Sydney Univ., Australia; Oslo Universitetet, Norway)
1987-01-01
Observed Stokes profiles of Mg I 4571 A are analyzed as a diagnostic of the magnetic field and thermal structure at the temperature minimum of sunspot umbrae. Multilevel non-LTE transfer calculations of the Mg I-II-III excitation and ionization balance in model umbral atmospheres show: (1) Mg I to be far less ionized in sunspot umbrae than in the quiet sun, leading to greatly enhanced opacity in 4571 A, and (2) LTE excitation of 4571 A. Existing umbral models predict emission cores of the Stokes I profile due to the chromospheric temperature rise. This feature is not present in observed umbral profiles. Moreover, such an emission reversal causes similar anomalous features in the Stokes Q, U, V profiles, which are also not observed. Umbral atmospheres with extended temperature minima are suggested. Implications for chromospheric heating mechanisms and the utility of this line for solar vector magnetic field measurements are discussed. 35 references
On vector fields having properties of Reeb fields
Hajduk, Boguslaw; Walczak, Rafal
2011-01-01
We study constructions of vector fields with properties which are characteristic to Reeb vector fields of contact forms. In particular, we prove that all closed oriented odd-dimensional manifold have geodesible vector fields.
Magnetic concentration of a retroviral vector using magnetite cationic liposomes.
Ito, Akira; Takahashi, Tetsuya; Kameyama, Yujiro; Kawabe, Yoshinori; Kamihira, Masamichi
2009-03-01
For tissue engineering purposes, retroviral vectors represent an efficient method of delivering exogenous genes such as growth factors to injured tissues because gene-transduced cells can produce stable and constant levels of the gene product. However, retroviral vector technology suffers from low yields. In the present study, we used magnetite nanoparticles and magnetic force to concentrate the retroviral vectors to enhance the transduction efficiency and to enable their magnetic manipulation. Magnetite nanoparticles modified with cationic liposomes were added to a solution containing a retroviral vector pseudotyped with vesicular stomatitis virus glycoprotein. The magnetic particles that captured the viral vectors were collected using a magnetic force and seeded into mouse neuroblastoma Neuro2a cells. The viral titer was up to 55 times greater (up to 3 x 10(8) infectious units/mL). Additionally, the magnetically labeled retroviral vectors can be directed to the desired regions for infection by applying magnetic fields, and micro-patterns of gene-transduced cell regions could be created on a cellular monolayer using micro-patterned magnetic concentrators. These results suggest that this technique provides a promising approach to capturing and concentrating viral vectors, thus achieving high transduction efficiency and the ability to deliver genes to a specific injured site by applying a magnetic field.
ESTIMATING ELECTRIC FIELDS FROM VECTOR MAGNETOGRAM SEQUENCES
International Nuclear Information System (INIS)
Fisher, G. H.; Welsch, B. T.; Abbett, W. P.; Bercik, D. J.
2010-01-01
Determining the electric field distribution on the Sun's photosphere is essential for quantitative studies of how energy flows from the Sun's photosphere, through the corona, and into the heliosphere. This electric field also provides valuable input for data-driven models of the solar atmosphere and the Sun-Earth system. We show how observed vector magnetogram time series can be used to estimate the photospheric electric field. Our method uses a 'poloidal-toroidal decomposition' (PTD) of the time derivative of the vector magnetic field. These solutions provide an electric field whose curl obeys all three components of Faraday's Law. The PTD solutions are not unique; the gradient of a scalar potential can be added to the PTD electric field without affecting consistency with Faraday's Law. We then present an iterative technique to determine a potential function consistent with ideal MHD evolution; but this field is also not a unique solution to Faraday's Law. Finally, we explore a variational approach that minimizes an energy functional to determine a unique electric field, a generalization of Longcope's 'Minimum Energy Fit'. The PTD technique, the iterative technique, and the variational technique are used to estimate electric fields from a pair of synthetic vector magnetograms taken from an MHD simulation; and these fields are compared with the simulation's known electric fields. The PTD and iteration techniques compare favorably to results from existing velocity inversion techniques. These three techniques are then applied to a pair of vector magnetograms of solar active region NOAA AR8210, to demonstrate the methods with real data. Careful examination of the results from all three methods indicates that evolution of the magnetic vector by itself does not provide enough information to determine the true electric field in the photosphere. Either more information from other measurements, or physical constraints other than those considered here are necessary to find
The vector meson with anomalous magnetic moment
International Nuclear Information System (INIS)
Boyarkin, O.M.
1976-01-01
The possibility of introducing an anomalous magnetic moment into the Stuckelberg version of the charged vector meson theory is considered. It is shown that the interference of states with spins equal to one and zero is absent in the presence of an anomalous magnetic moment of a particle. The differential cross section of scattering on the Coulomb field of a nucleus is calculated, and so are the differential and integral cross sections of meson pair production on annihilation of two gamma quanta. The two-photon mechanism of production of a meson pair in colliding electron-positron beams is considered. It is shown that with any value of the anomalous magnetic moment the cross section of the esup(+)esup(-) → esup(+)esup(-)γsup(*)γsup(*) → esup(+)esup(-)Wsup(+)Wsup(-) reaction exceeds that of the esup(+)esup(-) → γsup(*) → Wsup(+)Wsup(-) at sufficiently high energies
Farrugia, C. J.; Erkaev, N. V.; Torbert, R. B.; Biernat, H. K.; Gratton, F. T.; Szabo, A.; Kucharek, H.; Matsui, H.; Lin, R. P.; Ogilvie, K. W.; Lepping, R. P.; Smith, C. W.
2010-08-01
While there are many approximations describing the flow of the solar wind past the magnetosphere in the magnetosheath, the case of perfectly aligned (parallel or anti-parallel) interplanetary magnetic field (IMF) and solar wind flow vectors can be treated exactly in a magnetohydrodynamic (MHD) approach. In this work we examine a case of nearly-opposed (to within 15°) interplanetary field and flow vectors, which occurred on October 24-25, 2001 during passage of the last interplanetary coronal mass ejection in an ejecta merger. Interplanetary data are from the ACE spacecraft. Simultaneously Wind was crossing the near-Earth (X ˜ -13 Re) geomagnetic tail and subsequently made an approximately 5-hour-long magnetosheath crossing close to the ecliptic plane (Z = -0.7 Re). Geomagnetic activity was returning steadily to quiet, “ground” conditions. We first compare the predictions of the Spreiter and Rizzi theory with the Wind magnetosheath observations and find fair agreement, in particular as regards the proportionality of the magnetic field strength and the product of the plasma density and bulk speed. We then carry out a small-perturbation analysis of the Spreiter and Rizzi solution to account for the small IMF components perpendicular to the flow vector. The resulting expression is compared to the time series of the observations and satisfactory agreement is obtained. We also present and discuss observations in the dawnside boundary layer of pulsed, high-speed (v ˜ 600 km/s) flows exceeding the solar wind flow speeds. We examine various generating mechanisms and suggest that the most likely cause is a wave of frequency 3.2 mHz excited at the inner edge of the boundary layer by the Kelvin-Helmholtz instability.
Problems of vector Lagrangians in field theories
International Nuclear Information System (INIS)
Krivsky, I.Yu.; Simulik, V.M.
1997-01-01
A vector Lagrange approach to the Dirac spinor field and the relationship between the vector Lagrangians for the spinor and electromagnetic fields are considered. A vector Lagrange approach for the system of interacting electromagnetic B=(B μ υ)=(E-bar,H-bar) and spinor Ψ fields is constructed. New Lagrangians (scalar and vector) for electromagnetic field in terms of field strengths are found. The foundations of two new QED models are formulated
Vector fields and gravity on the lattice
International Nuclear Information System (INIS)
Khatsymovsky, V.M.
1988-01-01
The problem of discretization of vector field on Regge lattice is considered. Our approach is based on geometrical interpretation of the vector field as the field of infinitesimal coordinate transformation. A discrete version of the vector field action is obtained as a particular case of the continuum action, and it is shown to have the true continuum limit
Transversals of Complex Polynomial Vector Fields
DEFF Research Database (Denmark)
Dias, Kealey
Vector fields in the complex plane are defined by assigning the vector determined by the value P(z) to each point z in the complex plane, where P is a polynomial of one complex variable. We consider special families of so-called rotated vector fields that are determined by a polynomial multiplied...... by rotational constants. Transversals are a certain class of curves for such a family of vector fields that represent the bifurcation states for this family of vector fields. More specifically, transversals are curves that coincide with a homoclinic separatrix for some rotation of the vector field. Given...... a concrete polynomial, it seems to take quite a bit of work to prove that it is generic, i.e. structurally stable. This has been done for a special class of degree d polynomial vector fields having simple equilibrium points at the d roots of unity, d odd. In proving that such vector fields are generic...
Vector Fields and Flows on Differentiable Stacks
DEFF Research Database (Denmark)
A. Hepworth, Richard
2009-01-01
This paper introduces the notions of vector field and flow on a general differentiable stack. Our main theorem states that the flow of a vector field on a compact proper differentiable stack exists and is unique up to a uniquely determined 2-cell. This extends the usual result on the existence...... of vector fields....
Visualizing vector field topology in fluid flows
Helman, James L.; Hesselink, Lambertus
1991-01-01
Methods of automating the analysis and display of vector field topology in general and flow topology in particular are discussed. Two-dimensional vector field topology is reviewed as the basis for the examination of topology in three-dimensional separated flows. The use of tangent surfaces and clipping in visualizing vector field topology in fluid flows is addressed.
Introduction to Vector Field Visualization
Kao, David; Shen, Han-Wei
2010-01-01
Vector field visualization techniques are essential to help us understand the complex dynamics of flow fields. These can be found in a wide range of applications such as study of flows around an aircraft, the blood flow in our heart chambers, ocean circulation models, and severe weather predictions. The vector fields from these various applications can be visually depicted using a number of techniques such as particle traces and advecting textures. In this tutorial, we present several fundamental algorithms in flow visualization including particle integration, particle tracking in time-dependent flows, and seeding strategies. For flows near surfaces, a wide variety of synthetic texture-based algorithms have been developed to depict near-body flow features. The most common approach is based on the Line Integral Convolution (LIC) algorithm. There also exist extensions of LIC to support more flexible texture generations for 3D flow data. This tutorial reviews these algorithms. Tensor fields are found in several real-world applications and also require the aid of visualization to help users understand their data sets. Examples where one can find tensor fields include mechanics to see how material respond to external forces, civil engineering and geomechanics of roads and bridges, and the study of neural pathway via diffusion tensor imaging. This tutorial will provide an overview of the different tensor field visualization techniques, discuss basic tensor decompositions, and go into detail on glyph based methods, deformation based methods, and streamline based methods. Practical examples will be used when presenting the methods; and applications from some case studies will be used as part of the motivation.
Magnetic Fields Versus Gravity
Hensley, Kerry
2018-04-01
polarized emission toward all three sources. By extracting the magnetic field orientations from the polarization vectors, Koch and collaborators found that the molecular cloud contains an ordered magnetic field with never-before-seen structures. Several small clumps on the perimeter of the massive star-forming cores exhibit comet-shaped magnetic field structures, which could indicate that these smaller cores are being pulled toward the more massive cores.These findings hint that the magnetic field structure can tell us about the flow of material within star-forming regions key to understanding the nature of star formation itself.Maps of sin for two of the protostars (e2 and e8) and their surroundings. [Adapted from Koch et al. 2018]Guiding Star FormationDo the magnetic fields in W51 help or hinder star formation? To explore this question,Koch and collaborators introduced the quantity sin , where is the angle between the local gravity and the local magnetic field.When the angle between gravity and the magnetic field is small (sin 0), the magnetic field has little effect on the collapse of the cloud. If gravity and the magnetic field are perpendicular (sin 1), the magnetic field can slow the infall of gas and inhibit star formation.Based on this parameter, Koch and collaborators identified narrow channels where gravity acts unimpeded by the magnetic field. These magnetic channels may funnel gas toward the dense cores and aid the star-formation process.The authors observations demonstrate just one example of the broad realm ALMAs polarimetry capabilities have opened to discovery. These and future observations of dust polarization will continue to reveal more about the delicate magnetic structure within molecular clouds, furtherilluminating the role that magnetic fields play in star formation.CitationPatrick M. Koch et al 2018 ApJ 855 39. doi:10.3847/1538-4357/aaa4c1
National Oceanic and Atmospheric Administration, Department of Commerce — The Magnetic Field Calculator will calculate the total magnetic field, including components (declination, inclination, horizontal intensity, northerly intensity,...
Directory of Open Access Journals (Sweden)
Galimzian G. Islamov
2015-12-01
Full Text Available It is shown that a simple postulate “The displacement field of the vacuum is a normalized electric field”, is equivalent to three parametric representation of the displacement field of the vacuum: $$ u(x;t = P(x \\cos k(xt + Q(x \\sin k(xt. $$ Here $t$ — time; $k(x$ — frequency vibrations at the point of three-dimensional Euclidean space; $P(x, Q(x$ — a pair of stationary orthonormal vector fields; $(k,P, Q$ — parameter list of the displacement field. In this case, the normalization factor has dimension $T^{-2}$. The speed of the displacement field $$ v(x;t = \\frac{\\partial u(x;t}{\\partial t} = k(x(Q(x \\cos k(xt - P(x \\sin k(xt. $$ The electric field corresponding to this distribution of the displacement field of vacuum, is given by the formula $$ E(x;t = -\\frac{\\partial v(x;t}{\\partial t} = k^2(xu(x;t. $$ Moreover, the magnetic induction $$ B(x;t = \\mathop{\\mathrm{rot }} v(x; t. $$ These constructions are used in the determination of local and global solutions of Maxwell's equations describing the dynamics of electromagnetic fields.
Magnetic field line Hamiltonian
International Nuclear Information System (INIS)
Boozer, A.H.
1985-02-01
The basic properties of the Hamiltonian representation of magnetic fields in canonical form are reviewed. The theory of canonical magnetic perturbation theory is then developed and applied to the time evolution of a magnetic field embedded in a toroidal plasma. Finally, the extension of the energy principle to tearing modes, utilizing the magnetic field line Hamiltonian, is outlined
Interpolation of vector fields from human cardiac DT-MRI
International Nuclear Information System (INIS)
Yang, F; Zhu, Y M; Rapacchi, S; Robini, M; Croisille, P; Luo, J H
2011-01-01
There has recently been increased interest in developing tensor data processing methods for the new medical imaging modality referred to as diffusion tensor magnetic resonance imaging (DT-MRI). This paper proposes a method for interpolating the primary vector fields from human cardiac DT-MRI, with the particularity of achieving interpolation and denoising simultaneously. The method consists of localizing the noise-corrupted vectors using the local statistical properties of vector fields, removing the noise-corrupted vectors and reconstructing them by using the thin plate spline (TPS) model, and finally applying global TPS interpolation to increase the resolution in the spatial domain. Experiments on 17 human hearts show that the proposed method allows us to obtain higher resolution while reducing noise, preserving details and improving direction coherence (DC) of vector fields as well as fiber tracking. Moreover, the proposed method perfectly reconstructs azimuth and elevation angle maps.
International Nuclear Information System (INIS)
Han Jinlin
2006-01-01
A good progress has been made on studies of Galactic magnetic fields in last 10 years. I describe what we want to know about the Galactic magnetic fields, and then review we current knowledge about magnetic fields in the Galactic disk, the Galactic halo and the field strengths. I also listed many unsolved problems on this area
The Juno Magnetic Field Investigation
Connerney, J. E. P.; Benn, M.; Bjarno, J. B.; Denver, T.; Espley, J.; Jorgensen, J. L.; Jorgensen, P. S.; Lawton, P.; Malinnikova, A.; Merayo, J. M.; Murphy, S.; Odom, J.; Oliversen, R.; Schnurr, R.; Sheppard, D.; Smith, E. J.
2017-11-01
The Juno Magnetic Field investigation (MAG) characterizes Jupiter's planetary magnetic field and magnetosphere, providing the first globally distributed and proximate measurements of the magnetic field of Jupiter. The magnetic field instrumentation consists of two independent magnetometer sensor suites, each consisting of a tri-axial Fluxgate Magnetometer (FGM) sensor and a pair of co-located imaging sensors mounted on an ultra-stable optical bench. The imaging system sensors are part of a subsystem that provides accurate attitude information (to ˜20 arcsec on a spinning spacecraft) near the point of measurement of the magnetic field. The two sensor suites are accommodated at 10 and 12 m from the body of the spacecraft on a 4 m long magnetometer boom affixed to the outer end of one of 's three solar array assemblies. The magnetometer sensors are controlled by independent and functionally identical electronics boards within the magnetometer electronics package mounted inside Juno's massive radiation shielded vault. The imaging sensors are controlled by a fully hardware redundant electronics package also mounted within the radiation vault. Each magnetometer sensor measures the vector magnetic field with 100 ppm absolute vector accuracy over a wide dynamic range (to 16 Gauss = 1.6 × 106 nT per axis) with a resolution of ˜0.05 nT in the most sensitive dynamic range (±1600 nT per axis). Both magnetometers sample the magnetic field simultaneously at an intrinsic sample rate of 64 vector samples per second. The magnetic field instrumentation may be reconfigured in flight to meet unanticipated needs and is fully hardware redundant. The attitude determination system compares images with an on-board star catalog to provide attitude solutions (quaternions) at a rate of up to 4 solutions per second, and may be configured to acquire images of selected targets for science and engineering analysis. The system tracks and catalogs objects that pass through the imager field of
Multi-task Vector Field Learning.
Lin, Binbin; Yang, Sen; Zhang, Chiyuan; Ye, Jieping; He, Xiaofei
2012-01-01
Multi-task learning (MTL) aims to improve generalization performance by learning multiple related tasks simultaneously and identifying the shared information among tasks. Most of existing MTL methods focus on learning linear models under the supervised setting. We propose a novel semi-supervised and nonlinear approach for MTL using vector fields. A vector field is a smooth mapping from the manifold to the tangent spaces which can be viewed as a directional derivative of functions on the manifold. We argue that vector fields provide a natural way to exploit the geometric structure of data as well as the shared differential structure of tasks, both of which are crucial for semi-supervised multi-task learning. In this paper, we develop multi-task vector field learning (MTVFL) which learns the predictor functions and the vector fields simultaneously. MTVFL has the following key properties. (1) The vector fields MTVFL learns are close to the gradient fields of the predictor functions. (2) Within each task, the vector field is required to be as parallel as possible which is expected to span a low dimensional subspace. (3) The vector fields from all tasks share a low dimensional subspace. We formalize our idea in a regularization framework and also provide a convex relaxation method to solve the original non-convex problem. The experimental results on synthetic and real data demonstrate the effectiveness of our proposed approach.
Vector fields and differential operators: noncommutative case
International Nuclear Information System (INIS)
Borowiec, A.
1997-01-01
A notion of Cartan pairs as an analogy of vector fields in the realm of noncommutative geometry has been proposed previously. In this paper an outline is given of the construction of a noncommutative analogy of the algebra of differential operators as well as its (algebraic) Fock space realization. Co-universal vector fields and covariant derivatives will also be discussed
Magnetic Field Grid Calculator
National Oceanic and Atmospheric Administration, Department of Commerce — The Magnetic Field Properties Calculator will computes the estimated values of Earth's magnetic field(declination, inclination, vertical component, northerly...
Clifford Fourier transform on vector fields.
Ebling, Julia; Scheuermann, Gerik
2005-01-01
Image processing and computer vision have robust methods for feature extraction and the computation of derivatives of scalar fields. Furthermore, interpolation and the effects of applying a filter can be analyzed in detail and can be advantages when applying these methods to vector fields to obtain a solid theoretical basis for feature extraction. We recently introduced the Clifford convolution, which is an extension of the classical convolution on scalar fields and provides a unified notation for the convolution of scalar and vector fields. It has attractive geometric properties that allow pattern matching on vector fields. In image processing, the convolution and the Fourier transform operators are closely related by the convolution theorem and, in this paper, we extend the Fourier transform to include general elements of Clifford Algebra, called multivectors, including scalars and vectors. The resulting convolution and derivative theorems are extensions of those for convolution and the Fourier transform on scalar fields. The Clifford Fourier transform allows a frequency analysis of vector fields and the behavior of vector-valued filters. In frequency space, vectors are transformed into general multivectors of the Clifford Algebra. Many basic vector-valued patterns, such as source, sink, saddle points, and potential vortices, can be described by a few multivectors in frequency space.
Euclidean fields: vector mesons and photons
International Nuclear Information System (INIS)
Loffelholz, J.
1979-01-01
Free transverse vector fields of mass >= 0 are studied. The model is related to the usual free vector meson and electromagnetic quantum field theories by extension of the field operators from transverse to arbitrary test functions. The one-particle states in transverse gauge and their localization are described. Reflexion positivity is proved and derived are free Feynman-Kac-Nelson formulas. An Euclidean approach to a photon field in a spherical world using dilatation covariance and inversions is given
International Nuclear Information System (INIS)
Stupakov, G.V.
1982-01-01
In omnigenous magnetic fields particles' drift surfaces coincide with plasma magnetic surfaces. In this paper we formulate equations of omnigenous magnetic fields in natural curvilinear coordinates. An analysis of fields which are omnigenous only in the paraxial approximation is presented. (author)
Queitsch, M.; Schiffler, M.; Stolz, R.; Meyer, M.; Kukowski, N.
2017-12-01
Measurements of the Earth's magnetic field are one of the most used methods in geophysical exploration. The ambiguity of the method, especially during modeling and inversion of magnetic field data sets, is one of its biggest challenges. Additional directional information, e.g. gathered by gradiometer systems based on Superconducting Quantum Interference Devices (SQUIDs), will positively influence the inversion results and will thus lead to better subsurface magnetization models. This is especially beneficial, regarding the shape and direction of magnetized structures, especially when a significant remanent magnetization of the underlying sources is present. The possibility to separate induced and remanent contributions to the total magnetization may in future also open up advanced ways for geological interpretation of the data, e.g. a first estimation of diagenesis processes. In this study we present the results of airborne full tensor magnetic gradiometry (FTMG) surveys conducted over a dolerite intrusion in central Germany and the results of two magnetization vector inversions (MVI) of the FTMG and a conventional total field anomaly data set. A separation of the two main contributions of the acquired total magnetization will be compared with information of the rock magnetization measured on orientated rock samples. The FTMG inversion results show a much better agreement in direction and strength of both total and remanent magnetization compared to the inversion using only total field anomaly data. To enhance the separation process, the application of additional geophysical methods, i.e. frequency domain electromagnetics (FDEM), in order to gather spatial information of subsurface rock susceptibility will also be discussed. In this approach, we try to extract not only information on subsurface conductivity but also the induced magnetization. Using the total magnetization from the FTMG data and the induced magnetization from the FDEM data, the full separation of
Magnetization strucrure of thermal vent on island arc from vector magnetic anomlies using AUV
Isezaki, N.; Matsuo, J.; Sayanagi, K.
2012-04-01
The geomagnetic anomaly measured by a scalar magnetometer,such as a proton precession magnetometer cannot be defined its direction, then it does not satisfy the Laplace's equation. Therefore physical formula describing the relation between magnetic field and magnetization cannot be established.Because the difference between results obtained from scalar data and from vector data is very significant, we must use vector magnetic field data for magnetization analyses to get the more reliable and exact solutions. The development program of fundamental tools for exploration of deep seabed resources started with the financial support of the Ministry of Education, Culture, Sports, Science & Technology (MEXT) in 2008 and will end in 2012. In this project, we are developing magnetic exploration tools for seabed resources using AUV (Autonomous Underwater Vehicle) and other deep-towed vehicles to measure not the scalar magnetic field but the vector magnetic field in order to estimate magnetization structure below the sea-floor exactly and precisely. We conducted AUV magnetic survey in 2010 at the thermal area called Hakurei deposit in the Bayonnaise submarine caldera at the southern end of Izu island arc, about 400km south of Tokyo. We analyzed the observed vector magnetic fields to get the vector magnetic anomaly Fields using the method of Isezaki(1984). We inverted these vector magnetic anomaly fields to magnetization structure. CONCLUSIONS 1.The scalar magnetic field TIA (Total Intensity Anomaly) has no physical formula describing the relation between M (Magnetization) and TIA because TIA does not satisfy the Laplace's equation. Then it is impossible to estimate M from TIA. 2.Anlyses of M using TIA have been done so far under assumption TIA=PTA (Projected Total Anomay on MF (Main Geomagnetic Field)), however, which caused the analysis error due to ɛT= TIA - PTA . 3.We succeeded to measure the vector magnetic anomaly fields using AUV despite the severe magnetic noises
Sánchez Almeida, J.; Martínez González, M. J.
2018-05-01
Magnetic fields play an important role in many astrophysical processes. They are difficult to detect and characterize since often their properties have to be inferred through interpreting the polarization of the light. Magnetic fields are also challenging to model and understand. Magnetized plasmas behave following highly non-linear differential equations having no general solution, so that every astrophysical problem represents a special case to be studied independently. Hence, magnetic fields are often an inconvenient subject which is overlooked or simply neglected (the elephant in the room, as they are dubbed in poster of the school). Such difficulty burdens the research on magnetic fields, which has evolved to become a very technical subject, with many small disconnected communities studying specific aspects and details. The school tried to amend the situation by providing a unifying view of the subject. The students had a chance to understand the behavior of magnetic fields in all astrophysical contexts, from cosmology to the Sun, and from starbursts to AGNs. The school was planed to present a balanced yet complete review of our knowledge, with excursions into the unknown to point out present and future lines of research. The subject of Cosmic Magnetic Fields was split into seven different topics: cosmic magnetic field essentials, solar magnetic fields, stellar magnetic fields, the role of magnetic fields on AGN feedback, magnetic fields in galaxies, magnetic fields in galaxy clusters and at larger scales, and primordial magnetic fields and magnetic fields in the early Universe. The corresponding lectures were delivered by seven well known and experienced scientists that have played key roles in the major advances of the field during the last years: F. Cattaneo, P. Judge, O. Kochukhov, R. Keppens, R. Beck, K. Dolag, and F. Finelli. Their lectures were recorded and are freely available at the IAC website: http://iactalks.iac.es/talks/serie/19.
International Nuclear Information System (INIS)
Satoh, Akira; Hayasaka, Ryo; Majima, Tamotsu
2008-01-01
We have treated a dilute dispersion composed of ferromagnetic rodlike particles with a magnetic moment normal to the particle axis, such as hematites, to investigate the influences of the magnetic field strength, shear rate, and random forces on the orientational distribution of rodlike particles and also on transport coefficients, such as viscosity and diffusion coefficient. In the present analysis, these rodlike particles are assumed to conduct the rotational Brownian motion in a simple shear flow as well as an external magnetic field. The results obtained here are summarized as follows. In the case of a strong magnetic field and a smaller shear rate, the rodlike particle can freely rotate in the xy-plane with the magnetic moment continuing to point the magnetic field direction. On the other hand, for a strong shear flow, the particle has a tendency to incline in the flow direction with the magnetic moment pointing to the magnetic field direction. In the case of the magnetic field applied normal to the direction of the sedimentation, the diffusion coefficient gives rise to smaller values than expected, since the rodlike particle sediments with the particle axis inclining toward directions normal to the movement direction and, of course, toward the direction along that direction
Vector fields satisfying the barycenter property
Directory of Open Access Journals (Sweden)
Lee Manseob
2018-04-01
Full Text Available We show that if a vector field X has the C1 robustly barycenter property then it does not have singularities and it is Axiom A without cycles. Moreover, if a generic C1-vector field has the barycenter property then it does not have singularities and it is Axiom A without cycles. Moreover, we apply the results to the divergence free vector fields. It is an extension of the results of the barycenter property for generic diffeomorphisms and volume preserving diffeomorphisms [1].
Versatile generation of optical vector fields and vector beams using a non-interferometric approach.
Tripathi, Santosh; Toussaint, Kimani C
2012-05-07
We present a versatile, non-interferometric method for generating vector fields and vector beams which can produce all the states of polarization represented on a higher-order Poincaré sphere. The versatility and non-interferometric nature of this method is expected to enable exploration of various exotic properties of vector fields and vector beams. To illustrate this, we study the propagation properties of some vector fields and find that, in general, propagation alters both their intensity and polarization distribution, and more interestingly, converts some vector fields into vector beams. In the article, we also suggest a modified Jones vector formalism to represent vector fields and vector beams.
Equivalent magnetic vector potential model for low-frequency magnetic exposure assessment
Diao, Y. L.; Sun, W. N.; He, Y. Q.; Leung, S. W.; Siu, Y. M.
2017-10-01
In this paper, a novel source model based on a magnetic vector potential for the assessment of induced electric field strength in a human body exposed to the low-frequency (LF) magnetic field of an electrical appliance is presented. The construction of the vector potential model requires only a single-component magnetic field to be measured close to the appliance under test, hence relieving considerable practical measurement effort—the radial basis functions (RBFs) are adopted for the interpolation of discrete measurements; the magnetic vector potential model can then be directly constructed by summing a set of simple algebraic functions of RBF parameters. The vector potentials are then incorporated into numerical calculations as the equivalent source for evaluations of the induced electric field in the human body model. The accuracy and effectiveness of the proposed model are demonstrated by comparing the induced electric field in a human model to that of the full-wave simulation. This study presents a simple and effective approach for modelling the LF magnetic source. The result of this study could simplify the compliance test procedure for assessing an electrical appliance regarding LF magnetic exposure.
Meromorphic Vector Fields and Circle Packings
DEFF Research Database (Denmark)
Dias, Kealey
The objective of the Ph.D. project is to initiate a classification of bifurcations of meromorphic vector fields and to clarify their relation to circle packings. Technological applications are to image analysis and to effective grid generation using discrete conformal mappings. The two branches...... of dynamical systems, continuous and discrete, correspond to the study of differential equations (vector fields) and iteration of mappings respectively. In holomorphic dynamics, the systems studied are restricted to those described by holomorphic (complex analytic) functions or meromorphic (allowing poles...... as singularities) functions. There already exists a well-developed theory for iterative holomorphic dynamical systems, and successful relations found between iteration theory and flows of vector fields have been one of the main motivations for the recent interest in holomorphic vector fields. Restricting...
Strong Magnetic Field Characterisation
2012-04-01
an advertised surface field of approximately 0.5 T were used to supply the static magnetic field source. The disc magnet had a diameter of 50 mm and... colour bar indicates the magnetic field strength set to an arbitrary 0.25 T. The white area has a field >0.25 T. The size of the arrow is proportional...9 shows the magnetic field strength along a slice in the XZ plane. The colours represent the total UNCLASSIFIED 10 UNCLASSIFIED DSTO-TR-2699
The Juno Magnetic Field Investigation
DEFF Research Database (Denmark)
Connerney, J. E. P.; Benn, Mathias; Bjarnø, Jonas Bækby
2017-01-01
The Juno Magnetic Field investigation (MAG) characterizes Jupiter’s planetary magnetic field and magnetosphere, providing the first globally distributed and proximate measurements of the magnetic field of Jupiter. The magnetic field instrumentation consists of two independent magnetometer sensor ...
Cosmological magnetic fields - V
Indian Academy of Sciences (India)
Magnetic fields seem to be everywhere that we can look in the universe, from our own ... The field tensor is observer-independent, while the electric and magnetic .... based on string theory [11], in which vacuum fluctuations of the field are ...
Massive vector fields and black holes
International Nuclear Information System (INIS)
Frolov, V.P.
1977-04-01
A massive vector field inside the event horizon created by the static sources located outside the black hole is investigated. It is shown that the back reaction of such a field on the metric near r = 0 cannot be neglected. The possibility of the space-time structure changing near r = 0 due to the external massive field is discussed
Energy Technology Data Exchange (ETDEWEB)
McCamey, Dane; Boehme, Christoph
2017-01-24
An organic, spin-dependent magnetic field sensor (10) includes an active stack (12) having an organic material with a spin-dependence. The sensor (10) also includes a back electrical contact (14) electrically coupled to a back of the active stack (12) and a front electrical contact (16) electrically coupled to a front of the active stack (12). A magnetic field generator (18) is oriented so as to provide an oscillating magnetic field which penetrates the active stack (12).
Gerrits, T.; Silva, T.J.; Nibarger, J.P.; Rasing, T.H.M.
2004-01-01
We examine the relationship between nonlinear magnetic responses and the change in the Gilbert damping parameter alpha for patterned and unpatterned thin Permalloy films when subjected to pulsed magnetic fields. An improved magnetization-vector-resolved technique utilizing magnetization-induced
Vector supersymmetry in topological field theories
International Nuclear Information System (INIS)
Gieres, F.; Grimstrup, J.; Pisar, T.; Schweda, M.
2000-01-01
We present a simple derivation of vector supersymmetry transformations for topological field theories of Schwarz- and Witten-type. Our method is similar to the derivation of BRST-transformations from the so-called horizontality conditions or Russian formulae. We show that this procedure reproduces in a concise way the known vector supersymmetry transformations of various topological models and we use it to obtain some new transformations of this type for 4d topological YM-theories in different gauges. (author)
International Nuclear Information System (INIS)
Estevez Radio, H.; Fernandez Arenal, C.A.
1995-01-01
Here, the calculation of the magnetic field on board ships is performed, using matrix calculus, in a similar way as when the magnetic field in matter is studied. Thus the final formulas are written in a more compact form and they are obtained through a simpler way, more suitable for the university education. (Author)
Magnetic field line Hamiltonian
International Nuclear Information System (INIS)
Boozer, A.H.
1984-03-01
The magnetic field line Hamiltonian and the associated canonical form for the magnetic field are important concepts both for understanding toroidal plasma physics and for practical calculations. A number of important properties of the canonical or Hamiltonian representation are derived and their importance is explained
Bychkov, V. D.; Bychkova, L. V.; Madej, J.
2008-01-01
Now it is known about 1212 stars of the main sequence and giants (from them 610 stars - it is chemically peculiarity (CP) stars) for which direct measurements of magnetic fields were spent (Bychkov et al.,2008). Let's consider, what representations were generated about magnetic fields (MT) of stars on the basis of available observations data.
Controlling magnetic field profiles
International Nuclear Information System (INIS)
Freeman, J.R.
1979-04-01
A method for designing solenoid magnets with controlled field profiles is discussed. The method, originated by D.B. Montgomery, minimizes both the field errors and the power consumption. An NOS time-sharing computer program for the CDC-6600, entitled MAGCOR, was constructed to provide an interactive magnet design capability. Results obtained during the design of magnets for a radial line electron accelerator are presented. 9 figures
Determination of key parameters of vector multifractal vector fields
Schertzer, D. J. M.; Tchiguirinskaia, I.
2017-12-01
For too long time, multifractal analyses and simulations have been restricted to scalar-valued fields (Schertzer and Tchiguirinskaia, 2017a,b). For instance, the wind velocity multifractality has been mostly analysed in terms of scalar structure functions and with the scalar energy flux. This restriction has had the unfortunate consequences that multifractals were applicable to their full extent in geophysics, whereas it has inspired them. Indeed a key question in geophysics is the complexity of the interactions between various fields or they components. Nevertheless, sophisticated methods have been developed to determine the key parameters of scalar valued fields. In this communication, we first present the vector extensions of the universal multifractal analysis techniques to multifractals whose generator belong to a Levy-Clifford algebra (Schertzer and Tchiguirinskaia, 2015). We point out further extensions noting the increased complexity. For instance, the (scalar) index of multifractality becomes a matrice. Schertzer, D. and Tchiguirinskaia, I. (2015) `Multifractal vector fields and stochastic Clifford algebra', Chaos: An Interdisciplinary Journal of Nonlinear Science, 25(12), p. 123127. doi: 10.1063/1.4937364. Schertzer, D. and Tchiguirinskaia, I. (2017) `An Introduction to Multifractals and Scale Symmetry Groups', in Ghanbarian, B. and Hunt, A. (eds) Fractals: Concepts and Applications in Geosciences. CRC Press, p. (in press). Schertzer, D. and Tchiguirinskaia, I. (2017b) `Pandora Box of Multifractals: Barely Open ?', in Tsonis, A. A. (ed.) 30 Years of Nonlinear Dynamics in Geophysics. Berlin: Springer, p. (in press).
Optical currents in vector fields
DEFF Research Database (Denmark)
Angelsky, O. V.; Gorsky, M. P.; Maksimyak, P. P.
2011-01-01
The influence of phase relations and the degree of mutual coherence of superimposing waves in the arrangements of twowave superposition on the characteristics of the microparticle's motion has been analyzed. The prospects of studying temporal coherence using the proposed approach are made. For th....... For the first time, we have shown experimentally the possibility of diagnostics the optical currents in liquids caused by polarization characteristics of an optical field alone, using test metallic particles of nanoscale....
The optical analogy for vector fields
Parker, E. N. (Editor)
1991-01-01
This paper develops the optical analogy for a general vector field. The optical analogy allows the examination of certain aspects of a vector field that are not otherwise readily accessible. In particular, in the cases of a stationary Eulerian flow v of an ideal fluid and a magnetostatic field B, the vectors v and B have surface loci in common with their curls. The intrinsic discontinuities around local maxima in absolute values of v and B take the form of vortex sheets and current sheets, respectively, the former playing a fundamental role in the development of hydrodyamic turbulence and the latter playing a major role in heating the X-ray coronas of stars and galaxies.
International Nuclear Information System (INIS)
Ness, N.F.; Acuna, M.H.; Burlaga, L.F.; Connerney, J.E.P.; Lepping, R.P.; Neubauer, F.M.
1989-01-01
The National Aeronautics and Space Administration Goddard Space Flight Center-University of Delaware Bartol Research Institute magnetic field experiment on the Voyager 2 spacecraft discovered a strong and complex intrinsic magnetic field of Neptune and an associated magnetosphere and magnetic tail. A maximum magnetic field of nearly 10,000 nanoteslas (1 nanotesla = 10 -5 gauss) was observed near closest approach, at a distance of 1.18 R N . The planetary magnetic field between 4 and 15 R N can be well represented by an offset tilted magnetic dipole (OTD), displaced from the center of Neptune by the surprisingly large amount of 0.55 R N and inclined by 47 degrees with respect to the rotation axis. Within 4 R N , the magnetic field representation must include localized sources or higher order magnetic multipoles, or both, which are not yet well determined. As the spacecraft exited the magnetosphere, the magnetic tail appeared to be monopolar, and no crossings of an imbedded magnetic field reversal or plasma neutral sheet were observed. The auroral zones are most likely located far from the rotation poles and may have a complicated geometry. The rings and all the known moons of Neptune are imbedded deep inside the magnetosphere, except for Nereid, which is outside when sunward of the planet. The radiation belts will have a complex structure owing to the absorption of energetic particles by the moons and rings of Neptune and losses associated with the significant changes in the diurnally varying magnetosphere configuration. In an astrophysical context, the magnetic field of Neptune, like that of Uranus, may be described as that of an oblique rotator
Polynomial Vector Fields in One Complex Variable
DEFF Research Database (Denmark)
Branner, Bodil
In recent years Adrien Douady was interested in polynomial vector fields, both in relation to iteration theory and as a topic on their own. This talk is based on his work with Pierrette Sentenac, work of Xavier Buff and Tan Lei, and my own joint work with Kealey Dias.......In recent years Adrien Douady was interested in polynomial vector fields, both in relation to iteration theory and as a topic on their own. This talk is based on his work with Pierrette Sentenac, work of Xavier Buff and Tan Lei, and my own joint work with Kealey Dias....
International Nuclear Information System (INIS)
Madsen, M.S.
1989-01-01
The possible role of a large-scale relic magnetic field in the history of the Universe is considered. The perturbation of the cosmic microwave back-ground radiation on large angular scales due to a homogeneous magnetic field is estimated in a simple relativistic model. This allows corresponding limits to be placed on the magnitude of any such large-scale relic magnetic field at the present time. These limits are essentially the strongest which can be set on the largest scales. A corresponding bound is obtained by use of the requirement that the field should not spoil the predictions of primordial nucleosynthesis. It is noted that the existence of large-scale cosmic magnetic fields would circumvent the limits previously set - also on the basis of nucleosynthesis considerations - on the large-scale anisotropy now present in the Universe. (author)
On the non-Gaussian correlation of the primordial curvature perturbation with vector fields
DEFF Research Database (Denmark)
Kumar Jain, Rajeev; Sloth, Martin Snoager
2013-01-01
We compute the three-point cross-correlation function of the primordial curvature perturbation generated during inflation with two powers of a vector field in a model where conformal invariance is broken by a direct coupling of the vector field with the inflaton. If the vector field is identified...... with the electromagnetic field, this correlation would be a non-Gaussian signature of primordial magnetic fields generated during inflation. We find that the signal is maximized for the flattened configuration where the wave number of the curvature perturbation is twice that of the vector field and in this limit...
Circular Conditional Autoregressive Modeling of Vector Fields.
Modlin, Danny; Fuentes, Montse; Reich, Brian
2012-02-01
As hurricanes approach landfall, there are several hazards for which coastal populations must be prepared. Damaging winds, torrential rains, and tornadoes play havoc with both the coast and inland areas; but, the biggest seaside menace to life and property is the storm surge. Wind fields are used as the primary forcing for the numerical forecasts of the coastal ocean response to hurricane force winds, such as the height of the storm surge and the degree of coastal flooding. Unfortunately, developments in deterministic modeling of these forcings have been hindered by computational expenses. In this paper, we present a multivariate spatial model for vector fields, that we apply to hurricane winds. We parameterize the wind vector at each site in polar coordinates and specify a circular conditional autoregressive (CCAR) model for the vector direction, and a spatial CAR model for speed. We apply our framework for vector fields to hurricane surface wind fields for Hurricane Floyd of 1999 and compare our CCAR model to prior methods that decompose wind speed and direction into its N-S and W-E cardinal components.
Linearization of germs of hyperbolic vector fields
Bonckaert, P; Naudot, [No Value; Yang, JZ
2003-01-01
We develop a normal form to express asymptotically a conjugacy between a germ of resonant vector field and its linear part. We show that such an asymptotic expression can be written in terms of functions of the Logarithmic Mourtada type. To cite this article: P Bonckaert et al., C. R. Acad. Sci.
Null vectors in superconformal quantum field theory
International Nuclear Information System (INIS)
Huang Chaoshang
1993-01-01
The superspace formulation of the N=1 superconformal field theory and superconformal Ward identities are used to give a precise definition of fusion. Using the fusion procedure, superconformally covariant differential equations are derived and consequently a complete and straightforward algorithm for finding null vectors in Verma modules of the Neveu-Schwarz algebra is given. (orig.)
Normal equivariant forms of vector fields
International Nuclear Information System (INIS)
Sanchez Bringas, F.
1992-07-01
We prove a theorem of linearization of type Siegel and a theorem of normal forms of type Poincare-Dulac for germs of holomorphic vector fields in the origin of C 2 , Γ -equivariants, where Γ is a finite subgroup of GL (2,C). (author). 5 refs
Magnetic field dosimeter development
International Nuclear Information System (INIS)
Lemon, D.K.; Skorpik, J.R.; Eick, J.L.
1980-09-01
In recent years there has been increased concern over potential health hazards related to exposure of personnel to magnetic fields. If exposure standards are to be established, then a means for measuring magnetic field dose must be available. To meet this need, the Department of Energy has funded development of prototype dosimeters at the Battelle Pacific Northwest Laboratory. This manual reviews the principle of operation of the dosimeter and also contains step-by-step instructions for its operation
Screening vector field modifications of general relativity
International Nuclear Information System (INIS)
Beltrán Jiménez, Jose; Delvas Fróes, André Luís; Mota, David F.
