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Sample records for interplanetary magnetic field

  1. 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.)

  2. Intermittent character of interplanetary magnetic field fluctuations

    International Nuclear Information System (INIS)

    Bruno, Roberto; Carbone, Vincenzo; Chapman, Sandra; Hnat, Bogdan; Noullez, Alain; Sorriso-Valvo, Luca

    2007-01-01

    Interplanetary magnetic field magnitude fluctuations are notoriously more intermittent than velocity fluctuations in both fast and slow wind. This behavior has been interpreted in terms of the anomalous scaling observed in passive scalars in fully developed hydrodynamic turbulence. In this paper, the strong intermittent nature of the interplanetary magnetic field is briefly discussed comparing results performed during different phases of the solar cycle. The scaling properties of the interplanetary magnetic field magnitude show solar cycle variation that can be distinguished in the scaling exponents revealed by structure functions. The scaling exponents observed around the solar maximum coincide, within the errors, to those measured for passive scalars in hydrodynamic turbulence. However, it is also found that the values are not universal in the sense that the solar cycle variation may be reflected in dependence on the structure of the velocity field

  3. Interplanetary Magnetic Field Guiding Relativistic Particles

    Science.gov (United States)

    Masson, S.; Demoulin, P.; Dasso, S.; Klein, K. L.

    2011-01-01

    The origin and the propagation of relativistic solar particles (0.5 to few Ge V) in the interplanetary medium remains a debated topic. These relativistic particles, detected at the Earth by neutron monitors have been previously accelerated close to the Sun and are guided by the interplanetary magnetic field (IMF) lines, connecting the acceleration site and the Earth. Usually, the nominal Parker spiral is considered for ensuring the magnetic connection to the Earth. However, in most GLEs the IMF is highly disturbed, and the active regions associated to the GLEs are not always located close to the solar footprint of the nominal Parker spiral. A possible explanation is that relativistic particles are propagating in transient magnetic structures, such as Interplanetary Coronal Mass Ejections (ICMEs). In order to check this interpretation, we studied in detail the interplanetary medium where the particles propagate for 10 GLEs of the last solar cycle. Using the magnetic field and the plasma parameter measurements (ACE/MAG and ACE/SWEPAM), we found widely different IMF configurations. In an independent approach we develop and apply an improved method of the velocity dispersion analysis to energetic protons measured by SoHO/ERNE. We determined the effective path length and the solar release time of protons from these data and also combined them with the neutron monitor data. We found that in most of the GLEs, protons propagate in transient magnetic structures. Moreover, the comparison between the interplanetary magnetic structure and the interplanetary length suggest that the timing of particle arrival at Earth is dominantly determined by the type of IMF in which high energetic particles are propagating. Finally we find that these energetic protons are not significantly scattered during their transport to Earth.

  4. Interaction of the geomagnetic field with northward interplanetary magnetic field

    Science.gov (United States)

    Bhattarai, Shree Krishna

    The interaction of the solar wind with Earth's magnetic field causes the transfer of momentum and energy from the solar wind to geospace. The study of this interaction is gaining significance as our society is becoming more and more space based, due to which, predicting space weather has become more important. The solar wind interacts with the geomagnetic field primarily via two processes: viscous interaction and the magnetic reconnection. Both of these interactions result in the generation of an electric field in Earth's ionosphere. The overall topology and dynamics of the magnetosphere, as well as the electric field imposed on the ionosphere, vary with speed, density, and magnetic field orientation of the solar wind as well as the conductivity of the ionosphere. In this dissertation, I will examine the role of northward interplanetary magnetic field (IMF) and discuss the global topology of the magnetosphere and the interaction with the ionosphere using results obtained from the Lyon-Fedder-Mobarry (LFM) simulation. The electric potentials imposed on the ionosphere due to viscous interaction and magnetic reconnection are called the viscous and the reconnection potentials, respectively. A proxy to measure the overall effect of these potentials is to measure the cross polar potential (CPP). The CPP is defined as the difference between the maximum and the minimum of the potential in a given polar ionosphere. I will show results from the LFM simulation showing saturation of the CPP during periods with purely northward IMF of sufficiently large magnitude. I will further show that the viscous potential, which was assumed to be independent of IMF orientation until this work, is reduced during periods of northward IMF. Furthermore, I will also discuss the implications of these results for a simulation of an entire solar rotation.

  5. A study of the inferred interplanetary magnetic field polarity periodicities

    International Nuclear Information System (INIS)

    Xanthakis, J.; Tritakis, V.P.; Zerefos, Ch.

    1981-01-01

    A detailed Power Spectrum Analysis applied on the daily polarities of the inferred interplanetary magnetic field, published by Svalgaard, has pointed out that the main periodicity apparent in these data is 27-28 days, which suggests a recurrency of a 2-sector structure. There is also a secondary periodicity of 13-14 days which mainly appears in the yers of the descending branch of the solar cycle and superimposes on the 2-sector structure, transforming it into a 4-sector structure. A strict statistical study of the correlation between the predominant polarity of the interplanetary magnetic field and the heliographic latitude of the Earth, also known as the Rosenberg-Coleman effect, pointed out that perhaps there is a faint correspondence between these two elements, but one cannot speak of a systematic effect. (Auth.)

  6. The topology of intrasector reversals of the interplanetary magnetic field

    Science.gov (United States)

    Kahler, S. W.; Crooker, N. U.; Gosling, J. T.

    1996-11-01

    A technique has been developed recently to determine the polarities of interplanetary magnetic fields relative to their origins at the Sun by comparing energetic electron flow directions with local magnetic field directions. Here we use heat flux electrons from the Los Alamos National Laboratory (LANL) plasma detector on the ISEE 3 spacecraft to determine the field polarities. We examine periods within well-defined magnetic sectors when the field directions appear to be reversed from the normal spiral direction of the sector. About half of these intrasector field reversals (IFRs) are cases in which the polarities match those of the surrounding sectors, indicating that those fields have been folded back toward the Sun. The more interesting cases are those with polarity reversals. We find no clear cases of isolated reverse polarity fields, which suggests that islands of reverse polarity in the solar source dipole field probably do not exist. The IFRs with polarity reversals are strongly associated with periods of bidirectional electron flows, suggesting that those fields occur only in conjunction with closed fields. We propose that both those IFRs and the bidirectional flows are signatures of coronal mass ejections (CMEs). In that case, many interplanetary CMEs are larger and more complex than previously thought, consisting of both open and closed field components.

  7. The interplanetary magnetic field observed by Juno enroute to Jupiter

    Science.gov (United States)

    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.

  8. The Interplanetary Magnetic Field Observed by Juno Enroute to Jupiter

    Science.gov (United States)

    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.

  9. Dayside auroras in relation to the interplanetary magnetic field

    International Nuclear Information System (INIS)

    Sandholt, P.E.; Egeland, A.; Lybekk, B.; Deehr, C.S.

    1986-01-01

    Dynamics of dayside auroras, including cusp emissions, and their relation to the interplanetary magnetic field (IMF) have been investigated by optical ground-based observations from Svalbard, Norway, and IMF data from various satellites. Combined with the Svalbard program, simultaneous night-side observations from Alaska provide information on the large-scale behaviour of the auroral oval. Drift characteristics, spatial scale, time of duration and repetition frequency of auroral structures on the day-side, occuring at the time of large-scale oval expansions (IMF B z z positive and negative values

  10. Transport of solar electrons in the turbulent interplanetary magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Ablaßmayer, J.; Tautz, R. C., E-mail: robert.c.tautz@gmail.com [Zentrum für Astronomie und Astrophysik, Technische Universität Berlin, Hardenbergstraße 36, D-10623 Berlin (Germany); Dresing, N., E-mail: dresing@physik.uni-kiel.de [Institut für Experimentelle und Angewandte Physik, Christian-Albrechts-Universität zu Kiel, Leibnizstraße 11, D-24118 Kiel (Germany)

    2016-01-15

    The turbulent transport of solar energetic electrons in the interplanetary magnetic field is investigated by means of a test-particle Monte-Carlo simulation. The magnetic fields are modeled as a combination of the Parker field and a turbulent component. In combination with the direct calculation of diffusion coefficients via the mean-square displacements, this approach allows one to analyze the effect of the initial ballistic transport phase. In that sense, the model complements the main other approach in which a transport equation is solved. The major advancement is that, by recording the flux of particles arriving at virtual detectors, intensity and anisotropy-time profiles can be obtained. Observational indications for a longitudinal asymmetry can thus be explained by tracing the diffusive spread of the particle distribution. The approach may be of future help for the systematic interpretation of observations for instance by the solar terrestrial relations observatory (STEREO) and advanced composition explorer (ACE) spacecrafts.