2013-01-01
A screening mechanism for conformal vector–tensor modifications of general relativity is proposed. The conformal factor depends on the norm of the vector field and makes the field to vanish in high dense regions, whereas drives it to a non-null value in low density environments. Such process occurs due to a spontaneous symmetry breaking mechanism and gives rise to both the screening of fifth forces as well as Lorentz violations. The cosmology and local constraints are also computed
International Nuclear Information System (INIS)
Adly, A.A.; Davino, D.; Visone, C.
2006-01-01
Materials exhibiting gigantic magnetostriction and magnetic shape memory are currently being widely used in various applications. Recently, an approach based on simulating 1-D magnetostriction using 2-D anisotropic Preisach-type models has been introduced. The purpose of this paper is to present a detailed formulation and quantitative assessment for the simulation of field effects on the mechanical hysteresis of Terfenol rods and magnetic shape memory materials using this recently proposed model. Details of the model formulation, identification procedure and experimental testing are given in the paper
``Massless'' vector field in de Sitter universe
Garidi, T.; Gazeau, J.-P.; Rouhani, S.; Takook, M. V.
2008-03-01
We proceed to the quantization of the massless vector field in the de Sitter (dS) space. This work is the natural continuation of a previous article devoted to the quantization of the dS massive vector field [J. P. Gazeau and M. V. Takook, J. Math. Phys. 41, 5920 (2000); T. Garidi et al., ibid. 43, 6379 (2002).] The term ``massless'' is used by reference to conformal invariance and propagation on the dS lightcone whereas ``massive'' refers to those dS fields which unambiguously contract to Minkowskian massive fields at zero curvature. Due to the combined occurrences of gauge invariance and indefinite metric, the covariant quantization of the massless vector field requires an indecomposable representation of the de Sitter group. We work with the gauge fixing corresponding to the simplest Gupta-Bleuler structure. The field operator is defined with the help of coordinate-independent de Sitter waves (the modes). The latter are simple to manipulate and most adapted to group theoretical approaches. The physical states characterized by the divergencelessness condition are, for instance, easy to identify. The whole construction is based on analyticity requirements in the complexified pseudo-Riemannian manifold for the modes and the two-point function.
''Massless'' vector field in de Sitter universe
International Nuclear Information System (INIS)
Garidi, T.; Gazeau, J.-P.; Rouhani, S.; Takook, M. V.
2008-01-01
We proceed to the quantization of the massless vector field in the de Sitter (dS) space. This work is the natural continuation of a previous article devoted to the quantization of the dS massive vector field [J. P. Gazeau and M. V. Takook, J. Math. Phys. 41, 5920 (2000); T. Garidi et al., ibid. 43, 6379 (2002).] The term ''massless'' is used by reference to conformal invariance and propagation on the dS lightcone whereas ''massive'' refers to those dS fields which unambiguously contract to Minkowskian massive fields at zero curvature. Due to the combined occurrences of gauge invariance and indefinite metric, the covariant quantization of the massless vector field requires an indecomposable representation of the de Sitter group. We work with the gauge fixing corresponding to the simplest Gupta-Bleuler structure. The field operator is defined with the help of coordinate-independent de Sitter waves (the modes). The latter are simple to manipulate and most adapted to group theoretical approaches. The physical states characterized by the divergencelessness condition are, for instance, easy to identify. The whole construction is based on analyticity requirements in the complexified pseudo-Riemannian manifold for the modes and the two-point function
In situ preparation of magnetic nonviral gene vectors and magnetofection in vitro
International Nuclear Information System (INIS)
Shi Yunfeng; Pang Yan; Su Yue; Zhu Xinyuan; Yan Deyue; Zhou Linzhu; Xiao Wangchuan; Wang Xiaoliang; Gu Hongchen; Wang Ruibin; Li Huiqin; Zhu Bangshang
2010-01-01
Magnetic nonviral gene vectors were in situ prepared in the presence of ferrous salts and hyperbranched poly(ethylenimine)s (HPEI) with different molecular weights. HPEI, one of the most promising nonviral vectors, was not only utilized as the nanoreactor and stabilizer to prepare magnetic nanoparticles, but also skillfully used as a base supplier to avoid introducing alkali hydroxide or ammonia. Magnetic nonviral gene vectors with various magnetite contents and saturation magnetizations were obtained by changing the weight ratio of HPEI to FeSO 4 ·7H 2 O and the molecular weight of HPEI. MTT assays suggested that the resulting magnetite/HPEI gene vectors had lower cytotoxicity compared with pure HPEI. The magnetite/HPEI nonviral gene vectors were used for magnetofection. It was found that the luciferase expression level mediated by magnetite/HPEI in COS-7 cells under a magnetic gradient field was approximately 13-fold greater than that of standard HPEI transfection.
Transient anisotropic magnetic field calculation
International Nuclear Information System (INIS)
Jesenik, Marko; Gorican, Viktor; Trlep, Mladen; Hamler, Anton; Stumberger, Bojan
2006-01-01
For anisotropic magnetic material, nonlinear magnetic characteristics of the material are described with magnetization curves for different magnetization directions. The paper presents transient finite element calculation of the magnetic field in the anisotropic magnetic material based on the measured magnetization curves for different magnetization directions. For the verification of the calculation method some results of the calculation are compared with the measurement
Perturbations of ultralight vector field dark matter
Energy Technology Data Exchange (ETDEWEB)
Cembranos, J.A.R.; Maroto, A.L.; Jareño, S.J. Núñez [Departamento de Física Teórica I, Universidad Complutense de Madrid, E-28040 Madrid (Spain)
2017-02-13
We study the dynamics of cosmological perturbations in models of dark matter based on ultralight coherent vector fields. Very much as for scalar field dark matter, we find two different regimes in the evolution: for modes with k{sup 2}≪Hma, we have a particle-like behaviour indistinguishable from cold dark matter, whereas for modes with k{sup 2}≫Hma, we get a wave-like behaviour in which the sound speed is non-vanishing and of order c{sub s}{sup 2}≃k{sup 2}/m{sup 2}a{sup 2}. This implies that, also in these models, structure formation could be suppressed on small scales. However, unlike the scalar case, the fact that the background evolution contains a non-vanishing homogeneous vector field implies that, in general, the evolution of the three kinds of perturbations (scalar, vector and tensor) can no longer be decoupled at the linear level. More specifically, in the particle regime, the three types of perturbations are actually decoupled, whereas in the wave regime, the three vector field perturbations generate one scalar-tensor and two vector-tensor perturbations in the metric. Also in the wave regime, we find that a non-vanishing anisotropic stress is present in the perturbed energy-momentum tensor giving rise to a gravitational slip of order (Φ−Ψ)/Φ∼c{sub s}{sup 2}. Moreover in this regime the amplitude of the tensor to scalar ratio of the scalar-tensor modes is also h/Φ∼c{sub s}{sup 2}. This implies that small-scale density perturbations are necessarily associated to the presence of gravity waves in this model. We compare their spectrum with the sensitivity of present and future gravity waves detectors.
Properties of invariant modelling and invariant glueing of vector fields
International Nuclear Information System (INIS)
Petukhov, V.R.
1987-01-01
Invariant modelling and invariant glueing of both continuous (rates and accelerations) and descrete vector fields, gradient and divergence cases are considered. The following appendices are discussed: vector fields in crystals, crystal disclinations, topological charges and their fields
Antisymmetric tensor generalizations of affine vector fields.
Houri, Tsuyoshi; Morisawa, Yoshiyuki; Tomoda, Kentaro
2016-02-01
Tensor generalizations of affine vector fields called symmetric and antisymmetric affine tensor fields are discussed as symmetry of spacetimes. We review the properties of the symmetric ones, which have been studied in earlier works, and investigate the properties of the antisymmetric ones, which are the main theme in this paper. It is shown that antisymmetric affine tensor fields are closely related to one-lower-rank antisymmetric tensor fields which are parallelly transported along geodesics. It is also shown that the number of linear independent rank- p antisymmetric affine tensor fields in n -dimensions is bounded by ( n + 1)!/ p !( n - p )!. We also derive the integrability conditions for antisymmetric affine tensor fields. Using the integrability conditions, we discuss the existence of antisymmetric affine tensor fields on various spacetimes.
Multifractal vector fields and stochastic Clifford algebra.
Schertzer, Daniel; Tchiguirinskaia, Ioulia
2015-12-01
In the mid 1980s, the development of multifractal concepts and techniques was an important breakthrough for complex system analysis and simulation, in particular, in turbulence and hydrology. Multifractals indeed aimed to track and simulate the scaling singularities of the underlying equations instead of relying on numerical, scale truncated simulations or on simplified conceptual models. However, this development has been rather limited to deal with scalar fields, whereas most of the fields of interest are vector-valued or even manifold-valued. We show in this paper that the combination of stable Lévy processes with Clifford algebra is a good candidate to bridge up the present gap between theory and applications. We show that it indeed defines a convenient framework to generate multifractal vector fields, possibly multifractal manifold-valued fields, based on a few fundamental and complementary properties of Lévy processes and Clifford algebra. In particular, the vector structure of these algebra is much more tractable than the manifold structure of symmetry groups while the Lévy stability grants a given statistical universality.
Multifractal vector fields and stochastic Clifford algebra
Energy Technology Data Exchange (ETDEWEB)
Schertzer, Daniel, E-mail: Daniel.Schertzer@enpc.fr; Tchiguirinskaia, Ioulia, E-mail: Ioulia.Tchiguirinskaia@enpc.fr [University Paris-Est, Ecole des Ponts ParisTech, Hydrology Meteorology and Complexity HM& Co, Marne-la-Vallée (France)
2015-12-15
In the mid 1980s, the development of multifractal concepts and techniques was an important breakthrough for complex system analysis and simulation, in particular, in turbulence and hydrology. Multifractals indeed aimed to track and simulate the scaling singularities of the underlying equations instead of relying on numerical, scale truncated simulations or on simplified conceptual models. However, this development has been rather limited to deal with scalar fields, whereas most of the fields of interest are vector-valued or even manifold-valued. We show in this paper that the combination of stable Lévy processes with Clifford algebra is a good candidate to bridge up the present gap between theory and applications. We show that it indeed defines a convenient framework to generate multifractal vector fields, possibly multifractal manifold-valued fields, based on a few fundamental and complementary properties of Lévy processes and Clifford algebra. In particular, the vector structure of these algebra is much more tractable than the manifold structure of symmetry groups while the Lévy stability grants a given statistical universality.
Biotropic parameters of magnetic fields
Energy Technology Data Exchange (ETDEWEB)
Shishlo, M.A.
The use of magnetic fields (MF) in biology and medicine to control biological systems has led to appearance of the term, biotropic parameters of MF. They include the physical characteristics of MF, which determine the primary biologically significant physicochemical mechanisms of field action causing formation of corresponding reactions on the level of the integral organism. These parameters include MF intensity, gradient, vector, pulse frequency and shape, and duration of exposure. Factors that elicit responses by the biological system include such parameter of MF interaction with the integral organism as localization of exposure and volume of tissues interacting with the field, as well as the initial state of the organism. In essence, the findings of experimental studies of biotropic parameters of MF make it possible to control physiological processes and will aid in optimizing methods of MF therapy.
A vector model for off-axis hysteresis loops using anisotropy field
International Nuclear Information System (INIS)
Jamali, Ali; Torre, Edward Della; Cardelli, Ermanno; ElBidweihy, Hatem; Bennett, Lawrence H.
2016-01-01
A model for the off-axis vector magnetization of a distribution of uniaxial particles is presented. Recent work by the authors decomposed the magnetization into two components and modeled the total vector magnetization as their vector sum. In this paper, to account for anisotropy, the direction of the reversible magnetization component is specified by the vector sum of the applied field and an effective anisotropy field. The formulation of the new anisotropy field (AF) model is derived and its results are discussed considering (i) oscillation and rotational modes, (ii) lag angle, and (iii) unitary magnetization. The advantages of the AF model are outlined by comparing its results to the results of the classical Stoner–Wohlfarth model.
A vector model for off-axis hysteresis loops using anisotropy field
Energy Technology Data Exchange (ETDEWEB)
Jamali, Ali, E-mail: alijamal@gwu.edu [Electrical and Computer Engineering Department, The George Washington University, Washington, D.C. 20052 (United States); Torre, Edward Della [Electrical and Computer Engineering Department, The George Washington University, Washington, D.C. 20052 (United States); Cardelli, Ermanno [Department of Engineering, University of Perugia, Perugia (Italy); ElBidweihy, Hatem [Electrical and Computer Engineering Department, United States Naval Academy, Annapolis, MD 21402 (United States); Bennett, Lawrence H. [Electrical and Computer Engineering Department, The George Washington University, Washington, D.C. 20052 (United States)
2016-11-15
A model for the off-axis vector magnetization of a distribution of uniaxial particles is presented. Recent work by the authors decomposed the magnetization into two components and modeled the total vector magnetization as their vector sum. In this paper, to account for anisotropy, the direction of the reversible magnetization component is specified by the vector sum of the applied field and an effective anisotropy field. The formulation of the new anisotropy field (AF) model is derived and its results are discussed considering (i) oscillation and rotational modes, (ii) lag angle, and (iii) unitary magnetization. The advantages of the AF model are outlined by comparing its results to the results of the classical Stoner–Wohlfarth model.
1983-01-01
There were 37 (normal) + 3 (special) Radial Field magnets in the ISR to adjust vertically the closed orbit. Gap heights and strengths were 200 mm and .12 Tm in the normal magnets, 220 mm and .18 Tm in the special ones. The core length was 430 mm in both types. Due to their small length as compared to the gap heights the end fringe field errors were very important and had to be compensated by suitably shaping the poles. In order to save on cables, as these magnets were located very far from their power supplies, the coils of the normal type magnets were formed by many turns of solid cpper conductor with some interleaved layers of hollow conductor directly cooled by circulating water
Efficient morse decompositions of vector fields.
Chen, Guoning; Mischaikow, Konstantin; Laramee, Robert S; Zhang, Eugene
2008-01-01
Existing topology-based vector field analysis techniques rely on the ability to extract the individual trajectories such as fixed points, periodic orbits, and separatrices that are sensitive to noise and errors introduced by simulation and interpolation. This can make such vector field analysis unsuitable for rigorous interpretations. We advocate the use of Morse decompositions, which are robust with respect to perturbations, to encode the topological structures of a vector field in the form of a directed graph, called a Morse connection graph (MCG). While an MCG exists for every vector field, it need not be unique. Previous techniques for computing MCG's, while fast, are overly conservative and usually results in MCG's that are too coarse to be useful for the applications. To address this issue, we present a new technique for performing Morse decomposition based on the concept of tau-maps, which typically provides finer MCG's than existing techniques. Furthermore, the choice of tau provides a natural tradeoff between the fineness of the MCG's and the computational costs. We provide efficient implementations of Morse decomposition based on tau-maps, which include the use of forward and backward mapping techniques and an adaptive approach in constructing better approximations of the images of the triangles in the meshes used for simulation.. Furthermore, we propose the use of spatial tau-maps in addition to the original temporal tau-maps. These techniques provide additional trade-offs between the quality of the MCGs and the speed of computation. We demonstrate the utility of our technique with various examples in the plane and on surfaces including engine simulation data sets.
Kronberg, Philipp P
2016-01-01
Magnetic fields are important in the Universe and their effects contain the key to many astrophysical phenomena that are otherwise impossible to understand. This book presents an up-to-date overview of this fast-growing topic and its interconnections to plasma processes, astroparticle physics, high energy astrophysics, and cosmic evolution. The phenomenology and impact of magnetic fields are described in diverse astrophysical contexts within the Universe, from galaxies to the filaments and voids of the intergalactic medium, and out to the largest redshifts. The presentation of mathematical formulae is accessible and is designed to add insight into the broad range of topics discussed. Written for graduate students and researchers in astrophysics and related disciplines, this volume will inspire readers to devise new ways of thinking about magnetic fields in space on galaxy scales and beyond.
How the geomagnetic field vector reverses polarity
Prevot, M.; Mankinen, E.A.; Gromme, C.S.; Coe, R.S.
1985-01-01
A highly detailed record of both the direction and intensity of the Earth's magnetic field as it reverses has been obtained from a Miocene volcanic sequence. The transitional field is low in intensity and is typically non-axisymmetric. Geomagnetic impulses corresponding to astonishingly high rates of change of the field sometimes occur, suggesting that liquid velocity within the Earth's core increases during geomagnetic reversals. ?? 1985 Nature Publishing Group.
Gauge structure of neutral-vector field theory. [Massive vector fields, massless limits
Energy Technology Data Exchange (ETDEWEB)
Kubo, R; Yokoyama, [Hiroshima univ., Takehara (Japan). Research Inst. for Theoretical Physics
1975-03-01
General aspects of gauge structure of neutral-vector field theory are investigated from an extended standpoint, where massive vector fields are treated in a form corresponding to the electromagnetic fields in a general gauge formalism reported previously. All results obtained are shown to have unique massless limits. It is shown that a generalized q-number gauge transformation for fields makes the theory invariant in cooperation with a simultaneous transformation for relevant gauge parameters. A method of differentiation with respect to a gauge variable is found to clarify some essential features of the gauge structure. Two possible types of gauge structure also emerge correspondingly to the massless case. A neutral-vector field theory proposed in a preceding paper is included in the present framework as the most preferable case.
Spline techniques for magnetic fields
International Nuclear Information System (INIS)
Aspinall, J.G.
1984-01-01
This report is an overview of B-spline techniques, oriented toward magnetic field computation. These techniques form a powerful mathematical approximating method for many physics and engineering calculations. In section 1, the concept of a polynomial spline is introduced. Section 2 shows how a particular spline with well chosen properties, the B-spline, can be used to build any spline. In section 3, the description of how to solve a simple spline approximation problem is completed, and some practical examples of using splines are shown. All these sections deal exclusively in scalar functions of one variable for simplicity. Section 4 is partly digression. Techniques that are not B-spline techniques, but are closely related, are covered. These methods are not needed for what follows, until the last section on errors. Sections 5, 6, and 7 form a second group which work toward the final goal of using B-splines to approximate a magnetic field. Section 5 demonstrates how to approximate a scalar function of many variables. The necessary mathematics is completed in section 6, where the problems of approximating a vector function in general, and a magnetic field in particular, are examined. Finally some algorithms and data organization are shown in section 7. Section 8 deals with error analysis
High field superconducting magnets
Hait, Thomas P. (Inventor); Shirron, Peter J. (Inventor)
2011-01-01
A superconducting magnet includes an insulating layer disposed about the surface of a mandrel; a superconducting wire wound in adjacent turns about the mandrel to form the superconducting magnet, wherein the superconducting wire is in thermal communication with the mandrel, and the superconducting magnet has a field-to-current ratio equal to or greater than 1.1 Tesla per Ampere; a thermally conductive potting material configured to fill interstices between the adjacent turns, wherein the thermally conductive potting material and the superconducting wire provide a path for dissipation of heat; and a voltage limiting device disposed across each end of the superconducting wire, wherein the voltage limiting device is configured to prevent a voltage excursion across the superconducting wire during quench of the superconducting magnet.
Nuclear magnetic resonance and earth magnetic field
International Nuclear Information System (INIS)
Anon.
1998-01-01
Nuclear magnetic resonance concerns nuclei whose spin is different from 0. These nuclei exposed to a magnetic field is comparable to a peg top spinning around its axis while being moved by a precession movement called Larmor precession. This article presents an experiment whose aim is to reveal nuclear magnetism of nuclei by observing Larmor precession phenomena due to the earth magnetic field. The earth magnetic field being too weak, it is necessary to increase the magnetization of the sample during a polarization phase. First the sample is submitted to a magnetic field B perpendicular to the earth magnetic field B 0 , then B is cut off and the nuclei move back to their equilibrium position by executing a precession movement due to B 0 field. (A.C.)
International Nuclear Information System (INIS)
Jackson, D.J.; Beard, D.B.
1977-01-01
The geomagnetic field, suitably scaled down and parameterized, is shown to give a very good fit to the magnetic field measurements taken on the first and third passes of the Mariner 10 space probe past Mercury. The excellence of the fit to a reliable planetary magnetospheric model is good evidence that the Mercury magnetosphere is formed by a simple, permanent, intrinsic planetary magnetic field distorted by the effects of the solar wind. The parameters used for a best fit to all the data are (depending slightly on the choice of data) 2.44--2.55 for the ratio of Mercury's magnetic field strength at the subsolar point to that of the earth's subsolar point field (this results in a dipole moment of 170 γR/sub M/ 3 (R/sub M/ is Mercury Radius), i.e., 2.41 x 10 22 G cm 3 in the same direction as the earth's dipole), approx.-113 γR/sub M/ 4 for the planetary quadrupole moment parallel to the dipole moment, 10degree--17degree for the tilt of the planet dipole toward the sun, 4.5degree for the tilt of the dipole toward dawn, and 2.5degree--7.6degree aberration angle for the shift in the tail axis from the planet-sun direction because of the planet's orbital velocity. The rms deviation overall for the entire data set compared with the theoretical fitted model for the magnetic field strength was 17 γ (approx.4% of the maximum field measured). If the data from the first pass that show presumed strong time variations are excluded, the overall rms deviation for the field magnitude is only 10 γ
On Discrete Killing Vector Fields and Patterns on Surfaces
Ben-Chen, Mirela; Butscher, Adrian; Solomon, Justin; Guibas, Leonidas
2010-01-01
, and show how to discretize these concepts for generating such vector fields on a triangulated mesh. We discuss the properties of approximate Killing Vector Fields, and propose an application to utilize them for texture and geometry synthesis. Journal
Designing magnets with prescribed magnetic fields
International Nuclear Information System (INIS)
Liu Liping
2011-01-01
We present a novel design method capable of finding the magnetization densities that generate prescribed magnetic fields. The method is based on the solution to a simple variational inequality and the resulting designs have simple piecewise-constant magnetization densities. By this method, we obtain new designs of magnets that generate commonly used magnetic fields: uniform magnetic fields, self-shielding fields, quadrupole fields and sextupole fields. Further, it is worth noting that this method is not limited to the presented examples, and in particular, three-dimensional designs can be constructed in a similar manner. In conclusion, this novel design method is anticipated to have broad applications where specific magnetic fields are important for the performance of the devices.
High magnetic field MRI system
International Nuclear Information System (INIS)
Maeda, Hideaki; Urata, Masami; Satoh, Kozo
1990-01-01
A high field superconducting magnet, 4-5 T in central magnetic field, is required for magnetic resonance spectroscopic imaging (MRSI) on 31 P, essential nuclei for energy metabolism of human body. This paper reviews superconducting magnets for high field MRSI systems. Examples of the cross-sectional image and the spectrum of living animals are shown in the paper. (author)
Vertical gradients of sunspot magnetic fields
Hagyard, M. J.; Teuber, D.; West, E. A.; Tandberg-Hanssen, E.; Henze, W., Jr.; Beckers, J. M.; Bruner, M.; Hyder, C. L.; Woodgate, B. E.
1983-01-01
The results of a Solar Maximum Mission (SMM) guest investigation to determine the vertical gradients of sunspot magnetic fields for the first time from coordinated observations of photospheric and transition-region fields are described. Descriptions are given of both the photospheric vector field of a sunspot, derived from observations using the NASA Marshall Space Flight Center vector magnetograph, and of the line-of-sight component in the transition region, obtained from the SMM Ultraviolet Spectrometer and Polarimeter instrument. On the basis of these data, vertical gradients of the line-of-sight magnetic field component are calculated using three methods. It is found that the vertical gradient of Bz is lower than values from previous studies and that the transition-region field occurs at a height of approximately 4000-6000 km above the photosphere.
Conformal Vector Fields on Doubly Warped Product Manifolds and Applications
Directory of Open Access Journals (Sweden)
H. K. El-Sayied
2016-01-01
Full Text Available This article aimed to study and explore conformal vector fields on doubly warped product manifolds as well as on doubly warped spacetime. Then we derive sufficient conditions for matter and Ricci collineations on doubly warped product manifolds. A special attention is paid to concurrent vector fields. Finally, Ricci solitons on doubly warped product spacetime admitting conformal vector fields are considered.
n-Characteristic Vector Fields of Contact Manifoldss
Hassanzadeh, Babak
2017-01-01
In present paper we define and study $n$-characteristic vector fields. We present definition of Tanaka-Webster connection, then use it for studying the behavior of $n$-characteristic vector fields. Also we show some results about of these vector fields by Tanaka-Webster connection.
Surface magnetic field measurement with magnetic shielding
Czech Academy of Sciences Publication Activity Database
Perevertov, Oleksiy
2010-01-01
Roč. 61, č. 7 (2010), 66-68 ISSN 1335-3632 Grant - others:AVČR(CZ) M100100906 Institutional research plan: CEZ:AV0Z10100520 Keywords : magnetic hysteresis * magnetic field measurement * magnetic shielding * extrapolation Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.270, year: 2010
An evaluation of Tsyganenko magnetic field model
International Nuclear Information System (INIS)
Fairfield, D.H.
1991-01-01
A long-standing goal of magnetospheric physics has been to produce a model of the Earth's magnetic field that can accurately predict the field vector at all locations within the magnetosphere for all dipole tilt angles and for various solar wind or magnetic activity conditions. A number of models make such predictions, but some only for limited spatial regions, some only for zero tilt angle, and some only for arbitrary conditions. No models depend explicitly on solar wind conditions. A data set of more than 22,000 vector averages of the magnetosphere magnetic field over 0.5 R E regions is used to evaluate Tsyganenko's 1982 and 1987 magnetospheric magnetic field models. The magnetic field predicted by the model in various regions is compared to observations to find systematic discrepancies which future models might address. While agreement is generally good, discrepancies are noted which include: (1) a lack of adequate field line stretching in the tail and ring current regions; (2) an inability to predict weak enough fields in the polar cusps; and (3) a deficiency of Kp as a predictor of the field configuration
International Nuclear Information System (INIS)
Merrill, R.T.
1983-01-01
After a historical introduction in Chapter 1, the more traditional aspects of geomagnetism relating to the present field and historical observations are presented in Chapter 2. The various methods and techniques and theoretical background of palaeomagnetism are given in Chapter 3. Chapters 4, 5 and 6 present the results of palaeomagnetic and archaeomagnetic studies in three topics. Chapter 4 relates to studies of the geomagnetic field roughly back to about 50,000 years ago. Chapter 5 is about reversals of the geomagnetic field and Chapter 6 presents studies of the field for times older than 50,000 years and on the geological time scale of millions or hundreds of millions of years. Chapters 7, 8 and 9 provide insight into dynamo theory. Chapter 7 is essentially a non-mathematical attempt to explain the physical basis of dynamo theories to palaeomagnetists. This is followed in Chapter 8 by a more advanced theoretical treatment. Chapter 9 explains theoretical aspects of secular variation and the origin of reversals of the geomagnetic field. Chapter 10 is our attempt to relate theory to experiment and vice versa. The final two chapters consider the magnetic fields of the moon, sun, planets and meteorites, in an attempt to determine the necessary and sufficient conditions for magnetic field generation in large solar system bodies. (author)
The magnetic universe through vector potential SPMHD simulations
Stasyszyn, F. A.
2017-10-01
The use of Smoothed Particle Magneto Hydrodynamics (SPMHD) is getting nowadays more and more common in Astrophysics. From galaxy clusters to neutron starts, there are multiple applications already existing in the literature. I will review some of the common methods used and highlight the successful approach of using vector potentials to describe the evolution of the magnetic fields. The latter have some interesting advantages, and their results challenge previous findings, being the magnetic divergence problem naturally vanished. We select a few examples to discuss some areas of interest. First, we show some Galaxy Clusters from the MUSIC project. These cosmological simulations are done with the usual sub-grid recipes, as radiative cooling and star formation, being the first ones obtained with an SPH code in a self consistent way. This demonstrates the robustness of the new method in a variety of astrophysical scenarios.
Xu, Danfeng; Gu, Bing; Rui, Guanghao; Zhan, Qiwen; Cui, Yiping
2016-02-22
We present an arbitrary vector field with hybrid polarization based on the combination of a pair of orthogonal elliptically polarized base vectors on the Poincaré sphere. It is shown that the created vector field is only dependent on the latitude angle 2χ but is independent on the longitude angle 2ψ on the Poincaré sphere. By adjusting the latitude angle 2χ, which is related to two identical waveplates in a common path interferometric arrangement, one could obtain arbitrary type of vector fields. Experimentally, we demonstrate the generation of such kind of vector fields and confirm the distribution of state of polarization by the measurement of Stokes parameters. Besides, we investigate the tight focusing properties of these vector fields. It is found that the additional degree of freedom 2χ provided by arbitrary vector field with hybrid polarization allows one to control the spatial structure of polarization and to engineer the focusing field.
Magnetic field in the magnetosphere. Numerical simulation of the magnetospheric magnetic field
International Nuclear Information System (INIS)
Mal'kov, M.V.
1993-01-01
The last version of the empirical model of the magnetospheric magnetic field (Tsyganenko, 1989) is considered. Total number of data used for construction of the model contains 36682 average vector values of the field. This number of data is obtained by satellite measurements at distances of r=4-66 R e (R e is the Earth radius). 5 figs., 2 tabs
International Nuclear Information System (INIS)
Maeda, Yoshitaka; Todaka, Takashi; Shimoji, Hiroyasu; Enokizono, Masato; Sievert, Johanes
2006-01-01
Recently, two-dimensional vector magnetic measurement has become popular and many researchers concerned with this field have attracted to develop more accurate measuring systems and standard measurement systems. Because the two-dimensional vector magnetic property is the relationship between the magnetic flux density vector B and the magnetic field strength vector H , the most important parameter is those components. For the accurate measurement of the field strength vector, we have developed an evaluation apparatus, which consists of a standard solenoid coil and a high-precision turntable. Angle errors of a double H-coil (a cross-type H-coil), which is wound one after the other around a former, can be evaluated with this apparatus. The magnetic field strength is compensated with the measured angle error
International Nuclear Information System (INIS)
Mansfield, P.; Turner, R.; Chapman, B.L.W.; Bowley, R.M.
1990-01-01
A screen for a magnetic coil, for producing, for example, a homogeneous, gradient or RF field in nuclear magnetic resonance imaging, is described. It is provided by surround the coil with a set of electrical conductors. The currents within the conductors are controlled in such a manner that the field is neutralised in a specific region of space. The current distribution within the conductors is determined by calculating the current within a hypothetical superconductive shield which would have the effect of neutralising the field, the current through the conductors thereby being a substitute for the superconductive shield. The conductors may be evenly spaced and connected in parallel, their resistances being determined by thickness or composition to provide the desired current, or they may carry equal currents but be differently spaced. A further set or sets of controlled conductors outside the first set may ensure that the first set does not upset the field from the NMR coil. The shield may selectively reflect certain fields while transmitting others and may prevent acoustic vibration e.g. when switching gradient fields. An RF coil arrangement may consist of two orthogonal coils, one coil within the other for use as a transmit/receive set or as a double resonance transmitter; a shield between the coils is in series with, and formed from the same winding as, the inner coil. (author)
Magnetic fields in diffuse media
Pino, Elisabete; Melioli, Claudio
2015-01-01
This volume presents the current knowledge of magnetic fields in diffuse astrophysical media. Starting with an overview of 21st century instrumentation to observe astrophysical magnetic fields, the chapters cover observational techniques, origin of magnetic fields, magnetic turbulence, basic processes in magnetized fluids, the role of magnetic fields for cosmic rays, in the interstellar medium and for star formation. Written by a group of leading experts the book represents an excellent overview of the field. Nonspecialists will find sufficient background to enter the field and be able to appreciate the state of the art.
Jabbari, Ali
2018-01-01
Surface inset permanent magnet DC machine can be used as an alternative in automation systems due to their high efficiency and robustness. Magnet segmentation is a common technique in order to mitigate pulsating torque components in permanent magnet machines. An accurate computation of air-gap magnetic field distribution is necessary in order to calculate machine performance. An exact analytical method for magnetic vector potential calculation in surface inset permanent magnet machines considering magnet segmentation has been proposed in this paper. The analytical method is based on the resolution of Laplace and Poisson equations as well as Maxwell equation in polar coordinate by using sub-domain method. One of the main contributions of the paper is to derive an expression for the magnetic vector potential in the segmented PM region by using hyperbolic functions. The developed method is applied on the performance computation of two prototype surface inset magnet segmented motors with open circuit and on load conditions. The results of these models are validated through FEM method.
Dependence of the amount of open magnetic flux on the direction of the interplanetary magnetic field
International Nuclear Information System (INIS)
Akasofu, S.I.; Ahn, B.H.
1980-01-01
The power generated by the solar wind-magnetosphere dynamo is proportional to the amount of the open magnetic flux phi. It is difficult to use this fact in determining observationally the dependence of phi on the orientation of the interplanetary magnetic field vector. It is shown that, for a simple vacuum superposition of the earth's dipole field and a uniform magnetic field, PHI is very closely proportional to sin(theta/2) for a wide range of the intensity of the uniform field, where theta denotes the polar angle of the interplanetary magnetic field vector in the Y-Z plane of solar-magnetospheric coordinates. (author)
DEFF Research Database (Denmark)
This volume provides a comprehensive view on the different sources of the geomagnetic field both in the Earth’s interior and from the field’s interaction with the terrestrial atmosphere and the solar wind. It combines expertise from various relevant areas of geomagnetic and near Earth space...... research with the aim to better characterise the state and dynamics of Earth’s magnetic field. Advances in the exploitation of geomagnetic observations hold a huge potential not only for an improved quantitative description of the field source but also for a better understanding of the underlying processes...... and space observations, and on state-of-the-art empirical models and physics-based simulations. Thus, it provides an in-depth overview over recent achievements, current limitations and challenges, and future opportunities in the field of geomagnetism and space sciences....
Gauge anomaly with vector and axial-vector fields in 6D curved space
Yajima, Satoshi; Eguchi, Kohei; Fukuda, Makoto; Oka, Tomonori
2018-03-01
Imposing the conservation equation of the vector current for a fermion of spin 1/2 at the quantum level, a gauge anomaly for the fermion coupling with non-Abelian vector and axial-vector fields in 6D curved space is expressed in tensorial form. The anomaly consists of terms that resemble the chiral U(1) anomaly and the commutator terms that disappear if the axial-vector field is Abelian.
Electric control of wave vector filtering in a hybrid magnetic-electric-barrier nanostructure
Kong, Yong-Hong; Lu, Ke-Yu; He, Ya-Ping; Liu, Xu-Hui; Fu, Xi; Li, Ai-Hua
2018-06-01
We theoretically investigate how to manipulate the wave vector filtering effect by a traverse electric field for electrons across a hybrid magnetic-electric-barrier nanostructure, which can be experimentally realized by depositing a ferromagnetic stripe and a Schottky-metal stripe on top and bottom of a GaAs/Al x Ga1- x As heterostructure, respectively. The wave vector filtering effect is found to be related closely to the applied electric field. Moreover, the wave vector filtering efficiency can be manipulated by changing direction or adjusting strength of the traverse electric field. Therefore, such a nanostructure can be employed as an electrically controllable electron-momentum filter for nanoelectronics applications.
Magnetization reversal in ultrashort magnetic field pulses
International Nuclear Information System (INIS)
Bauer, M.; Lopusnik, R.; Fassbender, J.; Hillebrands, B.
2000-01-01
We report the switching properties of a thin magnetic film subject to an ultrashort, laterally localized magnetic field pulse, obtained by numerical investigations. The magnetization distribution in the film is calculated on a grid assuming Stoner-like coherent rotation within the grid square size. Perpendicularly and in-plane magnetized films exhibit a magnetization reversal due to a 4 ps magnetic field pulse. Outside the central region the pulse duration is short compared to the precession period. In this area the evolution of the magnetization during the field pulse does not depend strongly on magnetic damping and/or pulse shape. However, the final magnetization distribution is affected by the magnetic damping. Although the pulse duration is short compared to the precession period, the time needed for the relaxation of the magnetization to the equilibrium state is rather large. The influence of the different magnetic anisotropy contributions and the magnetic damping parameter enters into the magnetization reversal process. Comparing the case of perpendicular anisotropy with different kinds of in-plane anisotropies, a principal difference is found due to the symmetry of the shape anisotropy with respect to the anisotropy in question
Slow decay of magnetic fields in open Friedmann universes
International Nuclear Information System (INIS)
Barrow, John D.; Tsagas, Christos G.
2008-01-01
Magnetic fields in Friedmann universes can experience superadiabatic growth without departing from conventional electromagnetism. The reason is the relativistic coupling between vector fields and spacetime geometry, which slows down the decay of large-scale magnetic fields in open universes, compared to that seen in perfectly flat models. The result is a large relative gain in magnetic strength that can lead to astrophysically interesting B fields, even if our Universe is only marginally open today
Magnetic Field Topology in Jets
Gardiner, T. A.; Frank, A.
2000-01-01
We present results on the magnetic field topology in a pulsed radiative. jet. For initially helical magnetic fields and periodic velocity variations, we find that the magnetic field alternates along the, length of the jet from toroidally dominated in the knots to possibly poloidally dominated in the intervening regions.
Low field magnetic resonance imaging
Pines, Alexander; Sakellariou, Dimitrios; Meriles, Carlos A.; Trabesinger, Andreas H.
2010-07-13
A method and system of magnetic resonance imaging does not need a large homogenous field to truncate a gradient field. Spatial information is encoded into the spin magnetization by allowing the magnetization to evolve in a non-truncated gradient field and inducing a set of 180 degree rotations prior to signal acquisition.
Initial geomagnetic field model from Magsat vector data
Langel, R. A.; Mead, G. D.; Lancaster, E. R.; Estes, R. H.; Fabiano, E. B.
1980-01-01
Magsat data from the magnetically quiet days of November 5-6, 1979, were used to derive a thirteenth degree and order spherical harmonic geomagnetic field model, MGST(6/80). The model utilized both scalar and high-accuracy vector data and fit that data with root-mean-square deviations of 8.2, 6.9, 7.6 and 7.4 nT for the scalar magnitude, B(r), B(theta), and B(phi), respectively. The model includes the three first-order coefficients of the external field. Comparison with averaged Dst indicates that zero Dst corresponds with 25 nT of horizontal field from external sources. When compared with earlier models, the earth's dipole moment continues to decrease at a rate of about 26 nT/yr. Evaluation of earlier models with Magsat data shows that the scalar field at the Magsat epoch is best predicted by the POGO(2/72) model but that the WC80, AWC/75 and IGS/75 are better for predicting vector fields.
Electrically induced magnetic fields; a consistent approach
Batell, Brian; Ferstl, Andrew
2003-09-01
Electromagnetic radiation exists because changing magnetic fields induce changing electric fields and vice versa. This fact often appears inconsistent with the way some physics textbooks solve particular problems using Faraday's law. These types of problems often ask students to find the induced electric field given a current that does not vary linearly with time. A typical example involves a long solenoid carrying a sinusoidal current. This problem is usually solved as an example or assigned as a homework exercise. The solution offered by many textbooks uses the approximation that the induced, changing electric field produces a negligible magnetic field, which is only valid at low frequencies. If this approximation is not explicitly acknowledged, then the solution appears inconsistent with the description of electromagnetic radiation. In other cases, when the problem is solved without this approximation, the electric and magnetic fields are derived from the vector potential. We present a detailed calculation of the electric and magnetic fields inside and outside the long solenoid without using the vector potential. We then offer a comparison of our solution and a solution given in an introductory textbook.
Comments on conformal Killing vector fields and quantum field theory
International Nuclear Information System (INIS)
Brown, M.R.; Ottewill, A.C.; Siklos, S.T.C.
1982-01-01
We give a comprehensive analysis of those vacuums for flat and conformally flat space-times which can be defined by timelike, hypersurface-orthogonal, conformal Killing vector fields. We obtain formulas for the difference in stress-energy density between any two such states and display the correspondence with the renormalized stress tensors. A brief discussion is given of the relevance of these results to quantum-mechanical measurements made by noninertial observers moving through flat space
An educational path for the magnetic vector potential and its physical implications
International Nuclear Information System (INIS)
Barbieri, S; Cavinato, M; Giliberti, M
2013-01-01
We present an educational path for the magnetic vector potential A aimed at undergraduate students and pre-service physics teachers. Starting from the generalized Ampère–Laplace law, in the framework of a slowly varying time-dependent field approximation, the magnetic vector potential is written in terms of its empirical references, i.e. the conduction currents. Therefore, once the currents are known, our approach allows for a clear and univocal physical determination of A, overcoming the mathematical indeterminacy due to the gauge transformations. We have no need to fix a gauge, since for slowly varying time-dependent electric and magnetic fields, the ‘natural’ gauge for A is the Coulomb one. We stress the difference between our approach and those usually presented in the literature. Finally, a physical interpretation of the magnetic vector potential is discussed and some examples of the calculation of A are analysed. (paper)
The Capacitive Magnetic Field Sensor
Zyatkov, D. O.; Yurchenko, A. V.; Balashov, V. B.; Yurchenko, V. I.
2016-01-01
The results of a study of sensitive element magnetic field sensor are represented in this paper. The sensor is based on the change of the capacitance with an active dielectric (ferrofluid) due to the magnitude of magnetic field. To prepare the ferrofluid magnetic particles are used, which have a followingdispersion equal to 50 brand 5BDSR. The dependence of the sensitivity of the capacitive element from the ferrofluid with different dispersion of magnetic particles is considered. The threshold of sensitivity and sensitivity of a measuring cell with ferrofluid by a magnetic field was determined. The experimental graphs of capacitance change of the magnitude of magnetic field are presented.
Helicons in uniform fields. II. Poynting vector and angular momenta
Stenzel, R. L.; Urrutia, J. M.
2018-03-01
The orbital and spin angular momenta of helicon modes have been determined quantitatively from laboratory experiments. The current density is obtained unambiguously from three dimensional magnetic field measurements. The only approximation made is to obtain the electric field from Hall Ohm's law which is usually the case for low frequency whistler modes. This allows the evaluation of the Poynting vector from which the angular momentum is obtained. Comparing two helicon modes (m = 0 and m = 1), one can separate the contribution of angular momentum of a rotating and non-rotating wave field. The orbital angular momentum is important to assess the wave-particle interaction by the transverse Doppler shift of rotating waves which has not been considered so far.
Vector optical fields with bipolar symmetry of linear polarization.
Pan, Yue; Li, Yongnan; Li, Si-Min; Ren, Zhi-Cheng; Si, Yu; Tu, Chenghou; Wang, Hui-Tian
2013-09-15
We focus on a new kind of vector optical field with bipolar symmetry of linear polarization instead of cylindrical and elliptical symmetries, enriching members of family of vector optical fields. We design theoretically and generate experimentally the demanded vector optical fields and then explore some novel tightly focusing properties. The geometric configurations of states of polarization provide additional degrees of freedom assisting in engineering the field distribution at the focus to the specific applications such as lithography, optical trapping, and material processing.
Robust point matching via vector field consensus.
Jiayi Ma; Ji Zhao; Jinwen Tian; Yuille, Alan L; Zhuowen Tu
2014-04-01
In this paper, we propose an efficient algorithm, called vector field consensus, for establishing robust point correspondences between two sets of points. Our algorithm starts by creating a set of putative correspondences which can contain a very large number of false correspondences, or outliers, in addition to a limited number of true correspondences (inliers). Next, we solve for correspondence by interpolating a vector field between the two point sets, which involves estimating a consensus of inlier points whose matching follows a nonparametric geometrical constraint. We formulate this a maximum a posteriori (MAP) estimation of a Bayesian model with hidden/latent variables indicating whether matches in the putative set are outliers or inliers. We impose nonparametric geometrical constraints on the correspondence, as a prior distribution, using Tikhonov regularizers in a reproducing kernel Hilbert space. MAP estimation is performed by the EM algorithm which by also estimating the variance of the prior model (initialized to a large value) is able to obtain good estimates very quickly (e.g., avoiding many of the local minima inherent in this formulation). We illustrate this method on data sets in 2D and 3D and demonstrate that it is robust to a very large number of outliers (even up to 90%). We also show that in the special case where there is an underlying parametric geometrical model (e.g., the epipolar line constraint) that we obtain better results than standard alternatives like RANSAC if a large number of outliers are present. This suggests a two-stage strategy, where we use our nonparametric model to reduce the size of the putative set and then apply a parametric variant of our approach to estimate the geometric parameters. Our algorithm is computationally efficient and we provide code for others to use it. In addition, our approach is general and can be applied to other problems, such as learning with a badly corrupted training data set.
Multiscale vector fields for image pattern recognition
Low, Kah-Chan; Coggins, James M.
1990-01-01
A uniform processing framework for low-level vision computing in which a bank of spatial filters maps the image intensity structure at each pixel into an abstract feature space is proposed. Some properties of the filters and the feature space are described. Local orientation is measured by a vector sum in the feature space as follows: each filter's preferred orientation along with the strength of the filter's output determine the orientation and the length of a vector in the feature space; the vectors for all filters are summed to yield a resultant vector for a particular pixel and scale. The orientation of the resultant vector indicates the local orientation, and the magnitude of the vector indicates the strength of the local orientation preference. Limitations of the vector sum method are discussed. Investigations show that the processing framework provides a useful, redundant representation of image structure across orientation and scale.
Heisenberg Model in a Rotating Magnetic Field
Institute of Scientific and Technical Information of China (English)
LIN Qiong-Gui
2005-01-01
We study the Heisenberg model under the influence of a rotating magnetic field. By using a time-dependent unitary transformation, the time evolution operator for the Schrodinger equation is obtained, which involves no chronological product. The spin vectors (mean values of the spin operators) are obtained as explicit functions of time in the most general case. A series of cyclic solutions are presented. The nonadiabatic geometric phases of these cyclic solutions are calculated, and are expressed in terms of the solid angle subtended by the closed trace of the total spin vector, as well as in terms of those of the individual spins.
Magnetization reversal mechanisms under oblique magnetic fields
Energy Technology Data Exchange (ETDEWEB)
Ntallis, N.; Efthimiadis, K.G., E-mail: kge@auth.gr
2017-03-01
In this work finite element micromagnetic simulations were performed in order to study the reversal mechanisms of spherical ferromagnetic particles with uniaxial magnetocrystalline anisotropy, when they are magnetized along an oblique direction with respect to the anisotropy axis. Magnetization loops are taken in different directions of external magnetic field, at different anisotropy constants and particle sizes. In the simulation results, the three reversal mechanisms (coherent, curling and domains) are observed and new phenomena arise due to the action of oblique magnetic fields. Moreover, the dependence of the critical fields with respect to the angle of the external field is presented. - Highlights: • Finite element micromagnetic simulation of the three different reversal mechanisms. • For the curling mechanism, the new phenomenon is the rotation of the vortex. • In the domain reversal mechanism, the formed domain wall is smaller than 180°. • In soft ferromagnetic particles a rearrangement of the magnetic domains is observed.
Parallel Vector Fields and Einstein Equations of Gravity | Mahara ...
African Journals Online (AJOL)
In this paper, we prove that no nontrivial timelike or spacelike parallel vector field exists in a region where the gravitational field created by macroscopic bodies and governed by Einstein's equations does not vanish. In other words, we prove that the existence of such vector fields in a region implies the vanishing of the ...
TFTR magnetic field design analyses
International Nuclear Information System (INIS)
Davies, K.; Iwinski, E.; McWhirter, J.M.
1975-11-01
The three main magnetic field windings for the TFTR are the toroidal field (TF) windings, the ohmic heating (OH) winding, and the equilibrium field (EF) winding. The following information is provided for these windings: (1) descriptions, (2) functions, (3) magnetic designs, e.g., number and location of turns, (4) design methods, and (5) descriptions of resulting magnetic fields. This report does not deal with the thermal, mechanical support, or construction details of the windings
The Strongest Magnetic Field in Sunspots
Okamoto, J.; Sakurai, T.
2017-12-01
Sunspots are concentrations of magnetic fields on the solar surface. Generally, the strongest magnetic field in each sunspot is located in the dark umbra in most cases. A typical field strength in sunspots is around 3,000 G. On the other hand, some exceptions also have been found in complex sunspots with bright regions such as light bridges that separate opposite polarity umbrae, for instance with a strength of 4,300 G. However, the formation mechanism of such strong fields outside umbrae is still puzzling. Here we report an extremely strong magnetic field in a sunspot, which was located in a bright region sandwiched by two opposite-polarity umbrae. The strength is 6,250 G, which is the largest ever observed since the discovery of magnetic field on the Sun in 1908 by Hale. We obtained 31 scanned maps of the active region observed by Hinode/SOT/SP with a cadence of 3 hours over 5 days (February 1-6, 2014). Considering the spatial and temporal evolution of the vector magnetic field and the Doppler velocity in the bright region, we suggested that this strong field region was generated as a result of compression of one umbra pushed by the outward flow from the other umbra (Evershed flow), like the subduction of the Earth's crust in plate tectonics.
Transport in a magnetic field modulated graphene superlattice.
Li, Yu-Xian
2010-01-13
Using the transfer matrix method, we study the transport properties through a magnetic field modulated graphene superlattice. It is found that the electrostatic barrier, the magnetic vector potential, and the number of wells in a superlattice modify the transmission remarkably. The angular dependent transmission is blocked by the magnetic vector potential because of the appearance of the evanescent states at certain incident angles, and the region of Klein tunneling shifts to the left. The angularly averaged conductivities exhibit oscillatory behavior. The magnitude and period of oscillation depend sensitively on the height of the electrostatic barrier, the number of wells, and the strength of the modulated magnetic field.
Fast superconducting magnetic field switch
Goren, Yehuda; Mahale, Narayan K.
1996-01-01
The superconducting magnetic switch or fast kicker magnet is employed with electron stream or a bunch of electrons to rapidly change the direction of flow of the electron stream or bunch of electrons. The apparatus employs a beam tube which is coated with a film of superconducting material. The tube is cooled to a temperature below the superconducting transition temperature and is subjected to a constant magnetic field which is produced by an external dc magnet. The magnetic field produced by the dc magnet is less than the critical field for the superconducting material, thus, creating a Meissner Effect condition. A controllable fast electromagnet is used to provide a magnetic field which supplements that of the dc magnet so that when the fast magnet is energized the combined magnetic field is now greater that the critical field and the superconducting material returns to its normal state allowing the magnetic field to penetrate the tube. This produces an internal field which effects the direction of motion and of the electron stream or electron bunch. The switch can also operate as a switching mechanism for charged particles.
Fast superconducting magnetic field switch
International Nuclear Information System (INIS)
Goren, Y.; Mahale, N.K.
1996-01-01
The superconducting magnetic switch or fast kicker magnet is employed with electron stream or a bunch of electrons to rapidly change the direction of flow of the electron stream or bunch of electrons. The apparatus employs a beam tube which is coated with a film of superconducting material. The tube is cooled to a temperature below the superconducting transition temperature and is subjected to a constant magnetic field which is produced by an external dc magnet. The magnetic field produced by the dc magnet is less than the critical field for the superconducting material, thus, creating a Meissner Effect condition. A controllable fast electromagnet is used to provide a magnetic field which supplements that of the dc magnet so that when the fast magnet is energized the combined magnetic field is now greater that the critical field and the superconducting material returns to its normal state allowing the magnetic field to penetrate the tube. This produces an internal field which effects the direction of motion and of the electron stream or electron bunch. The switch can also operate as a switching mechanism for charged particles. 6 figs
Magnetic field modification of optical magnetic dipoles.
Armelles, Gaspar; Caballero, Blanca; Cebollada, Alfonso; Garcia-Martin, Antonio; Meneses-Rodríguez, David
2015-03-11
Acting on optical magnetic dipoles opens novel routes to govern light-matter interaction. We demonstrate magnetic field modification of the magnetic dipolar moment characteristic of resonant nanoholes in thin magnetoplasmonic films. This is experimentally shown through the demonstration of the magneto-optical analogue of Babinet's principle, where mirror imaged MO spectral dependencies are obtained for two complementary magnetoplasmonic systems: holes in a perforated metallic layer and a layer of disks on a substrate.
Magnetic phase diagram of UNi2Si2 under magnetic field and high-pressure
International Nuclear Information System (INIS)
Honda, F.; Oomi, G.; Svoboda, P.; Syshchenko, A.; Sechovsky, V.; Khmelevski, S.; Divis, M.; Andreev, A.V.; Takeshita, N.; Mori, N.; Menovsky, A.A.
2001-01-01
Measurements of electrical resistance under high pressure and neutron diffraction in high-magnetic field of single crystalline UNi 2 Si 2 have been performed. We have found the analogy between the p-T and B-T magnetic phase diagrams. It is also found that the propagation vector q Z of incommensurate antiferromagnetic phase decreases with increasing magnetic field. A new pronounced pressure-induced incommensurate-commensurate magnetic phase transition has been detected
Mercury's magnetic field and interior
International Nuclear Information System (INIS)
Connerney, J.E.P.; Ness, N.F.
1988-01-01
The magnetic-field data collected on Mercury by the Mariner-10 spacecraft present substantial evidence for an intrinsic global magnetic field. However, studies of Mercury's thermal evolution show that it is most likely that the inner core region of Mercury solidified or froze early in the planet's history. Thus, the explanation of Mercury's magnetic field in the framework of the traditional planetary dynamo is less than certain
Lagrangian vector field and Lagrangian formulation of partial differential equations
Directory of Open Access Journals (Sweden)
M.Chen
2005-01-01
Full Text Available In this paper we consider the Lagrangian formulation of a system of second order quasilinear partial differential equations. Specifically we construct a Lagrangian vector field such that the flows of the vector field satisfy the original system of partial differential equations.
The Curl of a Vector Field: Beyond the Formula
Burch, Kimberly Jordan; Choi, Youngna
2006-01-01
It has been widely acknowledged that there is some discrepancy in the teaching of vector calculus in mathematics courses and other applied fields. The curl of a vector field is one topic many students can calculate without understanding its significance. In this paper, we explain the origin of the curl after presenting the standard mathematical…
Space-times carrying a quasirecurrent pairing of vector fields
International Nuclear Information System (INIS)
Rosca, R.; Ianus, S.
1977-01-01
A quasirecurrent pairing of vector fields(X 1 ,X 2 ,) defined previously by Rosca (C.R. Acad. Sci. 282 (1976)) is investigated on a space-time in two cases: (1) X 1 is spacelike and X 2 is timelike; (2) X 1 is null and X 2 is spacelike. The physical interpretation of these vector fields is given. (author)
Avoiding ergodicity and turbulence in R3 vector fields
International Nuclear Information System (INIS)
Ancochea, J.M.; Campoamor-Stursberg, R.; Gonzalez-Gascon, F.
2003-01-01
We show that analytic R 3 vector fields having the property of being transversal to either analytic functions or foliations F 2 , or parallel to a foliation, are free from ergodicity and turbulence. The absence of turbulence and ergodicity via induced vector fields is also proven
Magnetically modified biocells in constant magnetic field
Energy Technology Data Exchange (ETDEWEB)
Abramov, E.G.; Panina, L.K. [Saint Petersburg State University, St. Petersburg (Russian Federation); Kolikov, V.A., E-mail: kolikov1@yandex.ru [Institute for Electrophysics and Electric Power of the RAS, St. Petersburg (Russian Federation); Bogomolova, E.V. [Botanical Institute of the RAS after V.L.Komarov, St. Petersburg (Russian Federation); Snetov, V.N. [Institute for Electrophysics and Electric Power of the RAS, St. Petersburg (Russian Federation); Cherepkova, I.A. [Saint Petersburg State Institute of Technology, St. Petersburg (Russian Federation); Kiselev, A.A. [Institute for Electrophysics and Electric Power of the RAS, St. Petersburg (Russian Federation)
2017-02-01
Paper addresses the inverse problem in determining the area, where the external constant magnetic field captures the biological cells modified by the magnetic nanoparticles. Zero velocity isolines, in area where the modified cells are captured by the magnetic field were determined by numerical method for two locations of the magnet. The problem was solved taking into account the gravitational field, magnetic induction, density of medium, concentration and size of cells, and size and magnetization of nanoparticles attached to the cell. Increase in the number of the nanoparticles attached to the cell and decrease in the cell’ size, enlarges the area, where the modified cells are captured and concentrated by the magnet. Solution is confirmed by the visible pattern formation of the modified cells Saccharomyces cerevisiae. - Highlights: • The inverse problem was solved for finding zero velocity isolines of magnetically modified biological cells. • Solution of the inverse problem depends on the size of cells and the number of nanoparticles attached to the single cell. • The experimental data are in agreement with theoretical solution.
Design of 2D Time-Varying Vector Fields
Chen, Guoning; Kwatra, Vivek; Wei, Li-Yi; Hansen, Charles D.; Zhang, Eugene
2012-01-01
Design of time-varying vector fields, i.e., vector fields that can change over time, has a wide variety of important applications in computer graphics. Existing vector field design techniques do not address time-varying vector fields. In this paper, we present a framework for the design of time-varying vector fields, both for planar domains as well as manifold surfaces. Our system supports the creation and modification of various time-varying vector fields with desired spatial and temporal characteristics through several design metaphors, including streamlines, pathlines, singularity paths, and bifurcations. These design metaphors are integrated into an element-based design to generate the time-varying vector fields via a sequence of basis field summations or spatial constrained optimizations at the sampled times. The key-frame design and field deformation are also introduced to support other user design scenarios. Accordingly, a spatial-temporal constrained optimization and the time-varying transformation are employed to generate the desired fields for these two design scenarios, respectively. We apply the time-varying vector fields generated using our design system to a number of important computer graphics applications that require controllable dynamic effects, such as evolving surface appearance, dynamic scene design, steerable crowd movement, and painterly animation. Many of these are difficult or impossible to achieve via prior simulation-based methods. In these applications, the time-varying vector fields have been applied as either orientation fields or advection fields to control the instantaneous appearance or evolving trajectories of the dynamic effects. © 1995-2012 IEEE.
Design of 2D time-varying vector fields.
Chen, Guoning; Kwatra, Vivek; Wei, Li-Yi; Hansen, Charles D; Zhang, Eugene
2012-10-01
Design of time-varying vector fields, i.e., vector fields that can change over time, has a wide variety of important applications in computer graphics. Existing vector field design techniques do not address time-varying vector fields. In this paper, we present a framework for the design of time-varying vector fields, both for planar domains as well as manifold surfaces. Our system supports the creation and modification of various time-varying vector fields with desired spatial and temporal characteristics through several design metaphors, including streamlines, pathlines, singularity paths, and bifurcations. These design metaphors are integrated into an element-based design to generate the time-varying vector fields via a sequence of basis field summations or spatial constrained optimizations at the sampled times. The key-frame design and field deformation are also introduced to support other user design scenarios. Accordingly, a spatial-temporal constrained optimization and the time-varying transformation are employed to generate the desired fields for these two design scenarios, respectively. We apply the time-varying vector fields generated using our design system to a number of important computer graphics applications that require controllable dynamic effects, such as evolving surface appearance, dynamic scene design, steerable crowd movement, and painterly animation. Many of these are difficult or impossible to achieve via prior simulation-based methods. In these applications, the time-varying vector fields have been applied as either orientation fields or advection fields to control the instantaneous appearance or evolving trajectories of the dynamic effects.
Design of 2D Time-Varying Vector Fields
Chen, Guoning
2012-10-01
Design of time-varying vector fields, i.e., vector fields that can change over time, has a wide variety of important applications in computer graphics. Existing vector field design techniques do not address time-varying vector fields. In this paper, we present a framework for the design of time-varying vector fields, both for planar domains as well as manifold surfaces. Our system supports the creation and modification of various time-varying vector fields with desired spatial and temporal characteristics through several design metaphors, including streamlines, pathlines, singularity paths, and bifurcations. These design metaphors are integrated into an element-based design to generate the time-varying vector fields via a sequence of basis field summations or spatial constrained optimizations at the sampled times. The key-frame design and field deformation are also introduced to support other user design scenarios. Accordingly, a spatial-temporal constrained optimization and the time-varying transformation are employed to generate the desired fields for these two design scenarios, respectively. We apply the time-varying vector fields generated using our design system to a number of important computer graphics applications that require controllable dynamic effects, such as evolving surface appearance, dynamic scene design, steerable crowd movement, and painterly animation. Many of these are difficult or impossible to achieve via prior simulation-based methods. In these applications, the time-varying vector fields have been applied as either orientation fields or advection fields to control the instantaneous appearance or evolving trajectories of the dynamic effects. © 1995-2012 IEEE.
Magnetic response to applied electrostatic field in external magnetic field
Energy Technology Data Exchange (ETDEWEB)
Adorno, T.C. [Universidade de Sao Paulo, Instituto de Fisica, Caixa Postal 66318, Sao Paulo, SP (Brazil); University of Florida, Department of Physics, Gainesville, FL (United States); Gitman, D.M. [Universidade de Sao Paulo, Instituto de Fisica, Caixa Postal 66318, Sao Paulo, SP (Brazil); Tomsk State University, Department of Physics, Tomsk (Russian Federation); Shabad, A.E. [P. N. Lebedev Physics Institute, Moscow (Russian Federation)
2014-04-15
We show, within QED and other possible nonlinear theories, that a static charge localized in a finite domain of space becomes a magnetic dipole, if it is placed in an external (constant and homogeneous) magnetic field in the vacuum. The magnetic moment is quadratic in the charge, depends on its size and is parallel to the external field, provided the charge distribution is at least cylindrically symmetric. This magneto-electric effect is a nonlinear response of the magnetized vacuum to an applied electrostatic field. Referring to the simple example of a spherically symmetric applied field, the nonlinearly induced current and its magnetic field are found explicitly throughout the space; the pattern of the lines of force is depicted, both inside and outside the charge, which resembles that of a standard solenoid of classical magnetostatics. (orig.)
Student difficulties regarding symbolic and graphical representations of vector fields
Directory of Open Access Journals (Sweden)
Laurens Bollen
2017-08-01
Full Text Available The ability to switch between various representations is an invaluable problem-solving skill in physics. In addition, research has shown that using multiple representations can greatly enhance a person’s understanding of mathematical and physical concepts. This paper describes a study of student difficulties regarding interpreting, constructing, and switching between representations of vector fields, using both qualitative and quantitative methods. We first identified to what extent students are fluent with the use of field vector plots, field line diagrams, and symbolic expressions of vector fields by conducting individual student interviews and analyzing in-class student activities. Based on those findings, we designed the Vector Field Representations test, a free response assessment tool that has been given to 196 second- and third-year physics, mathematics, and engineering students from four different universities. From the obtained results we gained a comprehensive overview of typical errors that students make when switching between vector field representations. In addition, the study allowed us to determine the relative prevalence of the observed difficulties. Although the results varied greatly between institutions, a general trend revealed that many students struggle with vector addition, fail to recognize the field line density as an indication of the magnitude of the field, confuse characteristics of field lines and equipotential lines, and do not choose the appropriate coordinate system when writing out mathematical expressions of vector fields.
Student difficulties regarding symbolic and graphical representations of vector fields
Bollen, Laurens; van Kampen, Paul; Baily, Charles; Kelly, Mossy; De Cock, Mieke
2017-12-01
The ability to switch between various representations is an invaluable problem-solving skill in physics. In addition, research has shown that using multiple representations can greatly enhance a person's understanding of mathematical and physical concepts. This paper describes a study of student difficulties regarding interpreting, constructing, and switching between representations of vector fields, using both qualitative and quantitative methods. We first identified to what extent students are fluent with the use of field vector plots, field line diagrams, and symbolic expressions of vector fields by conducting individual student interviews and analyzing in-class student activities. Based on those findings, we designed the Vector Field Representations test, a free response assessment tool that has been given to 196 second- and third-year physics, mathematics, and engineering students from four different universities. From the obtained results we gained a comprehensive overview of typical errors that students make when switching between vector field representations. In addition, the study allowed us to determine the relative prevalence of the observed difficulties. Although the results varied greatly between institutions, a general trend revealed that many students struggle with vector addition, fail to recognize the field line density as an indication of the magnitude of the field, confuse characteristics of field lines and equipotential lines, and do not choose the appropriate coordinate system when writing out mathematical expressions of vector fields.
Classification of complex polynomial vector fields in one complex variable
DEFF Research Database (Denmark)
Branner, Bodil; Dias, Kealey
2010-01-01
This paper classifies the global structure of monic and centred one-variable complex polynomial vector fields. The classification is achieved by means of combinatorial and analytic data. More specifically, given a polynomial vector field, we construct a combinatorial invariant, describing...... the topology, and a set of analytic invariants, describing the geometry. Conversely, given admissible combinatorial and analytic data sets, we show using surgery the existence of a unique monic and centred polynomial vector field realizing the given invariants. This is the content of the Structure Theorem......, the main result of the paper. This result is an extension and refinement of Douady et al. (Champs de vecteurs polynomiaux sur C. Unpublished manuscript) classification of the structurally stable polynomial vector fields. We further review some general concepts for completeness and show that vector fields...
On Discrete Killing Vector Fields and Patterns on Surfaces
Ben-Chen, Mirela
2010-09-21
Symmetry is one of the most important properties of a shape, unifying form and function. It encodes semantic information on one hand, and affects the shape\\'s aesthetic value on the other. Symmetry comes in many flavors, amongst the most interesting being intrinsic symmetry, which is defined only in terms of the intrinsic geometry of the shape. Continuous intrinsic symmetries can be represented using infinitesimal rigid transformations, which are given as tangent vector fields on the surface - known as Killing Vector Fields. As exact symmetries are quite rare, especially when considering noisy sampled surfaces, we propose a method for relaxing the exact symmetry constraint to allow for approximate symmetries and approximate Killing Vector Fields, and show how to discretize these concepts for generating such vector fields on a triangulated mesh. We discuss the properties of approximate Killing Vector Fields, and propose an application to utilize them for texture and geometry synthesis. Journal compilation © 2010 The Eurographics Association and Blackwell Publishing Ltd.
Measurements of magnetic field alignment
International Nuclear Information System (INIS)
Kuchnir, M.; Schmidt, E.E.
1987-01-01
The procedure for installing Superconducting Super Collider (SSC) dipoles in their respective cryostats involves aligning the average direction of their field with the vertical to an accuracy of 0.5 mrad. The equipment developed for carrying on these measurements is described and the measurements performed on the first few prototypes SSC magnets are presented. The field angle as a function of position in these 16.6 m long magnets is a characteristic of the individual magnet with possible feedback information to its manufacturing procedure. A comparison of this vertical alignment characteristic with a magnetic field intensity (by NMR) characteristic for one of the prototypes is also presented. 5 refs., 7 figs
Abou-Hamad, Edy; Bontemps, P.; Rikken, Geert L J A
2011-01-01
Nuclear magnetic resonance (NMR) experiments in pulsed magnetic fields up to 30.4 T focused on 1H and 93Nb nuclei are reported. Here we discuss the advantage and limitation of pulsed field NMR and why this technique is able to become a promising research tool. © 2011 Elsevier Inc. All Rights Reserved.
Abou-Hamad, Edy
2011-09-01
Nuclear magnetic resonance (NMR) experiments in pulsed magnetic fields up to 30.4 T focused on 1H and 93Nb nuclei are reported. Here we discuss the advantage and limitation of pulsed field NMR and why this technique is able to become a promising research tool. © 2011 Elsevier Inc. All Rights Reserved.
Discrete Spin Vector Approach for Monte Carlo-based Magnetic Nanoparticle Simulations
Senkov, Alexander; Peralta, Juan; Sahay, Rahul
The study of magnetic nanoparticles has gained significant popularity due to the potential uses in many fields such as modern medicine, electronics, and engineering. To study the magnetic behavior of these particles in depth, it is important to be able to model and simulate their magnetic properties efficiently. Here we utilize the Metropolis-Hastings algorithm with a discrete spin vector model (in contrast to the standard continuous model) to model the magnetic hysteresis of a set of protected pure iron nanoparticles. We compare our simulations with the experimental hysteresis curves and discuss the efficiency of our algorithm.
Magnetic Field Measurements in Beam Guiding Magnets
Henrichsen, K N
1998-01-01
Electromagnets used as beam guiding elements in particle accelerators and colliders require very tight tole-rances on their magnetic fields and on their alignment along the particle path. This article describes the methods and equipment used for magnetic measurements in beam transport magnets. Descriptions are given of magnetic resonance techniques, various induction coil methods, Hall generator measurements, the fluxgate magnetometer as well as the recently developed method of beam based alignment. References of historical nature as well as citations of recent work are given. The present commercial availability of the different sensors and asso-ciated equipment is indicated. Finally we shall try to analyze possible future needs for developments in those fields.
The ARASE (ERG) magnetic field investigation
Matsuoka, Ayako; Teramoto, Mariko; Nomura, Reiko; Nosé, Masahito; Fujimoto, Akiko; Tanaka, Yoshimasa; Shinohara, Manabu; Nagatsuma, Tsutomu; Shiokawa, Kazuo; Obana, Yuki; Miyoshi, Yoshizumi; Mita, Makoto; Takashima, Takeshi; Shinohara, Iku
2018-03-01
The fluxgate magnetometer for the Arase (ERG) spacecraft mission was built to investigate particle acceleration processes in the inner magnetosphere. Precise measurements of the field intensity and direction are essential in studying the motion of particles, the properties of waves interacting with the particles, and magnetic field variations induced by electric currents. By observing temporal field variations, we will more deeply understand magnetohydrodynamic and electromagnetic ion-cyclotron waves in the ultra-low-frequency range, which can cause production and loss of relativistic electrons and ring-current particles. The hardware and software designs of the Magnetic Field Experiment (MGF) were optimized to meet the requirements for studying these phenomena. The MGF makes measurements at a sampling rate of 256 vectors/s, and the data are averaged onboard to fit the telemetry budget. The magnetometer switches the dynamic range between ± 8000 and ± 60,000 nT, depending on the local magnetic field intensity. The experiment is calibrated by preflight tests and through analysis of in-orbit data. MGF data are edited into files with a common data file format, archived on a data server, and made available to the science community. Magnetic field observation by the MGF will significantly improve our knowledge of the growth and decay of radiation belts and ring currents, as well as the dynamics of geospace storms.
Bouchard, Louis-Serge; Pines, Alexander; Demas, Vasiliki
2014-01-21
A system and method for Fourier encoding a nuclear magnetic resonance (NMR) signal is disclosed. A static magnetic field B.sub.0 is provided along a first direction. An NMR signal from the sample is Fourier encoded by applying a rotating-frame gradient field B.sub.G superimposed on the B.sub.0, where the B.sub.G comprises a vector component rotating in a plane perpendicular to the first direction at an angular frequency .omega.in a laboratory frame. The Fourier-encoded NMR signal is detected.
Energy Technology Data Exchange (ETDEWEB)
Sun Xudong; Hoeksema, J. Todd; Liu Yang; Chen Ruizhu [W. W. Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305 (United States); Kazachenko, Maria, E-mail: xudong@Sun.stanford.edu [Space Sciences Laboratory, University of California, Berkeley, CA 94720 (United States)
2017-04-10
The solar active region photospheric magnetic field evolves rapidly during major eruptive events, suggesting appreciable feedback from the corona. Previous studies of these “magnetic imprints” are mostly based on line of sight only or lower-cadence vector observations; a temporally resolved depiction of the vector field evolution is hitherto lacking. Here, we introduce the high-cadence (90 s or 135 s) vector magnetogram data set from the Helioseismic and Magnetic Imager, which is well suited for investigating the phenomenon. These observations allow quantitative characterization of the permanent, step-like changes that are most pronounced in the horizontal field component (B {sub h}). A highly structured pattern emerges from analysis of an archetypical event, SOL2011-02-15T01:56, where B {sub h} near the main polarity inversion line increases significantly during the earlier phase of the associated flare with a timescale of several minutes, while B {sub h} in the periphery decreases at later times with smaller magnitudes and a slightly longer timescale. The data set also allows effective identification of the “magnetic transient” artifact, where enhanced flare emission alters the Stokes profiles and the inferred magnetic field becomes unreliable. Our results provide insights on the momentum processes in solar eruptions. The data set may also be useful to the study of sunquakes and data-driven modeling of the corona.
Gaussian vector fields on triangulated surfaces
DEFF Research Database (Denmark)
Ipsen, John H
2016-01-01
proven to be very useful to resolve the complex interplay between in-plane ordering of membranes and membrane conformations. In the present work we have developed a procedure for realistic representations of Gaussian models with in-plane vector degrees of freedoms on a triangulated surface. The method...
The divergence theorem for unbounded vector fields
De Pauw, Thierry; Pfeffer, Washek F.
2007-01-01
In the context of Lebesgue integration, we derive the divergence theorem for unbounded vector. elds that can have singularities at every point of a compact set whose Minkowski content of codimension greater than two is. nite. The resulting integration by parts theorem is applied to removable sets of holomorphic and harmonic functions.
Process γγ → νν-bar in a strong magnetic field
International Nuclear Information System (INIS)
Kuznetsov, A.V.; Mikheev, N.V.; Rumyantsev, D.A.
2003-01-01
The three-vertex loop amplitude in a strong magnetic field are analyzed in a general form by using the asymptotic behavior of the electron propagator in an external field. The process γγ → νν-bar is studied in terms of the scalar-vector-vector (SVV), pseudoscalar-vector-vector (PVV), vector-vector-vector (VVV), and axial-vector-vector-vector (AVV) combinations of couplings. It is shown that only in the case of the SVV combination does the amplitude grow linearly with increasing magnetic-field strength, the amplitudes evaluated with the other combinations of couplings (PVV, VVV, and AVV) featuring no linearly increasing terms. The process γγ → νν-bar is also studied within the left-right model, which is an extension of the Standard Model of electroweak interactions and which may involve an effective scalar ννee coupling. Possible astrophysical manifestations of this process are discussed
The Local Stellar Velocity Field via Vector Spherical Harmonics
Markarov, V. V.; Murphy, D. W.
2007-01-01
), but here we surmise its existence in the thin disk at z less than 200 pc. The most unexpected and unexplained term within the Ogorodnikov-Milne model is the first-degree magnetic harmonic, representing a rigid rotation of the stellar field about the axis -Y pointing opposite to the direction of rotation. This harmonic comes out with a statistically robust coefficient of 6.2 +/- 0.9 km s(exp -1) kpc(exp -1) and is also present in the velocity field of more distant stars. The ensuing upward vertical motion of stars in the general direction of the Galactic center and the downward motion in the anticenter direction are opposite to the vector field expected from the stationary Galactic warp model.
Baryshevsky, Vladimir G.
1999-01-01
It is shown that the T- and P-odd weak interactions yield to the existence of both electric field and magnetic (directed along the electric field) field around an electric charge. Similarly the assotiated magnetic field is directed along the vector of strength of stationary gravitational field.
The index of a vector field under blow ups
International Nuclear Information System (INIS)
Seade, J.
1991-08-01
A useful technique when studying the behaviour of holomorphic vector fields around their isolated singularities is that of blowing up the singular points. On the other hand, the most basic invariant of a vector field with isolated singularities is its local index, as defined by Poincare and Hopf. It is thus natural to ask how does the index of a vector field behaves under blowing ups? The purpose of this work is to study and answer this question, by taking a rather general point of view and bearing in mind that complex manifolds have a powerful birational invariant, the Todd genus. 20 refs
Visualizing Vector Fields Using Line Integral Convolution and Dye Advection
Shen, Han-Wei; Johnson, Christopher R.; Ma, Kwan-Liu
1996-01-01
We present local and global techniques to visualize three-dimensional vector field data. Using the Line Integral Convolution (LIC) method to image the global vector field, our new algorithm allows the user to introduce colored 'dye' into the vector field to highlight local flow features. A fast algorithm is proposed that quickly recomputes the dyed LIC images. In addition, we introduce volume rendering methods that can map the LIC texture on any contour surface and/or translucent region defined by additional scalar quantities, and can follow the advection of colored dye throughout the volume.
Synthesis of magnetic systems producing field with maximal scalar characteristics
International Nuclear Information System (INIS)
Klevets, Nickolay I.
2005-01-01
A method of synthesis of the magnetic systems (MSs) consisting of uniformly magnetized blocks is proposed. This method allows to synthesize MSs providing maximum value of any magnetic field scalar characteristic. In particular, it is possible to synthesize the MSs providing the maximum of a field projection on a given vector, a gradient of a field modulus and a gradient of a field energy on a given directing vector, a field magnitude, a magnetic flux through a given surface, a scalar product of a field or a force by a directing function given in some area of space, etc. The synthesized MSs provide maximal efficiency of permanent magnets utilization. The usage of the proposed method of MSs synthesis allows to change a procedure of projecting in principal, namely, to execute it according to the following scheme: (a) to choose the sizes, a form and a number of blocks of a system proceeding from technological (economical) reasons; (b) using the proposed synthesis method, to find an orientation of site magnetization providing maximum possible effect of magnet utilization in a system obtained in (a). Such approach considerably reduces a time of MSs projecting and guarantees maximal possible efficiency of magnets utilization. Besides it provides absolute assurance in 'ideality' of a MS design and allows to obtain an exact estimate of the limit parameters of a field in a working area of a projected MS. The method is applicable to a system containing the components from soft magnetic material with linear magnetic properties
Reciprocity relationships in vector acoustics and their application to vector field calculations.
Deal, Thomas J; Smith, Kevin B
2017-08-01
The reciprocity equation commonly stated in underwater acoustics relates pressure fields and monopole sources. It is often used to predict the pressure measured by a hydrophone for multiple source locations by placing a source at the hydrophone location and calculating the field everywhere for that source. A similar equation that governs the orthogonal components of the particle velocity field is needed to enable this computational method to be used for acoustic vector sensors. This paper derives a general reciprocity equation that accounts for both monopole and dipole sources. This vector-scalar reciprocity equation can be used to calculate individual components of the received vector field by altering the source type used in the propagation calculation. This enables a propagation model to calculate the received vector field components for an arbitrary number of source locations with a single model run for each vector field component instead of requiring one model run for each source location. Application of the vector-scalar reciprocity principle is demonstrated with analytic solutions for a range-independent environment and with numerical solutions for a range-dependent environment using a parabolic equation model.
Magnetic field reconnexion in a sheared field
International Nuclear Information System (INIS)
Ugai, M.
1981-01-01
A nonlinear development of the Petschek mode in a sheared magnetic field where there is a field component Bsub(z) along an X line is numerically studied. It is found that finite-amplitude intermediate waves, adjacent to the slow shock, may eventually stand in the quasi-steady configuration; on the other hand, the fundamental characteristics of the Petschek-mode development are scarcely influenced, either qualitatively or quantitatively, by the Bsub(z) field. (author)
Magnetic fields and scintillator performance
International Nuclear Information System (INIS)
Green, D.; Ronzhin, A.; Hagopian, V.
1995-06-01
Experimental data have shown that the light output of a scintillator depends on the magnitude of the externally applied magnetic fields, and that this variation can affect the calorimeter calibration and possibly resolution. The goal of the measurements presented here is to study the light yield of scintillators in high magnetic fields in conditions that are similar to those anticipated for the LHC CMS detector. Two independent measurements were performed, the first at Fermilab and the second at the National High Magnetic Field Laboratory at Florida State University
Henan Zhao; Bryant, Garnett W; Griffin, Wesley; Terrill, Judith E; Jian Chen
2017-06-01
We designed and evaluated SplitVectors, a new vector field display approach to help scientists perform new discrimination tasks on large-magnitude-range scientific data shown in three-dimensional (3D) visualization environments. SplitVectors uses scientific notation to display vector magnitude, thus improving legibility. We present an empirical study comparing the SplitVectors approach with three other approaches - direct linear representation, logarithmic, and text display commonly used in scientific visualizations. Twenty participants performed three domain analysis tasks: reading numerical values (a discrimination task), finding the ratio between values (a discrimination task), and finding the larger of two vectors (a pattern detection task). Participants used both mono and stereo conditions. Our results suggest the following: (1) SplitVectors improve accuracy by about 10 times compared to linear mapping and by four times to logarithmic in discrimination tasks; (2) SplitVectors have no significant differences from the textual display approach, but reduce cluttering in the scene; (3) SplitVectors and textual display are less sensitive to data scale than linear and logarithmic approaches; (4) using logarithmic can be problematic as participants' confidence was as high as directly reading from the textual display, but their accuracy was poor; and (5) Stereoscopy improved performance, especially in more challenging discrimination tasks.
ACHIEVING CONSISTENT DOPPLER MEASUREMENTS FROM SDO /HMI VECTOR FIELD INVERSIONS
International Nuclear Information System (INIS)
Schuck, Peter W.; Antiochos, S. K.; Leka, K. D.; Barnes, Graham
2016-01-01
NASA’s Solar Dynamics Observatory is delivering vector magnetic field observations of the full solar disk with unprecedented temporal and spatial resolution; however, the satellite is in a highly inclined geosynchronous orbit. The relative spacecraft–Sun velocity varies by ±3 km s −1 over a day, which introduces major orbital artifacts in the Helioseismic Magnetic Imager (HMI) data. We demonstrate that the orbital artifacts contaminate all spatial and temporal scales in the data. We describe a newly developed three-stage procedure for mitigating these artifacts in the Doppler data obtained from the Milne–Eddington inversions in the HMI pipeline. The procedure ultimately uses 32 velocity-dependent coefficients to adjust 10 million pixels—a remarkably sparse correction model given the complexity of the orbital artifacts. This procedure was applied to full-disk images of AR 11084 to produce consistent Dopplergrams. The data adjustments reduce the power in the orbital artifacts by 31 dB. Furthermore, we analyze in detail the corrected images and show that our procedure greatly improves the temporal and spectral properties of the data without adding any new artifacts. We conclude that this new procedure makes a dramatic improvement in the consistency of the HMI data and in its usefulness for precision scientific studies.
Non-existence of limit cycles for planar vector fields
Directory of Open Access Journals (Sweden)
Jaume Gine
2014-03-01
Full Text Available This article presents sufficient conditions for the non-existence of limit cycles for planar vector fields. Classical methods for the nonexistence of limit cycles are connected with the theory developed here.
Lipschitz estimates for convex functions with respect to vector fields
Directory of Open Access Journals (Sweden)
Valentino Magnani
2012-12-01
Full Text Available We present Lipschitz continuity estimates for a class of convex functions with respect to Hörmander vector fields. These results have been recently obtained in collaboration with M. Scienza, [22].
2D Vector Field Simplification Based on Robustness
Skraba, Primoz; Wang, Bei; Chen, Guoning; Rosen, Paul
2014-01-01
Vector field simplification aims to reduce the complexity of the flow by removing features in order of their relevance and importance, to reveal prominent behavior and obtain a compact representation for interpretation. Most existing simplification
Study of marine magnetic field
Digital Repository Service at National Institute of Oceanography (India)
Bhattacharya, G.C.
magnetized in the direction of the Earth’s magnetic field at that time. As seafloor spreading pulls the new oceanic crust apart, stripes of approximately the same size gets carried away from the ridge on each side. The basaltic oceanic crust formed...
Invariant hyperplanes and Darboux integrability of polynomial vector fields
International Nuclear Information System (INIS)
Zhang Xiang
2002-01-01
This paper is composed of two parts. In the first part, we provide an upper bound for the number of invariant hyperplanes of the polynomial vector fields in n variables. This result generalizes those given in Artes et al (1998 Pac. J. Math. 184 207-30) and Llibre and Rodriguez (2000 Bull. Sci. Math. 124 599-619). The second part gives an extension of the Darboux theory of integrability to polynomial vector fields on algebraic varieties
Creation of a new vector field and focusing engineering
Wang, Xi-Lin; Chen, Jing; Li, Yongnan; Ding, Jianping; Guo, Cheng-Shan; Wang, Hui-Tian
2009-01-01
Recently many methods have been proposed to create the vector fields, due to the academic interest and a variety of attractive applications such as for particle acceleration, optical trapping, particle manipulation, and fluorescence imaging. For the most of the created vector fields, the spatial distribution in states of polarization (SoPs) is dependent of azimuthal angle only. It is very interesting and crucial that if we can introduce the radial controlling freedom, which undoubtedly opens ...
International Nuclear Information System (INIS)
Huang, Qiu; Peng, Qiyu; Huang, Bin; Cheryauka, Arvi; Gullberg, Grant T.
2008-01-01
The measurement of flow obtained using continuous wave Doppler ultrasound is formulated as a directional projection of a flow vector field. When a continuous ultrasound wave bounces against a flowing particle, a signal is backscattered. This signal obtains a Doppler frequency shift proportional to the speed of the particle along the ultrasound beam. This occurs for each particle along the beam, giving rise to a Doppler velocity spectrum. The first moment of the spectrum provides the directional projection of the flow along the ultrasound beam. Signals reflected from points further away from the detector will have lower amplitude than signals reflected from points closer to the detector. The effect is very much akin to that modeled by the attenuated Radon transform in emission computed tomography.A least-squares method was adopted to reconstruct a 2D vector field from directional projection measurements. Attenuated projections of only the longitudinal projections of the vector field were simulated. The components of the vector field were reconstructed using the gradient algorithm to minimize a least-squares criterion. This result was compared with the reconstruction of longitudinal projections of the vector field without attenuation. If attenuation is known, the algorithm was able to accurately reconstruct both components of the full vector field from only one set of directional projection measurements. A better reconstruction was obtained with attenuation than without attenuation implying that attenuation provides important information for the reconstruction of flow vector fields.This confirms previous work where we showed that knowledge of the attenuation distribution helps in the reconstruction of MRI diffusion tensor fields from fewer than the required measurements. In the application of ultrasound the attenuation distribution is obtained with pulse wave transmission computed tomography and flow information is obtained with continuous wave Doppler
Measuring Earth's Magnetic Field Simply.
Stewart, Gay B.
2000-01-01
Describes a method for measuring the earth's magnetic field using an empty toilet paper tube, copper wire, clear tape, a battery, a linear variable resistor, a small compass, cardboard, a protractor, and an ammeter. (WRM)
CERN PhotoLab
1975-01-01
The experimental apparatus used at intersection 4 around the Split-Field Magnet by the CERN-Bologna Collaboration (experiment R406). The plastic scintillator telescopes are used for precise pulse-height and time-of-flight measurements.
High-Field Accelerator Magnets
International Nuclear Information System (INIS)
Rijk, G de
2014-01-01
In this lecture an overview is given of the present technology for high field accelerator magnets. We indicate how to get high fields and what are the most important parameters. The available conductors and their limitations are presented followed by the most relevant types of coils and support structures. We conclude by showing a number of recent examples of development magnets which are either pure R&D objects or models for the LHC luminosity upgrade
Theorem on magnet fringe field
International Nuclear Information System (INIS)
Wei, Jie; Talman, R.