  11. August 1972 solar-terrestrial events: interplanetary magnetic field observations

    Energy Technology Data Exchange (ETDEWEB)

    Smith, E J [Jet Propulsion Lab., Pasadena, Calif. (USA)

    1976-10-01

    A review is presented of the interplanetary magnetic field observations acquired in early August 1972 when four solar flares erupted in McMath Plage region 1976. Measurements of the interplanetary field were obtained by Earth satellites, HEOS-2 and Explorer 41, and by Pioneers 9 and 10 which, by good fortune, were radially aligned and only 45/sup 0/ east of the Earth-Sun direction. In response to the four flares, four interplanetary shocks were seen at Earth and at Pioneer 9, which was then at a heliocentric distance of 0.78 AU. However, at Pioneer 10, which was 2.2 AU from the Sun, only two forward shocks and one reverse shock were seen. The available magnetic field data acquired in the vicinity of the shocks are presented. Efforts to identify corresponding shocks at the several locations and to deduce their velocities of propagation between 0.8 and 2.2 AU are reviewed. The early studies were based on average velocities between the Sun and Pioneer 9, the Sun and Earth and the Sun and Pioneer 10. A large deceleration of the shocks between the Sun and 0.8 AU as well as between 0.8 and 2.2 AU was inferred. More recently the local velocities of the shocks at Pioneers 9 and 10 have become available. A comparision of these velocities shows little, if any, deceleration between 0.8 and 2.2 AU and implies that most or all of the deceleration actually occurred nearer the Sun. Evidence is also presented that shows a significant departure of the flare-generated shock fronts from spherical symmetry.

  12. 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)

  13. Equatorial storm sudden commencements and interplanetary magnetic field

    International Nuclear Information System (INIS)

    Rastogi, R.G.

    1980-01-01

    A comparison is made of the signatures of interplanetary (IP) shocks in the B and theta plots of interplanetary magnetic field (IMF) data of satellites Explorer 33, 34 and 35 and in the H magnetograms at ground observatories within the equatorial electrojet belt, Huancayo, Addis Ababa and Trivandrum associated with major storm sudden commencements during 1967-70. The IP shocks showing sudden increase of the scalar value of IMF, i.e. B without any change of the latitude theta or with the southward turning of theta, were followed by a purely positive sudden increase of H, at any of the magnetic observatories, either on the dayside or the nightside of the earth. The IP shocks identified by a sudden increase of B and with the northward turning of the latitude theta (positive ΔBsub(z)) were associated with purely positive sudden commencement (SC) at the observatories in the nightside, but at the equatorial observatories in the dayside of the earth the signature of the shock was a SC in H with a preliminary negative impulse followed by the main positive excursion (SC-+). It is suggested that the SCs in H at low latitudes are composed of two effects, viz. (i) one due to hydromagnetic pressure on the magnetosphere by the solar plasma and (ii) the other due to the induced electric field associated with the solar wind velocity, V and the Z-component of the IP magnetic field (E = - V x Bsub(z)). The effect of magnetosphere electric field is faster than the effect due to the compression of the magnetosphere by the impinging solar plasma. The negative impulse of SC-+ at low latitude is seen at stations close to the dip equator and only during daytime due to the existence of high ionospheric conductivities in the equatorial electrojet region. (author)

  14. Forecasting intense geomagnetic activity using interplanetary magnetic field data

    Science.gov (United States)

    Saiz, E.; Cid, C.; Cerrato, Y.

    2008-12-01

    Southward interplanetary magnetic fields are considered traces of geoeffectiveness since they are a main agent of magnetic reconnection of solar wind and magnetosphere. The first part of this work revises the ability to forecast intense geomagnetic activity using different procedures available in the literature. The study shows that current methods do not succeed in making confident predictions. This fact led us to develop a new forecasting procedure, which provides trustworthy results in predicting large variations of Dst index over a sample of 10 years of observations and is based on the value Bz only. The proposed forecasting method appears as a worthy tool for space weather purposes because it is not affected by the lack of solar wind plasma data, which usually occurs during severe geomagnetic activity. Moreover, the results obtained guide us to provide a new interpretation of the physical mechanisms involved in the interaction between the solar wind and the magnetosphere using Faraday's law.

  15. Heliocentric distance dependence of the interplanetary magnetic field

    International Nuclear Information System (INIS)

    Behannon, K.W.

    1978-01-01

    Recent and ongoing planetary missions have provided and are continuing to provide extensive observations of the variations of the interplanetary magnetic field (IMF) both in time and with heliocentric distance from the sun. Large time variations in both the IMF and its fluctuations are observed. These are produced predominantly by dynamical processes in the interplanetary medium associated with stream interactions. Magnetic field variations near the sun are propagated to greater heliocentric distances, a process also contributing to the observed variability of the IMF. Temporal variations on a time scale comparable to or less than the corotation period complicate attempts to deduce radial gradients of the field and its fluctuations from the various observations. However, recent measurements inward to 0.46 AU and outward to 5 AU suggest that the radial component of the field on average decreases approximately as r -2 , as was predicted by Parker, while the azimuthal component decreases more rapidly than the r -1 dependence predicted by simple theory. Three sets of observations are consistent with r/sup -1.3/ dependence for vertical-barB/sub phi/vertical-bar. The temporal variability of solar wind speed is most likely the predominant contributor to this latter observational result. The long-term average azimuthal component radial gradient is probably consistent with the Parker r -1 dependence when solar wind speed variations are taken into account. The observations of the normal component magnitude vertical-barB/sub theta/vertical-bar are roughly consistent with a heliocentric distance dependence of r/sup -1.4/. The observed radial distance dependence of the total magnitude of the IMF is well described by the Parker formulation. There is observational evidence that amplitudes of fluctuations of the vector field with periods less than 1 day vary with heliocentric distance as approximately r/sup -3/2/, in agreement with theoretical models by Whang and Hollweg

  16. Stochastic diffusion of dust grains by the interplanetary magnetic field

    International Nuclear Information System (INIS)

    Hassan, M.H.A.; Wallis, M.K.

    1983-10-01

    The effects of the sectored Interplanetary Magnetic Field on charged dust grains orbiting around the sun under radiation pressure and Poynting-Robertson drag forces are examined for initially circular and non-inclined orbits. The distribution function of the charged grains satisfies a Fokker-Planck equation in which the sectored field is taken as a source of stochastic impulses. By adopting the integrals of the impulse-free motion as variable parameters, the Fokker-Planck equation can be properly treated as a diffusion equation. Analytic solutions of the resulting diffusion equation show that dust grains injected near the ecliptic plane are scattered strongly to high helio-latitudes. The scattering is more pronounced for small grains injected at large distances from the Sun. (author)

  17. Interplanetary Magnetic Field and Plasma Values Related to Hildcaas Events

    Science.gov (United States)

    Prestes, A.; Serra, S. L.; Vieira, L. A.

    2013-05-01

    In this work we investigate the interplanetary conditions during the occurrence of 150 HILDCAAs/QUASI-HILDCAAs events occurred between 1998 and 2007. These events were chosen by following strictly the selection criteria for this kind of phenomena and with some criteria flexible. Among the criteria used to characterize events HILDCAAs, the criterion that considers "the AE values never dropped below 200 nT for more than 2 h at a time" was more restrictive, thus only this was modified by changing from 2 to 4 hours the period in which the AE value can't be below 200 nT. In the interplanetary medium, HILDCAAs are associated with high speed solar wind streams, which are frequently embedded with alfvénic fluctuations. At the Sun, these high speed streams are originated in coronal holes. The distribution of events HILDCAAs/quasi-HILDCAAs along the solar cycle shows a pattern of double peak, a less intense around the maximum of the sunspot cycle and other intense in the descending phase, similar to the distribution of low-latitude coronal holes. For each one of the selected events we have found the most probable value of interplanetary magnetic field and plasma. The average values of AE, AU, AL and Dst indices, the density and temperature of the solar wind protons, the solar wind speed, the Bz component of the IMF, the IMF intensity, dynamic pressure and factor beta, among all the 150 events HILDCAAs/quasi-HILDCAAs, were: AE (344.5 ± 65.0 nT), AU (131.0 ± 33.0 nT), AL (-213.7 ± 51.2 nT), Dst (-25.8 ± 12.2 nT), Density (5,0 ± 1,8 cm-3), Temperature (151269.5 ± 48907.7 K), |V| (538.2 ± 83.3 km/s) Bz (-0.71 ± 1.02 nT), |B| (6.7 ± 1.4 nT) pressure (2.6 ± 0.7 nPa) and Beta (0.66 ± 0.27).

  18. On an effect of interplanetary magnetic field on a distribution electric fields in the polar ionosphere

    International Nuclear Information System (INIS)

    Uvarov, V.M.; Barashkov, P.D.

    1985-01-01

    The problem on the effect of the interplanetary magnetic field (IMF) on the distribution of electric fields in polar ionosphere is discussed. The problem on excitation of electric fields is reduced to the solution of the system of continuity equations for the current in three regions-northern polar cap, southern cap and the region outside the caps. It is shown that one succeeds in reproducing the observed types of distributions of electric fields

  19. Interplanetary magnetic field associated changes in cosmic ray intensity and geomagnetic field during 1973-75

    International Nuclear Information System (INIS)

    Singh, R.L.; Shukla, J.P.; Shukla, A.K.; Sharma, S.M.; Agrawal, S.P.

    1979-01-01

    The effects of interplanetary magnetic field (IMF) B and its Bsub(z) component on cosmic ray intensity and geomagnetic field variations have been examined for the period 1973-75. It is observed that: (1) B >= 10γ (magnetic blobs) is pre-requisite in producing cosmic ray intensity and geomagnetic field variations of varying magnitudes, (2) the longer existence of magnetic blobs on successive days produces larger decreases in cosmic ray intensity and geomagnetic field and (3) the southward component (Bsub(z)) of IMF generally gives rise to large Asub(p) changes, though it is not effective in producing cosmic ray intensity decreases. (auth.)

  20. Interplanetary magnetic field orientations associated with bidirectional electron heat fluxes detected at ISEE 3

    International Nuclear Information System (INIS)

    Stansberry, J.A.; Gosling, J.T.; Thomsen, M.F.; Bame, S.J.; Smith, E.J.

    1988-01-01

    A statistical survey of interplanetary magnetic field orientations associated with bidirectional electron heat fluxes observed at ISEE 3 in orbit about the Sunward Lagrange point indicates that magnetic connection of the spacecraft to the Earth's bow shock was frequently the source of the bidirectionality. When the interplanetary magnetic field was oriented within 5 0 of the Earth-spacecraft line, backstreaming electrons from the bow shock were clearly observed approximately 18% of the time, and connections apparently occurred for angles as large as ∼30 0 --35 0 . copyright American Geophysical Union 1988

  1. Long-term Regularities in Distribution of Global Solar and Interplanetary Magnetic Fields

    Czech Academy of Sciences Publication Activity Database

    Ambrož, Pavel

    2013-01-01

    Roč. 37, č. 2 (2013), s. 637-642 ISSN 1845-8319. [Hvar Astrophysical Colloquium /12./. Hvar, 03.09.2012-07.09.2012] R&D Projects: GA AV ČR IAA300030808 Institutional support: RVO:67985815 Keywords : interplanetary magnetic field * solar wind Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics

  2. Effect of Interplanetary Magnetic Field and Disturb Storm Time on H ...

    Indian Academy of Sciences (India)

    2016-01-27

    Jan 27, 2016 ... Home; Journals; Journal of Astrophysics and Astronomy; Volume 29; Issue 1-2. Effect of Interplanetary Magnetic Field and Disturb Storm Time on H Component. Rajni Devi Smita Dubey Shailendra Saini Babita Devi Ajay Dhar S. K. Vijay A. K. Gwal. Volume 29 Issue 1-2 March-June 2008 pp 281-286 ...

  3. Effect of Interplanetary Magnetic Field and Disturb Storm Time on H ...

    Indian Academy of Sciences (India)

    E). We also study the effect of vertical component of interplanetary magnetic field (IMF) on the variation of the magnitude of H component during storm time of April, July and. November 2004. Results show that before sudden storm commencement. (SSC) time magnitude of H component and IMF show smooth variation but.

  4. EVIDENCE OF CONFINEMENT OF SOLAR-ENERGETIC PARTICLES TO INTERPLANETARY MAGNETIC FIELD LINES

    International Nuclear Information System (INIS)

    Chollet, E. E.; Giacalone, J.

    2011-01-01

    We present new observations of solar-energetic particles (SEPs) associated with impulsive solar flares that show evidence for their confinement to interplanetary magnetic field lines. Some SEP events exhibit intermittent intensity dropouts because magnetic field lines filled with and empty of particle flux mix together. The edges of these dropouts are observed to be very sharp, suggesting that particles cannot easily move from a filled to an empty field line in the time available during their transport from the Sun. In this paper, we perform high time-resolution observations of intensity fall-off at the edges of observed SEP dropouts in order to look for signatures of particle motion off field lines. However, the statistical study is dominated by one particularly intense event. The inferred length scale of the intensity decay is comparable to the gyroradii of the particles, suggesting that particles only rarely scatter off magnetic field lines during interplanetary transport.

  5. DECLINE AND RECOVERY OF THE INTERPLANETARY MAGNETIC FIELD DURING THE PROTRACTED SOLAR MINIMUM

    International Nuclear Information System (INIS)

    Smith, Charles W.; Schwadron, Nathan A.; DeForest, Craig E.

    2013-01-01

    The interplanetary magnetic field (IMF) is determined by the amount of solar magnetic flux that passes through the top of the solar corona into the heliosphere, and by the dynamical evolution of that flux. Recently, it has been argued that the total flux of the IMF evolves over the solar cycle due to a combination of flux that extends well outside of 1 AU and is associated with the solar wind, and additionally, transient flux associated with coronal mass ejections (CMEs). In addition to the CME eruption rate, there are three fundamental processes involving conversion of magnetic flux (from transient to wind-associated), disconnection, and interchange reconnection that control the levels of each form of magnetic flux in the interplanetary medium. This is distinct from some earlier models in which the wind-associated component remains steady across the solar cycle. We apply the model of Schwadron et al. that quantifies the sources, interchange, and losses of magnetic flux to 50 yr of interplanetary data as represented by the Omni2 data set using the sunspot number as a proxy for the CME eruption rate. We do justify the use of that proxy substitution. We find very good agreement between the predicted and observed interplanetary magnetic flux. In the absence of sufficient CME eruptions, the IMF falls on the timescale of ∼6 yr. A key result is that rising toroidal flux resulting from CME eruption predates the increase in wind-associated IMF

  6. The mean magnetic field of the sun - Method of observation and relation to the interplanetary magnetic field

    Science.gov (United States)

    Scherrer, P. H.; Wilcox, J. M.; Kotov, V.; Severnyi, A. B.; Howard, R.

    1977-01-01

    The mean solar magnetic field as measured in integrated light has been observed since 1968. Since 1970 it has been observed both at Hale Observatories and at the Crimean Astrophysical Observatory. The observing procedures at both observatories and their implications for mean field measurements are discussed. A comparison of the two sets of daily observations shows that similar results are obtained at both observatories. A comparison of the mean field with the interplanetary magnetic polarity shows that the IMF sector structure has the same pattern as the mean field polarity.

  7. Strong geomagnetic activity forecast by neural networks under dominant southern orientation of the interplanetary magnetic field

    Czech Academy of Sciences Publication Activity Database

    Valach, F.; Bochníček, Josef; Hejda, Pavel; Revallo, M.

    2014-01-01

    Roč. 53, č. 4 (2014), s. 589-598 ISSN 0273-1177 R&D Projects: GA AV ČR(CZ) IAA300120608; GA MŠk OC09070 Institutional support: RVO:67985530 Keywords : geomagnetic activity * interplanetary magnetic field * artificial neural network * ejection of coronal mass * X-ray flares Subject RIV: DE - Earth Magnetism, Geodesy, Geography Impact factor: 1.358, year: 2014

  8. Correlation Between Monthly Cumulative Auroral Electrojet Indices, DST Index and Interplanetary Electric Field During Magnetic Storms

    Directory of Open Access Journals (Sweden)

    Yoon-Kyung Park

    2005-12-01

    Full Text Available Magnetospheric substorms occur frequently during magnetic storms, suggesting that the two phenomena are closely associated. We can investigate the relation between magnetospheric substorms and magnetic storms by examining the correlation between AE and Dst indices. For this purpose, we calculated the monthly cumulative AU, |AL| and |Dst| indices. The correlation coefficient between the monthly cumulative |AL| and |Dst| index is found to be 0.60, while that between monthly cumulative AU and |Dst| index is 0.28. This result indicates that substorms seem to contribute to the development of magnetic storms. On the other hand, it has been reported that the interplanetary electric field associated with southward IMF intensifies the magnetospheric convection, which injects charged particles into the inner magnetosphere, thus developing the ring current. To evaluate the contribution of the interplanetary electric field to the development of the storm time ring current belt, we compared the monthly cumulative interplanetary electric field and the monthly cumulative Dst index. The correlation coefficient between the two cumulative indices is 0.83 for southward IMF and 0.39 for northward IMF. It indicates that magnetospheric convection induced by southward IMF is also important in developing magnetic storms. Therefore, both magnetospheric substorm and enhanced magnetospheric convection seem to contribute to the buildup of magnetic storm.

  9. Coupling coefficient between the Pc3 frequency and the value of the interplanetary magnetic field

    International Nuclear Information System (INIS)

    Gul'el'mi, A.V.

    1988-01-01

    Mean value and spread of coupling coefficient g between geomagnetic pulsation Ps3 frequency and interplanetary magnetic field (IMF) value are evaluated according to a set of all measurements described in literature and to additional measurements at Borok observatory (50 hour intervals in January, 1973). Attention is paid to a relatively small spread of g and to a weak g dependence on IMF orientation. The both facts are out of scope of the elementary Ps3 theory

  10. Are Polar Field Magnetic Flux Concentrations Responsible for Missing Interplanetary Flux?

    Science.gov (United States)

    Linker, Jon A.; Downs, C.; Mikic, Z.; Riley, P.; Henney, C. J.; Arge, C. N.

    2012-05-01

    Magnetohydrodynamic (MHD) simulations are now routinely used to produce models of the solar corona and inner heliosphere for specific time periods. These models typically use magnetic maps of the photospheric magnetic field built up over a solar rotation, available from a number of ground-based and space-based solar observatories. The line-of-sight field at the Sun's poles is poorly observed, and the polar fields in these maps are filled with a variety of interpolation/extrapolation techniques. These models have been found to frequently underestimate the interplanetary magnetic flux (Riley et al., 2012, in press, Stevens et al., 2012, in press) near the minimum part of the cycle unless mitigating correction factors are applied. Hinode SOT observations indicate that strong concentrations of magnetic flux may be present at the poles (Tsuneta et al. 2008). The ADAPT flux evolution model (Arge et al. 2010) also predicts the appearance of such concentrations. In this paper, we explore the possibility that these flux concentrations may account for a significant amount of magnetic flux and alleviate discrepancies in interplanetary magnetic flux predictions. Research supported by AFOSR, NASA, and NSF.