1995-01-01
Transverse particle motion in particle accelerators is governed almost totally by non-solenoidal magnets for which the body magnetic field can be expressed as a series expansion of the normal (b n ) and skew (a n ) multipoles, B y + iB x = summation(b n + ia n )(x + iy) n , where x, y, and z denote horizontal, vertical, and longitudinal (along the magnet) coordinates. Since the magnet length L is necessarily finite, deflections are actually proportional to ''field integrals'' such as bar BL ≡ ∫ B(x,y,z)dz where the integration range starts well before the magnet and ends well after it. For bar a n , bar b n , bar B x , and bar B y defined this way, the same expansion Eq. 1 is valid and the ''standard'' approximation is to neglect any deflections not described by this expansion, in spite of the fact that Maxwell's equations demand the presence of longitudinal field components at the magnet ends. The purpose of this note is to provide a semi-quantitative estimate of the importance of |Δp ∝ |, the transverse deflection produced by the ion-gitudinal component of the fringe field at one magnet end relative to |Δp 0 |, the total deflection produced by passage through the whole magnet. To emphasize the generality and simplicity of the result it is given in the form of a theorem. The essence of the proof is an evaluation of the contribution of the longitudinal field B x from the vicinity of one magnet end since, along a path parallel to the magnet axis such as path BC
Three axis vector magnet set-up for cryogenic scanning probe microscopy
International Nuclear Information System (INIS)
Galvis, J. A.; Herrera, E.; Buendía, A.; Guillamón, I.; Vieira, S.; Suderow, H.; Azpeitia, J.; Luccas, R. F.; Munuera, C.; García-Hernandez, M.
2015-01-01
We describe a three axis vector magnet system for cryogenic scanning probe microscopy measurements. We discuss the magnet support system and the power supply, consisting of a compact three way 100 A current source. We obtain tilted magnetic fields in all directions with maximum value of 5T along z-axis and of 1.2T for XY-plane magnetic fields. We describe a scanning tunneling microscopy-spectroscopy (STM-STS) set-up, operating in a dilution refrigerator, which includes a new high voltage ultralow noise piezodrive electronics and discuss the noise level due to vibrations. STM images and STS maps show atomic resolution and the tilted vortex lattice at 150 mK in the superconductor β-Bi 2 Pd. We observe a strongly elongated hexagonal lattice, which corresponds to the projection of the tilted hexagonal vortex lattice on the surface. We also discuss Magnetic Force Microscopy images in a variable temperature insert
Three axis vector magnet set-up for cryogenic scanning probe microscopy
Energy Technology Data Exchange (ETDEWEB)
Galvis, J. A. [Laboratorio de Bajas Temperaturas, Departamento de Física de la Materia Condensada, Instituto de Ciencia de Materiales Nicolás Cabrera, Condensed Matter Physics Center (IFIMAC), Facultad de Ciencias Universidad Autónoma de Madrid, 28049 Madrid (Spain); Departamento de Ciencias Naturales Facultad de Ingeniería Universidad Central, Bogotá (Colombia); Herrera, E.; Buendía, A. [Laboratorio de Bajas Temperaturas, Departamento de Física de la Materia Condensada, Instituto de Ciencia de Materiales Nicolás Cabrera, Condensed Matter Physics Center (IFIMAC), Facultad de Ciencias Universidad Autónoma de Madrid, 28049 Madrid (Spain); Guillamón, I.; Vieira, S.; Suderow, H. [Laboratorio de Bajas Temperaturas, Departamento de Física de la Materia Condensada, Instituto de Ciencia de Materiales Nicolás Cabrera, Condensed Matter Physics Center (IFIMAC), Facultad de Ciencias Universidad Autónoma de Madrid, 28049 Madrid (Spain); Unidad Asociada de Bajas Temperaturas y Altos Campos Magnéticos, UAM, CSIC, Cantoblanco, E-28049 Madrid (Spain); Azpeitia, J.; Luccas, R. F.; Munuera, C.; García-Hernandez, M. [Unidad Asociada de Bajas Temperaturas y Altos Campos Magnéticos, UAM, CSIC, Cantoblanco, E-28049 Madrid (Spain); Instituto de Ciencia de Materiales de Madrid, Consejo Superior de Investigaciones Científicas (ICMM-CSIC), Sor Juana Inés de la Cruz 3, 28049 Madrid (Spain); and others
2015-01-15
We describe a three axis vector magnet system for cryogenic scanning probe microscopy measurements. We discuss the magnet support system and the power supply, consisting of a compact three way 100 A current source. We obtain tilted magnetic fields in all directions with maximum value of 5T along z-axis and of 1.2T for XY-plane magnetic fields. We describe a scanning tunneling microscopy-spectroscopy (STM-STS) set-up, operating in a dilution refrigerator, which includes a new high voltage ultralow noise piezodrive electronics and discuss the noise level due to vibrations. STM images and STS maps show atomic resolution and the tilted vortex lattice at 150 mK in the superconductor β-Bi{sub 2}Pd. We observe a strongly elongated hexagonal lattice, which corresponds to the projection of the tilted hexagonal vortex lattice on the surface. We also discuss Magnetic Force Microscopy images in a variable temperature insert.
Johnson, Catherine L; Phillips, Roger J; Purucker, Michael E; Anderson, Brian J; Byrne, Paul K; Denevi, Brett W; Feinberg, Joshua M; Hauck, Steven A; Head, James W; Korth, Haje; James, Peter B; Mazarico, Erwan; Neumann, Gregory A; Philpott, Lydia C; Siegler, Matthew A; Tsyganenko, Nikolai A; Solomon, Sean C
2015-05-22
Magnetized rocks can record the history of the magnetic field of a planet, a key constraint for understanding its evolution. From orbital vector magnetic field measurements of Mercury taken by the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft at altitudes below 150 kilometers, we have detected remanent magnetization in Mercury's crust. We infer a lower bound on the average age of magnetization of 3.7 to 3.9 billion years. Our findings indicate that a global magnetic field driven by dynamo processes in the fluid outer core operated early in Mercury's history. Ancient field strengths that range from those similar to Mercury's present dipole field to Earth-like values are consistent with the magnetic field observations and with the low iron content of Mercury's crust inferred from MESSENGER elemental composition data. Copyright © 2015, American Association for the Advancement of Science.
Magnetic field induced dynamical chaos.
Ray, Somrita; Baura, Alendu; Bag, Bidhan Chandra
2013-12-01
In this article, we have studied the dynamics of a particle having charge in the presence of a magnetic field. The motion of the particle is confined in the x-y plane under a two dimensional nonlinear potential. We have shown that constant magnetic field induced dynamical chaos is possible even for a force which is derived from a simple potential. For a given strength of the magnetic field, initial position, and velocity of the particle, the dynamics may be regular, but it may become chaotic when the field is time dependent. Chaotic dynamics is very often if the field is time dependent. Origin of chaos has been explored using the Hamiltonian function of the dynamics in terms of action and angle variables. Applicability of the present study has been discussed with a few examples.
Controllability of linear vector fields on Lie groups
International Nuclear Information System (INIS)
Ayala, V.; Tirao, J.
1994-11-01
In this paper, we shall deal with a linear control system Σ defined on a Lie group G with Lie algebra g. The dynamic of Σ is determined by the drift vector field which is an element in the normalizer of g in the Lie algebra of all smooth vector field on G and by the control vectors which are elements in g considered as left-invariant vector fields. We characterize the normalizer of g identifying vector fields on G with C ∞ -functions defined on G into g. For this class of control systems we study algebraic conditions for the controllability problem. Indeed, we prove that if the drift vector field has a singularity then the Lie algebra rank condition is necessary for the controllability property, but in general this condition does not determine this property. On the other hand, we show that the rank (ad-rank) condition is sufficient for the controllability of Σ. In particular, we extend the fundamental Kalman's theorem when G is an Abelian connected Lie group. Our work is related with a paper of L. Markus and we also improve his results. (author). 7 refs
TWO FERROMAGNETIC SPHERES IN HOMOGENEOUS MAGNETIC FIELD
Directory of Open Access Journals (Sweden)
Yury A. Krasnitsky
2018-01-01
Full Text Available The problem of two spherical conductors is studied quite in detail with bispherical coordinates usage and has numerous appendices in an electrostatics. The boundary-value problem about two ferromagnetic spheres enclosed on homogeneous and infinite environment in which the lack of spheres exists like homogeneous magnetic field is considered. The solution of Laplace's equation in the bispherical system of coordinates allows us to find the potential and field distribution in all spaces, including area between spheres. The boundary conditions in potential continuity and in ordinary density constituent of spheres surfaces induction flux are used. It is supposed that spheres are identical, and magnetic permeability of their material is expressed in >> 0. The problem about falling of electromagnetic plane wave on the system of two spheres, which possesses electrically small sizes, can be considered as quasistationary. The scalar potentials received as a result of Laplace's equation solution are represented by the series containing Legendre polynomials. The concept of two spheres system effective permeability is introduced. It is equal to the advantage in magnitude of magnetic induction flux vector through a certain system’s section arising due to its magnetic properties. Necessary ratios for the effective permeability referred to the central system’s section are obtained. Particularly, the results can be used during the analysis of ferroxcube core clearance, which influences on the magnetic antenna properties.
Accurate magnetic field calculations for contactless energy transfer coils
Sonntag, C.L.W.; Spree, M.; Lomonova, E.A.; Duarte, J.L.; Vandenput, A.J.A.
2007-01-01
In this paper, a method for estimating the magnetic field intensity from hexagon spiral windings commonly found in contactless energy transfer applications is presented. The hexagonal structures are modeled in a magneto-static environment using Biot-Savart current stick vectors. The accuracy of the models are evaluated by mapping the current sticks and the hexagon spiral winding tracks to a local twodimensional plane, and comparing their two-dimensional magnetic field intensities. The accurac...
A Swarm lithospheric magnetic field model to SH degree 80
Thébault, Erwan; Vigneron, Pierre; Langlais, Benoit; Hulot, Gauthier
2016-01-01
International audience; The Swarm constellation of satellites was launched in November 2013 and since then has delivered high-quality scalar and vector magnetic field measurements. A consortium of several research institutions was selected by the European Space Agency to provide a number of scientific products to be made available to the scientific community on a regular basis. In this study, we present the dedicated lithospheric field inversion model. It uses carefully selected magnetic fiel...
Classical electromagnetic field theory in the presence of magnetic sources
Chen, Wen-Jun; Li, Kang; Naón, Carlos
2001-01-01
Using two new well defined 4-dimensional potential vectors, we formulate the classical Maxwell's field theory in a form which has manifest Lorentz covariance and SO(2) duality symmetry in the presence of magnetic sources. We set up a consistent Lagrangian for the theory. Then from the action principle we get both Maxwell's equation and the equation of motion of a dyon moving in the electro-magnetic field.
DEFF Research Database (Denmark)
Zhang, Xiaoxu; Liu, Xiao; Chen, Zhe
2015-01-01
This paper presents a rapid approach to compute the magnetic field distribution in a flux-modulated permanent-magnet brushless motor. Partial differential equations are used to describe the magnet field behavior in terms of magnetic vector potentials. The whole computational domain is divided...... into several regions, i.e., magnet, air-gaps, slot-openings, and slots. The numerical solution could be obtained by applying the boundary constraints on the interfaces between these regions. The accuracy of the proposed analytical model is verified by comparing the no-load magnetic field and armature reaction...... magnetic field with those calculated by finite element method....
Performance of silicon drift detectors in a magnetic field
International Nuclear Information System (INIS)
Castoldi, A.; Gatti, E.; Manzari, V.; Rehak, P.
1997-01-01
A study of the properties of silicon drift detectors in a magnetic field was carried out. A silicon drift detector with 41 anodes, providing unambiguous x and y position information, was used for measurements. Studies were done in three principal orientations of the detector relative to the direction of the magnetic field. The magnetic field was varied between 0 and 0.7 T and the drift field between 300 and 600 V/cm. Basic agreement with the theory of electron transport in semiconductors in a magnetic field was found. The transport properties of electrons in a magnetic field can be described by a mobility matrix. The components of the matrix depend on the electron mobility, Hall mobility and on the vector of the magnetic field. The precision of measurement was better than 0.2% for most of the parameters. For the electric field of a silicon drift detector, there is a first-order effect of the magnetic field only in one out of three principal directions. In this direction, the plane of the detector is perpendicular to the magnetic field and electrons drift at an angle α relative to the direction of the drift field. In two other principal directions, which are more important for tracking of the particles with drift detectors, there are no first-order magnetic effects. (orig.)
MAGNETIC FIELD MEASUREMENTS FOR FAST-CHANGING MAGNETIC FIELDS
International Nuclear Information System (INIS)
2004-01-01
Several recent applications for fast ramped magnets have been found that require rapid measurement of the field quality during the ramp. (In one instance, accelerator dipoles will be ramped at 1 T/sec, with measurements needed to the accuracy typically required for accelerators.) We have built and tested a new type of magnetic field measuring system to meet this need. The system consists of 16 stationary pickup windings mounted on a cylinder. The signals induced in the windings in a changing magnetic field are sampled and analyzed to obtain the field harmonics. To minimize costs, printed circuit boards were used for the pickup windings and a combination of amplifiers and ADPs used for the voltage readout system. New software was developed for the analysis. Magnetic field measurements of a model dipole developed for the SIS200 accelerator at GSI are presented. The measurements are needed to insure that eddy currents induced by the fast ramps do not impact the field quality needed for successful accelerator operation
Spin waves in terbium. III. Magnetic anisotropy at zero wave vector
DEFF Research Database (Denmark)
Houmann, Jens Christian Gylden; Jensen, J.; Touborg, P.
1975-01-01
The energy gap at zero wave vector in the spin-wave dispersion relation of ferromagnetic. Tb has been studied by inelastic neutron scattering. The energy was measured as a function of temperature and applied magnetic field, and the dynamic anisotropy parameters were deduced from the results...... the effects of zero-point deviations from the fully aligned ground state, and we tentatively propose polarization-dependent two-ion couplings as their origin........ The axial anisotropy is found to depend sensitively on the orientation of the magnetic moments in the basal plane. This behavior is shown to be a convincing indication of considerable two-ion contributions to the magnetic anisotropy at zero wave vector. With the exception of the sixfold basal...
Stable solutions of inflation driven by vector fields
Energy Technology Data Exchange (ETDEWEB)
Emami, Razieh [Institute for Advanced Study, The Hong Kong University of Science and Technology, Clear Water Bay, Kowloon (Hong Kong); Mukohyama, Shinji [Center for Gravitational Physics, Yukawa Institute for Theoretical Physics, Kyoto University, 606-8502, Kyoto (Japan); Namba, Ryo [Department of Physics, McGill University, Montréal, QC, H3A 2T8 (Canada); Zhang, Ying-li, E-mail: iasraziehm@ust.hk, E-mail: shinji.mukohyama@yukawa.kyoto-u.ac.jp, E-mail: namba@physics.mcgill.ca, E-mail: yingli@bao.ac.cn [National Astronomy Observatories, Chinese Academy of Science, Beijing 100012 (China)
2017-03-01
Many models of inflation driven by vector fields alone have been known to be plagued by pathological behaviors, namely ghost and/or gradient instabilities. In this work, we seek a new class of vector-driven inflationary models that evade all of the mentioned instabilities. We build our analysis on the Generalized Proca Theory with an extension to three vector fields to realize isotropic expansion. We obtain the conditions required for quasi de-Sitter solutions to be an attractor analogous to the standard slow-roll one and those for their stability at the level of linearized perturbations. Identifying the remedy to the existing unstable models, we provide a simple example and explicitly show its stability. This significantly broadens our knowledge on vector inflationary scenarios, reviving potential phenomenological interests for this class of models.
Stable solutions of inflation driven by vector fields
International Nuclear Information System (INIS)
Emami, Razieh; Mukohyama, Shinji; Namba, Ryo; Zhang, Ying-li
2017-01-01
Many models of inflation driven by vector fields alone have been known to be plagued by pathological behaviors, namely ghost and/or gradient instabilities. In this work, we seek a new class of vector-driven inflationary models that evade all of the mentioned instabilities. We build our analysis on the Generalized Proca Theory with an extension to three vector fields to realize isotropic expansion. We obtain the conditions required for quasi de-Sitter solutions to be an attractor analogous to the standard slow-roll one and those for their stability at the level of linearized perturbations. Identifying the remedy to the existing unstable models, we provide a simple example and explicitly show its stability. This significantly broadens our knowledge on vector inflationary scenarios, reviving potential phenomenological interests for this class of models.
Magnetic field effects in proteins
Jones, Alex R.
2016-06-01
Many animals can sense the geomagnetic field, which appears to aid in behaviours such as migration. The influence of man-made magnetic fields on biology, however, is potentially more sinister, with adverse health effects being claimed from exposure to fields from mobile phones or high voltage power lines. Do these phenomena have a common, biophysical origin, and is it even plausible that such weak fields can profoundly impact noisy biological systems? Radical pair intermediates are widespread in protein reaction mechanisms, and the radical pair mechanism has risen to prominence as perhaps the most plausible means by which even very weak fields might impact biology. In this New Views article, I will discuss the literature over the past 40 years that has investigated the topic of magnetic field effects in proteins. The lack of reproducible results has cast a shadow over the area. However, magnetic field and spin effects have proven to be useful mechanistic tools for radical mechanism in biology. Moreover, if a magnetic effect on a radical pair mechanism in a protein were to influence a biological system, the conditions necessary for it to do so appear increasing unlikely to have come about by chance.
Separation of magnetic field lines
International Nuclear Information System (INIS)
Boozer, Allen H.
2012-01-01
The field lines of magnetic fields that depend on three spatial coordinates are shown to have a fundamentally different behavior from those that depend on two coordinates. Unlike two-coordinate cases, a flux tube in a magnetic field that depends on all three spatial coordinates that has a circular cross section at one location along the tube characteristically has a highly distorted cross section at other locations. In an ideal evolution of a magnetic field, the current densities typically increase. Crudely stated, if the current densities increase by a factor σ, the ratio of the long to the short distance across a cross section of a flux tube characteristically increases by e 2σ , and the ratio of the longer distance to the initial radius increases as e σ . Electron inertia prevents a plasma from isolating two magnetic field structures on a distance scale shorter than c/ω pe , which is about 10 cm in the solar corona, and reconnection must be triggered if σ becomes sufficiently large. The radius of the sun, R ⊙ =7×10 10 cm is about e 23 times larger, so when σ≳23, two lines separated by c/ω pe at one location can be separated by the full scale of any magnetic structures in the corona at another. The conditions for achieving a large exponentiation, σ, are derived, and the importance of exponentiation is discussed.
Lasers plasmas and magnetic field
International Nuclear Information System (INIS)
Albertazzi, Bruno
2014-01-01
We studied the coupling between a laser produced plasmas and a magnetic field in two cases: 1) in the context of Inertial Fusion Confinement (ICF), we first studied how magnetic fields are self generated during the interaction between a target and a laser, then 2) to progress in the understanding of the large-scale shaping of astrophysical jets, we studied the influence of an externally applied magnetic field on the dynamics of a laser-produced plasma expanding into vacuum. The first part of this thesis is thus dedicated to a numerical and experimental study of the self generated magnetic fields that are produced following the irradiation of a solid target by a high power laser (having pulse duration in the nanosecond and picosecond regimes). These fields play an important role in the frame of ICF since they influence the dynamics of the electrons produced during the laser-matter interaction, and thus condition the success of ICF experiments. The second part of this thesis is a numerical and experimental study of the influence of an externally applied magnetic field on the morphology of a laser produced plasma freely otherwise expanding into vacuum. This work aims at better understanding the observed large-scale collimation of astrophysical jets which cannot be understood in the frame of existing models. We notably show that a purely axial magnetic field can force an initially isotropic laboratory flow, scaled to be representative of a flow emerging from a Young Star Object, in a re-collimation shock, from which emerges a narrow, well collimated jet. We also show that the plasma heating induced at the re-collimation point could explain the 'puzzling' observations of stationary X ray emission zones embedded within astrophysical jets. (author) [fr
Computation of Surface Integrals of Curl Vector Fields
Hu, Chenglie
2007-01-01
This article presents a way of computing a surface integral when the vector field of the integrand is a curl field. Presented in some advanced calculus textbooks such as [1], the technique, as the author experienced, is simple and applicable. The computation is based on Stokes' theorem in 3-space calculus, and thus provides not only a means to…
A Chargeless Complex Vector Matter Field in Supersymmetric Scenario
Directory of Open Access Journals (Sweden)
L. P. Colatto
2015-01-01
Full Text Available We construct and study a formulation of a chargeless complex vector matter field in a supersymmetric framework. To this aim we combine two nochiral scalar superfields in order to take the vector component field to build the chargeless complex vector superpartner where the respective field strength transforms into matter fields by a global U1 gauge symmetry. For the aim of dealing with consistent terms without breaking the global U1 symmetry we imposes a choice to the complex combination revealing a kind of symmetry between the choices and eliminates the extra degrees of freedom which is consistent with the supersymmetry. As the usual case the mass supersymmetric sector contributes as a complement to dynamics of the model. We obtain the equations of motion of the Proca’s type field for the chiral spinor fields and for the scalar field on the mass-shell which show the same mass as expected. This work establishes the first steps to extend the analysis of charged massive vector field in a supersymmetric scenario.
Indoor localization using magnetic fields
Pathapati Subbu, Kalyan Sasidhar
Indoor localization consists of locating oneself inside new buildings. GPS does not work indoors due to multipath reflection and signal blockage. WiFi based systems assume ubiquitous availability and infrastructure based systems require expensive installations, hence making indoor localization an open problem. This dissertation consists of solving the problem of indoor localization by thoroughly exploiting the indoor ambient magnetic fields comprising mainly of disturbances termed as anomalies in the Earth's magnetic field caused by pillars, doors and elevators in hallways which are ferromagnetic in nature. By observing uniqueness in magnetic signatures collected from different campus buildings, the work presents the identification of landmarks and guideposts from these signatures and further develops magnetic maps of buildings - all of which can be used to locate and navigate people indoors. To understand the reason behind these anomalies, first a comparison between the measured and model generated Earth's magnetic field is made, verifying the presence of a constant field without any disturbances. Then by modeling the magnetic field behavior of different pillars such as steel reinforced concrete, solid steel, and other structures like doors and elevators, the interaction of the Earth's field with the ferromagnetic fields is described thereby explaining the causes of the uniqueness in the signatures that comprise these disturbances. Next, by employing the dynamic time warping algorithm to account for time differences in signatures obtained from users walking at different speeds, an indoor localization application capable of classifying locations using the magnetic signatures is developed solely on the smart phone. The application required users to walk short distances of 3-6 m anywhere in hallway to be located with accuracies of 80-99%. The classification framework was further validated with over 90% accuracies using model generated magnetic signatures representing
Use of along-track magnetic field differences in lithospheric field modelling
DEFF Research Database (Denmark)
Kotsiaros, Stavros; Finlay, Chris; Olsen, Nils
2015-01-01
. Experiments in modelling the Earth's lithospheric magnetic field with along-track differences are presented here as a proof of concept. We anticipate that use of such along-track differences in combination with east–west field differences, as are now provided by the Swarm satellite constellation......We demonstrate that first differences of polar orbiting satellite magnetic data in the along-track direction can be used to obtain high resolution models of the lithospheric field. Along-track differences approximate the north–south magnetic field gradients for non-polar latitudes. In a test case......, using 2 yr of low altitude data from the CHAMP satellite, we show that use of along-track differences of vector field data results in an enhanced recovery of the small scale lithospheric field, compared to the use of the vector field data themselves. We show that the along-track technique performs...
Linearized interactions of scalar and vector fields with the higher spin field in AdSD
International Nuclear Information System (INIS)
Mkrtchyan, K.
2011-01-01
The explicit form of linearized gauge and generalized 'Weyl invariant' interactions of scalar and general higher even spin fields in the AdS D space is reviewed. Also a linearized interaction of vector field with general higher even spin gauge field is obtained. It is shown that the gauge-invariant action of linearized vector field interacting with the higher spin field also includes the whole tower of invariant actions for couplings of the same vector field with the gauge fields of smaller even spin
Popov, Aleksey
2013-04-01
The magnetic field of the Earth has global meaning for a life on the Earth. The world geophysical science explains: - occurrence of a magnetic field of the Earth it is transformation of kinetic energy of movements of the fused iron in the liquid core of Earth - into the magnetic energy; - the warming up of a kernel of the Earth occurs due to radioactive disintegration of elements, with excretion of thermal energy. The world science does not define the reasons: - drift of a magnetic dipole on 0,2 a year to the West; - drift of lithospheric slabs and continents. The author offers: an alternative variant existing in a world science the theories "Geodynamo" - it is the theory « the Magnetic field of the Earth », created on the basis of physical laws. Education of a magnetic field of the Earth occurs at moving the electric charge located in a liquid kernel, at rotation of the Earth. At calculation of a magnetic field is used law the Bio Savara for a ring electric current: dB = . Magnetic induction in a kernel of the Earth: B = 2,58 Gs. According to the law of electromagnetic induction the Faradey, rotation of a iron kernel of the Earth in magnetic field causes occurrence of an electric field Emf which moves electrons from the center of a kernel towards the mantle. So of arise the radial electric currents. The magnetic field amplifies the iron of mantle and a kernel of the Earth. As a result of action of a radial electric field the electrons will flow from the center of a kernel in a layer of an electric charge. The central part of a kernel represents the field with a positive electric charge, which creates inverse magnetic field Binv and Emfinv When ?mfinv = ?mf ; ?inv = B, there will be an inversion a magnetic field of the Earth. It is a fact: drift of a magnetic dipole of the Earth in the western direction approximately 0,2 longitude, into a year. Radial electric currents a actions with the basic magnetic field of a Earth - it turn a kernel. It coincides with laws
Magnetic field line reconnection experiments
International Nuclear Information System (INIS)
Gekelman, W.; Stenzel, R.L.; Wild, N.
1982-01-01
A laboratory experiment concerned with the basic physics of magnetic field line reconnection is discussed. Stimulated by important processes in space plasmas and anomalous transport in fusion plasmas the work addresses the following topics: Dynamic magnetic fields in a high beta plasma, magnetic turbulence, plasma dynamics and energy transport. First, the formation of magnetic neutral sheets, tearing and island coalescence are shown. Nonstationary magnetic fluctuations are statistically evaluated displaying the correlation tensor in the #betta#-k domain for mode identification. Then, the plasma properties are analyzed with particular emphasis on transport processes. Although the classical fluid flow across the separatrix can be observed, the fluctuation processes strongly modify the plasma dynamics. Direct measurements of the fluid force density and ion acceleration indicate the presence of an anomalous scattering process characterized by an effective scattering tensor. Turbulence also enhances the plasma resistivity by one to two orders of magnitude. Measurements of the three-dimensional electron distribution function using a novel energy analyzer exhibit the formation of runaway electrons in the current sheet. Associated micro-instabilities are observed. Finally, a macroscopic disruptive instability of the current sheet is observed. Excess magnetic field energy is converted at a double layer into particle kinetic energy and randomized through beam-plasma instabilities. These laboratory results are compared with related observations in space and fusion plasmas. (Auth.)
Isotope separation by magnetic fields
International Nuclear Information System (INIS)
Dawson, J.M.
1978-01-01
One of the isotopes of an element having several isotopes can be separated from the others in a dense, neutral plasma. Thus initially a neutral plasma is prepared including the element in question. This may consist of positive ions and negative electrons or alternatively of positive and negative ions, or else of a mixture of positive ions, negative ions and electrons. The plasma may then be injected into a magnetic field or may be generated in the field where more energy is imparted to a selected isotope than to the others. Finally, the isotopes are separated from each other on the basis of their differential energies. For example, the selected isotope may be given more energy than the others by stimulating it within the plasma at its resonant frequency which may be close to the cyclotron frequency, either by an electric field or by a magnetic field. In order to excite the other isotope, a different resonant frequency is required which depends on the plasma density, the relative concentration of electrons if the plasma contains electrons, the strength of the magnetic field, the ratio of charge to mass of the isotope, and possibly on the physical parameters of the plasma apparatus itself, such as the ratio of the length of the plasma column to its radius. The more energetic isotope may be separated by energy dependent chemical reactions, it may be collected by a positively biased probe or else the isotopes may be separated from each other by magnetic fields or in various other ways
Photographing magnetic fields in superconductors
International Nuclear Information System (INIS)
Harrison, R.B.; Wright, L.S.
Magneto-optic techniques coupled with high-speed photography are being used to study the destruction of superconductivity by a magnetic field. The phenomenon of superconductivity will be introduced with emphasis placed on the properties of type I and type II superconductors in a magnetic field. The Faraday effect and its application to the study of the penetration of magnetic fields into these superconductors will be described; the relative effectiveness of some types of paramagnetic glass will be demonstrated. A number of cinefilms will be shown to illustrate the versatility of the magneto-optic method for observing flux motion and patterns. The analysis of data obtained from a high speed film (10,200 fps) of a flux jump in Nb-Zr will be presented and discussed
Energy-momentum tensor of intermediate vector bosons in an external electromagnetic field
International Nuclear Information System (INIS)
Mostepanenko, V.M.; Sokolov, I.Yu.
1988-01-01
Expressions are obtained for the canonical and metric energy-momentum tensors of the vector field of intermediate bosons in an external electromagnetic field. It is shown that in the case of a gyromagnetic ratio not equal to unity the energy-momentum tensor cannot be symmetrized on its indices, and an additional term proportional to the anomalous magnetic moment appears in the conservation laws. A modification of the canonical formalism for scalar and vector fields in an external field is proposed in accordance with which the Hamiltonian density is equal to the 00 component of the energy-momentum tensor. An expression for the energy-momentum tensor of a closed system containing a gauge field of intermediate bosons and an electromagnetic field is obtained
Reconnection of magnetic field lines
International Nuclear Information System (INIS)
Heyn, M.F.; Gratton, F.T.; Gnavi, G.; Heindler, M.
1990-01-01
Magnetic field line diffusion in a plasma is studied on the basis of the non-linear boundary layer equations of dissipative, incompressible magnetohydrodynamics. Non-linear steady state solutions for a class of plasma parameters have been obtained which are consistent with the boundary conditions appropriate for reconnection. The solutions are self-consistent in connecting a stagnation point flow of a plasma with reconnecting magnetic field lines. The range of the validity of the solutions, their relation to other fluid models of reconnection, and their possible applications to space plasma configurations are pointed out. (Author)
Managing focal fields of vector beams with multiple polarization singularities.
Han, Lei; Liu, Sheng; Li, Peng; Zhang, Yi; Cheng, Huachao; Gan, Xuetao; Zhao, Jianlin
2016-11-10
We explore the tight focusing behavior of vector beams with multiple polarization singularities, and analyze the influences of the number, position, and topological charge of the singularities on the focal fields. It is found that the ellipticity of the local polarization states at the focal plane could be determined by the spatial distribution of the polarization singularities of the vector beam. When the spatial location and topological charge of singularities have even-fold rotation symmetry, the transverse fields at the focal plane are locally linearly polarized. Otherwise, the polarization state becomes a locally hybrid one. By appropriately arranging the distribution of the polarization singularities in the vector beam, the polarization distributions of the focal fields could be altered while the intensity maintains unchanged.
Center type performance of differentiable vector fields in R2
International Nuclear Information System (INIS)
Rabanal, Roland
2007-08-01
Let X : R 2 / D → R 2 be a differentiable vector field, where D is compact. If the eigenvalues of the jacobian matrix DX z are (nonzero) purely imaginary, for all z element of R 2 / D . Then, X + v has a center type performance at infinity, for some v element of R 2 . More precisely, X + v has a periodic trajectory Γ subset of R2/ D which is surrounding D such that in the unbounded component of (R 2 / D )/ Γ all the trajectories of X + v are nontrivial cycles. In the case of global vector fields Y : R 2 → R 2 with Y (0) = 0, we prove that such eigenvalue condition implies the topological equivalency of Y with the linear vector field (x, y) → (-y, x). (author)
Combinatorial vector fields and the valley structure of fitness landscapes.
Stadler, Bärbel M R; Stadler, Peter F
2010-12-01
Adaptive (downhill) walks are a computationally convenient way of analyzing the geometric structure of fitness landscapes. Their inherently stochastic nature has limited their mathematical analysis, however. Here we develop a framework that interprets adaptive walks as deterministic trajectories in combinatorial vector fields and in return associate these combinatorial vector fields with weights that measure their steepness across the landscape. We show that the combinatorial vector fields and their weights have a product structure that is governed by the neutrality of the landscape. This product structure makes practical computations feasible. The framework presented here also provides an alternative, and mathematically more convenient, way of defining notions of valleys, saddle points, and barriers in landscape. As an application, we propose a refined approximation for transition rates between macrostates that are associated with the valleys of the landscape.
The Lie Bracket of Adapted Vector Fields on Wiener Spaces
International Nuclear Information System (INIS)
Driver, B. K.
1999-01-01
Let W(M) be the based (at o element of M) path space of a compact Riemannian manifold M equipped with Wiener measure ν . This paper is devoted to considering vector fields on W(M) of the form X s h (σ )=P s (σ)h s (σ ) where P s (σ ) denotes stochastic parallel translation up to time s along a Wiener path σ element of W(M) and {h s } i sanelementof [0,1] is an adapted T o M -valued process on W(M). It is shown that there is a large class of processes h (called adapted vector fields) for which we may view X h as first-order differential operators acting on functions on W(M) . Moreover, if h and k are two such processes, then the commutator of X h with X k is again a vector field on W(M) of the same form
Sun, J.; Li, Y.
2017-12-01
Magnetic data contain important information about the subsurface rocks that were magnetized in the geological history, which provides an important avenue to the study of the crustal heterogeneities associated with magmatic and hydrothermal activities. Interpretation of magnetic data has been widely used in mineral exploration, basement characterization and large scale crustal studies for several decades. However, interpreting magnetic data has been often complicated by the presence of remanent magnetizations with unknown magnetization directions. Researchers have developed different methods to deal with the challenges posed by remanence. We have developed a new and effective approach to inverting magnetic data for magnetization vector distributions characterized by region-wise consistency in the magnetization directions. This approach combines the classical Tikhonov inversion scheme with fuzzy C-means clustering algorithm, and constrains the estimated magnetization vectors to a specified small number of possible directions while fitting the observed magnetic data to within noise level. Our magnetization vector inversion recovers both the magnitudes and the directions of the magnetizations in the subsurface. Magnetization directions reflect the unique geological or hydrothermal processes applied to each geological unit, and therefore, can potentially be used for the purpose of differentiating various geological units. We have developed a practically convenient and effective way of assessing the uncertainty associated with the inverted magnetization directions (Figure 1), and investigated how geological differentiation results might be affected (Figure 2). The algorithm and procedures we have developed for magnetization vector inversion and uncertainty analysis open up new possibilities of extracting useful information from magnetic data affected by remanence. We will use a field data example from exploration of an iron-oxide-copper-gold (IOCG) deposit in Brazil to
Motions and solar magnetic fields
Energy Technology Data Exchange (ETDEWEB)
Krat, V A [AN SSSR, Leningrad. Glavnaya Astronomicheskaya Observatoriya
1977-02-01
Fine structure of magnetic fields in the Sun has been investigated. The data of the Soviet solar stratospheric observatory (SSO) with the telescope with a mirror first of 50 and then 100 cm in diameter obtained for the period of 1970-1973 served as material for research. The experiments give evidence of the presence of photospheric granulation with the characteristic dimension of granules below 150 km. The angular resolution of instruments does not make it possible to realize direct measurements of magnetic fields of such sizes. The indirect estimates indicate the fact that the magnetic fields of photosphere cannot be less than 10/sup 2/ Oe. A comparison of Hsub(..cap alpha..) lines with lines of metals and with the continuous spectrum shows that the least dimensions of chromosphere elements account for 500 km. Since in chromosphere density decreases drastically, than in order to suppress hydrodynamic flows fields should be of the order of 10/sup 3/ Oe. It has been concluded that the problem of the origin and evolution of the magnetic field of the Sun should be also solved by applying data on other stars.
DEFF Research Database (Denmark)
Madsen, Kristoffer Hougaard; Ewald, Lars; Siebner, Hartwig R.
2015-01-01
Background: Field calculations for transcranial magnetic stimulation (TMS) are increasingly implemented online in neuronavigation systems and in more realistic offline approaches based on finite-element methods. They are often based on simplified and/or non-validated models of the magnetic vector...... potential of the TMS coils. Objective: To develop an approach to reconstruct the magnetic vector potential based on automated measurements. Methods: We implemented a setup that simultaneously measures the three components of the magnetic field with high spatial resolution. This is complemented by a novel...... approach to determine the magnetic vector potential via volume integration of the measured field. Results: The integration approach reproduces the vector potential with very good accuracy. The vector potential distribution of a standard figure-of-eight shaped coil determined with our setup corresponds well...
DC corona discharge ozone production enhanced by magnetic field
Pekárek, S.
2010-01-01
We have studied the effect of a stationary magnetic field on the production of ozone from air at atmospheric pressure by a negative corona discharge in a cylindrical electrode configuration. We used a stainless steel hollow needle placed at the axis of the cylindrical discharge chamber as a cathode. The outer wall of the cylinder was used as an anode. The vector of magnetic induction was perpendicular to the vector of current density. We found that: (a) the magnetic field extends the current voltage range of the discharge; (b) for the discharge in the Trichel pulses regime and in the pulseless glow regime, the magnetic field has no substantial effect on the discharge voltage or on the concentration of ozone that is produced; (c) for the discharge in the filamentary streamer regime for a particular current, the magnetic field increases the discharge voltage and consequently an approximately 30% higher ozone concentration can be obtained; (d) the magnetic field does not substantially increase the maximum ozone production yield. A major advantage of using a magnetic field is that the increase in ozone concentration produced by the discharge can be obtained without additional energy requirements.
DEFF Research Database (Denmark)
Kother, Livia Kathleen; Hammer, Magnus Danel; Finlay, Chris
. Advantages of the equivalent source method include its local nature and the ease of transforming to spherical harmonics when needed. The method can also be applied in local, high resolution, investigations of the lithospheric magnetic field, for example where suitable aeromagnetic data is available......We present a technique for modelling the lithospheric magnetic field based on estimation of equivalent potential field sources. As a first demonstration we present an application to magnetic field measurements made by the CHAMP satellite during the period 2009-2010. Three component vector field...... for the remaining lithospheric magnetic field consists of magnetic point sources (monopoles) arranged in an icosahedron grid with an increasing grid resolution towards the airborne survey area. The corresponding source values are estimated using an iteratively reweighted least squares algorithm that includes model...
The local structure of a Liouville vector field
International Nuclear Information System (INIS)
Ciriza, E.
1990-05-01
In this work we investigate the local structure of a Liouville vector field ξ of a Kaehler manifold (P,Ω) which vanishes on an isotropic submanifold Q of P. Some of the eigenvalues of its linear part at the singular points are zero and the remaining ones are in resonance. We show that there is a C 1 -smooth linearizing conjugation between the Liouville vector field ξ and its linear part. To do this we construct Darboux coordinates adapted to the unstable foliation which is provided by the Centre Manifold Theorem. We then apply recent linearization results due to G. Sell. (author). 11 refs
Generalized Proca action for an Abelian vector field
International Nuclear Information System (INIS)
Allys, Erwan; Peter, Patrick; Rodríguez, Yeinzon
2016-01-01
We revisit the most general theory for a massive vector field with derivative self-interactions, extending previous works on the subject to account for terms having trivial total derivative interactions for the longitudinal mode. In the flat spacetime (Minkowski) case, we obtain all the possible terms containing products of up to five first-order derivatives of the vector field, and provide a conjecture about higher-order terms. Rendering the metric dynamical, we covariantize the results and add all possible terms implying curvature
The analysis of the permanent magnet motor using the new magnetic field analysis
International Nuclear Information System (INIS)
Shimoji, Hiroyasu; Enokizono, Masato; Todaka, Takashi
2002-01-01
In this paper iron loss analysis of the permanent magnet motor considering anisotropy of magnetic material is carried out. Recently the magnetic material can be measured using of vector quantity technique. Non-oriented silicon steel sheets for the iron core material have the anisotropy. Therefore, it is necessary to carry out the analysis considering the anisotropy of the magnetic material. We used the magnetic field analysis, which consider the anisotropy by combining finite element method with the E and S (Enokizono and Soda) modeling. (Author)
ATLAS cavern magnetic field calculations
International Nuclear Information System (INIS)
Vorojtsov, S.B.; Vorozhtsov, A.S.; Butin, F.; Price, M.
2000-01-01
A new approach has been adopted in an attempt to produce a complete ATLAS cavern B-field map using a more precise methodological approach (variable magnetisation, depending on the external field) and the latest design taking into account of the structural elements. The basic idea was to produce a dedicated basic TOSCA model and then to insert a series of ferromagnetic structure elements to monitor the perturbative effect on the basic field map. Eventually, it was found: the bedplate field perturbation is an order of magnitude above the permissible level; manufacturing of the bedplates from nonmagnetic material or careful evaluation of their field contribution in the event reconstruction codes is required; the field value at the rack positions is higher than the permissible one; the final position of racks should be chosen taking into account the detailed magnetic field distribution
Vector fields in a tight laser focus: comparison of models.
Peatross, Justin; Berrondo, Manuel; Smith, Dallas; Ware, Michael
2017-06-26
We assess several widely used vector models of a Gaussian laser beam in the context of more accurate vector diffraction integration. For the analysis, we present a streamlined derivation of the vector fields of a uniformly polarized beam reflected from an ideal parabolic mirror, both inside and outside of the resulting focus. This exact solution to Maxwell's equations, first developed in 1920 by V. S. Ignatovsky, is highly relevant to high-intensity laser experiments since the boundary conditions at a focusing optic dictate the form of the focus in a manner analogous to a physical experiment. In contrast, many models simply assume a field profile near the focus and develop the surrounding vector fields consistent with Maxwell's equations. In comparing the Ignatovsky result with popular closed-form analytic vector models of a Gaussian beam, we find that the relatively simple model developed by Erikson and Singh in 1994 provides good agreement in the paraxial limit. Models involving a Lax expansion introduce a divergences outside of the focus while providing little if any improvement in the focal region. Extremely tight focusing produces a somewhat complicated structure in the focus, and requires the Ignatovsky model for accurate representation.
Vector field statistical analysis of kinematic and force trajectories.
Pataky, Todd C; Robinson, Mark A; Vanrenterghem, Jos
2013-09-27
When investigating the dynamics of three-dimensional multi-body biomechanical systems it is often difficult to derive spatiotemporally directed predictions regarding experimentally induced effects. A paradigm of 'non-directed' hypothesis testing has emerged in the literature as a result. Non-directed analyses typically consist of ad hoc scalar extraction, an approach which substantially simplifies the original, highly multivariate datasets (many time points, many vector components). This paper describes a commensurately multivariate method as an alternative to scalar extraction. The method, called 'statistical parametric mapping' (SPM), uses random field theory to objectively identify field regions which co-vary significantly with the experimental design. We compared SPM to scalar extraction by re-analyzing three publicly available datasets: 3D knee kinematics, a ten-muscle force system, and 3D ground reaction forces. Scalar extraction was found to bias the analyses of all three datasets by failing to consider sufficient portions of the dataset, and/or by failing to consider covariance amongst vector components. SPM overcame both problems by conducting hypothesis testing at the (massively multivariate) vector trajectory level, with random field corrections simultaneously accounting for temporal correlation and vector covariance. While SPM has been widely demonstrated to be effective for analyzing 3D scalar fields, the current results are the first to demonstrate its effectiveness for 1D vector field analysis. It was concluded that SPM offers a generalized, statistically comprehensive solution to scalar extraction's over-simplification of vector trajectories, thereby making it useful for objectively guiding analyses of complex biomechanical systems. © 2013 Published by Elsevier Ltd. All rights reserved.