  11. Interplanetary Magnetic Field Control of the Entry of Solar Energetic Particles into the Magnetosphere

    Science.gov (United States)

    Richard, R. L.; El-Alaoui, M.; Ashour-Abdalla, M.; Walker, R. J.

    2002-01-01

    We have investigated the entry of energetic ions of solar origin into the magnetosphere as a function of the interplanetary magnetic field orientation. We have modeled this entry by following high energy particles (protons and 3 He ions) ranging from 0.1 to 50 MeV in electric and magnetic fields from a global magnetohydrodynamic (MHD) model of the magnetosphere and its interaction with the solar wind. For the most part these particles entered the magnetosphere on or near open field lines except for some above 10 MeV that could enter directly by crossing field lines due to their large gyroradii. The MHD simulation was driven by a series of idealized solar wind and interplanetary magnetic field (IMF) conditions. It was found that the flux of particles in the magnetosphere and transport into the inner magnetosphere varied widely according to the IMF orientation for a constant upstream particle source, with the most efficient entry occurring under southward IMF conditions. The flux inside the magnetosphere could approach that in the solar wind implying that SEPs can contribute significantly to the magnetospheric energetic particle population during typical SEP events depending on the state of the magnetosphere.

  12. Electron heat flux dropouts in the solar wind: Evidence for interplanetary magnetic field reconnection?

    International Nuclear Information System (INIS)

    McComas, D.J.; Gosling, J.T.; Phillips, J.L.; Bame, S.J.; Luhmann, J.G.; Smith, E.J.

    1989-01-01

    Electron heat flux dropout events have been observed in the solar wind using the ISEE 3 plasma electron data set. These events manifest themselves as dropouts of the solar wind halo electrons which are normally found streaming outward along the local magnetic field. These dropouts leave nearly isotropic distributions of solar wind halo electrons, and consequently, the heat flux in these events is reduced to near the observational noise level. We have examined ISEE 3 data from shortly after launch (August 16, 1978) through the end of 1978 and identified 25 such events ranging in duration from 20 min to over 11 hours. Comparison with the ISEE 3 magnetometer data indicates that these intervals nearly always occur in conjunction with large rotations of the interplanetary magnetic field. Statistical analyses of the plasma and magnetic field data for the 25 dropout intervals indicate that heat flux dropouts generally occur in association with high plasma densities low plasma velocities, low ion and electron temperatures, and low magnetic field magnitudes. A second set of 25 intervals chosen specifically to lie at large field rotations, but at times at which not heat flux dropouts were observed, do not show these characteristic plalsma variations. This suggests that the dropout intervals comprise a unique set of events. Since the hot halo electrons normally found streaming outward from the Sun along the interplanetary magnetic field (the solar wind electron heat flux) are a result of direct magnetic connection to the hot solar corona, heat flux dropout intervals may indicate that the spacecraft is sampling plasma regimes which are magnetically disconnected from the Sun and instead are connected to the outer heliosphere at both ends

  13. Effect of the interplanetary magnetic field azimuthal component on dynamics of magnetospheric substorms

    International Nuclear Information System (INIS)

    Troshichev, O.A.; Kotikov, A.L.; Bolotinskaya, B.D.

    1987-01-01

    The effect of azimuthal component of interplanetary magnetic field (IMF) on the dynamics of magnetospheric substorms is considered. The turning of the azimuthal component of IMF from the positive direction to the negative one and, vice versa, negative and positive impulses in B y -component at B z z -component to the North, positive impulses in B z -component, are investigated. The importance of corresponding variations in magnetic activity level is evaluated. It is shown that turning of B y -component from the positive direction to the negative one increases magnetic activity, whereas the reverse transition affects but slightly the level of magnetic activity in the Northern auroral zone. The turning of B z -component to the North also results in the increase of magnetic activity but with a less intensity than in the case of the negative turning in B y -component

  14. The F-region trough: seasonal morphology and relation to interplanetary magnetic field

    Directory of Open Access Journals (Sweden)

    M. Voiculescu

    2006-03-01

    Full Text Available We present here the results of a statistical study of the ionospheric trough observed in 2003 by means of satellite tomography. We focus on the seasonal morphology of the trough occurrence and investigate the trough latitude, width and the horizontal gradients at the edges, at different magnetic local times, as well as their relations to geomagnetic activity and the interplanetary magnetic field. A seasonal effect is noticed in the diurnal variation of the trough latitude, indicating that summer clearly differs from the other seasons. In winter the troughs seem to follow the solar terminator. The width of the trough has a diurnal variation and it depends on the season, as well. The broadest troughs are observed in winter and the narrowest ones in summer. A discontinuity in the diurnal variation of the trough latitude is observed before noon. It is suggested that this is an indication of a difference between the generation mechanisms of morningside and eveningside troughs. The density gradients at the edges have a complex dependence on the latitude of the trough and on geomagnetic activity. The photoionization and the auroral precipitation are competing in the formation of the trough walls at different magnetic local times. An important finding is that the interplanetary magnetic field plays a role in the occurrence of the trough at different levels of geomagnetic activity. This is probably associated with the topology of the polar cap convection pattern, which depends on the directions of the IMF components By and Bz.

  15. Influence of the interplanetary magnetic field on the occurrence and thickness of the plasma mantle

    Science.gov (United States)

    Sckopke, N.; Paschmann, G.; Rosenbauer, H.; Fairfield, D. H.

    1976-01-01

    The response of the plasma mantle to the orientation of the interplanetary magnetic field (IMF) has been studied by correlating Heos 2 plasma and Imp 6 magnetic field data. The mantle is nearly always present when the IMF has a southward component and often also when the field has a weak northward component. In addition, the mantle appears increasingly thicker with greater southward components. On the other hand, the mantle is thin or missing (from the region where it is normally found) when the average IMF has a strong northward component. This result supports the idea that polar cap convection plays a dominant role in the formation of the plasma mantle: mantle plasma originates in the magnetosheath, enters the magnetosphere through the day side polar cusps, and is transported across the cusp to the night side by means of a convection electric field whose magnitude is controlled by the orientation of the IMF.

  16. Observation and analysis of abrupt changes in the interplanetary plasma velocity and magnetic field.

    Science.gov (United States)

    Martin, R. N.; Belcher, J. W.; Lazarus, A. J.

    1973-01-01

    This paper presents a limited study of the physical nature of abrupt changes in the interplanetary plasma velocity and magnetic field based on 19 day's data from the Pioneer 6 spacecraft. The period was chosen to include a high-velocity solar wind stream and low-velocity wind. Abrupt events were accepted for study if the sum of the energy density in the magnetic field and velocity changes was above a specified minimum. A statistical analysis of the events in the high-velocity solar wind stream shows that Alfvenic changes predominate. This conclusion is independent of whether steady state requirements are imposed on conditions before and after the event. Alfvenic changes do not dominate in the lower-speed wind. This study extends the plasma field evidence for outwardly propagating Alfvenic changes to time scales as small as 1 min (scale lengths on the order of 20,000 km).

  17. Interplanetary Magnetic Field Power Spectrum Variations in the Inner Heliosphere: A Wind and MESSENGER Study

    Science.gov (United States)

    Szabo, Adam; Koval, A.

    2011-01-01

    The newly reprocessed high time resolution (11/22 vectors/sec) Wind mission interplanetary magnetic field data and the similar observations made by the MESSENGER spacecraft in the inner heliosphere affords an opportunity to compare magnetic field power spectral density variations as a function of radial distance from the Sun under different solar wind conditions. In the reprocessed Wind Magnetic Field Investigation (MFI) data, the spin tone and its harmonics are greatly reduced that allows the meaningful fitting of power spectra to the approx.2 Hz limit above which digitization noise becomes apparent. The powe'r spectral density is computed and the spectral index is fitted for the MHD and ion inertial regime separately along with the break point between the two for various solar wind conditions. Wind and MESSENGER magnetic fluctuations are compared for times when the two spacecraft are close to radial and Parker field alignment. The functional dependence of the ion inertial spectral index and break point on solar wind plasma and magnetic field conditions will be discussed.

  18. The F-region trough: seasonal morphology and relation to interplanetary magnetic field

    Directory of Open Access Journals (Sweden)

    M. Voiculescu

    2006-03-01

    Full Text Available We present here the results of a statistical study of the ionospheric trough observed in 2003 by means of satellite tomography. We focus on the seasonal morphology of the trough occurrence and investigate the trough latitude, width and the horizontal gradients at the edges, at different magnetic local times, as well as their relations to geomagnetic activity and the interplanetary magnetic field. A seasonal effect is noticed in the diurnal variation of the trough latitude, indicating that summer clearly differs from the other seasons. In winter the troughs seem to follow the solar terminator. The width of the trough has a diurnal variation and it depends on the season, as well. The broadest troughs are observed in winter and the narrowest ones in summer. A discontinuity in the diurnal variation of the trough latitude is observed before noon. It is suggested that this is an indication of a difference between the generation mechanisms of morningside and eveningside troughs. The density gradients at the edges have a complex dependence on the latitude of the trough and on geomagnetic activity. The photoionization and the auroral precipitation are competing in the formation of the trough walls at different magnetic local times. An important finding is that the interplanetary magnetic field plays a role in the occurrence of the trough at different levels of geomagnetic activity. This is probably associated with the topology of the polar cap convection pattern, which depends on the directions of the IMF components By and Bz.

  19. CHARGED DUST GRAIN DYNAMICS SUBJECT TO SOLAR WIND, POYNTING–ROBERTSON DRAG, AND THE INTERPLANETARY MAGNETIC FIELD

    Energy Technology Data Exchange (ETDEWEB)

    Lhotka, Christoph; Bourdin, Philippe; Narita, Yasuhito, E-mail: christoph.lhotka@oeaw.ac.at, E-mail: philippe.bourdin@oeaw.ac.at, E-mail: yasuhito.narita@oeaw.ac.at [Space Research Institute, Austrian Academy of Sciences, Schmiedlstrasse 6, A-8042 Graz (Austria)

    2016-09-01

    We investigate the combined effect of solar wind, Poynting–Robertson drag, and the frozen-in interplanetary magnetic field on the motion of charged dust grains in our solar system. For this reason, we derive a secular theory of motion by the means of an averaging method and validate it with numerical simulations of the unaveraged equations of motions. The theory predicts that the secular motion of charged particles is mainly affected by the z -component of the solar magnetic axis, or the normal component of the interplanetary magnetic field. The normal component of the interplanetary magnetic field leads to an increase or decrease of semimajor axis depending on its functional form and sign of charge of the dust grain. It is generally accepted that the combined effects of solar wind and photon absorption and re-emmision (Poynting–Robertson drag) lead to a decrease in semimajor axis on secular timescales. On the contrary, we demonstrate that the interplanetary magnetic field may counteract these drag forces under certain circumstances. We derive a simple relation between the parameters of the magnetic field, the physical properties of the dust grain, as well as the shape and orientation of the orbital ellipse of the particle, which is a necessary conditions for the stabilization in semimajor axis.

  20. Relation of the Dsub(st) index to the azimuth component of the interplanetary magnetic field vector during separate storms

    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

  1. Intensity of low-frequency radiations and the interplanetary magnetic field

    International Nuclear Information System (INIS)

    Larkina, V.I.; Likhter, Ya.I.

    1983-01-01

    The data of measurements of ELF/VLF radiations at ''Interkosmos-13'' artificial Earth satellite in auroral latitudes and in the polar cap in the vernal equinox of 1975 are compared with characteristics of interplanetary magnetic field (IMF). The absence of north-south asymmetry of variations of ELF/VLF-radiation Intensity in the outer ionosphere versus the IMF characteristics is noted. The intensity of natural ELF- and VLF-radiations depends in a complex way on parameters of the magnetospheric plasma: composition and concentration of ''cold'' particles, geomagnetic field intensity, properties of energetic particle fluxes. The considered variations in the radiation amplitude versus the IMF characteristics show the predominant role of the sector structure polarity and IMF Bsub(y) component sign

  2. Control of particle precipitation into the middle atmosphere by regular changes of the interplanetary magnetic field

    International Nuclear Information System (INIS)

    Bremer, J.

    1987-01-01

    After DUNGEY (1961) negative B Z -components induced by the interplanetary magnetic field (IMF) in the solar-magnetospheric coordinate system should favour precipitation of high energetic particles into the middle atmosphere whereas positive B Z -values should inhibit such precipitation. In high subauroral and auroral latitudes this expected dependence of particle precipitation on IMF structure can be confirmed. In mid-latitudes, however, the most important precipitation events, the so-called aftereffects after strong geomagnetic disturbances, are only partly controlled by IMF sector structure. In particular, during the second part of the aftereffect after the main phase, internal magnetospheric loss processes which seem to be independent of solar sector structure play a dominant role. (author)

  3. Intensity fluctuations of mid-latitude background VLF-noises and the interplanetary magnetic field

    International Nuclear Information System (INIS)

    Gorshkov, Yu.N.; Klejmenova, N.G.

    1986-01-01

    Influence of interplanetary magnetic field (IMF) sector structure polarity and also variations of solar wind velocity and density on the intensity of mid-latitude VLF background noises are studied. For analysis continuous observations of VLF radiations in Magadan Observatory (phi=53.7 deg, L=2.7) from November, 1972 to June, 1973 were used. It is shown that IMF sector sign has no sufficient effect on the level of mid-latitude VLF background noises at the frequences f < 4-5 kHz. In magnetoperturbed periods when IMF Bsub(z)-component was directed to the South and the Earth was in the region of high-speed plasma flux, in mid-latitudes abatement of intensity of VLF background noises was seen

  4. On an effect of the interplanetary magnetic field sector structure on the upper Earth's ionosphere

    International Nuclear Information System (INIS)

    Kolomijtsev, O.P.; Livshits, M.A.; Soboleva, T.N.

    1985-01-01

    According to the data from vertical probing stations, changes are studied in the critical frequency and height of the ionosphere F2 layer after the Earth crosses the boundaries of the interplanetary magnetic field (IMF) sectors in the periods of equinox during decreases in the solar activity. A reversal of the IMF sign causes ionospheric effects, which in some cases are comparable, as to the value, with the effects observed in the presence of flares and strong geomagnetic perturbations. The IMF sector sign reversal is a key momentum, stimulating such changes in the Earth's magnetosphere state which result in the rearrangement of the ionosphere structure near the maximum of electron concentration on the planetary scale

  5. Sharp Trapping Boundaries in the Random Walk of Interplanetary Magnetic Field Lines

    Science.gov (United States)

    Ruffolo, D.; Chuychai, P.; Meechai, J.; Pongkitiwanichkul, P.; Kimpraphan, N.; Matthaeus, W. H.; Rowlands, G.

    2004-05-01

    Although magnetic field lines in space are believed to undergo a diffusive random walk in the long-distance limit, observed dropouts of solar energetic particles, as well as computer simulations, indicate sharply defined filaments in which interplanetary magnetic field lines have been temporarily trapped. We identify mechanisms that can explain such sharp boundaries in the framework of 2D+slab turbulence, a model that provides a good explanation of solar wind turbulence spectra and the parallel transport of solar energetic particles. Local trapping boundaries (LTBs) are empirically defined as trajectories of 2D turbulence where the mean 2D field is a local maximum. In computer simulations, the filaments (or ``islands'' in the two dimensions perpendicular to the mean field) that are most resistant to slab diffusion correspond closely to the mathematically defined LTBs, that is, there is a mathematical prescription for defining the trapping regions. Furthermore, we provide computational evidence and a theoretical explanation that strong 2D turbulence can inhibit diffusion due to the slab component. Therefore, while these filaments are basically defined by the small-scale topology of 2D turbulence, there can be sharp trapping boundaries where the 2D field is strongest. This work was supported by the Thailand Research Fund, the Rachadapisek Sompoj Fund of Chulalongkorn University, and NASA Grant NAG5-11603. G.R. thanks Mahidol University for its hospitality and the Thailand Commission for Higher Education for travel support.

  6. STRONG SOLAR WIND DYNAMIC PRESSURE PULSES: INTERPLANETARY SOURCES AND THEIR IMPACTS ON GEOSYNCHRONOUS MAGNETIC FIELDS

    International Nuclear Information System (INIS)

    Zuo, Pingbing; Feng, Xueshang; Wang, Yi; Xie, Yanqiong; Xu, Xiaojun

    2015-01-01

    In this investigation, we first present a statistical result of the interplanetary sources of very strong solar wind dynamic pressure pulses (DPPs) detected by WIND during solar cycle 23. It is found that the vast majority of strong DPPs reside within solar wind disturbances. Although the variabilities of geosynchronous magnetic fields (GMFs) due to the impact of positive DPPs have been well established, there appears to be no systematic investigations on the response of GMFs to negative DPPs. Here, we study both the decompression effects of very strong negative DPPs and the compression from strong positive DPPs on GMFs at different magnetic local time sectors. In response to the decompression of strong negative DPPs, GMFs on the dayside near dawn and near dusk on the nightside, are generally depressed. But near the midnight region, the responses of GMF are very diverse, being either positive or negative. For part of the events when GOES is located at the midnight sector, the GMF is found to abnormally increase as the result of magnetospheric decompression caused by negative DPPs. It is known that under certain conditions magnetic depression of nightside GMFs can be caused by the impact of positive DPPs. Here, we find that a stronger pressure enhancement may have a higher probability of producing the exceptional depression of GMF at the midnight region. Statistically, both the decompression effect of strong negative DPPs and the compression effect of strong positive DPPs depend on the magnetic local time, which are stronger at the noon sector

  7. STRONG SOLAR WIND DYNAMIC PRESSURE PULSES: INTERPLANETARY SOURCES AND THEIR IMPACTS ON GEOSYNCHRONOUS MAGNETIC FIELDS

    Energy Technology Data Exchange (ETDEWEB)