Accurate magnetic field calculations for contactless energy transfer coils
Sonntag, C.L.W.; Spree, M.; Lomonova, E.A.; Duarte, J.L.; Vandenput, A.J.A.
2007-01-01
In this paper, a method for estimating the magnetic field intensity from hexagon spiral windings commonly found in contactless energy transfer applications is presented. The hexagonal structures are modeled in a magneto-static environment using Biot-Savart current stick vectors. The accuracy of the
Spacecraft attitude determination using the earth's magnetic field
Simpson, David G.
1989-01-01
A method is presented by which the attitude of a low-Earth orbiting spacecraft may be determined using a vector magnetometer, a digital Sun sensor, and a mathematical model of the Earth's magnetic field. The method is currently being implemented for the Solar Maximum Mission spacecraft (as a backup for the failing star trackers) as a way to determine roll gyro drift.
Method and means for measuring the anisotropy of a plasma in a magnetic field
Shohet, J.L.; Greene, D.G.S.
1973-10-23
Anisotropy is measured of a free-free-bremsstrahlungradiation-generating plasma in a magnetic field by collimating the free-free bremsstrahlung radiation in a direction normal to the magnetic field and scattering the collimated free- free bremsstrahlung radiation to resolve the radiation into its vector components in a plane parallel to the electric field of the bremsstrahlung radiation. The scattered vector components are counted at particular energy levels in a direction parallel to the magnetic field and also normal to the magnetic field of the plasma to provide a measure of anisotropy of the plasma. (Official Gazette)
A filament supported by different magnetic field configurations
Guo, Y.; Schmieder, B.; Démoulin, P.; Wiegelmann, T.; Aulanier, G.; Török, T.; Bommier, V.
2011-08-01
A nonlinear force-free magnetic field extrapolation of vector magnetogram data obtained by THEMIS/MTR on 2005 May 27 suggests the simultaneous existence of different magnetic configurations within one active region filament: one part of the filament is supported by field line dips within a flux rope, while the other part is located in dips within an arcade structure. Although the axial field chirality (dextral) and the magnetic helicity (negative) are the same along the whole filament, the chiralities of the filament barbs at different sections are opposite, i.e., right-bearing in the flux rope part and left-bearing in the arcade part. This argues against past suggestions that different barb chiralities imply different signs of helicity of the underlying magnetic field. This new finding about the chirality of filaments will be useful to associate eruptive filaments and magnetic cloud using the helicity parameter in the Space Weather Science.
Behaviour of a neutral particle with spin in an axial magnetic field
International Nuclear Information System (INIS)
Sorokin, S.V.; Ehpp, V.Ya.
1982-01-01
Proceeding from the Tamm-Good equation taking into account the spin influence on motion trajectory, the neutral particle motion tracjectory and vector turn of spin polarizition in axial magnetic field have been found. The behaviour of a neutral particle possessing its own magnetic moment in an axially-symmetric stationary magnetic field is considered
The reversal of the Sun's magnetic field in cycle 24
Mordvinov, Alexander V.; Pevtsov, Alexei A.; Bertello, Luca; Petrie, Gordon J. D.
2016-01-01
Analysis of synoptic data from the Vector Stokes Magnetograph (VSM) of the Synoptic Optical Long-term Investigations of the Sun (SOLIS) and the NASA/NSO Spectromagnetograph (SPM) at the NSO/Kitt Peak Vacuum Telescope facility shows that the reversals of solar polar magnetic fields exhibit elements of a stochastic process, which may include the development of specific patterns of emerging magnetic flux, and the asymmetry in activity between northern and southern hemispheres. The presence of su...
Wigner functions for fermions in strong magnetic fields
Sheng, Xin-li; Rischke, Dirk H.; Vasak, David; Wang, Qun
2018-02-01
We compute the covariant Wigner function for spin-(1/2) fermions in an arbitrarily strong magnetic field by exactly solving the Dirac equation at non-zero fermion-number and chiral-charge densities. The Landau energy levels as well as a set of orthonormal eigenfunctions are found as solutions of the Dirac equation. With these orthonormal eigenfunctions we construct the fermion field operators and the corresponding Wigner-function operator. The Wigner function is obtained by taking the ensemble average of the Wigner-function operator in global thermodynamical equilibrium, i.e., at constant temperature T and non-zero fermion-number and chiral-charge chemical potentials μ and μ_5, respectively. Extracting the vector and axial-vector components of the Wigner function, we reproduce the currents of the chiral magnetic and separation effect in an arbitrarily strong magnetic field.
Transitive Lie algebras of vector fields: an overview
Draisma, J.
2011-01-01
This overview paper is intended as a quick introduction to Lie algebras of vector fields. Originally introduced in the late 19th century by Sophus Lie to capture symmetries of ordinary differential equations, these algebras, or infinitesimal groups, are a recurring theme in 20th-century research on
Interactive exploratory visualization of 2D vector fields
Isenberg, Tobias; Everts, Maarten H.; Grubert, Jens; Carpendale, Sheelagh
In this paper we present several techniques to interactively explore representations of 2D vector fields. Through a set of simple hand postures used on large, touch-sensitive displays, our approach allows individuals to custom design glyphs (arrows, lines, etc.) that best reveal patterns of the
Desingularization strategies for three-dimensional vector fields
Torres, Felipe Cano
1987-01-01
For a vector field #3, where Ai are series in X, the algebraic multiplicity measures the singularity at the origin. In this research monograph several strategies are given to make the algebraic multiplicity of a three-dimensional vector field decrease, by means of permissible blowing-ups of the ambient space, i.e. transformations of the type xi=x'ix1, 2s. A logarithmic point of view is taken, marking the exceptional divisor of each blowing-up and by considering only the vector fields which are tangent to this divisor, instead of the whole tangent sheaf. The first part of the book is devoted to the logarithmic background and to the permissible blowing-ups. The main part corresponds to the control of the algorithms for the desingularization strategies by means of numerical invariants inspired by Hironaka's characteristic polygon. Only basic knowledge of local algebra and algebraic geometry is assumed of the reader. The pathologies we find in the reduction of vector fields are analogous to pathologies in the pro...
Galactic and intergalactic magnetic fields
Klein, Ulrich
2014-01-01
This course-tested textbook conveys the fundamentals of magnetic fields and relativistic plasma in diffuse cosmic media, with a primary focus on phenomena that have been observed at different wavelengths. Theoretical concepts are addressed wherever necessary, with derivations presented in sufficient detail to be generally accessible.In the first few chapters the authors present an introduction to various astrophysical phenomena related to cosmic magnetism, with scales ranging from molecular clouds in star-forming regions and supernova remnants in the Milky Way, to clusters of galaxies. Later c
Electron dynamics in inhomogeneous magnetic fields
Energy Technology Data Exchange (ETDEWEB)
Nogaret, Alain, E-mail: A.R.Nogaret@bath.ac.u [Department of Physics, University of Bath, Bath BA2 7AY (United Kingdom)
2010-06-30
This review explores the dynamics of two-dimensional electrons in magnetic potentials that vary on scales smaller than the mean free path. The physics of microscopically inhomogeneous magnetic fields relates to important fundamental problems in the fractional quantum Hall effect, superconductivity, spintronics and graphene physics and spins out promising applications which will be described here. After introducing the initial work done on electron localization in random magnetic fields, the experimental methods for fabricating magnetic potentials are presented. Drift-diffusion phenomena are then described, which include commensurability oscillations, magnetic channelling, resistance resonance effects and magnetic dots. We then review quantum phenomena in magnetic potentials including magnetic quantum wires, magnetic minibands in superlattices, rectification by snake states, quantum tunnelling and Klein tunnelling. The third part is devoted to spintronics in inhomogeneous magnetic fields. This covers spin filtering by magnetic field gradients and circular magnetic fields, electrically induced spin resonance, spin resonance fluorescence and coherent spin manipulation. (topical review)
Exchange coupling in hybrid anisotropy magnetic multilayers quantified by vector magnetometry
Energy Technology Data Exchange (ETDEWEB)
Morrison, C., E-mail: C.Morrison.2@warwick.ac.uk; Miles, J. J.; Thomson, T. [School of Computer Science, University of Manchester, Manchester M13 9PL (United Kingdom); Anh Nguyen, T. N. [Materials Physics, School of ICT, KTH Royal Institute of Technology, Electrum 229, 164 40 Kista (Sweden); Spintronics Research Group, Laboratory for Nanotechnology (LNT), VNU-HCM, Ho Chi Minh City (Viet Nam); Fang, Y.; Dumas, R. K. [Department of Physics, University of Gothenburg, 412 96 Gothenburg (Sweden); Åkerman, J. [Materials Physics, School of ICT, KTH Royal Institute of Technology, Electrum 229, 164 40 Kista (Sweden); Department of Physics, University of Gothenburg, 412 96 Gothenburg (Sweden)
2015-05-07
Hybrid anisotropy thin film heterostructures, where layers with perpendicular and in-plane anisotropy are separated by a thin spacer, are novel materials for zero/low field spin torque oscillators and bit patterned media. Here, we report on magnetization reversal and exchange coupling in a archetypal Co/Pd (perpendicular)-NiFe (in-plane) hybrid anisotropy system studied using vector vibrating sample magnetometry. This technique allows us to quantify the magnetization reversal in each individual magnetic layer, and measure of the interlayer exchange as a function of non-magnetic spacer thickness. At large (>1 nm) spacer thicknesses Ruderman-Kittel-Kasuya-Yosida-like exchange dominates, with orange-peel coupling providing a significant contribution only for sub-nm spacer thickness.
RESICALC: Magnetic field modeling program
International Nuclear Information System (INIS)
Silva, J.M.
1992-12-01
RESICALC, Version 1.0, is a Microsoft Windows application that describes the magnetic field environment produced by user-defined arrays of transmission lines, distribution lines, and custom conductors. These arrays simulate specific situations that may be encountered in real-world community settings. RESICALC allows the user to define an area or ''world'' that contains the transmission and/or distribution lines, user-defined conductors, and locations of residences. The world contains a ''reference grid'' within which RESICALC analyzes the magnetic field environment due to all conductors within the world. Unique physical parameters (e.g., conductor height and spacing) and operating characteristics can be assigned to all electrical conductors. RESICALC's output is available for the x, y, z axis separately, the resultant (the three axes added in quadrature), and the major axis, each in three possible formats: a three-dimensional map of the magnetic field, two dimensional-contours, and as a table with statistical values. All formats may be printed, accompanied by a three-dimensional view of the world the user has drawn. The view of the world and the corresponding three-dimensional field map may be adjusted to the elevation and rotation angle of the user's preference
Off disk-center potential field calculations using vector magnetograms
Venkatakrishnan, P.; Gary, G. Allen
1989-01-01
A potential field calculation for off disk-center vector magnetograms that uses all the three components of the measured field is investigated. There is neither any need for interpolation of grid points between the image plane and the heliographic plane nor for an extension or a truncation to a heliographic rectangle. Hence, the method provides the maximum information content from the photospheric field as well as the most consistent potential field independent of the viewing angle. The introduction of polarimetric noise produces a less tolerant extrapolation procedure than using the line-of-sight extrapolation, but the resultant standard deviation is still small enough for the practical utility of this method.
The process γγ → νν-bar in a strong magnetic field
International Nuclear Information System (INIS)
Kuznetsov, A.V.; Mikheev, N.V.; Rumyantsev, D.A.
2003-01-01
A general analysis of the three-vertex loop amplitude in a strong magnetic field, based on the asymptotic form of the electron propagator in the field, is performed. In order to investigate the photon-neutrino process γγ → νν-bar, the vertex combinations of the scalar-vector-vector (SVV), pseudoscalar- vector-vector (PVV), 3-vector (VVV), and axial-vector-vector (AVV) types are considered. It is shown that only the SVV amplitude grows linearly with the magnetic-field strength, while in the other amplitudes, PVV, VVV, and AVV, the linearly growing terms are cancelled. The process γγ → νν-bar is investigated in the left-right-symmetric extension of the standard model of electroweak interaction, where the effective scalar ννee coupling could exist. Possible astrophysical manifestations of the considered process are discussed [ru
Triaxial fiber optic magnetic field sensor for MRI applications
Filograno, Massimo L.; Pisco, Marco; Catalano, Angelo; Forte, Ernesto; Aiello, Marco; Soricelli, Andrea; Davino, Daniele; Visone, Ciro; Cutolo, Antonello; Cusano, Andrea
2016-05-01
In this paper, we report a fiber-optic triaxial magnetic field sensor, based on Fiber Bragg Gratings (FBGs) integrated with giant magnetostrictive material, the Terfenol-D. The realized sensor has been designed and engineered for Magnetic Resonance Imaging (MRI) applications. A full magneto-optical characterization of the triaxial sensing probe has been carried out, providing the complex relationship among the FBGs wavelength shift and the applied magnetostatic field vector. Finally, the developed fiber optic sensors have been arranged in a sensor network composed of 20 triaxial sensors for mapping the magnetic field distribution in a MRI-room at a diagnostic center in Naples (SDN), equipped with Positron emission tomography/magnetic resonance (PET/MR) instrumentation. Experimental results reveal that the proposed sensor network can be efficiently used in MRI centers for performing quality assurance tests, paving the way for novel integrated tools to measure the magnetic dose accumulated day by day by MRI operators.
Generation of magnetic fields for accelerators with permanent magnets
International Nuclear Information System (INIS)
Meinander, T.
1994-01-01
Commercially available permanent magnet materials and their properties are reviewed. Advantages and disadvantages of using permanent magnets as compared to electromagnets for the generation of specific magnetic fields are discussed. Basic permanent magnet configurations in multipole magnets and insertion devices are presented. (orig.)
Magnetic fluid bridge in a non-uniform magnetic field
International Nuclear Information System (INIS)
Pelevina, D.A.; Naletova, V.A.; Turkov, V.A.
2017-01-01
The shape of a magnetic fluid bridge between a horizontal ferrite rod of circular cross-section and a horizontal plate above the rod in a vertical applied uniform magnetic field is studied. Various static shapes of the bridges are obtained theoretically and experimentally for the same magnetic field value. Abrupt changes and the hysteresis of the bridge shape in alternating magnetic fields are observed experimentally. - Highlights: • Magnetic fluid bridge between rod and horizontal plate in magnetic field is studied. • Magnetic field is created by a ferrite rod in a uniform vertical magnetic field. • Various static bridge shapes for fixed field are obtained in theory and experiment. • A good agreement of experimental and theoretical results is obtained. • Hysteresis of the bridge shape in alternating field is observed experimentally.
Establishment of magnetic coordinates for a given magnetic field
International Nuclear Information System (INIS)
Boozer, A.H.
1981-04-01
A method is given for expressing the magnetic field strength in magnetic coordinates for a given field. This expression is central to the study of equilibrium, stability, and transport in asymmetric plasmas
Magnetic fluid bridge in a non-uniform magnetic field
Energy Technology Data Exchange (ETDEWEB)
Pelevina, D.A., E-mail: pelevina.daria@gmail.com; Naletova, V.A.; Turkov, V.A.
2017-06-01
The shape of a magnetic fluid bridge between a horizontal ferrite rod of circular cross-section and a horizontal plate above the rod in a vertical applied uniform magnetic field is studied. Various static shapes of the bridges are obtained theoretically and experimentally for the same magnetic field value. Abrupt changes and the hysteresis of the bridge shape in alternating magnetic fields are observed experimentally. - Highlights: • Magnetic fluid bridge between rod and horizontal plate in magnetic field is studied. • Magnetic field is created by a ferrite rod in a uniform vertical magnetic field. • Various static bridge shapes for fixed field are obtained in theory and experiment. • A good agreement of experimental and theoretical results is obtained. • Hysteresis of the bridge shape in alternating field is observed experimentally.
Field errors in superconducting magnets
International Nuclear Information System (INIS)
Barton, M.Q.
1982-01-01
The mission of this workshop is a discussion of the techniques for tracking particles through arbitrary accelerator field configurations to look for dynamical effects that are suggested by various theoretical models but are not amenable to detailed analysis. A major motivation for this type of study is that many of our accelerator projects are based on the use of superconducting magnets which have field imperfections that are larger and of a more complex nature than those of conventional magnets. Questions such as resonances, uncorrectable closed orbit effects, coupling between planes, and diffusion mechanisms all assume new importance. Since, simultaneously, we are trying to do sophisticated beam manipulations such as stacking, high current accelerator, long life storage, and low loss extraction, we clearly need efficient and accurate tracking programs to proceed with confidence
Magnetic Fields of Neutron Stars
Indian Academy of Sciences (India)
Sushan Konar
2017-09-12
Sep 12, 2017 ... the material properties of the region where currents supporting the .... 1The evolution of magnetic field in neutron stars, in particular, the question of .... −10, 10. −9, 10. −8. M⊙/yr respec- tively. See Konar & Bhattacharya (1997) for details. Peq ≃ 1.9 ms ..... ported by a grant (SR/WOS-A/PM-1038/2014) from.
Measurement of 2D vector magnetic properties under the distorted flux density conditions
International Nuclear Information System (INIS)
Urata, Shinya; Todaka, Takashi; Enokizono, Masato; Maeda, Yoshitaka; Shimoji, Hiroyasu
2006-01-01
Under distorted flux density condition, it is very difficult to evaluate the field intensity, because there is no criterion for the measurement. In the linear approximation, the measured field intensity waveform (MFI) is compared with the linear synthesis of field intensity waveform (LSFI) in each frequency, and it is shown that they are not in good agreement at higher induction. In this paper, we examined the 2D vector magnetic properties excited by distorted flux density, which consists of the 1st (fundamental frequency: 50 Hz), 3rd, and 5th harmonics. Improved linear synthesis of the field intensity waveform (ILSFI) is proposed as a new estimation method of the field intensity, instead of the conventional linear synthesis of field intensity waveform (LSFI). The usefulness of the proposed ILSFI is demonstrated in the comparison with the measured results
Measurement of 2D vector magnetic properties under the distorted flux density conditions
Energy Technology Data Exchange (ETDEWEB)
Urata, Shinya [Department of Electrical and Electronic Engineering, Faculty of Engineering, Oita University, 700 Dannoharu, Oita 870-1192 (Japan)]. E-mail: urata@mag.eee.oita-u.ac.jp; Todaka, Takashi [Department of Electrical and Electronic Engineering, Faculty of Engineering, Oita University, 700 Dannoharu, Oita 870-1192 (Japan); Enokizono, Masato [Department of Electrical and Electronic Engineering, Faculty of Engineering, Oita University, 700 Dannoharu, Oita 870-1192 (Japan); Maeda, Yoshitaka [Department of Electrical and Electronic Engineering, Faculty of Engineering, Oita University, 700 Dannoharu, Oita 870-1192 (Japan); Shimoji, Hiroyasu [Department of Electrical and Electronic Engineering, Faculty of Engineering, Oita University, 700 Dannoharu, Oita 870-1192 (Japan)
2006-09-15
Under distorted flux density condition, it is very difficult to evaluate the field intensity, because there is no criterion for the measurement. In the linear approximation, the measured field intensity waveform (MFI) is compared with the linear synthesis of field intensity waveform (LSFI) in each frequency, and it is shown that they are not in good agreement at higher induction. In this paper, we examined the 2D vector magnetic properties excited by distorted flux density, which consists of the 1st (fundamental frequency: 50 Hz), 3rd, and 5th harmonics. Improved linear synthesis of the field intensity waveform (ILSFI) is proposed as a new estimation method of the field intensity, instead of the conventional linear synthesis of field intensity waveform (LSFI). The usefulness of the proposed ILSFI is demonstrated in the comparison with the measured results.
The interplanetary magnetic field observed by Juno enroute to Jupiter
Gruesbeck, Jacob R.; Gershman, Daniel J.; Espley, Jared R.; Connerney, John E. P.
2017-06-01
The Juno spacecraft was launched on 5 August 2011 and spent nearly 5 years traveling through the inner heliosphere on its way to Jupiter. The Magnetic Field Investigation was powered on shortly after launch and obtained vector measurements of the interplanetary magnetic field (IMF) at sample rates from 1 to 64 samples/second. The evolution of the magnetic field with radial distance from the Sun is compared to similar observations obtained by Voyager 1 and 2 and the Ulysses spacecraft, allowing a comparison of the radial evolution between prior solar cycles and the current depressed one. During the current solar cycle, the strength of the IMF has decreased throughout the inner heliosphere. A comparison of the variance of the normal component of the magnetic field shows that near Earth the variability of the IMF is similar during all three solar cycles but may be less at greater radial distances.
Properties of a Bound Polaron under a Perpendicular Magnetic Field
International Nuclear Information System (INIS)
Liu Jia; Chen Ziyu; Xiao Jinglin; Huo Shufen
2007-01-01
We investigate the influence of a perpendicular magnetic field on a bound polaron near the interface of a polar-polar semiconductor with Rashba effect. The external magnetic field strongly changes the ground state binding energy of the polaron and the Rashba spin-orbit (SO) interaction originating from the inversion asymmetry in the heterostructure splits the ground state binding energy of the bound polaron. In this paper, we have shown how the ground state binding energy will be with the change of the external magnetic field, the location of a single impurity, the wave vector of the electron and the electron areal density, taking into account the SO coupling. Due to the presence of the phonons, whose energy gives negative contribution to the polaron's, the spin-splitting states of the bound polaron are more stable, and we find that in the condition of week magnetic field, the Zeeaman effect can be neglected.
The Interplanetary Magnetic Field Observed by Juno Enroute to Jupiter
Gruesbeck, Jacob R.; Gershman, Daniel J.; Espley, Jared R.; Connerney, John E. P.
2017-01-01
The Juno spacecraft was launched on 5 August 2011 and spent nearly 5 years traveling through the inner heliosphere on its way to Jupiter. The Magnetic Field Investigation was powered on shortly after launch and obtained vector measurements of the interplanetary magnetic field (IMF) at sample rates from 1 to 64 samples/second. The evolution of the magnetic field with radial distance from the Sun is compared to similar observations obtained by Voyager 1 and 2 and the Ulysses spacecraft, allowing a comparison of the radial evolution between prior solar cycles and the current depressed one. During the current solar cycle, the strength of the IMF has decreased throughout the inner heliosphere. A comparison of the variance of the normal component of the magnetic field shows that near Earth the variability of the IMF is similar during all three solar cycles but may be less at greater radial distances.
Periodical plasma structures controlled by external magnetic field
Schweigert, I. V.; Keidar, M.
2017-11-01
The plasma of Hall thruster type in external magnetic field is studied in 2D3V kinetic simulations using PIC MCC method. The periodical structure with maxima of electron and ion densities is formed and becomes more pronounced with increase of magnetic field incidence angle in the plasma. These ridges of electron and ion densities are aligned with the magnetic field vector and shifted relative each other. This leads to formation of two-dimensional double-layers structure in cylindrical plasma chamber. Depending on Larmor radius and Debye length up to nineteen potential steps appear across the oblique magnetic field. The electrical current gathered on the wall is associated with the electron and ion density ridges.
Linear optical response of carbon nanotubes under axial magnetic field
Moradian, Rostam; Chegel, Raad; Behzad, Somayeh
2010-04-01
We considered single walled carbon naotubes (SWCNTs) as real three dimensional (3D) systems in a cylindrical coordinate. The optical matrix elements and linear susceptibility, χ(ω), in the tight binding approximation in terms of one-dimensional wave vector, kz and subband index, l are calculated. In an external axial magnetic field optical frequency dependence of linear susceptibility are investigated. We found that axial magnetic field has two effects on the imaginary part of the linear susceptibility spectrum, in agreement with experimental results. The first effect is broadening and the second, splitting. Also we found that for all metallic zigzag and armchair SWCNTs, the axial magnetic field leads to the creation of a peak with energy less than 1.5 eV, contrary to what is observed in the absence of a magnetic field.
Behaviour of magnetic superconductors in a magnetic field
International Nuclear Information System (INIS)
Buzdin, A.I.
1984-01-01
The behaviour of magnetic superconductors with close ferromagnetic and superconducting transition temperatures in a magnetic field is considered. It is shown that on lowering of the temperature the superconducting transition changes from a second to first order transition. The respective critical fields and dependence of the magnetization on the magnetic field and temperature are found. The magnetization discontinuity in the vortex core in magnetic superconductors is noted. Due to this property and the relatively large scattering cross section, magnetic superconductors are convenient for studying the superconducting vortex lattice by neutron diffraction techniques
Closed expressions for the magnetic field of toroidal multipole configurations
International Nuclear Information System (INIS)
Sheffield, G.V.
1983-04-01
Closed analytic expressions for the vector potential and the magnetic field for the lower order toroidal multipoles are presented. These expressions can be applied in the study of tokamak plasma cross section shaping. An example of such an application is included. These expressions also allow the vacuum fields required for plasma equilibrium to be specified in a general form independent of a particular coil configuration
Ghost instabilities of cosmological models with vector fields nonminimally coupled to the curvature
International Nuclear Information System (INIS)
Himmetoglu, Burak; Peloso, Marco; Contaldi, Carlo R.
2009-01-01
We prove that many cosmological models characterized by vectors nonminimally coupled to the curvature (such as the Turner-Widrow mechanism for the production of magnetic fields during inflation, and models of vector inflation or vector curvaton) contain ghosts. The ghosts are associated with the longitudinal vector polarization present in these models and are found from studying the sign of the eigenvalues of the kinetic matrix for the physical perturbations. Ghosts introduce two main problems: (1) they make the theories ill defined at the quantum level in the high energy/subhorizon regime (and create serious problems for finding a well-behaved UV completion), and (2) they create an instability already at the linearized level. This happens because the eigenvalue corresponding to the ghost crosses zero during the cosmological evolution. At this point the linearized equations for the perturbations become singular (we show that this happens for all the models mentioned above). We explicitly solve the equations in the simplest cases of a vector without a vacuum expectation value in a Friedmann-Robertson-Walker geometry, and of a vector with a vacuum expectation value plus a cosmological constant, and we show that indeed the solutions of the linearized equations diverge when these equations become singular.
Anomalous scaling of a passive vector advected by the Navier-Stokes velocity field
International Nuclear Information System (INIS)
Jurcisinova, E; Jurcisin, M; Remecky, R
2009-01-01
Using the field theoretic renormalization group and the operator-product expansion, the model of a passive vector field (a weak magnetic field in the framework of the kinematic MHD) advected by the velocity field which is governed by the stochastic Navier-Stokes equation with the Gaussian random stirring force δ-correlated in time and with the correlator proportional to k 4-d-2ε is investigated to the first order in ε (one-loop approximation). It is shown that the single-time correlation functions of the advected vector field have anomalous scaling behavior and the corresponding exponents are calculated in the isotropic case, as well as in the case with the presence of large-scale anisotropy. The hierarchy of the anisotropic critical dimensions is briefly discussed and the persistence of the anisotropy inside the inertial range is demonstrated on the behavior of the skewness and hyperskewness (dimensionless ratios of correlation functions) as functions of the Reynolds number Re. It is shown that even though the present model of a passive vector field advected by the realistic velocity field is mathematically more complicated than, on one hand, the corresponding models of a passive vector field advected by 'synthetic' Gaussian velocity fields and, on the other hand, than the corresponding model of a passive scalar quantity advected by the velocity field driven by the stochastic Navier-Stokes equation, the final one-loop approximate asymptotic scaling behavior of the single-time correlation or structure functions of the advected fields of all models are defined by the same anomalous dimensions (up to normalization)
Shaped superconductor cylinder retains intense magnetic field
Hildebrandt, A. F.; Wahlquist, H.
1964-01-01
The curve of the inner walls of a superconducting cylinder is plotted from the flux lines of the magnetic field to be contained. This shaping reduces maximum flux densities and permits a stronger and more uniform magnetic field.
Anisotropic magnetism in field-structured composites
International Nuclear Information System (INIS)
Martin, James E.; Venturini, Eugene; Odinek, Judy; Anderson, Robert A.
2000-01-01
Magnetic field-structured composites (FSCs) are made by structuring magnetic particle suspensions in uniaxial or biaxial (e.g., rotating) magnetic fields, while polymerizing the suspending resin. A uniaxial field produces chainlike particle structures, and a biaxial field produces sheetlike particle structures. In either case, these anisotropic structures affect the measured magnetic hysteresis loops, with the magnetic remanence and susceptibility increased significantly along the axis of the structuring field, and decreased slightly orthogonal to the structuring field, relative to the unstructured particle composite. The coercivity is essentially unaffected by structuring. We present data for FSCs of magnetically soft particles, and demonstrate that the altered magnetism can be accounted for by considering the large local fields that occur in FSCs. FSCs of magnetically hard particles show unexpectedly large anisotropies in the remanence, and this is due to the local field effects in combination with the large crystalline anisotropy of this material. (c) 2000 The American Physical Society
Evidence for a devil's staircase in holmium produced by an applied magnetic field
International Nuclear Information System (INIS)
Cowley, R.A.; Jehan, D.A.; McMorrow, D.F.; McIntyre, G.J.
1991-01-01
The magnetic structure of holmium has been studied using neutron diffraction when a magnetic field is applied along the c axis. The field has the effect of suppressing the onset of the commensurate cone phase found at low temperatures in zero field, and instead produces a series of spin-slip structures. In contrast to the zero-field diffraction experiments, where a continuous variation of the magnetic wave vector q was observed, we find that below ∼15 K the wave vector q is always commensurate and forms a devil's staircase with increasing field
Theory of charged vector mesons interacting with the electromagnetic field
International Nuclear Information System (INIS)
Lee, T.D.; Yang, C.N.
1983-01-01
It is shown that starting from the usual canonical formalism for the electromagnetic interaction of a charged vector meson with arbitrary magnetic moment one is led to a set of rules for Feynman diagrams, which appears to contain terms that are both infinite and noncovariant. These difficulties, however, can be circumvented by introducing a xi-limiting process which depends on a dimensionless positive parameter xi → 0. Furthermore, by using the mathematical artifice of a negative metric the theory becomes renormalizable (for xi > 0)
International Nuclear Information System (INIS)
Lim, Eun-Kyung; Yurchyshyn, Vasyl; Goode, Philip
2012-01-01
The formation and the temporal evolution of a bipolar moving magnetic feature (MMF) was studied with high-spatial and temporal resolution. The photometric properties were observed with the New Solar Telescope at Big Bear Solar Observatory using a broadband TiO filter (705.7 nm), while the magnetic field was analyzed using the spectropolarimetric data obtained by Hinode. For the first time, we observed a bipolar MMF simultaneously in intensity images and magnetic field data, and studied the details of its structure. The vector magnetic field and the Doppler velocity of the MMF were also studied. A bipolar MMF with its positive polarity closer to the negative penumbra formed, accompanied by a bright, filamentary structure in the TiO data connecting the MMF and a dark penumbral filament. A fast downflow (≤2 km s –1 ) was detected at the positive polarity. The vector magnetic field obtained from the full Stokes inversion revealed that a bipolar MMF has a U-shaped magnetic field configuration. Our observations provide a clear intensity counterpart of the observed MMF in the photosphere, and strong evidence of the connection between the MMF and the penumbral filament as a serpentine field.
Relativistic gravitation from massless systems of scalar and vector fields
International Nuclear Information System (INIS)
Fonseca Teixeira, A.F. da.
1979-01-01
Under the laws of Einstein's gravitational theory, a massless system consisting of the diffuse sources of two fields is discussed. One fields is scalar, of long range, the other is a vector field of short range. A proportionality between the sources is assumed. Both fields are minimally coupled to gravitation, and contribute positive definitely to the time component of the energy momentum tensor. A class of static, spherically symmetric solutions of the equations is obtained, in the weak field limit. The solutions are regular everywhere, stable, and can represent large or small physical systems. The gravitational field presents a Schwarzschild-type asymptotic behavior. The dependence of the energy on the various parameters characterizing the system is discussed in some detail. (Author) [pt
New techniques in 3D scalar and vector field visualization
International Nuclear Information System (INIS)
Max, N.; Crawfis, R.; Becker, B.
1993-01-01
At Lawrence Livermore National Laboratory (LLNL) we have recently developed several techniques for volume visualization of scalar and vector fields, all of which use back-to-front compositing. The first renders volume density clouds by compositing polyhedral volume cells or their faces. The second is a ''splatting'' scheme which composites textures used to reconstruct the scalar or vector fields. One version calculates the necessary texture values in software, and another takes advantage of hardware texture mapping. The next technique renders contour surface polygons using semi-transparent textures, which adjust appropriately when the surfaces deform in a flow, or change topology. The final one renders the ''flow volume'' of smoke or dye tracer swept out by a fluid flowing through a small generating polygon. All of these techniques are applied to a climate model data set, to visualize cloud density and wind velocity
New techniques in 3D scalar and vector field visualization
Energy Technology Data Exchange (ETDEWEB)
Max, N.; Crawfis, R.; Becker, B.
1993-05-05
At Lawrence Livermore National Laboratory (LLNL) we have recently developed several techniques for volume visualization of scalar and vector fields, all of which use back-to-front compositing. The first renders volume density clouds by compositing polyhedral volume cells or their faces. The second is a ``splatting`` scheme which composites textures used to reconstruct the scalar or vector fields. One version calculates the necessary texture values in software, and another takes advantage of hardware texture mapping. The next technique renders contour surface polygons using semi-transparent textures, which adjust appropriately when the surfaces deform in a flow, or change topology. The final one renders the ``flow volume`` of smoke or dye tracer swept out by a fluid flowing through a small generating polygon. All of these techniques are applied to a climate model data set, to visualize cloud density and wind velocity.
Electric field vector measurements in a surface ionization wave discharge
International Nuclear Information System (INIS)
Goldberg, Benjamin M; Adamovich, Igor V; Lempert, Walter R; Böhm, Patrick S; Czarnetzki, Uwe
2015-01-01
This work presents the results of time-resolved electric field vector measurements in a short pulse duration (60 ns full width at half maximum), surface ionization wave discharge in hydrogen using a picosecond four-wave mixing technique. Electric field vector components are measured separately, using pump and Stokes beams linearly polarized in the horizontal and vertical planes, and a polarizer placed in front of the infrared detector. The time-resolved electric field vector is measured at three different locations across the discharge gap, and for three different heights above the alumina ceramic dielectric surface, ∼100, 600, and 1100 μm (total of nine different locations). The results show that after breakdown, the discharge develops as an ionization wave propagating along the dielectric surface at an average speed of 1 mm ns −1 . The surface ionization wave forms near the high voltage electrode, close to the dielectric surface (∼100 μm). The wave front is characterized by significant overshoot of both vertical and horizontal electric field vector components. Behind the wave front, the vertical field component is rapidly reduced. As the wave propagates along the dielectric surface, it also extends further away from the dielectric surface, up to ∼1 mm near the grounded electrode. The horizontal field component behind the wave front remains quite significant, to sustain the electron current toward the high voltage electrode. After the wave reaches the grounded electrode, the horizontal field component experiences a secondary rise in the quasi-dc discharge, where it sustains the current along the near-surface plasma sheet. The measurement results indicate presence of a cathode layer formed near the grounded electrode with significant cathode voltage fall, ≈3 kV, due to high current density in the discharge. The peak reduced electric field in the surface ionization wave is 85–95 Td, consistent with dc breakdown field estimated from the Paschen
Method of regulating magnetic field of magnetic pole center
International Nuclear Information System (INIS)
Watanabe, Masao; Yamada, Teruo; Kato, Norihiko; Toda, Yojiro; Kaneda, Yasumasa.
1978-01-01
Purpose: To provide the subject method comprising using a plurality of magnetic metal pieces having different thicknesses, regulating very easily symmetry of the field of the magnetic pole center depending upon the combination of said metal pieces, thereby obtaining a magnetic field of high precision. Method: The regulation of magnetic field at the central part of the magnetic field is not depending only upon processing of the center plug, axial movement of trim coil and ion source but by providing a magnetic metal piece such as an iron ring, primary higher harmonics of the field at the center of the magnetic field can be regulated simply while the position of the ion source slit is on the equipotential surface in the field. (Yoshihara, H.)
Lovelock vacua with a recurrent null vector field
Czech Academy of Sciences Publication Activity Database
Ortaggio, Marcello
2018-01-01
Roč. 97, č. 4 (2018), č. článku 044051. ISSN 2470-0010 R&D Projects: GA ČR GA13-10042S Institutional support: RVO:67985840 Keywords : Lovelock gravity * recurrent null vector field Subject RIV: BA - General Mathematics OBOR OECD: Applied mathematics Impact factor: 4.568, year: 2016 https://journals.aps.org/prd/abstract/10.1103/PhysRevD.97.044051
Algebraic characterization of vector supersymmetry in topological field theories
International Nuclear Information System (INIS)
Vilar, L.C.Q.; Ventura, O.S.; Sasaki, C.A.G.; Sorella, S.P.
1997-01-01
An algebraic cohomological characterization of a class of linearly broken Ward identities is provided. The examples of the topological vector supersymmetry and of the Landau ghost equation are discussed in detail. The existence of such a linearly broken Ward identities turns out to be related to BRST exact anti-field dependent cocycles with negative ghost number, according to the cohomological reformulation of the Noether theorem given by M. Henneaux et al. (author)
Algebraic characterization of vector supersymmetry in topological field theories
Energy Technology Data Exchange (ETDEWEB)
Vilar, L.C.Q.; Ventura, O.S.; Sasaki, C.A.G. [Centro Brasileiro de Pesquisas Fisicas (CBPF), Rio de Janeiro, RJ (Brazil); Sorella, S.P. [Universidade do Estado, Rio de Janeiro, RJ (Brazil). Inst. de Fisica. Dept. de Fisica Teorica
1997-01-01
An algebraic cohomological characterization of a class of linearly broken Ward identities is provided. The examples of the topological vector supersymmetry and of the Landau ghost equation are discussed in detail. The existence of such a linearly broken Ward identities turns out to be related to BRST exact anti-field dependent cocycles with negative ghost number, according to the cohomological reformulation of the Noether theorem given by M. Henneaux et al. (author). 32 refs., 5 tabs.
Lovelock vacua with a recurrent null vector field
Czech Academy of Sciences Publication Activity Database
Ortaggio, Marcello
2018-01-01
Roč. 97, č. 4 (2018), č. článku 044051. ISSN 2470-0010 R&D Projects: GA ČR GA13-10042S Institutional support: RVO:67985840 Keywords : Lovelock gravity * recurrent null vector field Subject RIV: BA - General Mathematics OBOR OECD: Applied mathematics Impact factor: 4.568, year: 2016 https://journals. aps .org/prd/abstract/10.1103/PhysRevD.97.044051
Rotation invariants of vector fields from orthogonal moments
Czech Academy of Sciences Publication Activity Database
Yang, B.; Kostková, Jitka; Flusser, Jan; Suk, Tomáš; Bujack, R.
2018-01-01
Roč. 74, č. 1 (2018), s. 110-121 ISSN 0031-3203 R&D Projects: GA ČR GA15-16928S Institutional support: RVO:67985556 Keywords : Vector field * Total rotation * Invariants * Gaussian–Hermite moments * Zernike moments * Numerical stability Subject RIV: JD - Computer Applications, Robotics Impact factor: 4.582, year: 2016 http://library.utia.cas.cz/separaty/2017/ZOI/flusser-0478329.pdf
Bats respond to very weak magnetic fields.
Directory of Open Access Journals (Sweden)
Lan-Xiang Tian
Full Text Available How animals, including mammals, can respond to and utilize the direction and intensity of the Earth's magnetic field for orientation and navigation is contentious. In this study, we experimentally tested whether the Chinese Noctule, Nyctalus plancyi (Vespertilionidae can sense magnetic field strengths that were even lower than those of the present-day geomagnetic field. Such field strengths occurred during geomagnetic excursions or polarity reversals and thus may have played an important role in the evolution of a magnetic sense. We found that in a present-day local geomagnetic field, the bats showed a clear preference for positioning themselves at the magnetic north. As the field intensity decreased to only 1/5th of the natural intensity (i.e., 10 μT; the lowest field strength tested here, the bats still responded by positioning themselves at the magnetic north. When the field polarity was artificially reversed, the bats still preferred the new magnetic north, even at the lowest field strength tested (10 μT, despite the fact that the artificial field orientation was opposite to the natural geomagnetic field (P<0.05. Hence, N. plancyi is able to detect the direction of a magnetic field even at 1/5th of the present-day field strength. This high sensitivity to magnetic fields may explain how magnetic orientation could have evolved in bats even as the Earth's magnetic field strength varied and the polarity reversed tens of times over the past fifty million years.
Magnetic field approaches in dc thermal plasma modelling
International Nuclear Information System (INIS)
Freton, P; Gonzalez, J J; Masquere, M; Reichert, Frank
2011-01-01
The self-induced magnetic field has an important role in thermal plasma configurations generated by electric arcs as it generates velocity through Lorentz forces. In the models a good representation of the magnetic field is thus necessary. Several approaches exist to calculate the self-induced magnetic field such as the Maxwell-Ampere formulation, the vector potential approach combined with different kinds of boundary conditions or the Biot and Savart (B and S) formulation. The calculation of the self-induced magnetic field is alone a difficult problem and only few papers of the thermal plasma community speak on this subject. In this study different approaches with different boundary conditions are applied on two geometries to compare the methods and their limitations. The calculation time is also one of the criteria for the choice of the method and a compromise must be found between method precision and computation time. The study shows the importance of the current carrying path representation in the electrode on the deduced magnetic field. The best compromise consists of using the B and S formulation on the walls and/or edges of the calculation domain to determine the boundary conditions and to solve the vector potential in a 2D system. This approach provides results identical to those obtained using the B and S formulation over the entire domain but with a considerable decrease in calculation time.
Magnetic fields for transporting charged beams
International Nuclear Information System (INIS)
Parzen, G.
1976-01-01
The transport of charged particle beams requires magnetic fields that must be shaped correctly and very accurately. During the last 20 years or so, many studies have been made, both analytically and through the use of computer programs, of various magnetic shapes that have proved to be useful. Many of the results for magnetic field shapes can be applied equally well to electric field shapes. A report is given which gathers together the results that have more general significance and would be useful in designing a configuration to produce a desired magnetic field shape. The field shapes studied include the fields in dipoles, quadrupoles, sextupoles, octupoles, septum magnets, combined-function magnets, and electrostatic septums. Where possible, empirical formulas are proposed, based on computer and analytical studies and on magnetic field measurements. These empirical formulas are often easier to use than analytical formulas and often include effects that are difficult to compute analytically. In addition, results given in the form of tables and graphs serve as illustrative examples. The field shapes studied include uniform fields produced by window-frame magnets, C-magnets, H-magnets, and cosine magnets; linear fields produced by various types of quadrupoles; quadratic and cubic fields produced by sextupoles and octupoles; combinations of uniform and linear fields; and septum fields with sharp boundaries
Directory of Open Access Journals (Sweden)
Sapunov V.A., Denisov A.Y., Saveliev D.V., Soloviev A.A., Khomutov S.Y., Borodin P.B., Narkhov E.D., Sergeev A.V., Shirokov A.N.