    Zuo, Pingbing; Feng, Xueshang; Wang, Yi [SIGMA Weather Group, State Key Laboratory of Space Weather, National Space Science Center, Chinese Academy of Sciences, Beijing (China); Xie, Yanqiong [College of Meteorology and Oceanography, PLA University of Science and Technology, Nanjing (China); Xu, Xiaojun, E-mail: pbzuo@spaceweather.ac.cn, E-mail: fengx@spaceweather.ac.cn [Space Science Institute, Macau University of Science and Technology, Macao (China)

    2015-10-20

    In this investigation, we first present a statistical result of the interplanetary sources of very strong solar wind dynamic pressure pulses (DPPs) detected by WIND during solar cycle 23. It is found that the vast majority of strong DPPs reside within solar wind disturbances. Although the variabilities of geosynchronous magnetic fields (GMFs) due to the impact of positive DPPs have been well established, there appears to be no systematic investigations on the response of GMFs to negative DPPs. Here, we study both the decompression effects of very strong negative DPPs and the compression from strong positive DPPs on GMFs at different magnetic local time sectors. In response to the decompression of strong negative DPPs, GMFs on the dayside near dawn and near dusk on the nightside, are generally depressed. But near the midnight region, the responses of GMF are very diverse, being either positive or negative. For part of the events when GOES is located at the midnight sector, the GMF is found to abnormally increase as the result of magnetospheric decompression caused by negative DPPs. It is known that under certain conditions magnetic depression of nightside GMFs can be caused by the impact of positive DPPs. Here, we find that a stronger pressure enhancement may have a higher probability of producing the exceptional depression of GMF at the midnight region. Statistically, both the decompression effect of strong negative DPPs and the compression effect of strong positive DPPs depend on the magnetic local time, which are stronger at the noon sector.

  8. Effects of interplanetary magnetic field and magnetospheric substorm variations on the dayside aurora

    Science.gov (United States)

    Sandholt, P. E.; Egeland, A.; Lybekk, B.; Deehr, C. S.; Sivjee, G. G.; Romick, G. J.

    1983-11-01

    Photometric auroral observations and geomagnetic measurements obtained simultaneously on the dayside in Norway and the nightside in the USSR, Alaska, and Canada are combined with ISEE-1 and 3 data on the interplanetary magnetic field (IMF) to study the relative importance of substorm perturbations and IMF in determining dayside auroral (DA) motion. Ten events from December, 1978, and January and December, 1979, are characterized, the data are presented in tables, illustrated with charts and graphs, and summarized. The equatorward and poleward motion of the DA is correlated with the growth and decay of DP2-mode geomagnetic disturbances and changes in the north-south component of the IMF. Discrete DA forms appear in a region of sunward-convecting field lines. A detailed model of DA motion is developed which explains these phenomena as the result of a direct global response of the magnetospheric electromagnetic state to the solar-wind magnetic field. Using the model, the potential drop, Pedersen current, and Joule heat-dissipation rate of the polar-cap ionosphere are estimated as 125 kV, 800,000 A, and 100 GW, respectively.

  9. Seasonal and interplanetary magnetic field dependence of the field-aligned currents for both Northern and Southern Hemispheres

    Directory of Open Access Journals (Sweden)

    D. L. Green

    2009-04-01

    Full Text Available The configuration of the Earth's magnetosphere under various Interplanetary Magnetic Field (IMF and solar wind conditions alters the global distribution of Field-Aligned Currents (FACs at the high latitude ionospheres. We use magnetic field data obtained from the Iridium constellation to extend recent studies that infer the dependence of the global FAC configuration on IMF direction and magnitude, hemisphere and season. New results are a reduced IMF By influence on the FAC configuration for the winter hemisphere and a redistribution of FAC to the nightside for winter relative to the summer hemisphere. These effects are linked to the winter ionosphere conductance distribution being dominated by localised nightside enhancement associated with ionisation from energetic particle precipitation. A comparison of an estimated open-closed field line boundary (OCFLB with the Region 1 FAC locations shows reasonable agreement for summer FAC configurations. However, the OCFLB location is decoupled from the Region 1 FACs in winter, especially for IMF Bz>0.

  10. The instantaneous relationship between polar cap and oval auroras at times of northward interplanetary magnetic field

    International Nuclear Information System (INIS)

    Murphree, J.S.; Anger, C.D.; Cogger, L.L.

    1982-01-01

    Optical images of the polar cap region at both 5577 and 3914 A obtained from 1400 km above the earth have been used to study the relationship between polar cap and oval aurora during periods when the interplanetary magnetic field is strongly northward, i.e., B > 3.5 nT. When this rather rare condition occurs, distinction between the two types of aurora is no longer as clear as depicted on the basis of statistical definitions of the auroral oval. Diffuse, weak emission can fill in the region between the auroral oval and discrete auroral features in the polar cap. The polar cap discrete features can appear very similar to auroral oval arcs in intensity, intensity ratio, and structure. Even more striking are the situations where discrete polar cap features merge with oval auroras. From this study it is concluded that under conditions of large positive B the region of closed magnetic field lines can expand poleward to occupy much of the high latitude region

  11. The location and rate of dayside reconnection during an interval of southward interplanetary magnetic field

    Directory of Open Access Journals (Sweden)

    M. Pinnock

    2003-07-01

    Full Text Available Using ionospheric data from the SuperDARN radar network and a DMSP satellite we obtain a comprehensive description of the spatial and temporal pattern of day-side reconnection. During a period of southward interplanetary magnetic field (IMF, the data are used to determine the location of the ionospheric projection of the dayside magnetopause reconnection X-line. From the flow of plasma across the projected X-line, we derive the reconnection rate across 7 h of longitude and estimate it for the total length of the X-line footprint, which was found to be 10 h of longitude. Using the Tsyganenko 96 magnetic field model, the ionospheric data are mapped to the magnetopause, in order to provide an estimate of the extent of the reconnection X-line. This is found to be ~ 38 RE in extent, spanning the whole dayside magnetopause from dawn to dusk flank. Our results are compared with previously reported encounters by the Equator-S and Geotail spacecraft with a reconnecting magnetopause, near the dawn flank, for the same period. The SuperDARN observations allow the satellite data to be set in the context of the whole magnetopause reconnection X-line. The total potential associated with dayside reconnection was ~ 150 kV. The reconnection signatures detected by the Equator-S satellite mapped to a region in the ionosphere showing continuous flow across the polar cap boundary, but the reconnection rate was variable and showed a clear spatial variation, with a distinct minimum at 14:00 magnetic local time which was present throughout the 30-min study period.Key words. Magnetospheric physics (magnetopause, cusp and boundary layers; magnetosphere-ionoshere interactions – Space plasma physics (magnetic reconnection

  12. A study of the geomagnetic indices asymmetry based on the interplanetary magnetic field polarities

    Science.gov (United States)

    El-Borie, M. A.; El-Taher, A. M.; Aly, N. E.; Bishara, A. A.

    2018-05-01

    Data of geomagnetic indices ( aa, Kp, Ap, and Dst) recorded near 1 AU over the period 1967-2016, have been studied based on the asymmetry between the interplanetary magnetic field (IMF) directions above and below of the heliospheric current sheet (HCS). Our results led to the following conclusions: (i) Throughout the considered period, 31 random years (62%) showed apparent asymmetries between Toward (T) and Away (A) polarity days and 19 years (38%) exhibited nearly a symmetrical behavior. The days of A polarity predominated over the T polarity days by 4.3% during the positive magnetic polarity epoch (1991-1999). While the days of T polarity exceeded the days of A polarity by 5.8% during the negative magnetic polarity epoch (2001-2012). (ii) Considerable yearly North-South (N-S) asymmetries of geomagnetic indices observed throughout the considered period. (iii) The largest toward dominant peaks for aa and Ap indices occurred in 1995 near to minimum of solar activity. Moreover, the most substantial away dominant peaks for aa and Ap indices occurred in 2003 (during the descending phase of the solar cycle 23) and in 1991 (near the maximum of solar activity cycle) respectively. (iv) The N-S asymmetry of Kp index indicated a most significant away dominant peak occurred in 2003. (v) Four of the away dominant peaks of Dst index occurred at the maxima of solar activity in the years 1980, 1990, 2000, and 2013. The largest toward dominant peak occurred in 1991 (at the reversal of IMF polarity). (vi) The geomagnetic indices ( aa, Ap, and Kp) all have northern dominance during positive magnetic polarity epoch (1971-1979), while the asymmetries shifts to the southern solar hemisphere during negative magnetic polarity epoch (2001-2012).

  13. High-latitude dayside electric fields and currents during strong northward interplanetary magnetic field: Observations and model simulation

    International Nuclear Information System (INIS)

    Clauer, C.R.; Friis-Christensen, E.

    1988-01-01

    On July 23, 1983, the Interplanetary Magnetic Field turned strongly northward, becoming about 22 nT for several hours. Using a combined data set of ionospheric convection measurements made by the Sondre Stromfjord incoherent scatter radar and convection inferred from Greenland magnetometer measurements, we observe the onset of the reconfiguration of the high-latitude ionospheric currents to occur about 3 min following the northward IMF encountering the magnetopause. The large-scale reconfiguration of currents, however, appears to evolve over a period of about 22 min. Using a computer model in which the distribution of field-aligned current in the polar cleft is directly determined by the strength and orientation of the interplanetary electric field, we are able to simulate the time-varying pattern of ionospheric convection, including the onset of high-latitude ''reversed convection'' cells observed to form during the interval of strong northward IMF. These observations and the simulation results indicate that the dayside polar cap electric field observed during strong northward IMF is produced by a direct electrical current coupling with the solar wind. copyright American Geophysical Union 1988

  14. Some low-altitude cusp dependencies on the interplanetary magnetic field

    International Nuclear Information System (INIS)

    Newell, P.T.; Meng, C.; Sibeck, D.G.; Lepping, R.

    1989-01-01

    Although it has become well established that the low-altitude polar cusp moves equatorward during intervals of southward interplanetary magnetic field (IMF B z y negative (positive) in the northern (southern) hemisphere and postnoon for B y positive (negative) in the northern (southern) hemisphere. The B y induced shift is much more pronounced for southward than for northward B z , a result that appears to be consistent with elementary considerations from, for example, the antiparallel merging model. No interhemispherical latitudinal differences in cusp positions were found that could be attributed to the IMF B x component. As expected, the cusp latitudinal position correlated reasonably well (0.70) with B z when the IMF had a southward component; the previously much less investigated correlation for B z northward proved to be only 0.18, suggestive of a half-wave rectifier effect. The ratio of cusp ion number flux precipitation for B z southward to that for B z northward was 1.75±0.12. The statistical local time (full) width of the cusp proper was found to be 2.1 hours for B z northward and 2.8 hours for B z southward. copyright American Geophysical Union 1989

  15. Sector structure of the interplanetary magnetic field and anisotropy of 50-1000 GV cosmic radiation

    International Nuclear Information System (INIS)

    Erdoes, G.; Kota, J.

    1978-12-01

    It is demonstrated that the main features of high-rigidity solar originated anisotropy can be explained in terms of regular particle motion - without diffusion being involved - in the large scale interplanetary magnetic field (IMF). A simple model of the IMF is adopted with a corotating warped current sheet separating the two polarities. The warped shape of the current sheet is essential in producing anisotropy. By calculating energy loss along various computed trajectories, the resulting sidereal, solar and antisidereal variations are determined for both the pre- and post-1969 epochs. The predicted variations turn out fairly stable against changing the parameters of the IMF model. The sense and amplitude of the polarity dependent sidereal vectors are compatible with those established experimentally. Also reproduced is the prediction of corotation as well as the 3 hr phase of the semidiurnal wave. The corotation is found to be near perfect at 50 GV while it decreases at 100 GV. The model presented accounts for the change of solar daily variation taking place in 1969. (author)

  16. Comparison of S3-3 polar cap potential drops with the interplanetary magnetic field and models of magnetopause reconnection

    International Nuclear Information System (INIS)

    Wygant, J.R.; Torbert, R.B.; Mozer, F.S.

    1983-01-01

    Measurements of the cross polar cap electric potential, by the double probe electric field experiment aboard S3-3, from 55 orbits in the dawn-dusk plane are compared with the reconnection electric fields predicted by a variety of models, both theoretical and experimental. The purpose of these comparisons is to understand the extent to which nonreconnection contributes to the polar cap potential must be included, to determine the time response of the polar cap potential to time varying reconnection rates, and to determine the efficiency and saturation levels of the reconnection process. It is found that (1) After several hours of northward interplanetary magnetic field, the cross polar cap potential declines to progressively lower values than those after 1 hour of northward interplanetary magnetic field. This suggests that it requires several hours for the ionospheric polar cap potential to respond to the ''turning off'' of ''turning down'' of the reconnection process. (2) The decay of the polar cap potential is used to demonstrate that contirubtions to the polar cap potential not associated with the reconnection process can be limited to less than 20 kV. It is shown that contributions to the polar cap potential that scale with the dynamic pressure of the solar wind are limited to less than 1 kV. (3) The cross polar cap electric potential is best predicted by a weighted sum of contributions from interplanetary magnetic field parameter over the 4 hours previous to the measurement. The weighting functions have the form of an exponential decay 2--3 hours with the strongest weight on interplanetary parameters over the 1 hour previous to the measurement

  17. Effect of the interplanetary magnetic field on the distribution of electric fields in the polar ionosphere

    Science.gov (United States)

    Uvarov, V. M.; Barashkov, P. D.

    1985-08-01

    Heppner (1972), in an analysis of satellite data, observed 12 types of electric-field distributions in the polar ionosphere along the morning-evening meridian. In the present paper it is shown that these distribution types can be described by the analytical model of Uvarov and Barashkov (1984). In this model the excitation of the electric fields is investigated by solving the set of continuity equations for current in three regions (the north and south polar caps and a region outside the caps) with allowance for the magnetic conjugacy of the ionosphere in the two hemispheres.

  18. Relations between turbulent regions of interplanetary magnetic field and Jovian decametric radio wave emissions from the main source

    International Nuclear Information System (INIS)

    Oya, H.; Morioka, A.

    1981-01-01

    Jovian decametric radio wave emissions that were observed at Goddard Space Flight Center, U.S.A. for a period from 1 October to 31 December, 1974 and data obtained at Mt. Zao observatory, Tohoku University, Japan, for a period from 14 July to 6 December, 1975 have been used to investigate the relationship of the occurrence of the Jovian decametric radio waves (JDW), from the main source, to the geomagnetic disturbance index, ΣKAPPA sub(rho). The dynamic cross-correlation between JDW and ΣKAPPAsubrho indicates an enhanced correlation for certain values of delay time. The delay time is consistent with predicted values based on a model of rotating turbulent regions in interplanetary space associated with two sector boundaries of the interplanetary magnetic field, i.e. the rotating sector boundaries of the interplanetary magnetic field first encounter the Earth's magnetosphere producing the geomagnetic field disturbances, and after a certain period, they encounter the Jovian magnetosphere. There are also cases where the order of the encounter is opposite, i.e. the sector boundaries encounter first Jovian magnetosphere and encounter the Earth's magnetosphere after a certain period. (author)

  19. Polar cap electric field structures with a northward interplanetary magnetic field

    International Nuclear Information System (INIS)

    Burke, W.J.; Kelley, M.C.; Sagalyn, R.C.; Smiddy, M.; Lai, S.T.

    1979-01-01

    Polar cap electric fields patterns are presented from times when the S3-2 Satellite was near the dawn-dusk meridian and IMF data were available. With B/sub z/> or =0.7γ, two characteristic types of electric field patterns were measured in the polar cap. In the sunlit polar cap the convection pattern usually consisted of four cells. Two of the cells were confined to the polar cap with sunward convection in the central portion of the cap. The other pair of cells were marked by anti-sunward flow along the flanks of the polar cap and by sunward flow in the auroral oval. These observations are interpreted in terms of a model for magnetic merging at the poleward wall of the dayside polar cusp. The sunward flow in the auroral zone is not predicted by the magnetic model and may be due to a viscous interaction between the solar wind and and magnetosphere. The second type, which was observed in some of the summer hemisphere passes and all of the winter ones, was characterized by an electric field pattern which was very turbulent, and may be related to inhomogeneous merging

  20. Reconstruction of geomagnetic activity and near-Earth interplanetary conditions over the past 167 yr – Part 2: A new reconstruction of the interplanetary magnetic field

    Directory of Open Access Journals (Sweden)

    M. Lockwood

    2013-11-01

    Full Text Available We present a new reconstruction of the interplanetary magnetic field (IMF, B for 1846–2012 with a full analysis of errors, based on the homogeneously constructed IDV(1d composite of geomagnetic activity presented in Part 1 (Lockwood et al., 2013a. Analysis of the dependence of the commonly used geomagnetic indices on solar wind parameters is presented which helps explain why annual means of interdiurnal range data, such as the new composite, depend only on the IMF with only a very weak influence of the solar wind flow speed. The best results are obtained using a polynomial (rather than a linear fit of the form B = χ · (IDV(1d − βα with best-fit coefficients χ = 3.469, β = 1.393 nT, and α = 0.420. The results are contrasted with the reconstruction of the IMF since 1835 by Svalgaard and Cliver (2010.

  1. An Alternative Interpretation of the Relationship between the Inferred Open Solar Flux and the Interplanetary Magnetic Field

    Science.gov (United States)

    Riley, Pete

    2007-01-01

    Photospheric observations at the Wilcox Solar Observatory (WSO) represent an uninterrupted data set of 32 years and are therefore unique for modeling variations in the magnetic structure of the corona and inner heliosphere over three solar cycles. For many years, modelers have applied a latitudinal correction factor to these data, believing that it provided a better estimate of the line-of-sight magnetic field. Its application was defended by arguing that the computed open flux matched observations of the interplanetary magnetic field (IMF) significantly better than the original WSO correction factor. However, no physically based argument could be made for its use. In this Letter we explore the implications of using the constant correction factor on the value and variation of the computed open solar flux and its relationship to the measured IMF. We find that it does not match the measured IMF at 1 AU except at and surrounding solar minimum. However, we argue that interplanetary coronal mass ejections (ICMEs) may provide sufficient additional magnetic flux to the extent that a remarkably good match is found between the sum of the computed open flux and inferred ICME flux and the measured flux at 1 AU. If further substantiated, the implications of this interpretation may be significant, including a better understanding of the structure and strength of the coronal field and I N providing constraints for theories of field line transport in the corona, the modulation of galactic cosmic rays, and even possibly terrestrial climate effects.