2016-12-01
Full Text Available This paper covers same results of the research directed at developing an absolute vector proton magnetometer POS-4 based on the switching bias magnetic fields methods. Due to the high absolute precision and stability magnetometer POS-4 found application not only for observatories and to directional drilling support of oi and gas well. Also we discuss the some basic errors of measurements and discuss the long-term experience in the testing of magnetic observatories ART and PARATUNKA.
Dynamics of molecular superrotors in an external magnetic field
Korobenko, Aleksey; Milner, Valery
2015-08-01
We excite diatomic oxygen and nitrogen to high rotational states with an optical centrifuge and study their dynamics in an external magnetic field. Ion imaging is employed to directly visualize, and follow in time, the rotation plane of the molecular superrotors. The two different mechanisms of interaction between the magnetic field and the molecular angular momentum in paramagnetic oxygen and non-magnetic nitrogen lead to qualitatively different behaviour. In nitrogen, we observe the precession of the molecular angular momentum around the field vector. In oxygen, strong spin-rotation coupling results in faster and richer dynamics, encompassing the splitting of the rotation plane into three separate components. As the centrifuged molecules evolve with no significant dispersion of the molecular wave function, the observed magnetic interaction presents an efficient mechanism for controlling the plane of molecular rotation.
Dynamics of molecular superrotors in an external magnetic field
International Nuclear Information System (INIS)
Korobenko, Aleksey; Milner, Valery
2015-01-01
We excite diatomic oxygen and nitrogen to high rotational states with an optical centrifuge and study their dynamics in an external magnetic field. Ion imaging is employed to directly visualize, and follow in time, the rotation plane of the molecular superrotors. The two different mechanisms of interaction between the magnetic field and the molecular angular momentum in paramagnetic oxygen and non-magnetic nitrogen lead to qualitatively different behaviour. In nitrogen, we observe the precession of the molecular angular momentum around the field vector. In oxygen, strong spin–rotation coupling results in faster and richer dynamics, encompassing the splitting of the rotation plane into three separate components. As the centrifuged molecules evolve with no significant dispersion of the molecular wave function, the observed magnetic interaction presents an efficient mechanism for controlling the plane of molecular rotation. (paper)
Probing Black Hole Magnetic Fields with QED
Directory of Open Access Journals (Sweden)
Ilaria Caiazzo
2018-05-01
Full Text Available The effect of vacuum birefringence is one of the first predictions of quantum electrodynamics (QED: the presence of a charged Dirac field makes the vacuum birefringent when threaded by magnetic fields. This effect, extremely weak for terrestrial magnetic fields, becomes important for highly magnetized astrophysical objects, such as accreting black holes. In the X-ray regime, the polarization of photons traveling in the magnetosphere of a black hole is not frozen at emission but is changed by the local magnetic field. We show that, for photons traveling along the plane of the disk, where the field is expected to be partially organized, this results in a depolarization of the X-ray radiation. Because the amount of depolarization depends on the strength of the magnetic field, this effect can provide a way to probe the magnetic field in black-hole accretion disks and to study the role of magnetic fields in astrophysical accretion in general.
Effective magnetic moment of neutrinos in strong magnetic fields
International Nuclear Information System (INIS)
Perez M, A.; Perez R, H.; Masood, S.S.; Gaitan, R.; Rodriguez R, S.
2002-01-01
In this paper we compute the effective magnetic moment of neutrinos propagating in dense high magnetized medium. Taking typical values of magnetic field and densities of astrophysical objects (such as the cores of supernovae and neutron stars) we obtain an effective type of dipole magnetic moment in agreement with astrophysical and cosmological bounds. (Author)
Magnetic field measuring system for remapping the ORIC magnetic field
International Nuclear Information System (INIS)
Mosko, S.W.; Hudson, E.D.; Lord, R.S.; Hensley, D.C.; Biggerstaff, J.A.
1977-01-01
The Holifield Heavy Ion Research Facility will integrate a new 25 MV tandem electrostatic acccelerator into the existing cyclotron laboratory which includes the Oak Ridge Isochronous Cyclotron (ORIC). Computations of ion paths for beam injection from the new tandem into ORIC require field mapping in the regions traversed by the beam. Additional field data is also desired for the higher levels (approx.19 kG) now used for most heavy ion beams. The magnetic field measurement system uses 39 flip coil/current integrator sets with computer controlled data scanning. The coils are spaced radially at 1 inch intervals in an arm which can be rotated azimuthally in 2 degree increments. The entire flip coil assembly can be shifted to larger radii to measure fields beyond the pole boundary. Temperature stabilization of electronic circuitry permits a measurement resolution of +-1 gauss over a dynamic range of +-25,000 gauss. The system will process a scan of 8000 points in about one hour
Magsat - A new satellite to survey the earth's magnetic field
Mobley, F. F.; Eckard, L. D.; Fountain, G. H.; Ousley, G. W.
1980-01-01
The Magsat satellite was launched on Oct. 30, 1979 into a sun-synchronous dawn-dusk orbit, of 97 deg inclination, 350 km perigee, and 550 km apogee. It contains a precision vector magnetometer and a cesium-vapor scalar magnetometer at the end of a 6-m long graphite epoxy scissors boom. The magnetometers are accurate to 2 nanotesla. A pair of star cameras are used to define the body orientation to 10 arc sec rms. An 'attitude transfer system' measures the orientation of the magnetometer sensors relative to the star cameras to approximately 5 arc sec rms. The satellite position is determined to 70 meters rms by Doppler tracking. The overall objective is to determine each component of the earth's vector magnetic field to an accuracy of 6 nanotesla rms. The Magsat satellite gathers a complete picture of the earth's magnetic field every 12 hours. The vector components are sampled 16 times per second with a resolution of 0.5 nanotesla. The data will be used by the U.S. Geological Survey to prepare 1980 world magnetic field charts and to detect large-scale magnetic anomalies in the earth's crust for use in planning resource exploration strategy.
Development of Techniques for Visualization of Scalar and Vector Fields in the Immersive Environment
Bidasaria, Hari B.; Wilson, John W.; Nealy, John E.
2005-01-01
Visualization of scalar and vector fields in the immersive environment (CAVE - Cave Automated Virtual Environment) is important for its application to radiation shielding research at NASA Langley Research Center. A complete methodology and the underlying software for this purpose have been developed. The developed software has been put to use for the visualization of the earth s magnetic field, and in particular for the study of the South Atlantic Anomaly. The methodology has also been put to use for the visualization of geomagnetically trapped protons and electrons within Earth's magnetosphere.
Self-generation of magnetic fields
International Nuclear Information System (INIS)
Dolan, T.J.
2000-01-01
The stars generate self-magnetic fields on large spatial scales and long time scales,and laser-produced plasmas generate intense self-magnetic fields on very short spatial and time scales. Two questions are posed : (1) Could a self-magnetic field be generated in a laboratory plasma with intermediate spatial and time scales? (2) If a self-magnetic field were generated,would it evolve towards a minimum energy state? If the answers turned out to be affirmative,then self-magnetic fields could possibly have interesting applications
The measurement of solar magnetic fields
International Nuclear Information System (INIS)
Stenflo, J.O.
1978-01-01
Solar activity is basically caused by the interaction between magnetic fields, solar rotation and convective motions. Detailed mapping of the Sun's rapidly varying magnetic field helps in the understanding of the mechanisms of solar activity. Observations in recent years have revealed unexpected and intriguing properties of solar magnetic fields, the explanation of which has become a challenge to plasma physicists. This review deals primarily with how the Sun's magnetic field is measured, but it also includes a brief review of the present observational picture of the magnetic field, which is needed to understand the problems of how to properly interpret the observations. 215 references. (author)
Frisch, H.; Anusha, L. S.; Sampoorna, M.; Nagendra, K. N.
2009-07-01
Context: The Hanle effect is used to determine weak turbulent magnetic fields in the solar atmosphere, usually assuming that the angular distribution is isotropic, the magnetic field strength constant, and that micro-turbulence holds, i.e. that the magnetic field correlation length is much less than a photon mean free path. Aims: To examine the sensitivity of turbulent magnetic field measurements to these assumptions, we study the dependence of Hanle effect on the magnetic field correlation length, its angular, and strength distributions. Methods: We introduce a fairly general random magnetic field model characterized by a correlation length and a magnetic field vector distribution. Micro-turbulence is recovered when the correlation length goes to zero and macro-turbulence when it goes to infinity. Radiative transfer equations are established for the calculation of the mean Stokes parameters and they are solved numerically by a polarized approximate lambda iteration method. Results: We show that optically thin spectral lines and optically very thick ones are insensitive to the correlation length of the magnetic field, while spectral lines with intermediate optical depths (around 10-100) show some sensitivity to this parameter. The result is interpreted in terms of the mean number of scattering events needed to create the surface polarization. It is shown that the single-scattering approximation holds good for thin and thick lines but may fail for lines with intermediate thickness. The dependence of the polarization on the magnetic field vector probability density function (PDF) is examined in the micro-turbulent limit. A few PDFs with different angular and strength distributions, but equal mean value of the magnetic field, are considered. It is found that the polarization is in general quite sensitive to the shape of the magnetic field strength PDF and somewhat to the angular distribution. Conclusions: The mean field derived from Hanle effect analysis of
Preparation and characterization of magnetic gene vectors for targeting gene delivery
Energy Technology Data Exchange (ETDEWEB)
Zheng, S.W.; Liu, G. [College of Chemistry, Chemical Engineering and Materials Science and Key Laboratory of Organic Synthesis of Jiangsu Province, Soochow University, SIP, Suzhou 215123 (China); Hong, R.Y., E-mail: rhong@suda.edu.cn [College of Chemistry, Chemical Engineering and Materials Science and Key Laboratory of Organic Synthesis of Jiangsu Province, Soochow University, SIP, Suzhou 215123 (China); State Key Laboratory of Multi-phase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100080 (China); Li, H.Z. [State Key Laboratory of Multi-phase Complex Systems, Institute of Process Engineering, Chinese Academy of Sciences, Beijing 100080 (China); Li, Y.G., E-mail: ilguoliang@sohu.com [Department of radiology, the First Affiliated Hospital of Soochow University, Suzhou 215007 (China); Wei, D.G., E-mail: dougwei@deas.harvard.edu [Center for Nanoscale Systems, School of Engineering and Applied Science, Harvard University, 11 Oxford Street, Cambridge, MA 02139 (United States)
2012-10-15
Highlights: Black-Right-Pointing-Pointer PEI is ideal candidate polymer for the design of gene delivery systems. Black-Right-Pointing-Pointer PEI-CMD-MNPs exhibited a typical superparamagnetic behavior. Black-Right-Pointing-Pointer PEI-CMD-MNPs were well stable over the entire range of pH and NaCl concentration. Black-Right-Pointing-Pointer DNA-PEI-CMD-MNPs transfected cells by a magnet have higher transfection efficiency and gene expression efficiency. - Abstract: The PEI-CMD-MNPs were successfully prepared by the surface modification of magnetic Fe{sub 3}O{sub 4} nanoparticles with carboxymethyl dextran (CMD) and polyethyleneimine (PEI). The PEI-CMD-MNPs polyplexes exhibited a typical superparamagnetic behavior and were well stable over the entire range of pH and NaCl concentration. These PEI-CMD-MNPs were used as magnetic gene vectors for targeting gene delivery. The prepared MNPs at different surface modification stages were characterized using Fourier transform infrared (FT-IR), thermogravimetric analysis (TGA), field emissions canning electron microscopy (FE-SEM), powder X-ray diffraction (XRD) and dynamic laser light scattering (DLS) analysis. The magnetic properties were studied by vibrating sample magnetometer (VSM). To evaluate the performance of the magnetic nanoparticles as gene transfer vector, the PEI-CMD-MNPs were used to delivery green fluorescent protein (GFP) gene into BHK21 cells. The expression of GFP gene was detected by fluorescence microscope. DNA-PEI-CMD-MNPs polyplexes absorbed by the cells were also monitored by Magnetic resonance imaging (MRI). The transfection efficiency and gene expression efficiency of that transfected with a magnet were much higher than that of standard transfection.
A lithospheric magnetic field model derived from the Swarm satellite magnetic field measurements
Hulot, G.; Thebault, E.; Vigneron, P.
2015-12-01
The Swarm constellation of satellites was launched in November 2013 and has since then delivered high quality scalar and vector magnetic field measurements. A consortium of several research institutions was selected by the European Space Agency (ESA) to provide a number of scientific products which will be made available to the scientific community. Within this framework, specific tools were tailor-made to better extract the magnetic signal emanating from Earth's the lithospheric. These tools rely on the scalar gradient measured by the lower pair of Swarm satellites and rely on a regional modeling scheme that is more sensitive to small spatial scales and weak signals than the standard spherical harmonic modeling. In this presentation, we report on various activities related to data analysis and processing. We assess the efficiency of this dedicated chain for modeling the lithospheric magnetic field using more than one year of measurements, and finally discuss refinements that are continuously implemented in order to further improve the robustness and the spatial resolution of the lithospheric field model.
Localization of vector field on dynamical domain wall
Directory of Open Access Journals (Sweden)
Masafumi Higuchi
2017-03-01
Full Text Available In the previous works (arXiv:1202.5375 and arXiv:1402.1346, the dynamical domain wall, where the four dimensional FRW universe is embedded in the five dimensional space–time, has been realized by using two scalar fields. In this paper, we consider the localization of vector field in three formulations. The first formulation was investigated in the previous paper (arXiv:1510.01099 for the U(1 gauge field. In the second formulation, we investigate the Dvali–Shifman mechanism (arXiv:hep-th/9612128, where the non-abelian gauge field is confined in the bulk but the gauge symmetry is spontaneously broken on the domain wall. In the third formulation, we investigate the Kaluza–Klein modes coming from the five dimensional graviton. In the Randall–Sundrum model, the graviton was localized on the brane. We show that the (5,μ components (μ=0,1,2,3 of the graviton are also localized on the domain wall and can be regarded as the vector field on the domain wall. There are, however, some corrections coming from the bulk extra dimension if the domain wall universe is expanding.
Measurements of magnetic field sources in schools
International Nuclear Information System (INIS)
Johnson, G.B.
1992-01-01
The Electrical Systems Division of the Electric Power Research Institute (EPRI) has initiated several research projects to investigate magnetic field levels, their characteristics, and their sources. This paper describes measurements of magnetic field sources in schools. Magnetic field measurements were made at four schools in the service areas of two utility companies. Magnetic field measurements included profiles of the magnetic field versus distance near power lines, around the perimeter of the school buildings, and at several locations within each school. Twenty-four hour measurements were also made to record the temporal variation of the magnetic field at several locations at each school. The instrumentation, measurement techniques, and magnetic field sources identified are discussed
Relativistic theory of vector mesons in laser fields
Energy Technology Data Exchange (ETDEWEB)
Becker, W; Mitter, H [Tuebingen Univ. (F.R. Germany). Inst. fuer Theoretische Physik
1975-01-01
The relativistic wave equation for a particle with spin 1 and an anomalous magnetic moment ..mu.. in an external wave field is reduced to a set of coupled ordinary differential equations for three amplitudes, which multiply the exponential known from the spin 0 case. These amplitudes are constant for ..mu..=1 (and not ..mu..=0). Exact solutions are given for a linear polarized laser wave of finite pulse shape and for an infinitely extended plane wave with circular polarization. In contrast to the situation in a constant magnetic field there are no internal inconsistencies.
Magnetic field driven domain-wall propagation in magnetic nanowires
International Nuclear Information System (INIS)
Wang, X.R.; Yan, P.; Lu, J.; He, C.
2009-01-01
The mechanism of magnetic field induced magnetic domain-wall (DW) propagation in a nanowire is revealed: A static DW cannot exist in a homogeneous magnetic nanowire when an external magnetic field is applied. Thus, a DW must vary with time under a static magnetic field. A moving DW must dissipate energy due to the Gilbert damping. As a result, the wire has to release its Zeeman energy through the DW propagation along the field direction. The DW propagation speed is proportional to the energy dissipation rate that is determined by the DW structure. The negative differential mobility in the intermediate field is due to the transition from high energy dissipation at low field to low energy dissipation at high field. For the field larger than the so-called Walker breakdown field, DW plane precesses around the wire, leading to the propagation speed oscillation.
A regularization method for extrapolation of solar potential magnetic fields
Gary, G. A.; Musielak, Z. E.
1992-01-01
The mathematical basis of a Tikhonov regularization method for extrapolating the chromospheric-coronal magnetic field using photospheric vector magnetograms is discussed. The basic techniques show that the Cauchy initial value problem can be formulated for potential magnetic fields. The potential field analysis considers a set of linear, elliptic partial differential equations. It is found that, by introducing an appropriate smoothing of the initial data of the Cauchy potential problem, an approximate Fourier integral solution is found, and an upper bound to the error in the solution is derived. This specific regularization technique, which is a function of magnetograph measurement sensitivities, provides a method to extrapolate the potential magnetic field above an active region into the chromosphere and low corona.
Guo, Yunsheng; Li, Jiansheng; Hou, Xiaojuan; Lv, Xiaolong; Liang, Hao; Zhou, Ji; Wu, Hongya
2017-04-07
Wireless power transfer is a nonradiative type of transmission that is performed in the near-field region. In this region, the electromagnetic fields that are produced by both the transmitting and receiving coils are evanescent fields, which should not transmit energy. This then raises the question of how the energy can be transferred. Here we describe a theoretical study of the two evanescent field distributions at different terminal loads. It is shown that the essential principle of wireless energy transfer is the superposition of the two evanescent fields, and the resulting superimposed field is mediated through the terminal load. If the terminal load is either capacitive or inductive, then the superimposed field cannot transfer the energy because its Poynting vector is zero; in contrast, if the load is resistive, energy can then be conveyed from the transmitting coil to the receiving coil. The simulation results for the magnetic field distributions and the time-domain current waveforms agree very well with the results of the theoretical analysis. This work thus provides a comprehensive understanding of the energy transfer mechanism involved in the magnetic resonant coupling system.
An example of a vector field with the oriented shadowing property
Tikhomirov, Sergey
2014-01-01
We consider shadowing properties for vector fields corresponding to different type of reparametrisations. We give an example of a vector field which has the oriented shadowing properties, but does not have the standard shadowing property.
Time-varying vector fields and their flows
Jafarpour, Saber
2014-01-01
This short book provides a comprehensive and unified treatment of time-varying vector fields under a variety of regularity hypotheses, namely finitely differentiable, Lipschitz, smooth, holomorphic, and real analytic. The presentation of this material in the real analytic setting is new, as is the manner in which the various hypotheses are unified using functional analysis. Indeed, a major contribution of the book is the coherent development of locally convex topologies for the space of real analytic sections of a vector bundle, and the development of this in a manner that relates easily to classically known topologies in, for example, the finitely differentiable and smooth cases. The tools used in this development will be of use to researchers in the area of geometric functional analysis.
Fringing field measurement of dipole magnet
International Nuclear Information System (INIS)
Lu Hongyou; Jiang Weisheng; Mao Naifeng; Mao Xingwang
1985-01-01
The fringing field of a dipole magnet with a C-type circuit and homogeneous field in the gap has been measured including the distributions of fringing fields with and without magnetic shield. The measured data was analyzed by using the concept of virtual field boundary
Generating the optimal magnetic field for magnetic refrigeration
DEFF Research Database (Denmark)
Bjørk, Rasmus; Insinga, Andrea Roberto; Smith, Anders
2016-01-01
In a magnetic refrigeration device the magnet is the single most expensive component, and therefore it is crucially important to ensure that an effective magnetic field as possible is generated using the least amount of permanent magnets. Here we present a method for calculating the optimal...... remanence distribution for any desired magnetic field. The method is based on the reciprocity theorem, which through the use of virtual magnets can be used to calculate the optimal remanence distribution. Furthermore, we present a method for segmenting a given magnet design that always results...... in the optimal segmentation, for any number of segments specified. These two methods are used to determine the optimal magnet design of a 12-piece, two-pole concentric cylindrical magnet for use in a continuously rotating magnetic refrigeration device....
Hawking radiation of a vector field and gravitational anomalies
International Nuclear Information System (INIS)
Murata, Keiju; Miyamoto, Umpei
2007-01-01
Recently, the relation between Hawking radiation and gravitational anomalies has been used to estimate the flux of Hawking radiation for a large class of black objects. In this paper, we extend the formalism, originally proposed by Robinson and Wilczek, to the Hawking radiation of vector particles (photons). It is explicitly shown, with the Hamiltonian formalism, that the theory of an electromagnetic field on d-dimensional spherical black holes reduces to one of an infinite number of massive complex scalar fields on 2-dimensional spacetime, for which the usual anomaly-cancellation method is available. It is found that the total energy emitted from the horizon for the electromagnetic field is just (d-2) times that for a scalar field. The results support the picture that Hawking radiation can be regarded as an anomaly eliminator on horizons. Possible extensions and applications of the analysis are discussed
Strong and superstrong pulsed magnetic fields generation
Shneerson, German A; Krivosheev, Sergey I
2014-01-01
Strong pulsed magnetic fields are important for several fields in physics and engineering, such as power generation and accelerator facilities. Basic aspects of the generation of strong and superstrong pulsed magnetic fields technique are given, including the physics and hydrodynamics of the conductors interacting with the field as well as an account of the significant progress in generation of strong magnetic fields using the magnetic accumulation technique. Results of computer simulations as well as a survey of available field technology are completing the volume.
Killing vector fields in three dimensions: a method to solve massive gravity field equations
Energy Technology Data Exchange (ETDEWEB)
Guerses, Metin, E-mail: gurses@fen.bilkent.edu.t [Department of Mathematics, Faculty of Sciences, Bilkent University, 06800 Ankara (Turkey)
2010-10-21
Killing vector fields in three dimensions play an important role in the construction of the related spacetime geometry. In this work we show that when a three-dimensional geometry admits a Killing vector field then the Ricci tensor of the geometry is determined in terms of the Killing vector field and its scalars. In this way we can generate all products and covariant derivatives at any order of the Ricci tensor. Using this property we give ways to solve the field equations of topologically massive gravity (TMG) and new massive gravity (NMG) introduced recently. In particular when the scalars of the Killing vector field (timelike, spacelike and null cases) are constants then all three-dimensional symmetric tensors of the geometry, the Ricci and Einstein tensors, their covariant derivatives at all orders, and their products of all orders are completely determined by the Killing vector field and the metric. Hence, the corresponding three-dimensional metrics are strong candidates for solving all higher derivative gravitational field equations in three dimensions.
Efficient and Enhanced Diffusion of Vector Field for Active Contour Model
Liu, Guoqi; Sun, Lin; Liu, Shangwang
2015-01-01
Gradient vector flow (GVF) is an important external force field for active contour models. Various vector fields based on GVF have been proposed. However, these vector fields are obtained with many iterations and have difficulty in capturing the whole image area. On the other hand, the ability to converge to deep and complex concavity with these vector fields is also needed to improve. In this paper, by analyzing the diffusion equation of GVF, a normalized set is defined and a dynamically nor...
Inertial fusion reactors and magnetic fields
International Nuclear Information System (INIS)
Cornwell, J.B.; Pendergrass, J.H.
1985-01-01
The application of magnetic fields of simple configurations and modest strengths to direct target debris ions out of cavities can alleviate recognized shortcomings of several classes of inertial confinement fusion (ICF) reactors. Complex fringes of the strong magnetic fields of heavy-ion fusion (HIF) focusing magnets may intrude into reactor cavities and significantly affect the trajectories of target debris ions. The results of an assessment of potential benefits from the use of magnetic fields in ICF reactors and of potential problems with focusing-magnet fields in HIF reactors conducted to set priorities for continuing studies are reported. Computational tools are described and some preliminary results are presented
Accurate method of the magnetic field measurement of quadrupole magnets
International Nuclear Information System (INIS)
Kumada, M.; Sakai, I.; Someya, H.; Sasaki, H.
1983-01-01
We present an accurate method of the magnetic field measurement of the quadrupole magnet. The method of obtaining the information of the field gradient and the effective focussing length is given. A new scheme to obtain the information of the skew field components is also proposed. The relative accuracy of the measurement was 1 x 10 -4 or less. (author)
Electrolytic tiltmeters inside magnetic fields: Some observations
International Nuclear Information System (INIS)
Alberdi, J.; Arce, P.; Barcala, J.M.; Calvo, E.; Ferrando, A.; Josa, M.I.; Luque, J.M.; Molinero, A.; Navarrete, J.; Oller, J.C.; Yuste, C.; Calderon, A.; Garcia-Moral, L.A.; Gomez, G.; Gonzalez-Sanchez, F.J.; Martinez-Rivero, C.; Matorras, F.; Rodrigo, T.; Ruiz-Arbol, P.; Scodellaro, L.; Sobron, M.; Vila, I.; Virto, A.L.
2007-01-01
We present observations of the electrolytic clinometers behaviour inside magnetic field environments introducing phenomenological expressions to account for the measured output voltage variations as functions of field gradients and field strengths
Electrolytic tiltmeters inside magnetic fields: Some observations
Energy Technology Data Exchange (ETDEWEB)
Alberdi, J. [CIEMAT, Madrid (Spain); Arce, P. [CIEMAT, Madrid (Spain); Barcala, J.M. [CIEMAT, Madrid (Spain); Calvo, E. [CIEMAT, Madrid (Spain); Ferrando, A. [CIEMAT, Madrid (Spain)]. E-mail: antonio.ferrando@ciemat.es; Josa, M.I. [CIEMAT, Madrid (Spain); Luque, J.M. [CIEMAT, Madrid (Spain); Molinero, A. [CIEMAT, Madrid (Spain); Navarrete, J. [CIEMAT, Madrid (Spain); Oller, J.C. [CIEMAT, Madrid (Spain); Yuste, C. [CIEMAT, Madrid (Spain); Calderon, A. [Instituto de Fisica de Cantabria, CSIC-University of Cantabria, Santander (Spain); Garcia-Moral, L.A. [Instituto de Fisica de Cantabria, CSIC-University of Cantabria, Santander (Spain); Gomez, G. [Instituto de Fisica de Cantabria, CSIC-University of Cantabria, Santander (Spain); Gonzalez-Sanchez, F.J. [Instituto de Fisica de Cantabria, CSIC-University of Cantabria, Santander (Spain); Martinez-Rivero, C. [Instituto de Fisica de Cantabria, CSIC-University of Cantabria, Santander (Spain); Matorras, F. [Instituto de Fisica de Cantabria, CSIC-University of Cantabria, Santander (Spain); Rodrigo, T. [Instituto de Fisica de Cantabria, CSIC-University of Cantabria, Santander (Spain); Ruiz-Arbol, P. [Instituto de Fisica de Cantabria, CSIC-University of Cantabria, Santander (Spain); Scodellaro, L. [Instituto de Fisica de Cantabria, CSIC-University of Cantabria, Santander (Spain); Sobron, M. [Instituto de Fisica de Cantabria, CSIC-University of Cantabria, Santander (Spain); Vila, I. [Instituto de Fisica de Cantabria, CSIC-University of Cantabria, Santander (Spain); Virto, A.L. [Instituto de Fisica de Cantabria, CSIC-University of Cantabria, Santander (Spain)
2007-04-21
We present observations of the electrolytic clinometers behaviour inside magnetic field environments introducing phenomenological expressions to account for the measured output voltage variations as functions of field gradients and field strengths.
Khine, Y. Y.; Walker, J. S.
1995-02-01
This paper treats the buoyant convection during the Czochralski growth of silicon crystals with a steady, strong, non-uniform, axisymmetric magnetic field. We consider a family of magnetic fields which includes a uniform axial magnetic field and a "cusp" field which is produced by identical solenoids placed symmetrically above and below the plane of the crystal-melt interface and free surface. We investigate the evolution of the buoyant convection as the magnetic field is changed continuously from a uniform axial field to a cusp field, with a constant value of the root-mean-squared magnetic flux density in the melt. We also investigate changes as the magnetic flux density is increased. While the cusp field appears very promising, perfect alignment between the local magnetic field vector and the crystal-melt interface or free surface is not possible, so the effects of a slight misalignment are also investigated.
Investigations on magnetic field induced optical transparency in magnetic nanofluids
Mohapatra, Dillip Kumar; Philip, John
2018-02-01
We study the magnetic field induced optical transparency and its origin in magnetic nanoemulsion of droplets of average size ∼200 nm containing superparamagnetic iron oxide nanoparticles. Beyond a certain volume fraction (Φ > 0.0021) of magnetic nanoemulsion and a critical magnetic field (Hc1), the transmitted light intensity increases drastically and reaches a maximum at another critical magnetic field (Hc2), beyond which the transmitted light intensity decreases and reaches a plateau. Interestingly, the transmitted light intensity at Hc2 is found to increase linearly with Φ and the critical magnetic fields Hc1 and Hc2 follow power law decay with Φ (i.e. Hc ∼ Φ-x), with exponents 0.48 and 0.27, respectively. The light intensity recovers to its initial value when the magnetic field is switched off, indicating the perfect reversibility of the field induced transparency process. The observed straight line scattered patterns above Hc2, on a screen placed perpendicular to the incident beam, confirms the formation of rod like anisotropic nanostructures perpendicular to the direction of light propagation. The magneto-optical measurements in the emulsion confirm that the observed field induced transparency in magnetic emulsions for Φ > 0.0021 is due to the optical birefringence caused by the rod like nanostructures. The reduced birefringence is found to be proportional to the square of the applied magnetic field. This finding offers several possibilities in using magnetic nanofluids in tunable optical devices.
Energy Technology Data Exchange (ETDEWEB)
Sudo, Seiichi, E-mail: sudo@akita-pu.ac.j [Faculty of Systems Science and Technology, Akita Prefectural University, Ebinokuchi 84-4, Yurihonjo 015-0055 (Japan); Asano, Daisaku [Faculty of Systems Science and Technology, Akita Prefectural University, Ebinokuchi 84-4, Yurihonjo 015-0055 (Japan); Takana, Hidemasa; Nishiyama, Hideya [Institute of Fluid Science, Tohoku University, Katahira 2-1-1, Aobaku, Sendai 980-8577 (Japan)
2011-05-15
The dynamic behavior of a magnetic fluid adsorbed to a small NdFeB permanent magnet subjected to an alternating magnetic field was studied with a high speed video camera system. The directions of alternating magnetic field are parallel and opposite to that of the permanent magnet. It was found that the surface of magnetic fluid responds to the external alternating magnetic field in elongation and contraction with a lot of spikes. Generation of a capillary magnetic fluid jet was observed in the neighbourhood of a specific frequency of alternating field. The effect of gravitational force on surface phenomena of magnetic fluid adsorbed to the permanent magnet was revealed. - Research Highlights: Magnetic fluid of the system responds to alternating magnetic field with higher frequencies. Large-amplitude surface motions of magnetic fluid occur at the specific frequencies of the external field. Capillary jets of magnetic fluid are generated at the natural frequency of the system.
Dynamic shielding of the magnetic fields
Directory of Open Access Journals (Sweden)
RAU, M.
2010-11-01
Full Text Available The paper presents a comparative study of the methods used to control and compensate the direct and alternative magnetic fields. Two frequently used methods in the electromagnetic compatibility of the complex biomagnetism installations were analyzed. The two methods refer to the use of inductive magnetic field sensors (only for alternative fields and of fluxgate magnetometers as active transducers which measures both the direct and alternative components of the magnetic field. The applications of the dynamic control of the magnetic field are: control of the magnetic field of the military ships, control of parasite magnetic field produced by power transformers and the electrical networks, protection of the mass spectrometers, electronic microscopes, SQUID and optical pumping magnetometers for applications in biomagnetism.
DEFF Research Database (Denmark)
Swierczynski, Dariusz; Kazmierkowski, Marian P.; Blaabjerg, Frede
2002-01-01
DSP Based Direct Torque Control of Permanent Magnet Synchronous Motor (PMSM) using Space Vector Modulation (DTC-SVM)......DSP Based Direct Torque Control of Permanent Magnet Synchronous Motor (PMSM) using Space Vector Modulation (DTC-SVM)...
Tripolar electric field Structure in guide field magnetic reconnection
S. Fu; S. Huang; M. Zhou; B. Ni; X. Deng
2018-01-01
It has been shown that the guide field substantially modifies the structure of the reconnection layer. For instance, the Hall magnetic and electric fields are distorted in guide field reconnection compared to reconnection without guide fields (i.e., anti-parallel reconnection). In this paper, we performed 2.5-D electromagnetic full particle simulation to study the electric field structures in magnetic reconnection under different initial guide fields (Bg). Once the amplit...
Magnetic structure of RPdSn (R=Tb, Ho) single crystal compounds under strong magnetic field
International Nuclear Information System (INIS)
Andoh, Y.; Kurisu, M.; Nakamoto, G.; Tsutaoka, T.; Kawano, S.
2003-01-01
Rare earth compounds RTX, where R stands for rare earth elements, T for Ni, Pd or Rh, and X for Sn or Ge, crystallize to a rhombic ε-TiNiSi structure. Only rare earth elements R contribute to magnetic properties since T and X atoms are nonmagnetic. The competition between RKKY indirect interaction and large magnetic anisotropy generates many complicated magnetic phases. At a low temperature phase, complicated magnetisms such as meta-magnetism were observed in magnetization curves with many steps. In previous experiments dealing with RPdSn where R means Tb or Ho, some characteristics of magnetic properties of these compounds were deduced from magnetization measurements and neutron diffraction without external magnetic field. In this report, the change of magnetic scattering of neutron diffraction was studied under external magnetic fields in order to reveal the mechanism of the phase transformations of the compounds. The difference between TbPdSn and HoPdSn compounds was observed in magnetic field dependence of the wave vectors of the magnetic scattering. Two independent wave vectors in magnetic scattering existed in HoPdSn compound. (Y. Kazumata)
Magnetic field measurements of the superEBIS superconducting magnet
International Nuclear Information System (INIS)
Herschcovitch, A.; Kponou, A.; Clipperton, R.; Hensel, W.; Usack, F.
1994-01-01
SuperEBIS was designed to have a solenoidal magnetic field of a 5 Tesla strength with a 120 cm long bore. The field was specified to be straight within 1 part in 10000 within the bore, and uniform to within 1 part in 1000 within the central 90 cm. Magnetic field measurements were performed with a computerized magnetic field measuring setup that was borrowed from W. Sampson's group. A preliminary test was made of a scheme to determine if the magnetic and mechanical axes of the solenoid coincided, and, if not, by how much
Evolution of coronal and interplanetary magnetic fields
International Nuclear Information System (INIS)
Levine, R.H.
1980-01-01
Numerous studies have provided the detailed information necessary for a substantive synthesis of the empirical relation between the magnetic field of the sun and the structure of the interplanetary field. The author points out the latest techniques and studies of the global solar magnetic field and its relation to the interplanetary field. The potential to overcome most of the limitations of present methods of analysis exists in techniques of modelling the coronal magnetic field using observed solar data. Such empirical models are, in principle, capable of establishing the connection between a given heliospheric point and its magnetically-connected photospheric point, as well as the physical basis for the connection. (Auth.)
Energy Technology Data Exchange (ETDEWEB)
Cao, Derang; Zhu, Zengtai; Feng, Hongmei; Pan, Lining; Cheng, Xiaohong; Wang, Zhenkun [Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou 730000 (China); Wang, Jianbo [Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou 730000 (China); Key Laboratory of Special Function Materials and Structure Design, Ministry of Education, Lanzhou University, Lanzhou 730000 (China); Liu, Qingfang, E-mail: liuqf@lzu.edu.cn [Key Laboratory for Magnetism and Magnetic Materials of the Ministry of Education, Lanzhou University, Lanzhou 730000 (China)
2016-10-15
FeCo films were prepared by a simple and convenient electrodeposition method. An external magnetic field was applied to the film to induce magnetic anisotropy during deposition. Comparing with the previous work, the angle between the direction of applied magnetic field and film plane is changed from in-plane to out-plane. The influence of the applied magnetic field on magnetic properties was investigated. As a result, it can be found that the in-plane anisotropy is driven by the in-plane component of the magnetic field applied during growth. In addition, the result can also be confirmed by the dynamic magnetic anisotropy of the film obtained by vector network analyzer ferromagnetic resonance technique. - Highlights: • FeCo films were prepared by electrodeposition method. • An external magnetic field was applied to induce anisotropy during deposition. • The direction of applied magnetic field is changed from in-plane to out-plane. • The magnetic properties of films were investigated by vector network analyzer. • The in-plane anisotropy is driven by the in-plane component of the field.
The intermittency of vector fields and random-number generators
Kalinin, A. O.; Sokoloff, D. D.; Tutubalin, V. N.
2017-09-01
We examine how well natural random-number generators can reproduce the intermittency phenomena that arise in the transfer of vector fields in random media. A generator based on the analysis of financial indices is suggested as the most promising random-number generator. Is it shown that even this generator, however, fails to reproduce the phenomenon long enough to confidently detect intermittency, while the C++ generator successfully solves this problem. We discuss the prospects of using shell models of turbulence as the desired generator.
Cosmic Rays in Intermittent Magnetic Fields
International Nuclear Information System (INIS)
Shukurov, Anvar; Seta, Amit; Bushby, Paul J.; Wood, Toby S.; Snodin, Andrew P.
2017-01-01
The propagation of cosmic rays in turbulent magnetic fields is a diffusive process driven by the scattering of the charged particles by random magnetic fluctuations. Such fields are usually highly intermittent, consisting of intense magnetic filaments and ribbons surrounded by weaker, unstructured fluctuations. Studies of cosmic-ray propagation have largely overlooked intermittency, instead adopting Gaussian random magnetic fields. Using test particle simulations, we calculate cosmic-ray diffusivity in intermittent, dynamo-generated magnetic fields. The results are compared with those obtained from non-intermittent magnetic fields having identical power spectra. The presence of magnetic intermittency significantly enhances cosmic-ray diffusion over a wide range of particle energies. We demonstrate that the results can be interpreted in terms of a correlated random walk.
Cosmic Rays in Intermittent Magnetic Fields
Energy Technology Data Exchange (ETDEWEB)
Shukurov, Anvar; Seta, Amit; Bushby, Paul J.; Wood, Toby S. [School of Mathematics and Statistics, Newcastle University, Newcastle Upon Tyne NE1 7RU (United Kingdom); Snodin, Andrew P., E-mail: a.seta1@ncl.ac.uk, E-mail: amitseta90@gmail.com [Department of Mathematics, Faculty of Applied Science, King Mongkut’s University of Technology North Bangkok, Bangkok 10800 (Thailand)
2017-04-10
The propagation of cosmic rays in turbulent magnetic fields is a diffusive process driven by the scattering of the charged particles by random magnetic fluctuations. Such fields are usually highly intermittent, consisting of intense magnetic filaments and ribbons surrounded by weaker, unstructured fluctuations. Studies of cosmic-ray propagation have largely overlooked intermittency, instead adopting Gaussian random magnetic fields. Using test particle simulations, we calculate cosmic-ray diffusivity in intermittent, dynamo-generated magnetic fields. The results are compared with those obtained from non-intermittent magnetic fields having identical power spectra. The presence of magnetic intermittency significantly enhances cosmic-ray diffusion over a wide range of particle energies. We demonstrate that the results can be interpreted in terms of a correlated random walk.
Nonlinear physics of twisted magnetic field lines
International Nuclear Information System (INIS)
Yoshida, Zensho
1998-01-01
Twisted magnetic field lines appear commonly in many different plasma systems, such as magnetic ropes created through interactions between the magnetosphere and the solar wind, magnetic clouds in the solar wind, solar corona, galactic jets, accretion discs, as well as fusion plasma devices. In this paper, we study the topological characterization of twisted magnetic fields, nonlinear effect induced by the Lorentz back reaction, length-scale bounds, and statistical distributions. (author)
Dilute Potts chain in a magnetic field
International Nuclear Information System (INIS)
Chaves, C.M.; Riera, R.
1983-03-01
The Potts lattice gas in presence of a uniform magnetic field is solved exactly in one dimension. For negative values of the exchange parameter, the magnetization curve exhibits two or three steps, depending on the concentration of vacancies. These steps arise as a result of the competition between the exchange interaction and the magnetic field, being associated to different structural distribution of vacancies and to the magnetic ordering of one or both sublattices. (Author) [pt
Magnetic field dependent atomic tunneling in non-magnetic glasses
International Nuclear Information System (INIS)
Ludwig, S.; Enss, C.; Hunklinger, S.
2003-01-01
The low-temperature properties of insulating glasses are governed by atomic tunneling systems (TSs). Recently, strong magnetic field effects in the dielectric susceptibility have been discovered in glasses at audio frequencies at very low temperatures. Moreover, it has been found that the amplitude of two-pulse polarization echoes generated in non-magnetic multi-component glasses at radio frequencies and at very low temperatures shows a surprising non-monotonic magnetic field dependence. The magnitude of the latter effect indicates that virtually all TSs are affected by the magnetic field, not only a small subset of systems. We have studied the variation of the magnetic field dependence of the echo amplitude as a function of the delay time between the two excitation pulses and at different frequencies. Our results indicate that the evolution of the phase of resonant TSs is changed by the magnetic field
Magnetic field dependent atomic tunneling in non-magnetic glasses
Ludwig, S.; Enss, C.; Hunklinger, S.
2003-05-01
The low-temperature properties of insulating glasses are governed by atomic tunneling systems (TSs). Recently, strong magnetic field effects in the dielectric susceptibility have been discovered in glasses at audio frequencies at very low temperatures. Moreover, it has been found that the amplitude of two-pulse polarization echoes generated in non-magnetic multi-component glasses at radio frequencies and at very low temperatures shows a surprising non-monotonic magnetic field dependence. The magnitude of the latter effect indicates that virtually all TSs are affected by the magnetic field, not only a small subset of systems. We have studied the variation of the magnetic field dependence of the echo amplitude as a function of the delay time between the two excitation pulses and at different frequencies. Our results indicate that the evolution of the phase of resonant TSs is changed by the magnetic field.
Swarm: ESA's Magnetic Field Mission
Plank, G.; Floberghagen, R.; Menard, Y.; Haagmans, R.
2013-12-01
Swarm is the fifth Earth Explorer mission in ESA's Living Planet Programme, and is scheduled for launch in fall 2013. The objective of the Swarm mission is to provide the best-ever survey of the geomagnetic field and its temporal evolution using a constellation of three identical satellites. The mission shall deliver data that allow access to new insights into the Earth system by improved scientific understanding of the Earth's interior and near-Earth electromagnetic environment. After launch and triple satellite release at an initial altitude of about 490 km, a pair of the satellites will fly side-by-side with slowly decaying altitude, while the third satellite will be lifted to 530 km to complete the Swarm constellation. High-precision and high-resolution measurements of the strength, direction and variation of the magnetic field, complemented by precise navigation, accelerometer and electric field measurements, will provide the observations required to separate and model various sources of the geomagnetic field and near-Earth current systems. The mission science goals are to provide a unique view into Earth's core dynamics, mantle conductivity, crustal magnetisation, ionospheric and magnetospheric current systems and upper atmosphere dynamics - ranging from understanding the geodynamo to contributing to space weather. The scientific objectives and results from recent scientific studies will be presented. In addition the current status of the project, which is presently in the final stage of the development phase, will be addressed. A consortium of European scientific institutes is developing a distributed processing system to produce geophysical (Level 2) data products for the Swarm user community. The setup of the Swarm ground segment and the contents of the data products will be addressed. In case the Swarm satellites are already in orbit, a summary of the on-going mission operations activities will be given. More information on Swarm can be found at www.esa.int/esaLP/LPswarm.html.
Magnetic resonance image compression using scalar-vector quantization
Mohsenian, Nader; Shahri, Homayoun
1995-12-01
A new coding scheme based on the scalar-vector quantizer (SVQ) is developed for compression of medical images. SVQ is a fixed-rate encoder and its rate-distortion performance is close to that of optimal entropy-constrained scalar quantizers (ECSQs) for memoryless sources. The use of a fixed-rate quantizer is expected to eliminate some of the complexity issues of using variable-length scalar quantizers. When transmission of images over noisy channels is considered, our coding scheme does not suffer from error propagation which is typical of coding schemes which use variable-length codes. For a set of magnetic resonance (MR) images, coding results obtained from SVQ and ECSQ at low bit-rates are indistinguishable. Furthermore, our encoded images are perceptually indistinguishable from the original, when displayed on a monitor. This makes our SVQ based coder an attractive compression scheme for picture archiving and communication systems (PACS), currently under consideration for an all digital radiology environment in hospitals, where reliable transmission, storage, and high fidelity reconstruction of images are desired.
Strongly interacting matter in magnetic fields
Landsteiner, Karl; Schmitt, Andreas; Yee, Ho-Ung
2013-01-01
The physics of strongly interacting matter in an external magnetic field is presently emerging as a topic of great cross-disciplinary interest for particle, nuclear, astro- and condensed matter physicists. It is known that strong magnetic fields are created in heavy ion collisions, an insight that has made it possible to study a variety of surprising and intriguing phenomena that emerge from the interplay of quantum anomalies, the topology of non-Abelian gauge fields, and the magnetic field. In particular, the non-trivial topological configurations of the gluon field induce a non-dissipative electric current in the presence of a magnetic field. These phenomena have led to an extended formulation of relativistic hydrodynamics, called chiral magnetohydrodynamics. Hitherto unexpected applications in condensed matter physics include graphene and topological insulators. Other fields of application include astrophysics, where strong magnetic fields exist in magnetars and pulsars. Last but not least, an important ne...
Construction of Solar-Wind-Like Magnetic Fields
Roberts, Dana Aaron
2012-01-01
Fluctuations in the solar wind fields tend to not only have velocities and magnetic fields correlated in the sense consistent with Alfven waves traveling from the Sun, but they also have the magnitude of the magnetic field remarkably constant despite their being broadband. This paper provides, for the first time, a method for constructing fields with nearly constant magnetic field, zero divergence, and with any specified power spectrum for the fluctuations of the components of the field. Every wave vector, k, is associated with two polarizations the relative phases of these can be chosen to minimize the variance of the field magnitude while retaining the\\random character of the fields. The method is applied to a case with one spatial coordinate that demonstrates good agreement with observed time series and power spectra of the magnetic field in the solar wind, as well as with the distribution of the angles of rapid changes (discontinuities), thus showing a deep connection between two seemingly unrelated issues. It is suggested that using this construction will lead to more realistic simulations of solar wind turbulence and of the propagation of energetic particles.
High magnetic fields science and technology
Miura, Noboru
2003-01-01
This three-volume book provides a comprehensive review of experiments in very strong magnetic fields that can only be generated with very special magnets. The first volume is entirely devoted to the technology of laboratory magnets: permanent, superconducting, high-power water-cooled and hybrid; pulsed magnets, both nondestructive and destructive (megagauss fields). Volumes 2 and 3 contain reviews of the different areas of research where strong magnetic fields are an essential research tool. These volumes deal primarily with solid-state physics; other research areas covered are biological syst
Structure and magnetic field of periodic permanent magnetic focusing system with open magnetic rings
International Nuclear Information System (INIS)
Peng Long; Li Lezhong; Yang Dingyu; Zhu Xinghua; Li Yuanxun
2011-01-01
The magnetic field along the central axis for an axially magnetized permanent magnetic ring was investigated by analytical and finite element methods. For open magnetic rings, both calculated and measured results show that the existence of the radial magnetic field creates a remarkable cosine distribution field along the central axis. A new structure of periodic permanent magnet focusing system with open magnetic rings is proposed. The structure provides a satisfactory magnetic field with a stable peak value of 120 mT for a traveling wave tube system. - Research highlights: → For open magnetic rings, both calculated and measured results show that the existence of the radial magnetic field creates a remarkable cosine distribution field along the central axis. → A new structure of periodic permanent magnet (PPM) focusing system with open magnetic rings is proposed. → The new PPM focusing system with open magnetic rings meets the requirements for TWT system.
Synchrotron Applications of High Magnetic Fields
Energy Technology Data Exchange (ETDEWEB)
NONE
2006-07-01
This workshop aims at discussing the scientific potential of X-ray diffraction and spectroscopy in magnetic fields above 30 T. Pulsed magnetic fields in the range of 30 to 40 T have recently become available at Spring-8 and the ESRF (European synchrotron radiation facility). This document gathers the transparencies of the 6 following presentations: 1) pulsed magnetic fields at ESRF: first results; 2) X-ray spectroscopy and diffraction experiments by using mini-coils: applications to valence state transition and frustrated magnet; 3) R{sub 5}(Si{sub x}Ge{sub 1-x}){sub 4}: an ideal system to be studied in X-ray under high magnetic field?; 4) high field studies at the Advanced Photon Source: present status and future plans; 5) synchrotron X-ray diffraction studies under extreme conditions; and 6) projects for pulsed and steady high magnetic fields at the ESRF.
Demagnetizing fields in active magnetic regenerators
DEFF Research Database (Denmark)
Nielsen, Kaspar Kirstein; Bahl, Christian R.H.; Smith, Anders
2014-01-01
A magnetic material in an externally applied magnetic field will in general experience a spatially varying internal magnetic field due to demagnetizing effects. When the performance of active magnetic regenerators (AMRs) is evaluated using numerical models the internal field is often assumed...... is in general both a function of the overall shape of the regenerator and its morphology (packed particles, parallel plates etc.) as well as the magnetization of the material. Due to the pronounced temperature dependence of the magnetization near the Curie temperature, the demagnetization field is also...... temperature dependent. We propose a relatively straightforward method to correct sufficiently for the demagnetizing field in AMR models. We discuss how the demagnetizing field behaves in regenerators made of packed spheres under realistic operation conditions....
Fleishman, G. D.; Anfinogentov, S.; Loukitcheva, M.; Mysh'yakov, I.; Stupishin, A.
2017-12-01
Measuring and modeling coronal magnetic field, especially above active regions (ARs), remains one of the central problems of solar physics given that the solar coronal magnetism is the key driver of all solar activity. Nowadays the coronal magnetic field is often modelled using methods of nonlinear force-free field reconstruction, whose accuracy has not yet been comprehensively assessed. Given that the coronal magnetic probing is routinely unavailable, only morphological tests have been applied to evaluate performance of the reconstruction methods and a few direct tests using available semi-analytical force-free field solution. Here we report a detailed casting of various tools used for the nonlinear force-free field reconstruction, such as disambiguation methods, photospheric field preprocessing methods, and volume reconstruction methods in a 3D domain using a 3D snapshot of the publicly available full-fledged radiative MHD model. We take advantage of the fact that from the realistic MHD model we know the magnetic field vector distribution in the entire 3D domain, which enables us to perform "voxel-by-voxel" comparison of the restored magnetic field and the true magnetic field in the 3D model volume. Our tests show that the available disambiguation methods often fail at the quiet sun areas, where the magnetic structure is dominated by small-scale magnetic elements, while they work really well at the AR photosphere and (even better) chromosphere. The preprocessing of the photospheric magnetic field, although does produce a more force-free boundary condition, also results in some effective `elevation' of the magnetic field components. The effective `elevation' height turns out to be different for the longitudinal and transverse components of the magnetic field, which results in a systematic error in absolute heights in the reconstructed magnetic data cube. The extrapolation performed starting from actual AR photospheric magnetogram (i.e., without preprocessing) are
Analysis of an adjustable field permanent magnet solenoid
Burris-Mog, T.; Burns, M.; Chavez, A.; Schillig, J.
2017-10-01
A feasibility study has been performed on an adjustable-field permanent magnet (PM) solenoid concept in an effort to reduce the dependence that linear induction accelerators have on large direct current power supplies and associated cooling systems. The concept relies on the ability to reorient sections of the PMs and thus redirect their magnetization vector to either add to or subtract from the on-axis magnetic field. This study concentrated on the focal strengths and emittance growths for two different designs, both with 19 cm bore diameters extending 53 cm in length. The first design is expected to produce peak magnetic fields ranging from 260 to 900 G (0.026 to 0.09 T) while the second design is expected to produce peak magnetic fields ranging from 580 to 2100 G (0.058 to 0.21 T). Although the PM configuration generates a variable magnetic field and the torques acting on PMs within the assembly appear manageable, the emittance growth is larger than that of a DC solenoid.
Trapped magnetic field measurements on HTS bulk by peak controlled pulsed field magnetization
International Nuclear Information System (INIS)
Ida, Tetsuya; Watasaki, Masahiro; Kimura, Yosuke; Miki, Motohiro; Izumi, Mitsuru
2010-01-01
For the past several years, we have studied the high-temperature superconducting (HTS) synchronous motor assembled with melt-textured Gd-Ba-Cu-O bulk magnets. If the single pulse field magnetizes a bulk effectively, size of electrical motor will become small for the strong magnetic field of the HTS magnets without reducing output power of motor. In the previous study, we showed that the HTS bulk was magnetized to excellent cone-shape magnetic field distribution by using the waveform control pulse magnetization (WCPM) method. The WCPM technique made possible the active control of the waveform on which magnetic flux motion depended. We generated the pulse waveform with controlled risetime for HTS bulk magnetization to suppress the magnetic flux motion which decreases magnetization efficiency. The pulsed maximum magnetic flux density with slow risetime is not beyond the maximum magnetic flux density which is trapped by the static field magnetization. But, as for applying the pulse which has fast risetime, the magnetic flux which exceed greatly the threshold penetrates the bulk and causes the disorder of the trapped magnetic distribution. This fact suggests the possibility that the threshold at pulsed magnetization influences the dynamic magnetic flux motion. In this study, Gd-Ba-Cu-O bulk is magnetized by the controlled arbitrary trapezoidal shape pulse, of which the maximum magnetic flux density is controlled not to exceed the threshold. We will present the trapped magnetic characteristics and the technique to generate the controlled pulsed field.
Anomalous variations of lithosphere magnetic field before several earthquakes
Ni, Z.; Chen, B.
2015-12-01
Based on the geomagnetic vector data measured each year since 2011 at more than 500 sites with a mean spatial interval of ~70km.we observed anomalous variations of lithospheric magnetic field before and after over 15 earthquakes having magnitude > 5. We find that the field in near proximity (about 50km) to the epicenter of large earthquakes shows high spatial and temporal gradients before the earthquake. Due to the low frequency of repeat measurements it is unclear when these variations occurred and how do them evolve. We point out anomalous magnetic filed using some circles with radius of 50km usually in June of each year, and then we would check whether quake will locat in our circles during one year after that time (June to next June). Now we caught 10 earthquakes of 15 main shocks having magnitude > 5, most of them located at less than10km away from our circles and some of them were in our circles. Most results show that the variations of lithosphere magnetic filed at the epicenter are different with surrending backgroud usually. When we figure out horizontal variations (vector) of lithosphere magnetic field and epicenter during one year after each June, we found half of them show that the earthquakes will locat at "the inlands in a flowing river", that means earthquakes may occur at "quiet"regions while the backgroud show character as"flow" as liquid. When we compared with GPS results, it appears that these variations of lithospere magnetic field may also correlate with displacement of earth's surface. However we do not compared with GPS results for each earthquake, we are not clear whether these anomalous variations of lithospere magnetic field may also correlate with anomalous displacement of earth's surface. Future work will include developing an automated method for identifying this type of anomalous field behavior and trying to short repeat measurement period to 6 month to try to find when these variations occur.
Effect of magnetic field on food freezing
村田, 圭治; 奥村, 太一; 荒賀, 浩一; 小堀, 康功
2010-01-01
[Abstract] This paper presents an experimental investigation on effects of magnetic field on food freezing process. Although purpose of food freezing is to suppress the deterioration of food, freezing breaks food tissue down, and some nutrient and delicious element flow out after thawing. Recently, a few of refrigeration equipments with electric and magnetic fields have attracted attention from food production companies and mass media. Water and tuna were freezed in magnetic field (100kH, 1.3...
Magnetic field sensor for isotropically sensing an incident magnetic field in a sensor plane
Pant, Bharat B. (Inventor); Wan, Hong (Inventor)
2001-01-01
A magnetic field sensor that isotropically senses an incident magnetic field. This is preferably accomplished by providing a magnetic field sensor device that has one or more circular shaped magnetoresistive sensor elements for sensing the incident magnetic field. The magnetoresistive material used is preferably isotropic, and may be a CMR material or some form of a GMR material. Because the sensor elements are circular in shape, shape anisotropy is eliminated. Thus, the resulting magnetic field sensor device provides an output that is relatively independent of the direction of the incident magnetic field in the sensor plane.
Novel Electrochemical Phenomena in Magnetic Fields(Research in High Magnetic Fields)
Mogi, Iwao; Kamiko, Masao
1996-01-01
Recent two topics are given of electrochemical studies in steady magnetic fields at the High Field Laboratory of Tohoku University. One is the magnetic-field-induced diffusion-limited-aggregation in the pattern formation of silver electrodeposits . The other is the magnetic field effect on the learning effect in a dopant-exchange process of an organic conducting polymer polypyrrole.
Magnetic field measurements and mapping techniques
CERN. Geneva
2003-01-01
These lectures will present an overview of the most common techniques used for the measurement of magnetic field in accelerator magnets. The formalism for a harmonic description of the magnetic field will be presented, including a discussion of harmonics allowed under various types of symmetries in the magnet. The harmonic coil technique for measurement of field harmonics will be covered in depth. Using examples from recent projects, magnetic measurements will be shown to be a powerful tool for monitoring magnet production. Measurements of magnetic axis using extensions of the harmonic coil technique, as well as other techniques, such as the colloidal cell and stretched wire, will be covered. Topics of interest in superconducting magnets, such as time decay and snapback, requiring relatively fast measurements of the harmonics, will also be described.
Minimizing magnetic fields for precision experiments
Energy Technology Data Exchange (ETDEWEB)
Altarev, I.; Fierlinger, P.; Lins, T.; Marino, M. G.; Nießen, B.; Petzoldt, G.; Reisner, M.; Stuiber, S., E-mail: stefan.stuiber@ph.tum.de; Sturm, M.; Taggart Singh, J.; Taubenheim, B. [Physikdepartment, Technische Universität München, D-85748 Garching (Germany); Rohrer, H. K. [Rohrer GmbH, D-80667 München (Germany); Schläpfer, U. [IMEDCO AG, CH-4614 Hägendorf (Switzerland)
2015-06-21
An increasing number of measurements in fundamental and applied physics rely on magnetically shielded environments with sub nano-Tesla residual magnetic fields. State of the art magnetically shielded rooms (MSRs) consist of up to seven layers of high permeability materials in combination with highly conductive shields. Proper magnetic equilibration is crucial to obtain such low magnetic fields with small gradients in any MSR. Here, we report on a scheme to magnetically equilibrate MSRs with a 10 times reduced duration of the magnetic equilibration sequence and a significantly lower magnetic field with improved homogeneity. For the search of the neutron's electric dipole moment, our finding corresponds to a 40% improvement of the statistical reach of the measurement. However, this versatile procedure can improve the performance of any MSR for any application.
Minimizing magnetic fields for precision experiments
International Nuclear Information System (INIS)
Altarev, I.; Fierlinger, P.; Lins, T.; Marino, M. G.; Nießen, B.; Petzoldt, G.; Reisner, M.; Stuiber, S.; Sturm, M.; Taggart Singh, J.; Taubenheim, B.; Rohrer, H. K.; Schläpfer, U.
2015-01-01
An increasing number of measurements in fundamental and applied physics rely on magnetically shielded environments with sub nano-Tesla residual magnetic fields. State of the art magnetically shielded rooms (MSRs) consist of up to seven layers of high permeability materials in combination with highly conductive shields. Proper magnetic equilibration is crucial to obtain such low magnetic fields with small gradients in any MSR. Here, we report on a scheme to magnetically equilibrate MSRs with a 10 times reduced duration of the magnetic equilibration sequence and a significantly lower magnetic field with improved homogeneity. For the search of the neutron's electric dipole moment, our finding corresponds to a 40% improvement of the statistical reach of the measurement. However, this versatile procedure can improve the performance of any MSR for any application
Measurement of magnetic fields in the direct proximity of power line conductors
International Nuclear Information System (INIS)
Mamishev, A.V.; Russell, B.D.
1995-01-01
Modeling and managing of power frequency magnetic fields requires verification of theory with actual measurements. Measurements only at ground level are not always sufficient for comprehensive studies. The technique and the results of three-dimensional mapping of the power frequency magnetic fields high above ground level are presented in this paper. Comparative calculations illustrate relevance and approximations of the existing theoretical approach to field modeling. The influence of harmonics on the elliptical rotation of the magnetic field vector is illustrated. The possibility of use of the magnetic fields for the power line proximity detection is discussed
2D Vector Field Simplification Based on Robustness
Skraba, Primoz
2014-03-01
Vector field simplification aims to reduce the complexity of the flow by removing features in order of their relevance and importance, to reveal prominent behavior and obtain a compact representation for interpretation. Most existing simplification techniques based on the topological skeleton successively remove pairs of critical points connected by separatrices, using distance or area-based relevance measures. These methods rely on the stable extraction of the topological skeleton, which can be difficult due to instability in numerical integration, especially when processing highly rotational flows. These geometric metrics do not consider the flow magnitude, an important physical property of the flow. In this paper, we propose a novel simplification scheme derived from the recently introduced topological notion of robustness, which provides a complementary view on flow structure compared to the traditional topological-skeleton-based approaches. Robustness enables the pruning of sets of critical points according to a quantitative measure of their stability, that is, the minimum amount of vector field perturbation required to remove them. This leads to a hierarchical simplification scheme that encodes flow magnitude in its perturbation metric. Our novel simplification algorithm is based on degree theory, has fewer boundary restrictions, and so can handle more general cases. Finally, we provide an implementation under the piecewise-linear setting and apply it to both synthetic and real-world datasets. © 2014 IEEE.
Magnetic field and magnetic isotope effects on photochemical reactions
International Nuclear Information System (INIS)
Wakasa, Masanobu
1999-01-01
By at present exact experiments and the theoretical analysis, it was clear that the magnetic field less than 2 T affected a radical pair reaction and biradical reaction. The radical pair life and the dissipative radical yield showed the magnetic field effects on chemical reactions. The radical pair mechanism and the triplet mechanism were known as the mechanism of magnetic field effects. The radical pair mechanism consists of four mechanisms such as the homogeneous hyperfine interaction (HFC), the delta-g mechanism, the relaxation mechanism and the level cross mechanism. In order to observe the magnetic effects of the radical pair mechanism, two conditions need, namely, the recombination rate of singlet radical pair > the dissipation rate and the spin exchange rate > the dissipation rate. A nanosecond laser photo-decomposition equipment can observe the magnetic field effects. The inversion phenomena of magnetic field effect, isolation of the relaxation mechanism and the delta-g mechanism, the magnetic field effect of heavy metal radical reaction, the magnetic field effect in homogeneous solvent, saturation of delta-g mechanism are explained. The succeeded examples of isotope concentration by the magnetic isotope effect are 17 O, 19 Si, 33 S, 73 Ge and 235 U. (S.Y.)
Ferroelectric Cathodes in Transverse Magnetic Fields
International Nuclear Information System (INIS)
Alexander Dunaevsky; Yevgeny Raitses; Nathaniel J. Fisch
2002-01-01
Experimental investigations of a planar ferroelectric cathode in a transverse magnetic field up to 3 kGs are presented. It is shown that the transverse magnetic field affects differently the operation of ferroelectric plasma cathodes in ''bright'' and ''dark'' modes in vacuum. In the ''bright'' mode, when the surface plasma is formed, the application of the transverse magnetic field leads to an increase of the surface plasma density. In the ''dark'' mode, the magnetic field inhibits the development of electron avalanches along the surface, as it does similarly in other kinds of surface discharges in the pre-breakdown mode
Five years of magnetic field management
International Nuclear Information System (INIS)
Durkin, C.J.; Fogarty, R.P.; Halleran, T.M.; Mark, Dr. D.A.; Mukhopadhyay, A.
1995-01-01
The extensive publicity of epidemiological studies inferring correlation between 60 Hz magnetic fields and childhood leukemia prompted world wide research programs that have as a goal to determine if low frequency magnetic fields represent any risk for the general population, children or utility workers. While supporting this research effort through EPRI, Con Edison embarked on a technical research program aimed to: characterize magnetic fields as to intensity and variation in time; and investigate practical means to manage these magnetic fields through currently known methods. The final goal of these research projects is to establish viable methods to reduce magnetic field intensity to desired values at reasonable distances from the sources. This goal was pursued step by step, starting with an inventory of the main sources of magnetic fields in substations, distribution and transmission facilities and generating plants. The characterization of the sources helped to identify typical cases and select specific cases, far practical applications. The next step was to analyze the specific cases and develop design criteria for managing the magnetic fields in new installations. These criteria included physical arrangement of equipment based oil calculation of magnetic fields, cancellation effect, desired maximum field intensity at specific points and shielding with high magnetic permeability metals (mu-metal and steel). This paper summarizes the authors' experiences and shows the results of the specific projects completed in recent years
Multiresolution and Explicit Methods for Vector Field Analysis and Visualization
Nielson, Gregory M.
1997-01-01
This is a request for a second renewal (3d year of funding) of a research project on the topic of multiresolution and explicit methods for vector field analysis and visualization. In this report, we describe the progress made on this research project during the second year and give a statement of the planned research for the third year. There are two aspects to this research project. The first is concerned with the development of techniques for computing tangent curves for use in visualizing flow fields. The second aspect of the research project is concerned with the development of multiresolution methods for curvilinear grids and their use as tools for visualization, analysis and archiving of flow data. We report on our work on the development of numerical methods for tangent curve computation first.
Numerical analysis of magnetic field in superconducting magnetic energy storage
International Nuclear Information System (INIS)
Kanamaru, Y.; Amemiya, Y.
1991-01-01
This paper reports that the superconducting magnetic energy storage (SMES) is more useful than the other systems of electric energy storage because of larger stored energy and higher efficiency. The other systems are the battery, the flywheel, the pumped-storage power station. Some models of solenoid type SMES are designed in U.S.A. and Japan. But a high magnetic field happens by the large scale SMES in the living environment, and makes the erroneous operations of the computer display, the pacemaker of the heart and the electronic equipments. We study some fit designs of magnetic shielding of the solenoidal type SMES for reduction of the magnetic field in living environment. When some superconducting shielding coils are over the main storage coil, magnetic field reduces remarkably than the case of non shielding coil. The calculated results of the magnetic field are obtained y the finite element method
The strongest magnetic fields in the universe
Balogh, A; Falanga, M; Lyutikov, M; Mereghetti, S; Piran, T; Treumann, RA
2016-01-01
This volume extends the ISSI series on magnetic fields in the Universe into the domain of what are by far the strongest fields in the Universe, and stronger than any field that could be produced on Earth. The chapters describe the magnetic fields in non-degenerate strongly magnetized stars, degenerate stars (such as white dwarfs and neutron stars), exotic members called magnetars, and in their environments, as well as magnetic fields in the environments of black holes. These strong fields have a profound effect on the behavior of matter, visible in particular in highly variable processes like radiation in all known wavelengths, including Gamma-Ray bursts. The generation and structure of such strong magnetic fields and effects on the environment are also described.
Resonance double magnetic bremsstrahlung in a strong magnetic field
International Nuclear Information System (INIS)
Fomin, P.I.; Kholodov, R.I.
2003-01-01
The possibility of resonance double magnetic bremsstrahlung in the approximation of weakly excited electron states in a strong external magnetic field is analyzed. The differential probability of this process in the Breit-Wigner form is obtained. The probability of double magnetic bremsstrahlung (second-order process of perturbation theory) is compared with the probability of magnetic bremsstrahlung (first-order process of perturbation theory)
Reducing Field Distortion in Magnetic Resonance Imaging
Eom, Byeong Ho; Penanen, Konstantin; Hahn, Inseob
2010-01-01
A concept for a magnetic resonance imaging (MRI) system that would utilize a relatively weak magnetic field provides for several design features that differ significantly from the corresponding features of conventional MRI systems. Notable among these features are a magnetic-field configuration that reduces (relative to the conventional configuration) distortion and blurring of the image, the use of a superconducting quantum interference device (SQUID) magnetometer as the detector, and an imaging procedure suited for the unconventional field configuration and sensor. In a typical application of MRI, a radio-frequency pulse is used to excite precession of the magnetic moments of protons in an applied magnetic field, and the decaying precession is detected for a short time following the pulse. The precession occurs at a resonance frequency proportional to the strengths of the magnetic field and the proton magnetic moment. The magnetic field is configured to vary with position in a known way; hence, by virtue of the aforesaid proportionality, the resonance frequency varies with position in a known way. In other words, position is encoded as resonance frequency. MRI using magnetic fields weaker than those of conventional MRI offers several advantages, including cheaper and smaller equipment, greater compatibility with metallic objects, and higher image quality because of low susceptibility distortion and enhanced spin-lattice-relaxation- time contrast. SQUID MRI is being developed into a practical MRI method for applied magnetic flux densities of the order of only 100 T
NMR magnetic field controller for pulsed nuclear magnetic resonance experiments
International Nuclear Information System (INIS)
Scheler, G.; Anacker, M.
1975-01-01
A nuclear magnetic resonance controller for magnetic fields, which can also be used for pulsed NMR investigations, is described. A longtime stability of 10 -7 is achieved. The control signal is generated by a modified time sharing circuit with resonance at the first side band of the 2 H signal. An exact calibration of the magnetic field is achieved by the variation of the H 1 - or of the time-sharing frequency. (author)
High-field superferric MR magnet
International Nuclear Information System (INIS)
Huson, F.R.; Carcagno, R.; Colvin, J.
1987-01-01
Current large-bore (>20 cm), high-field (2-T) MR magnets have major implementation disadvantages, mostly related to the extensive stray field of traditional air-core superconducting magnets. To circumvent this problem, the authors designed, constructed, and tested a 30-cm prototype superconducting, self-shielded, high field magnet. This unshimmed superferric magnet can operate between 0.5 and 4 T with a field quality of about one part per million over one quarter of its aperture. The magnet can be ramped from one field strength to another in approximately 10 minutes. The 5-Gauss line extends less than 1 meter outside the magnet structure. Further details, including MR measurements and images, are demonstrated, as well as 1-meter bore scale-up projections
Principles of power frequency magnetic field management
International Nuclear Information System (INIS)
Fugate, D.; Feero, W.
1995-01-01
At the most general level, magnetic field management is the creation, elimination, or modification of sources in order to alter the spatial distribution of magnetic fields over some region of space. The two main options for magnetic field management are source modification (elimination or modification of original sources) and cancellation (creation of new sources). Source modification includes any changes in the layout or location of field sources, elimination of ground paths, or any options that increase the distance between sources and regions of interest. Cancellation involves the creation of new magnetic field sources, passive and/or active that produce magnetic fields that are opposite to the original fields in the region of interest. Shielding using materials of high conductivity and/or high permeability falls under the cancellation option. Strategies for magnetic field management, whether they are source modification or cancellation, typically vary on a case to case basis depending on the regions of interest, the types of sources and resulting complexity of the field structure, the field levels, and the attenuation requirements. This paper gives an overview of magnetic field management based on fundamental concepts. Low field design principles are described, followed by a structured discussion of cancellation and shielding. The two basic material shielding mechanisms, induced current shielding, and flux-shunting are discussed
SIMULATING MAGNETIC FIELDS IN THE ANTENNAE GALAXIES
International Nuclear Information System (INIS)
Kotarba, H.; Karl, S. J.; Naab, T.; Johansson, P. H.; Lesch, H.; Dolag, K.; Stasyszyn, F. A.
2010-01-01
We present self-consistent high-resolution simulations of NGC 4038/4039 (the A ntennae galaxies ) including star formation, supernova feedback, and magnetic fields performed with the N-body/smoothed particle hydrodynamic (SPH) code GADGET, in which magnetohydrodynamics are followed with the SPH method. We vary the initial magnetic field in the progenitor disks from 10 -9 to 10 -4 G. At the time of the best match with the central region of the Antennae system, the magnetic field has been amplified by compression and shear flows to an equilibrium field value of ∼10 μG, independent of the initial seed field. These simulations are a proof of the principle that galaxy mergers are efficient drivers for the cosmic evolution of magnetic fields. We present a detailed analysis of the magnetic field structure in the central overlap region. Simulated radio and polarization maps are in good morphological and quantitative agreement with the observations. In particular, the two cores with the highest synchrotron intensity and ridges of regular magnetic fields between the cores and at the root of the southern tidal arm develop naturally in our simulations. This indicates that the simulations are capable of realistically following the evolution of the magnetic fields in a highly nonlinear environment. We also discuss the relevance of the amplification effect for present-day magnetic fields in the context of hierarchical structure formation.
Saturn's Internal Magnetic Field Revealed by Cassini Grand Finale
Cao, H.; Dougherty, M. K.; Khurana, K. K.; Hunt, G. J.; Provan, G.; Kellock, S.; Burton, M. E.; Burk, T. A.
2017-12-01
Saturn's internal magnetic field has been puzzling since the first in-situ measurements during the Pioneer 11 Saturn flyby. Cassini magnetometer measurements prior to the Grand Finale phase established 1) the highly axisymmetric nature of Saturn's internal magnetic field with a dipole tilt smaller than 0.06 degrees, 2) at least an order of magnitude slower secular variation rate compared to that of the current geomagnetic field, and 3) expulsion of magnetic fluxes from the equatorial region towards high latitude. The highly axisymmetric nature of Saturn's intrinsic magnetic field not only challenges dynamo theory but also makes an accurate determination of the interior rotation rate of Saturn extremely difficult. The Cassini spacecraft entered the Grand Finale phase in April 2017, during which time the spacecraft dived through the gap between Saturn's atmosphere and the inner edge of the D-ring 22 times before descending into the deep atmosphere of Saturn. The unprecedented proximity to Saturn (reaching 2500 km above the cloud deck) and the highly inclined nature of the Grand Finale orbits provided an ideal opportunity to decode Saturn's internal magnetic field. The fluxgate magnetometer onboard Cassini made precise vector measurements during the Grand Finale phase. Magnetic signals from the interior of the planet, the magnetospheric ring current, the high-latitude field-aligned current (FAC) modulated by the 10.7 hour planetary period oscillation, and low-latitude FACs were observed during the Grand Finale phase. Here we report the magnetometer measurements during the Cassini Grand Finale phase, new features of Saturn's internal magnetic field revealed by these measurements (e.g., the high degree magnetic moments of Saturn, the level of axisymmetry beyond dipole), and implications for the deep interior of Saturn.
Structure of magnetic field in Tokamaks
International Nuclear Information System (INIS)
Heller, M.V.A.P.; Caldas, I.L.
1990-01-01
Magnetic surfaces, necessary to plasma confinement, can be extinguished by resonant helical perturbations with small intensities due to plasma oscillations or external helical currents. The mapping of magnetic field is obtained intergrating numerically the differential equation of its lines. Criteria which evaluate the chaotic distribution of lines between resonant magnetic islands are presented. (M.C.K.) [pt
Surface flute modes in the bumpy magnetic field
International Nuclear Information System (INIS)
Girka, I.O.; Girka, V.O.; Lapshin, V.I.
2005-01-01
Surface electromagnetic waves are often determined as the most possible cause of undesirable heating of edge plasma that leads, in turn, to strengthening of plasma - wall interaction in stellarators and increased plasma contamination. The propagation of surface flute modes near the interface of plasma column separated by a vacuum layer from the ring cylindrical ideally conductive metallic chamber is studied. The external steady bumpy magnetic field B-vector 0 = B 0z e-vector z + B 0r e-vector r was considered, B 0z =B 00 [1+ε m (r)cos(k m z)], here ε m '≡dε m /dr, k m =2π/L, L is the period of nonuniformity. non-uniformity of B-vector 0 is planned to be dominant in the confining magnetic field of the modular stellarator Helias, ε m ∼ 0.13. In the bumpy magnetic field the electromagnetic disturbance propagates in the form of the wave envelope, in which one alongside with the fundamental harmonic, proportional to exp[i(mθ±-ωt)], infinite set of satellite spatial harmonics, proportional to exp[i(mθ ± jk m z - ωt)], j=1,2,3..., is present. It is shown, that in the first approximation in the respect to ε m , amplitudes of the fundamental harmonics of the E-wave with the field components E r , E θ , B z do not vary, small satellite harmonics of these fields arise, proportional to exp[i(mθ ± k m z - ωt)]. At the same time due to weak coupling of - and - modes, caused by B-vector 0 nonuniformity and nonzero axial wave number of satellite harmonics, small satellite harmonics of H-wave with the field components E z , B r , B θ also arise. The amplitudes of satellite harmonics of E-wave are shown to be symmetric: E r (+) =E r (-) , E θ (+) =E θ (-) , B z (+) =B z (-) , and the amplitudes of H-wave are antisymmetric: B r (+) =-B r (-) , B θ (+) =- B θ (-) , E z (+) =-E z (-) . In the second approximation in the respect to ε m corrections to the amplitudes of the fundamental harmonic of E-wave arise. The correction to the eigen frequency of the wave
Gauge theories of Yang-Mills vector fields coupled to antisymmetric tensor fields
International Nuclear Information System (INIS)
Anco, Stephen C.
2003-01-01
A non-Abelian class of massless/massive nonlinear gauge theories of Yang-Mills vector potentials coupled to Freedman-Townsend antisymmetric tensor potentials is constructed in four space-time dimensions. These theories involve an extended Freedman-Townsend-type coupling between the vector and tensor fields, and a Chern-Simons mass term with the addition of a Higgs-type coupling of the tensor fields to the vector fields in the massive case. Geometrical, field theoretic, and algebraic aspects of the theories are discussed in detail. In particular, the geometrical structure mixes and unifies features of Yang-Mills theory and Freedman-Townsend theory formulated in terms of Lie algebra valued curvatures and connections associated to the fields and nonlinear field strengths. The theories arise from a general determination of all possible geometrical nonlinear deformations of linear Abelian gauge theory for one-form fields and two-form fields with an Abelian Chern-Simons mass term in four dimensions. For this type of deformation (with typical assumptions on the allowed form considered for terms in the gauge symmetries and field equations), an explicit classification of deformation terms at first-order is obtained, and uniqueness of deformation terms at all higher orders is proven. This leads to a uniqueness result for the non-Abelian class of theories constructed here
Dirac equation in magnetic-solenoid field
Energy Technology Data Exchange (ETDEWEB)
Gavrilov, S.P. [Dept. Fisica e Quimica, UNESP, Campus de Guaratingueta (Brazil); Gitman, D.M.; Smirnov, A.A. [Instituto de Fisica, Universidade de Sao Paulo (Brazil)
2004-07-01
We consider the Dirac equation in the magnetic-solenoid field (the field of a solenoid and a collinear uniform magnetic field). For the case of Aharonov-Bohm solenoid, we construct self-adjoint extensions of the Dirac Hamiltonian using von Neumann's theory of deficiency indices. We find self-adjoint extensions of the Dirac Hamiltonian and boundary conditions at the AB solenoid. Besides, for the first time, solutions of the Dirac equation in the magnetic-solenoid field with a finite radius solenoid were found. We study the structure of these solutions and their dependence on the behavior of the magnetic field inside the solenoid. Then we exploit the latter solutions to specify boundary conditions for the magnetic-solenoid field with Aharonov-Bohm solenoid. (orig.)
Magnetic field decay in model SSC dipoles
International Nuclear Information System (INIS)
Gilbert, W.S.; Althaus, R.F.; Barale, P.J.; Benjegerdes, R.W.; Green, M.A.; Green, M.I.; Scanlan, R.M.
1988-08-01
We have observed that some of our model SSC dipoles have long time constant decays of the magnetic field harmonics with amplitudes large enough to result in significant beam loss, if they are not corrected. The magnets were run at constant current at the SSC injection field level of 0.3 tesla for one to three hours and changes in the magnetic field were observed. One explanation for the observed field decay is time dependent superconductor magnetization. Another explanation involves flux creep or flux flow. Data are presented on how the decay changes with previous flux history. Similar magnets with different Nb-Ti filament spacings and matrix materials have different long time field decay. A theoretical model using proximity coupling and flux creep for the observed field decay is discussed. 10 refs., 5 figs., 2 tabs
The Evolution of the Earth's Magnetic Field.
Bloxham, Jeremy; Gubbins, David
1989-01-01
Describes the change of earth's magnetic field at the boundary between the outer core and the mantle. Measurement techniques used during the last 300 years are considered. Discusses the theories and research for explaining the field change. (YP)
Tripolar electric field Structure in guide field magnetic reconnection
Fu, Song; Huang, Shiyong; Zhou, Meng; Ni, Binbin; Deng, Xiaohua
2018-03-01
It has been shown that the guide field substantially modifies the structure of the reconnection layer. For instance, the Hall magnetic and electric fields are distorted in guide field reconnection compared to reconnection without guide fields (i.e., anti-parallel reconnection). In this paper, we performed 2.5-D electromagnetic full particle simulation to study the electric field structures in magnetic reconnection under different initial guide fields (Bg). Once the amplitude of a guide field exceeds 0.3 times the asymptotic magnetic field B0, the traditional bipolar Hall electric field is clearly replaced by a tripolar electric field, which consists of a newly emerged electric field and the bipolar Hall electric field. The newly emerged electric field is a convective electric field about one ion inertial length away from the neutral sheet. It arises from the disappearance of the Hall electric field due to the substantial modification of the magnetic field and electric current by the imposed guide field. The peak magnitude of this new electric field increases linearly with the increment of guide field strength. Possible applications of these results to space observations are also discussed.
Tripolar electric field Structure in guide field magnetic reconnection
Directory of Open Access Journals (Sweden)
S. Fu
2018-03-01
Full Text Available It has been shown that the guide field substantially modifies the structure of the reconnection layer. For instance, the Hall magnetic and electric fields are distorted in guide field reconnection compared to reconnection without guide fields (i.e., anti-parallel reconnection. In this paper, we performed 2.5-D electromagnetic full particle simulation to study the electric field structures in magnetic reconnection under different initial guide fields (Bg. Once the amplitude of a guide field exceeds 0.3 times the asymptotic magnetic field B0, the traditional bipolar Hall electric field is clearly replaced by a tripolar electric field, which consists of a newly emerged electric field and the bipolar Hall electric field. The newly emerged electric field is a convective electric field about one ion inertial length away from the neutral sheet. It arises from the disappearance of the Hall electric field due to the substantial modification of the magnetic field and electric current by the imposed guide field. The peak magnitude of this new electric field increases linearly with the increment of guide field strength. Possible applications of these results to space observations are also discussed.
Observing Interstellar and Intergalactic Magnetic Fields
Han, J. L.
2017-08-01
Observational results of interstellar and intergalactic magnetic fields are reviewed, including the fields in supernova remnants and loops, interstellar filaments and clouds, Hii regions and bubbles, the Milky Way and nearby galaxies, galaxy clusters, and the cosmic web. A variety of approaches are used to investigate these fields. The orientations of magnetic fields in interstellar filaments and molecular clouds are traced by polarized thermal dust emission and starlight polarization. The field strengths and directions along the line of sight in dense clouds and cores are measured by Zeeman splitting of emission or absorption lines. The large-scale magnetic fields in the Milky Way have been best probed by Faraday rotation measures of a large number of pulsars and extragalactic radio sources. The coherent Galactic magnetic fields are found to follow the spiral arms and have their direction reversals in arms and interarm regions in the disk. The azimuthal fields in the halo reverse their directions below and above the Galactic plane. The orientations of organized magnetic fields in nearby galaxies have been observed through polarized synchrotron emission. Magnetic fields in the intracluster medium have been indicated by diffuse radio halos, polarized radio relics, and Faraday rotations of embedded radio galaxies and background sources. Sparse evidence for very weak magnetic fields in the cosmic web is the detection of the faint radio bridge between the Coma cluster and A1367. Future observations should aim at the 3D tomography of the large-scale coherent magnetic fields in our Galaxy and nearby galaxies, a better description of intracluster field properties, and firm detections of intergalactic magnetic fields in the cosmic web.
Fluxball magnetic field analysis using a hybrid analytical/FEM/BEM with equivalent currents
International Nuclear Information System (INIS)
Fernandes, João F.P.; Camilo, Fernando M.; Machado, V. Maló
2016-01-01
In this paper, a fluxball electric machine is analyzed concerning the magnetic flux, force and torque. A novel method is proposed based in a special hybrid FEM/BEM (Finite Element Method/Boundary Element Method) with equivalent currents by using an analytical treatment for the source field determination. The method can be applied to evaluate the magnetic field in axisymmetric problems, in the presence of several magnetic materials. Same results obtained by a commercial Finite Element Analysis tool are presented for validation purposes with the proposed method. - Highlights: • The Fluxball machine magnetic field is analyzed by a new FEM/BEM/Analytical method. • The method is adequate for axisymmetric non homogeneous magnetic field problems. • The source magnetic field is evaluated considering a non-magnetic equivalent problem. • Material magnetization vectors are accounted by using equivalent currents. • A strong reduction of the finite element domain is achieved.
Vector network analyzer ferromagnetic resonance spectrometer with field differential detection
Tamaru, S.; Tsunegi, S.; Kubota, H.; Yuasa, S.
2018-05-01
This work presents a vector network analyzer ferromagnetic resonance (VNA-FMR) spectrometer with field differential detection. This technique differentiates the S-parameter by applying a small binary modulation field in addition to the DC bias field to the sample. By setting the modulation frequency sufficiently high, slow sensitivity fluctuations of the VNA, i.e., low-frequency components of the trace noise, which limit the signal-to-noise ratio of the conventional VNA-FMR spectrometer, can be effectively removed, resulting in a very clean FMR signal. This paper presents the details of the hardware implementation and measurement sequence as well as the data processing and analysis algorithms tailored for the FMR spectrum obtained with this technique. Because the VNA measures a complex S-parameter, it is possible to estimate the Gilbert damping parameter from the slope of the phase variation of the S-parameter with respect to the bias field. We show that this algorithm is more robust against noise than the conventional algorithm based on the linewidth.
Derivative self-interactions for a massive vector field
Energy Technology Data Exchange (ETDEWEB)
Beltrán Jiménez, Jose, E-mail: jose.beltran@cpt.univ-mrs.fr [CPT, Aix Marseille Université, UMR 7332, 13288 Marseille (France); Heisenberg, Lavinia, E-mail: lavinia.heisenberg@eth-its.ethz.ch [Institute for Theoretical Studies, ETH Zurich, Clausiusstrasse 47, 8092 Zurich (Switzerland)
2016-06-10
In this work we revisit the construction of theories for a massive vector field with derivative self-interactions such that only the 3 desired polarizations corresponding to a Proca field propagate. We start from the decoupling limit by constructing healthy interactions containing second derivatives of the Stueckelberg field with itself and also with the transverse modes. The resulting interactions can then be straightforwardly generalized beyond the decoupling limit. We then proceed to a systematic construction of the interactions by using the Levi–Civita tensors. Both approaches lead to a finite family of allowed derivative self-interactions for the Proca field. This construction allows us to show that some higher order terms recently introduced as new interactions trivialize in 4 dimensions by virtue of the Cayley–Hamilton theorem. Moreover, we discuss how the resulting derivative interactions can be written in a compact determinantal form, which can also be regarded as a generalization of the Born-Infeld lagrangian for electromagnetism. Finally, we generalize our results for a curved background and give the necessary non-minimal couplings guaranteeing that no additional polarizations propagate even in the presence of gravity.
Coulomb blockade induced by magnetic field
International Nuclear Information System (INIS)
Kusmartsev, F.V.
1992-01-01
In this paper, the authors found that a Coulomb blockade can be induced by magnetic field. The authors illustrated this effect on the example of a ring consisting of two and many Josephson junctions. For the ring with two junctions we present an exact solution. The transition into Coulomb blockade state on a ring transforms into a linear array of Josephson junctions, although in latter case the effect of magnetic field disappears. In the state of Coulomb blockade the magnetization may be both diamagnetic and paramagnetic. The Coulomb blockade may also be removed by external magnetic field
Magnetic field errors tolerances of Nuclotron booster
Butenko, Andrey; Kazinova, Olha; Kostromin, Sergey; Mikhaylov, Vladimir; Tuzikov, Alexey; Khodzhibagiyan, Hamlet
2018-04-01
Generation of magnetic field in units of booster synchrotron for the NICA project is one of the most important conditions for getting the required parameters and qualitative accelerator operation. Research of linear and nonlinear dynamics of ion beam 197Au31+ in the booster have carried out with MADX program. Analytical estimation of magnetic field errors tolerance and numerical computation of dynamic aperture of booster DFO-magnetic lattice are presented. Closed orbit distortion with random errors of magnetic fields and errors in layout of booster units was evaluated.
Programming the control of magnetic field measurements
International Nuclear Information System (INIS)
David, L.
1998-01-01
This paper gives a short review concerning the new NMR probe measurement control system. Then it presents the new program 'CYCLOCHAMP' attached to the magnetic field measurement which also allows to cycle the magnetic field inside the cyclotrons and to equilibrate it among the SSC sectors. (authors)
Strong magnetic field generation in laser plasma
International Nuclear Information System (INIS)
Nakarmi, J.J.; Jha, L.N.
1996-12-01
An attempt has been made to solve the magnetic field evolution equation by using Green function and taking convective, diffusion and nabla n x nabla T as a dominant source term. The maximum magnetic field is obtained to be an order of megagauss. (author). 14 refs, 1 fig
Hydrogen atom moving across a magnetic field
International Nuclear Information System (INIS)
Lozovik, Yu.E.; Volkov, S.Yu.
2004-01-01
A hydrogen atom moving across a magnetic field is considered in a wide region of magnitudes of magnetic field and atom momentum. We solve the Schroedinger equation of the system numerically using an imaginary time method and find wave functions of the lowest states of atom. We calculate the energy and the mean electron-nucleus separation as a function of atom momentum and magnetic field. All the results obtained could be summarized as a phase diagram on the 'atom-momentum - magnetic-field' plane. There are transformations of wave-function structure at critical values of atom momentum and magnetic field that result in a specific behavior of dependencies of energy and mean interparticle separation on the atom momentum P. We discuss a transition from the Zeeman regime to the high magnetic field regime. A qualitative analysis of the complicated behavior of wave functions vs P based on the effective potential examination is given. We analyze a sharp transition at the critical momentum from a Coulomb-type state polarized due to atom motion to a strongly decentered (Landau-type) state at low magnetic fields. A crossover occurring at intermediate magnetic fields is also studied
Plattner, Alain; Simons, Frederik J.
2017-10-01
When modelling satellite data to recover a global planetary magnetic or gravitational potential field, the method of choice remains their analysis in terms of spherical harmonics. When only regional data are available, or when data quality varies strongly with geographic location, the inversion problem becomes severely ill-posed. In those cases, adopting explicitly local methods is to be preferred over adapting global ones (e.g. by regularization). Here, we develop the theory behind a procedure to invert for planetary potential fields from vector observations collected within a spatially bounded region at varying satellite altitude. Our method relies on the construction of spatiospectrally localized bases of functions that mitigate the noise amplification caused by downward continuation (from the satellite altitude to the source) while balancing the conflicting demands for spatial concentration and spectral limitation. The `altitude-cognizant' gradient vector Slepian functions (AC-GVSF) enjoy a noise tolerance under downward continuation that is much improved relative to the `classical' gradient vector Slepian functions (CL-GVSF), which do not factor satellite altitude into their construction. Furthermore, venturing beyond the realm of their first application, published in a preceding paper, in the present article we extend the theory to being able to handle both internal and external potential-field estimation. Solving simultaneously for internal and external fields under the limitation of regional data availability reduces internal-field artefacts introduced by downward-continuing unmodelled external fields, as we show with numerical examples. We explain our solution strategies on the basis of analytic expressions for the behaviour of the estimation bias and variance of models for which signal and noise are uncorrelated, (essentially) space- and band-limited, and spectrally (almost) white. The AC-GVSF are optimal linear combinations of vector spherical harmonics
Magnetic resonance imaging: effects of magnetic field strength
International Nuclear Information System (INIS)
Crooks, L.E.; Arakawa, M.; Hoenninger, J.; McCarten, B.; Watts, J.; Kaufman, L.
1984-01-01
Magnetic resonance images of the head, abdomen, and pelvis of normal adult men were obtained using varying magnetic field strength, and measurements of T1 and T2 relaxations and of signal-to-noise (SN) ratios were determined. For any one spin echo sequence, gray/white matter contrast decreases and muscle/fat contrast increases with field. SN levels rise rapidly up to 3.0 kgauss and then change more slowly, actually dropping for muscle. The optimum field for magnetic resonance imaging depends on tissue type, body part, and imaging sequence, so that it does not have a unique value. Magnetic resonance systems that operate in the 3.0-5.0 kgauss range achieve most or all of the gains that can be achieved by higher magnetic fields
Earth magnetism a guided tour through magnetic fields
Campbell, Wallace H
2001-01-01
An introductory guide to global magnetic field properties, Earth Magnetism addresses, in non-technical prose, many of the frequently asked questions about Earth''s magnetic field. Magnetism surrounds and penetrates our Earth in ways basic science courses can rarely address. It affects navigation, communication, and even the growth of crystals. As we observe and experience an 11-year solar maximum, we may witness spectacular satellite-destroying solar storms as they interact with our magnetic field. Written by an acknowledged expert in the field, this book will enrich courses in earth science, atmospheric science, geology, meteorology, geomagnetism, and geophysics. Contains nearly 200 original illustrations and eight pages of full-color plates.* Largely mathematics-free and with a wide breadth of material suitable for general readers* Integrates material from geomagnetism, paleomagnetism, and solar-terrestrial space physics.* Features nearly 200 original illustrations and 4 pages of colour plates
Parameterization and measurements of helical magnetic fields
International Nuclear Information System (INIS)
Fischer, W.; Okamura, M.
1997-01-01
Magnetic fields with helical symmetry can be parameterized using multipole coefficients (a n , b n ). We present a parameterization that gives the familiar multipole coefficients (a n , b n ) for straight magnets when the helical wavelength tends to infinity. To measure helical fields all methods used for straight magnets can be employed. We show how to convert the results of those measurements to obtain the desired helical multipole coefficients (a n , b n )
Classical theory of electric and magnetic fields
Good, Roland H
1971-01-01
Classical Theory of Electric and Magnetic Fields is a textbook on the principles of electricity and magnetism. This book discusses mathematical techniques, calculations, with examples of physical reasoning, that are generally applied in theoretical physics. This text reviews the classical theory of electric and magnetic fields, Maxwell's Equations, Lorentz Force, and Faraday's Law of Induction. The book also focuses on electrostatics and the general methods for solving electrostatic problems concerning images, inversion, complex variable, or separation of variables. The text also explains ma
Hybridization of electron states in a step quantum well in a magnetic field
International Nuclear Information System (INIS)
Barseghyan, M.G.; Kirakosyan, A.A.
2005-01-01
The quantum states and energy levels of an electrion in a rectangular step quantum well in a magnetic field parallel to the plane of two-dimentional electron gas are investigated. It is shown that the joint effect of the magnetic field and confining potential of the quantum well results in redical change of the electron spectrum. The dependence of the electron energy levels on the quantum well parameters, magnetic field induction and projection of the wave-vector along the magnetic field induction are calculated. Numerical calculations are carried out for a AlAs/GaAlAs/GaAs/AlAs step quantum well
Mechanics of magnetic fluid column in strong magnetic fields
Energy Technology Data Exchange (ETDEWEB)
Polunin, V.M.; Ryapolov, P.A., E-mail: r-piter@yandex.ru; Platonov, V.B.
2017-06-01
Elastic-and magnetic properties of magnetic fluid confined by ponderomotive force in a tube fixed in horizontal position are considered. The system is placed in a strong magnetic field under the influence of external static and dynamic perturbations. An experimental setup has been developed. A theoretical basis of the processes of magnetic colloid elastic deformation has been proposed. The values of the static ponderomotive elasticity coefficient and the elasticity coefficient under dynamic action are experimentally determined. The calculations of the saturation magnetization for two magnetic fluid samples, carried out according to the equation containing the dynamic elasticity coefficient, are in good agreement with the experimental magnetization curve. The described method is of interest when studying magnetophoresis and aggregation of nanoparticles in magnetic colloids.
Levitation of a magnet by an alternating magnetic field
International Nuclear Information System (INIS)
Gough, W; Hunt, M O; Summerskill, W S H
2013-01-01
An experiment is described in which a small strong cylindrical magnet is levitated by a vertical non-uniform alternating magnetic field. Surprisingly, no superimposed constant field is necessary, but the levitation can be explained when the vertical motion of the magnet is taken into account. The theoretical mean levitation force is (0.26 ± 0.06) N, which is in good agreement with the levitated weight of (0.239 ± 0.001) N. This experiment is suitable for an undergraduate laboratory, particularly as a final year project. Students have found it interesting, and it sharpens up knowledge of basic magnetism. (paper)
MAGNETIC FIELD OF THE VELA C MOLECULAR CLOUD
Energy Technology Data Exchange (ETDEWEB)
Kusune, Takayoshi; Sugitani, Koji [Graduate School of Natural Sciences, Nagoya City University, Mizuho-ku, Nagoya, Aichi 467-8501 (Japan); Nakamura, Fumitaka; Tamura, Motohide [National Astronomical Observatory, Mitaka, Tokyo 181-8588 (Japan); Watanabe, Makoto [Department of Applied Physics, Okayama University of Science, 1-1 Ridai-cho, Okayama-city, Okayama 700-0005 (Japan); Kwon, Jungmi [Institute of Space and Astronautical Science, Japan Aerospace Exploration Agency, 3-1-1 Yohinodai, Chuo-ku, Sagamihara, Kanagawa 252-5210 (Japan); Sato, Shuji, E-mail: t_kusune@nsc.nagoya-cu.ac.jp [Department of Astrophysics, Nagoya University, Chikusa-ku, Nagoya, Aichi 464-8602 (Japan)
2016-10-20
We have performed extensive near-infrared ( JHK {sub s}) imaging polarimetry toward the Vela C molecular cloud, which covers the five high-density sub-regions (North, Centre-Ridge, Centre-Nest, South-Ridge, and South-Nest) with distinct morphological characteristics. The obtained polarization vector map shows that three of these sub-regions have distinct plane-of-the-sky (POS) magnetic-field characteristics according to the morphological characteristics. (1) In the Centre-Ridge sub-region, a dominating ridge, the POS magnetic field is mostly perpendicular to the ridge. (2) In the Centre-Nest sub-region, a structure having a slightly extended nest of filaments, the POS magnetic field is nearly parallel to its global elongation. (3) In the South-Nest sub-region, which has a network of small filaments, the POS magnetic field appears to be chaotic. By applying the Chandrasekhar–Fermi method, we derived the POS magnetic field strength as ∼70–310 μ G in the Centre-Ridge, Centre-Nest, and South-Ridge sub-regions. In the South-Nest sub-region, the dispersion of polarization angles is too large to apply the C-F method. Because the velocity dispersion in this sub-region is not greater than those in the other sub-regions, we suggest that the magnetic field in this sub-region is weaker than those in other sub-regions. We also discuss the relationship between the POS magnetic field (configuration and strength) and the cloud structure of each sub-region.
MAGNETIC FIELD OF THE VELA C MOLECULAR CLOUD
International Nuclear Information System (INIS)
Kusune, Takayoshi; Sugitani, Koji; Nakamura, Fumitaka; Tamura, Motohide; Watanabe, Makoto; Kwon, Jungmi; Sato, Shuji
2016-01-01
We have performed extensive near-infrared ( JHK s ) imaging polarimetry toward the Vela C molecular cloud, which covers the five high-density sub-regions (North, Centre-Ridge, Centre-Nest, South-Ridge, and South-Nest) with distinct morphological characteristics. The obtained polarization vector map shows that three of these sub-regions have distinct plane-of-the-sky (POS) magnetic-field characteristics according to the morphological characteristics. (1) In the Centre-Ridge sub-region, a dominating ridge, the POS magnetic field is mostly perpendicular to the ridge. (2) In the Centre-Nest sub-region, a structure having a slightly extended nest of filaments, the POS magnetic field is nearly parallel to its global elongation. (3) In the South-Nest sub-region, which has a network of small filaments, the POS magnetic field appears to be chaotic. By applying the Chandrasekhar–Fermi method, we derived the POS magnetic field strength as ∼70–310 μ G in the Centre-Ridge, Centre-Nest, and South-Ridge sub-regions. In the South-Nest sub-region, the dispersion of polarization angles is too large to apply the C-F method. Because the velocity dispersion in this sub-region is not greater than those in the other sub-regions, we suggest that the magnetic field in this sub-region is weaker than those in other sub-regions. We also discuss the relationship between the POS magnetic field (configuration and strength) and the cloud structure of each sub-region.
DEFF Research Database (Denmark)
Boeriis, Morten; van Leeuwen, Theo
2017-01-01
should be taken into account in discussing ‘reactions’, which Kress and van Leeuwen link only to eyeline vectors. Finally, the question can be raised as to whether actions are always realized by vectors. Drawing on a re-reading of Rudolf Arnheim’s account of vectors, these issues are outlined......This article revisits the concept of vectors, which, in Kress and van Leeuwen’s Reading Images (2006), plays a crucial role in distinguishing between ‘narrative’, action-oriented processes and ‘conceptual’, state-oriented processes. The use of this concept in image analysis has usually focused...
Non-gaussianity from the trispectrum and vector field perturbations
International Nuclear Information System (INIS)
Valenzuela-Toledo, Cesar A.; Rodriguez, Yeinzon
2010-01-01
We use the δN formalism to study the trispectrum T ζ of the primordial curvature perturbation ζ when the latter is generated by vector field perturbations, considering the tree-level and one-loop contributions. The order of magnitude of the level of non-gaussianity in the trispectrum, τ NL , is calculated in this scenario and related to the order of magnitude of the level of non-gaussianity in the bispectrum, f NL , and the level of statistical anisotropy in the power spectrum, g ζ . Such consistency relations will put under test this scenario against future observations. Comparison with the expected observational bound on τ NL from WMAP, for generic inflationary models, is done.
Non-gaussianity from the trispectrum and vector field perturbations
Energy Technology Data Exchange (ETDEWEB)
Valenzuela-Toledo, Cesar A., E-mail: cavalto@ciencias.uis.edu.c [Escuela de Fisica, Universidad Industrial de Santander, Ciudad Universitaria, Bucaramanga (Colombia); Rodriguez, Yeinzon, E-mail: yeinzon.rodriguez@uan.edu.c [Escuela de Fisica, Universidad Industrial de Santander, Ciudad Universitaria, Bucaramanga (Colombia); Centro de Investigaciones, Universidad Antonio Narino, Cra 3 Este 47A-15, Bogota D.C. (Colombia)
2010-03-01
We use the deltaN formalism to study the trispectrum T{sub z}eta of the primordial curvature perturbation zeta when the latter is generated by vector field perturbations, considering the tree-level and one-loop contributions. The order of magnitude of the level of non-gaussianity in the trispectrum, tau{sub NL}, is calculated in this scenario and related to the order of magnitude of the level of non-gaussianity in the bispectrum, f{sub NL}, and the level of statistical anisotropy in the power spectrum, g{sub z}eta. Such consistency relations will put under test this scenario against future observations. Comparison with the expected observational bound on tau{sub NL} from WMAP, for generic inflationary models, is done.
Magnetic Fields in the Solar Convection Zone
Directory of Open Access Journals (Sweden)
Fan Yuhong
2004-07-01
Full Text Available Recent studies of the dynamic evolution of magnetic flux tubes in the solar convection zone are reviewed with focus on emerging flux tubes responsible for the formation of solar active regions. The current prevailing picture is that active regions on the solar surface originate from strong toroidal magnetic fields generated by the solar dynamo mechanism at the thin tachocline layer at the base of the solar convection zone. Thus the magnetic fields need to traverse the entire convection zone before they reach the photosphere to form the observed solar active regions. This review discusses results with regard to the following major topics: 1. the equilibrium properties of the toroidal magnetic fields stored in the stable overshoot region at the base of the convection zone, 2. the buoyancy instability associated with the toroidal magnetic fields and the formation of buoyant magnetic flux tubes, 3. the rise of emerging flux loops through the solar convective envelope as modeled by the thin flux tube calculations which infer that the field strength of the toroidal magnetic fields at the base of the solar convection zone is significantly higher than the value in equipartition with convection, 4. the minimum twist needed for maintaining cohesion of the rising flux tubes, 5. the rise of highly twisted kink unstable flux tubes as a possible origin of d -sunspots, 6. the evolution of buoyant magnetic flux tubes in 3D stratified convection, 7. turbulent pumping of magnetic flux by penetrative compressible convection, 8. an alternative mechanism for intensifying toroidal magnetic fields to significantly super-equipartition field strengths by conversion of the potential energy associated with the superadiabatic stratification of the solar convection zone, and finally 9. a brief overview of our current understanding of flux emergence at the surface and post-emergence evolution of the subsurface magnetic fields.
Cosmic microwave background polarization signals from tangled magnetic fields.
Seshadri, T R; Subramanian, K
2001-09-03
Tangled, primordial cosmic magnetic fields create small rotational velocity perturbations on the last scattering surface of the cosmic microwave background radiation. For fields which redshift to a present value of B0 = 3 x 10(-9) G, these vector modes are shown to generate polarization anisotropies of order 0.1-4 microK on small angular scales (500
Orienting Paramecium with intense static magnetic fields
Valles, James M., Jr.; Guevorkian, Karine; Quindel, Carl
2004-03-01
Recent experiments on cell division suggest the application of intense static magnetic fields as a novel tool for the manipulation of biological systems [1]. The magnetic field appears to couple to the intrinsic anisotropies in the diamagnetic components of the cells. Here, we present measurements of the intrinsic average diamagnetic anisotropy of the whole single celled ciliate, Paramecium Caudatum. Magnetic fields, 2.5 T Paramecium Caudatum that were suspended in a density matched medium. The organisms align with their long axis parallel to the applied magnetic field. Their intrinsic diamagnetic anisotropy is 3x10-11 in cgs units. We will discuss the implications of these results for employing magnetic fields to probe the behavior of swimming Paramecium. [1] J. M. Valles, Jr. et al., Expt. Cell Res.274, 112-118 (2002).
Five-dimensional rotating black hole in a uniform magnetic field: The gyromagnetic ratio
International Nuclear Information System (INIS)
Aliev, A.N.; Frolov, Valeri P.
2004-01-01
In four-dimensional general relativity, the fact that a Killing vector in a vacuum spacetime serves as a vector potential for a test Maxwell field provides one with an elegant way of describing the behavior of electromagnetic fields near a rotating Kerr black hole immersed in a uniform magnetic field. We use a similar approach to examine the case of a five-dimensional rotating black hole placed in a uniform magnetic field of configuration with biazimuthal symmetry that is aligned with the angular momenta of the Myers-Perry spacetime. Assuming that the black hole may also possess a small electric charge we construct the five-vector potential of the electromagnetic field in the Myers-Perry metric using its three commuting Killing vector fields. We show that, like its four-dimensional counterparts, the five-dimensional Myers-Perry black hole rotating in a uniform magnetic field produces an inductive potential difference between the event horizon and an infinitely distant surface. This potential difference is determined by a superposition of two independent Coulomb fields consistent with the two angular momenta of the black hole and two nonvanishing components of the magnetic field. We also show that a weakly charged rotating black hole in five dimensions possesses two independent magnetic dipole moments specified in terms of its electric charge, mass, and angular momentum parameters. We prove that a five-dimensional weakly charged Myers-Perry black hole must have the value of the gyromagnetic ratio g=3
Development of high field superconducting magnet
International Nuclear Information System (INIS)
Irie, Fujio; Takeo, Masakatsu.
1986-01-01
Recently, in connection with nuclear fusion research, the development of high field superconducting magnets showed rapid progress. The development of high field magnets of 15 T class by the techniques of winding after heat treatment has been continued in various places, as these techniques are suitable to make large magnets. In 1985, Kyushu University attained the record of 15.5 T. However in high field magnets, there are many problems peculiar to them, and the basic research related to those is demanded. In this report, these general problems, the experience of the design and manufacture in Kyushu University and the related problems are described. The superconducting magnet installed in the Superconducting Magnet Research Center of Kyushu University attained the record of 15.5 T for the first time in March, 1985. In superconducting magnets, very difficult problem must be solved since superconductivity, heat and mechanical force are inter related. The problems of the wire materials for high field, the scale of high field magnets, the condition limiting mean current density, and the development of high field magnets in Kyushu University are described. (Kako, I.)
Bats Respond to Very Weak Magnetic Fields
Tian, Lan-Xiang; Pan, Yong-Xin; Metzner, Walter; Zhang, Jin-Shuo; Zhang, Bing-Fang
2015-01-01
How animals, including mammals, can respond to and utilize the direction and intensity of the Earth’s magnetic field for orientation and navigation is contentious. In this study, we experimentally tested whether the Chinese Noctule, Nyctalus plancyi (Vespertilionidae) can sense magnetic field strengths that were even lower than those of the present-day geomagnetic field. Such field strengths occurred during geomagnetic excursions or polarity reversals and thus may have played an important role in the evolution of a magnetic sense. We found that in a present-day local geomagnetic field, the bats showed a clear preference for positioning themselves at the magnetic north. As the field intensity decreased to only 1/5th of the natural intensity (i.e., 10 μT; the lowest field strength tested here), the bats still responded by positioning themselves at the magnetic north. When the field polarity was artificially reversed, the bats still preferred the new magnetic north, even at the lowest field strength tested (10 μT), despite the fact that the artificial field orientation was opposite to the natural geomagnetic field (Preversed tens of times over the past fifty million years. PMID:25922944
Line formation in microturbulent magnetic fields
International Nuclear Information System (INIS)
Domke, H.; Pavlov, G.G.
1979-01-01
The formation of Zeeman lines in Gaussian microturbulent magnetic fields is considered assuming LTE. General formulae are derived for the local mean values of the transfer matrix elements. The cases of one-dimensional (longitudinal), isotropic, and two-dimensional (transversal) magnetic microturbulence are studied in some detail. Asymptotic formulae are given for small mean as well as for small microturbulent magnetic fields. Characteristic effects of magnetic microturbulence on the transfer coefficients are: (i) the broadening of the frequency contours, although only for the case of longitudinal Zeeman effect and longitudinal magnetic microturbulence this effect can be described analogous to Doppler broadening, (ii) the appearance of a pseudo-Zeeman structure for nonlongitudinal magnetic microturbulence, (iii) the reduction of maximal values of circular polarization, and (iv) the appearance of characteristic linear polarization effects due to the anisotropy of the magnetic microturbulence. Line contours and polarization of Zeeman triplets are computed for Milne-Eddington atmospheres. It is shown that magnetic intensification due to microturbulent magnetic fields may be much more efficient than that due to regular fields. The gravity center of a Zeeman line observed in circularly polarized light remains a reasonable measure of the line of sight component of the mean magnetic field for a line strength eta 0 < approx. 2. For saturated lines, the gravity center distance depends significantly on the magnetic microturbulence and its anisotropy. The influence of magnetic microturbulence on the ratio of longitudinal field magnetographic signals shows that unique conclusions about the magnetic microstructure can be drawn from the line ratio measurements only in combination with further spectroscopic data or physical reasoning. (orig.)
General projective relativity and the vector-tensor gravitational field
International Nuclear Information System (INIS)
Arcidiacono, G.
1986-01-01
In the general projective relativity, the induced 4-dimensional metric is symmetric in three cases, and we obtain the vector-tensor, the scalar-tensor, and the scalar-vector-tensor theories of gravitation. In this work we examine the vector-tensor theory, similar to the Veblen's theory, but with a different physical interpretation
Sayanagi, K.; Isezaki, N.; Matsuo, J.; Harada, M.; Kasaya, T.
2011-12-01
Bayonnaise Knoll is a submarine caldera with an outer rim of 2.5-3 km and a floor of 840-920 m, which is located in the Izu-Ogasawara arc. A large hydrothermal deposit, Hakurei deposit, lies in the southeast part of the caldera. In the R/V Bosei-maru cruise, we observed three components of magnetic anomalies at depths of 400-570 m along SE-NW and WE tracks across the caldera. In the R/V Yokosuka YK10-17 cruise, we observed three components and total intensity of magnetic anomalies at altitudes of 60-100 m around the Hakurei deposit and at depth of 500 m above the caldera. The analysis of these data is now energetically pushed forward. A 3D gridded data set of the vector magnetic anomaly in the latter cruise was made by solving the Laplace's equation in the areas where observation data were not available, which is the unique procedure for analysis of the vector anomalies. Several magnetization solutions have been so far obtained by successive approximation and inversion methods. We will here present the measurement of the geomagnetic field and analysis of magnetization structure in Bayonnaise Knoll caldera. Note that this study has been supported by the Ministry of Education, Culture, Sports, Science & Technology (MEXT).
DEFF Research Database (Denmark)
Hubrig, S.; González, J. F.; Ilyin, I.
2012-01-01
Context. The frequent presence of weak magnetic fields on the surface of spotted late-B stars with HgMn peculiarity in binary systems has been controversial during the two last decades. Recent studies of magnetic fields in these stars using the least-squares deconvolution (LSD) technique have...... failed to detect magnetic fields, indicating an upper limit on the longitudinal field between 8 and 15G. In these LSD studies, assumptions were made that all spectral lines are identical in shape and can be described by a scaled mean profile. Aims. We re-analyse the available spectropolarimetric material...
Lovelock vacua with a recurrent null vector field
Ortaggio, Marcello
2018-02-01
Vacuum solutions of Lovelock gravity in the presence of a recurrent null vector field (a subset of Kundt spacetimes) are studied. We first discuss the general field equations, which constrain both the base space and the profile functions. While choosing a "generic" base space puts stronger constraints on the profile, in special cases there also exist solutions containing arbitrary functions (at least for certain values of the coupling constants). These and other properties (such as the p p - waves subclass and the overlap with VSI, CSI and universal spacetimes) are subsequently analyzed in more detail in lower dimensions n =5 , 6 as well as for particular choices of the base manifold. The obtained solutions describe various classes of nonexpanding gravitational waves propagating, e.g., in Nariai-like backgrounds M2×Σn -2. An Appendix contains some results about general (i.e., not necessarily Kundt) Lovelock vacua of Riemann type III/N and of Weyl and traceless-Ricci type III/N. For example, it is pointed out that for theories admitting a triply degenerate maximally symmetric vacuum, all the (reduced) field equations are satisfied identically, giving rise to large classes of exact solutions.
International Nuclear Information System (INIS)
Jiang, Chao-Wei; Feng, Xue-Shang
2016-01-01
In the solar corona, the magnetic flux rope is believed to be a fundamental structure that accounts for magnetic free energy storage and solar eruptions. Up to the present, the extrapolation of the magnetic field from boundary data has been the primary way to obtain fully three-dimensional magnetic information about the corona. As a result, the ability to reliably recover the coronal magnetic flux rope is important for coronal field extrapolation. In this paper, our coronal field extrapolation code is examined with an analytical magnetic flux rope model proposed by Titov and Démoulin, which consists of a bipolar magnetic configuration holding a semi-circular line-tied flux rope in force-free equilibrium. By only using the vector field at the bottom boundary as input, we test our code with the model in a representative range of parameter space and find that the model field can be reconstructed with high accuracy. In particular, the magnetic topological interfaces formed between the flux rope and the surrounding arcade, i.e., the “hyperbolic flux tube” and “bald patch separatrix surface,” are also reliably reproduced. By this test, we demonstrate that our CESE–MHD–NLFFF code can be applied to recovering the magnetic flux rope in the solar corona as long as the vector magnetogram satisfies the force-free constraints. (paper)
Superposition of DC magnetic fields by cascading multiple magnets in magnetic loops
Directory of Open Access Journals (Sweden)
Fei Sun
2015-09-01
Full Text Available A novel method that can effectively collect the DC magnetic field produced by multiple separated magnets is proposed. With the proposed idea of a magnetic loop, the DC magnetic field produced by these separated magnets can be effectively superimposed together. The separated magnets can be cascaded in series or in parallel. A novel nested magnetic loop is also proposed to achieve a higher DC magnetic field in the common air region without increasing the DC magnetic field in each magnetic loop. The magnetic loop can be made by a magnetic hose, which is designed by transformation optics and can be realized by the combination of super-conductors and ferromagnetic materials.
DEFF Research Database (Denmark)
Toft, Katrine Nørgaard
The field-induced magnetic structures of ErNi2B2C and TmNi2B2C in are especially interesting because the field suppresses the superconducting order parameter and therefore the magnetic properties can be studied while varying the strength ofsuperconductivity. ErNi2B2C: For magnetic fields along all.......483,0,0). The appearance of the QN phase wasinitially believed to be caused by the suppression of superconductivity. This suppression should make it favorable to create a magnetic order with a Q-vector determined by the maximum in the magnetic susceptibility at the Fermi surface nesting vector QN.The phase diagram...... three symmetry directions, the observed magnetic structures have a period corresponding to the Fermi surface nesting structure. The phase diagrams present all the observed magnetic structures.Two results remain unresolved: 1. When applying the magnetic field along [010], the minority domain (QNB = (0,Q...
Magnetic fields in noninvasive brain stimulation.
Vidal-Dourado, Marcos; Conforto, Adriana Bastos; Caboclo, Luis Otávio Sales Ferreira; Scaff, Milberto; Guilhoto, Laura Maria de Figueiredo Ferreira; Yacubian, Elza Márcia Targas
2014-04-01
The idea that magnetic fields could be used therapeutically arose 2000 years ago. These therapeutic possibilities were expanded after the discovery of electromagnetic induction by the Englishman Michael Faraday and the American Joseph Henry. In 1896, Arsène d'Arsonval reported his experience with noninvasive brain magnetic stimulation to the scientific French community. In the second half of the 20th century, changing magnetic fields emerged as a noninvasive tool to study the nervous system and to modulate neural function. In 1985, Barker, Jalinous, and Freeston presented transcranial magnetic stimulation, a relatively focal and painless technique. Transcranial magnetic stimulation has been proposed as a clinical neurophysiology tool and as a potential adjuvant treatment for psychiatric and neurologic conditions. This article aims to contextualize the progress of use of magnetic fields in the history of neuroscience and medical sciences, until 1985.
Field Mapping System for Solenoid Magnet
Park, K. H.; Jung, Y. K.; Kim, D. E.; Lee, H. G.; Park, S. J.; Chung, C. W.; Kang, B. K.
2007-01-01
A three-dimensional Hall probe mapping system for measuring the solenoid magnet of PLS photo-cathode RF e-gun has been developed. It can map the solenoid field either in Cartesian or in cylindrical coordinate system with a measurement reproducibility better than 5 × 10-5 T. The system has three axis motors: one for the azimuthal direction and the other two for the x and z direction. This architecture makes the measuring system simple in fabrication. The magnetic center was calculated using the measured axial component of magnetic field Bz in Cartesian coordinate system because the accuracy of magnetic axis measurement could be improved significantly by using Bz, instead of the radial component of magnetic field Br. This paper describes the measurement system and summarizes the measurement results for the solenoid magnetic of PLS photo-cathode RF e-gun.
Hypernuclear matter in strong magnetic field
Energy Technology Data Exchange (ETDEWEB)
Sinha, Monika [Institute for Theoretical Physics, J.W. Goethe-University, D-60438 Frankfurt am Main (Germany); Indian Institute of Technology Rajasthan, Old Residency Road, Ratanada, Jodhpur 342011 (India); Mukhopadhyay, Banibrata [Department of Physics, Indian Institute of Science, Bangalore 560012 (India); Sedrakian, Armen, E-mail: sedrakian@th.physik.uni-frankfurt.de [Institute for Theoretical Physics, J.W. Goethe-University, D-60438 Frankfurt am Main (Germany)
2013-01-17
Compact stars with strong magnetic fields (magnetars) have been observationally determined to have surface magnetic fields of order of 10{sup 14}–10{sup 15} G, the implied internal field strength being several orders larger. We study the equation of state and composition of dense hypernuclear matter in strong magnetic fields in a range expected in the interiors of magnetars. Within the non-linear Boguta–Bodmer–Walecka model we find that the magnetic field has sizable influence on the properties of matter for central magnetic field B⩾10{sup 17} G, in particular the matter properties become anisotropic. Moreover, for the central fields B⩾10{sup 18} G, the magnetized hypernuclear matter shows instability, which is signalled by the negative sign of the derivative of the pressure parallel to the field with respect to the density, and leads to vanishing parallel pressure at the critical value B{sub cr}≃10{sup 19} G. This limits the range of admissible homogeneously distributed fields in magnetars to fields below the critical value B{sub cr}.
INTERSTELLAR MAGNETIC FIELD SURROUNDING THE HELIOPAUSE
International Nuclear Information System (INIS)
Whang, Y. C.
2010-01-01
This paper presents a three-dimensional analytical solution, in the limit of very low plasma β-ratio, for the distortion of the interstellar magnetic field surrounding the heliopause. The solution is obtained using a line dipole method that is the integration of point dipole along a semi-infinite line; it represents the magnetic field caused by the presence of the heliopause. The solution allows the variation of the undisturbed magnetic field at any inclination angle. The heliosphere is considered as having blunt-nosed geometry on the upwind side and it asymptotically approaches a cylindrical geometry having an open exit for the continuous outflow of the solar wind on the downwind side. The heliopause is treated as a magnetohydrodynamic tangential discontinuity; the interstellar magnetic field lines at the boundary are tangential to the heliopause. The interstellar magnetic field is substantially distorted due to the presence of the heliopause. The solution shows the draping of the field lines around the heliopause. The magnetic field strength varies substantially near the surface of the heliopause. The effect on the magnetic field due to the presence of the heliopause penetrates very deep into the interstellar space; the depth of penetration is of the same order of magnitude as the scale length of the heliosphere.
Magnetic field compression using pinch-plasma
International Nuclear Information System (INIS)
Koyama, K.; Tanimoto, M.; Matsumoto, Y.; Veno, I.
1987-01-01
In a previous report, the method for ultra-high magnetic field compression by using the pinchplasma was discussed. It is summarized as follows. The experiment is performed with the Mather-type plasma focus device tau/sub 1/4/ = 2 μs, I=880 kA at V=20 kV). An initial DC magnetic field is fed by an electromagnet embedded in the inner electrode. The axial component of the magnetic field diverges from the maximum field of 1 kG on the surface of the inner electrode. The density profile deduced from a Mach-Zehnder interferogram with a 2-ns N/sub 2/-laser shows a density dip lasting for 30 ns along the axes. Using the measured density of 8 x 10/sup 18/ cm/sup -3/, the temperature of 1.5 keV and the pressure balance relation, the magnitude of the trapped magnetic field is estimated to be 1.0 MG. The magnitude of the compressed magnetic field is also measured by Faraday rotation in a single-mode quartz fiber and a magnetic pickup soil. A protective polyethylene tube (3-mm o.d.) is used along the central axis through the inner electrode and the discharge chamber. The peak value of the compressed field range from 150 to 190 kG. No signal of the magnetic field appears up to the instance of the maximum pinch
Magnetic Field Measurements In Magnetized Plasmas Using Zeeman Broadening Diagnostics
Haque, Showera; Wallace, Matthew; Presura, Radu; Neill, Paul
2017-10-01
The Zeeman effect has been used to measure the magnetic field in high energy density plasmas. This method is limited when plasma conditions are such that the line broadening due to the high plasma density and temperature surpasses the Zeeman splitting. We have measured magnetic fields in magnetized laser plasmas under conditions where the Zeeman splitting was not spectrally resolved. The magnetic field strength was determined from the difference in widths of two doublet components, using an idea proposed by Tessarin et al. (2011). Time-gated spectra with one-dimensional space-resolution were obtained at the Nevada Terawatt Facility for laser plasmas created by 20 J, 1 ns Leopard laser pulses, and expanding in the azimuthal magnetic field produced by the 0.6 MA Zebra pulsed power generator. We explore the response of the Al III 4s 2S1/2 - 4p 2P1 / 2 , 3 / 2 doublet components to the external magnetic field spatially along the plasma. Radial magnetic field and electron density profiles were measured within the plasma plume. This work was supported by the DOE/OFES Grant DE-SC0008829 and DOE/NNSA contract DE-FC52-06NA27616.
The Poynting vector of a charged magnetic dipole: two limiting cases
Energy Technology Data Exchange (ETDEWEB)
Sod-Hoffs, J; Manko, V S [Departamento de Fisica, Centro de Investigacion y de Estudios Avanzados del I.P.N., A.P. 14-740, 07000 Mexico D.F. (Mexico)
2007-11-15
We consider the Poynting vector of two exact solutions describing a charged magnetized non-rotating mass in the following limiting cases: (i) m{sup 2} = q{sup 2}, and (ii) m = 0. Whereas the former limit leads to a non-vanishing Poynting vector only for one of the solutions, the latter limit in both solutions results in non-zero expressions of the azimuthal component of the Poynting vector, thus providing evidence that Bonnor's frame-dragging effect takes place even in the case of a charged massless magnetic dipole.
Hyperfine magnetic fields in substituted Finemet alloys
Energy Technology Data Exchange (ETDEWEB)
Brzózka, K., E-mail: k.brzozka@uthrad.pl [University of Technology and Humanities in Radom, Department of Physics (Poland); Sovák, P. [P.J. Šafárik University, Institute of Physics (Slovakia); Szumiata, T.; Gawroński, M.; Górka, B. [University of Technology and Humanities in Radom, Department of Physics (Poland)
2016-12-15
Transmission Mössbauer spectroscopy was used to determine the hyperfine fields of Finemet-type alloys in form of ribbons, substituted alternatively by Mn, Ni, Co, Al, Zn, V or Ge of various concentration. The comparative analysis of magnetic hyperfine fields was carried out which enabled to understand the role of added elements in as-quenched as well as annealed samples. Moreover, the influence of the substitution on the mean direction of the local hyperfine magnetic field was examined.
Ohm's law for mean magnetic fields
International Nuclear Information System (INIS)
Boozer, A.H.
1986-05-01
The magnetic fields associated with plasmas frequently exhibit small amplitude MHD fluctuations. It is useful to have equations for the magnetic field averaged over these fluctuations, the so-called mean field equations. Under very general assumptions it is shown that the effect of MHD fluctuations on a force-free plasma can be represented by one parameter in Ohm's law, which is effectively the coefficient of electric current viscosity
Ohm's law for mean magnetic fields
International Nuclear Information System (INIS)
Boozer, A.H.
1986-01-01
The magnetic fields associated with plasmas frequently exhibit small-amplitude MHD fluctuations. It is useful to have equations for the magnetic field averaged over these fluctuations, the so-called mean field equations. Under very general assumptions, it is shown that the effect of MHD fluctuations on a force-free plasma can be represented by one parameter in Ohm's law, which is effectively the coefficient of electric current viscosity. (author)
Lightning magnetic field measuring system in Bogota
Escobar Alvarado, Oscar Fernardo
2013-01-01
This thesis presents the configuration and performance of a lightning radiated electromagnetic field measuring system in Bogotá Colombia. The system is composed by both magnetic and electric field measuring systems working as separated sensors. The aim of the thesis is the design and construction of a Magnetic Field Measuring System and the implementation of a whole lightning measuring system in Bogotá. The theoretical background, design process, construction and implementation of the system ...
Regulation of fields excited by permanent magnets
International Nuclear Information System (INIS)
Savchenko, I.S.
1989-01-01
Two methods of fast regulation of fields excited by permanent magnets in salient-pole electron-optical lenses are described: 1)the hybrid method realized using the additional electromagnet introduced to a magnetic chain sequentially its field being composed or substracted with magnetosolid exciter field; 2)the method with saturation of a part of a magnetic circuit, with saturation being achievable at the begining or in the end of a regulation cycle. In the second method it is proposed to direct orthogonally the main flux excited by permanent magnets and the flux in the saturated part of the magnetic circuit excited using an electromagnet. It is shown that the second method allows one to reduce the required ampere-coils by more than an order as compared to the first method at one and the same regulation range and other equal conditions. The frequency of field regulation in the experimental mock-up was 10 kHz. 3 refs.; 2 figs
Planetary nebulae and the interstellar magnetic field
International Nuclear Information System (INIS)
Heiligman, G.M.
1980-01-01
Previous workers have found a statistical correlation between the projected directions of the interstellar magnetic field and the major axes of planetary nebulae. This result has been examined theoretically using a numerical hydromagnetic model of a cold plasma nebula expanding into a uniform vacuum magnetic field, with nebular gas accreting on the surface. It is found that magnetic pressure alone is probably not sufficient to shape most planetary nebulae to the observed degree. Phenomena are discussed which could amplify simple magnetic pressure, alter nebular morphology and account for the observed correlation. (author)
Tuning permanent magnets with adjustable field clamps
International Nuclear Information System (INIS)
Schermer, R.I.
1987-01-01
The effective length of a permanent-magnet assembly can be varied by adjusting the geometrical parameters of a field clamp. This paper presents measurements on a representative dipole and quadrupole as the field clamp is withdrawn axially or radially. The detailed behavior depends upon the magnet multipolarity and geometry. As a rule-of-thumb, a 3-mm-thick iron plate placed at one end plane of the magnet will shorten the length by one-third of the magnet bore radius
Neutron stars velocities and magnetic fields
Paret, Daryel Manreza; Martinez, A. Perez; Ayala, Alejandro.; Piccinelli, G.; Sanchez, A.
2018-01-01
We study a model that explain neutron stars velocities due to the anisotropic emission of neutrinos. Strong magnetic fields present in neutron stars are the source of the anisotropy in the system. To compute the velocity of the neutron star we model its core as composed by strange quark matter and analice the properties of a magnetized quark gas at finite temperature and density. Specifically we have obtained the electron polarization and the specific heat of magnetized fermions as a functions of the temperature, chemical potential and magnetic field which allow us to study the velocity of the neutron star as a function of these parameters.