  2. Cluster observations of continuous reconnection at the magnetopause under steady interplanetary magnetic field conditions

    Directory of Open Access Journals (Sweden)

    T. D. Phan

    2004-07-01

    Full Text Available On 26 January 2001, the Cluster spacecraft detected high-speed plasma jets at multiple crossings of the high-latitude duskside magnetopause (MP and boundary layer (BL over a period of more than 2h. The 4 spacecraft combined spent more than half of this time in the MP/BL and jets were observed whenever a spacecraft was in the MP. These observations were made under steady southward and dawnward interplanetary magnetic field (IMF conditions. The magnetic shear across the local MP was ~100° and β~1 in the adjacent magnetosheath. The jet velocity is in remarkable agreement with reconnection prediction throughout the entire interval, except for one crossing that had no ion measurements inside the current layer. The flow speed measured in the deHoffmann Teller frame is 90% of the Alfvén speed on average for the 10 complete MP current layer crossings that are resolved by the ion measurements. These findings strongly suggest that reconnection was continuously active for more than two hours. The jets were directed persistently in the same northward and anti-sunward direction, implying that the X-line was always below the spacecraft. This feature is inconsistent with patchy and random reconnection or convecting multiple X-lines. The majority of MP/BL crossings in this two-hour interval were partial crossings, implying that they are caused by bulges sliding along the MP, not by inward-outward motion of a uniformly thin MP/BL. The presence of the bulges suggests that, although reconnection is continuously active under steady IMF conditions, its rate may be modulated. The present investigation also reveals that (1 the predicted ion D-shaped distributions are absent in all reconnection jets on this day, (2 the electric field fluctuations are larger in the reconnecting MP than in the magnetosheath proper, but their amplitudes never exceed 20mV/m, (3 the ion-electron differential motion is ~20km/s for the observed MP current density of ~50nA/m2 (∇× B, thus

  3. Field-aligned currents during northward interplanetary magnetic field: Morphology and causes

    DEFF Research Database (Denmark)

    Vennerstrøm, Susanne; Moretto, T.; Rastatter, L.

    2005-01-01

    [1] We present the results of a global MHD simulation of solar wind magnetosphere interaction during northward IMF. In particular, we emphasize the effect of the IMF By component on the reconnection geometry and the mapping along field lines to the polar ionosphere, through field-aligned currents....... We find that the existence and geometry of the polar cap is closely connected to the IMF By component. During strictly northward IMF the simulated magnetosphere can remain essentially closed because the solar wind field lines reconnect in both hemispheres, thereby creating newly reconnected closed...... both on open and closed field lines and are created by the shear of the newly reconnected field lines against the mantle field as they are convected tailward by the solar wind. When the IMF rotates from northward toward east, the magnetospheric mapping regions of the NBZ currents likewise rotates...

  4. Statistical Study of Interplanetary Coronal Mass Ejections with Strong Magnetic Fields

    Science.gov (United States)

    Murphy, Matthew E.

    Coronal Mass Ejections (CMEs) with strong magnetic fields (B ) are typically associated with significant Solar Energetic Particle (SEP) events, high solar wind speed and solar flare events. Successful prediction of the arrival time of a CME at Earth is required to maximize the time available for satellite, infrastructure, and space travel programs to take protective action against the coming flux of high-energy particles. It is known that the magnetic field strength of a CME is linked to the strength of a geomagnetic storm on Earth. Unfortunately, the correlations between strong magnetic field CMEs from the entire sun (especially from the far side or non-Earth facing side of the sun) to SEP and flare events, solar source regions and other relevant solar variables are not well known. New correlation studies using an artificial intelligence engine (Eureqa) were performed to study CME events with magnetic field strength readings over 30 nanoteslas (nT) from January 2010 to October 17, 2014. This thesis presents the results of this study, validates Eureqa to obtain previously published results, and presents previously unknown functional relationships between solar source magnetic field data, CME initial speed and the CME magnetic field. These new results enable the development of more accurate CME magnetic field predictions and should help scientists develop better forecasts thereby helping to prevent damage to humanity's space and Earth assets.

  5. Magnetosheath plasma precipitation in the polar cusp and its control by the interplanetary magnetic field

    International Nuclear Information System (INIS)

    Woch, J.; Lundin, R.

    1992-01-01

    Magnetosheath particle precipitation in the polar cusp region is studied based on Viking hot plasma data obtained on meridional cusp crossings. Two distinctively different regions are commonly encountered on a typical pass. One region is characterized by high-density particle precipitation, with an ion population characterized by a convecting Maxwellian distribution. Typical magnetosheath parameters are inferred for the spectrum of the source population. The spectral shape of the ion population encountered in the second region suggests that here the magnetosheath ions have been energized by about 1 keV, corresponding to an ion velocity gain of about twice the magnetosheath Alfven velocity. The location of the region containing the accelerated plasma is dependent on the IMF B z component. For southward IMF the acceleration region is bounded by the ring current population on the equatorward side and by the unaccelerated magnetosheath plasma precipitation on the poleward side. For northward IMF the region is located at the poleward edge of the region with unaccelerated precipitation. The accelerated ion population is obviously transported duskward (dawnward) for a dawnward (duskward) directed IMF. These observations are interpreted as evidence for plasma acceleration due to magnetopause current sheet disruptions/merging of magnetospheric and interplanetary magnetic flux tubes

  6. Dynamics of magnetic clouds in interplanetary space

    International Nuclear Information System (INIS)

    Yeh, T.

    1987-01-01

    Magnetic clouds observed in interplanetary space may be regarded as extraneous bodies immersed in the magnetized medium of the solar wind. The interface between a magnetic cloud and its surrounding medium separates the internal and external magnetic fields. Polarization currents are induced in the peripheral layer to make the ambient magnetic field tangential. The motion of a magnetic cloud through the interplanetary medium may be partitioned into a translational motion of the magnetic cloud as a whole and an expansive motion of the volume relative to the axis of the magnetic cloud. The translational motion is determined by two kinds of forces, i.e., the gravitational force exerted by the Sun, and the hydromagnetic buoyancy force exerted by the surrounding medium. On the other hand, the expansive motion is determined by the pressure gradient sustaining the gross difference between the internal and external pressures and by the self-induced magnetic force that results from the interaction among the internal currents. The force resulting from the internal and external currents is a part of the hydromagnetic buoyancy force, manifested by a thermal stress caused by the inhomogeneity of the ambient magnetic pressure

  7. Dynamics of magnetic clouds in interplanetary space

    Science.gov (United States)

    Yeh, Tyan

    1987-09-01

    Magnetic clouds observed in interplanetary space may be regarded as extraneous bodies immersed in the magnetized medium of the solar wind. The interface between a magnetic cloud and its surrounding medium separates the internal and external magnetic fields. Polarization currents are induced in the peripheral layer to make the ambient magnetic field tangential. The motion of a magnetic cloud through the interplanetary medium may be partitioned into a translational motion of the magnetic cloud as a whole and an expansive motion of the volume relative to the axis of the magnetic cloud. The translational motion is determined by two kinds of forces, i.e., the gravitational force exerted by the Sun, and the hydromagnetic buoyancy force exerted by the surrounding medium. On the other hand, the expansive motion is determined by the pressure gradient sustaining the gross difference between the internal and external pressures and by the self-induced magnetic force that results from the interaction among the internal currents. The force resulting from the internal and external currents is a part of the hydromagnetic buoyancy force, manifested by a thermal stress caused by the inhomogeneity of the ambient magnetic pressure.

  8. Latitudinal Distributions of Auroral Zone Electric Fields and Ground Magnetic Perturbations and Their Response to Variations in the Interplanetary Magnetic Field

    International Nuclear Information System (INIS)

    Horwitz, J.L.; Doupnik, J.R.; Banks, P.M.; Kamide, Y.; Akasofu, S.

    1978-01-01

    Chatanika observations of latitudinal distributions of convection electric fields (E 1 ) are compared with isointensity ΔH contours in latitude and time from the Alaskan magnetometer chain and with the north-south component of the interplanetary magnetic field (IMF B/sub z/m) from Imp-J. As expected, northward electric fields were generally observed within latitude and time regions where ΔH was positive, while southward electric fields were observed within negative ΔH regions. However, correlation between the magnitudes of the electric fields and of the ΔH perturbations was not strong, owing to variability in ionospheric conductivities produced by precipitation and solar illumination. In the midnight sector the northward-to-southward transition in the electric field and positive-to-negative ΔH transition were roughly collocated (to within 1 hour in local time) as signatures of the Harang discontinuity. The most important findings are that (1) southward (northward) IMF B/sub z/m transitions caused rapid equatorward (poleward) shifts of the electric field and ΔH patterns and (2) southward IMF B/sub z/ transitions, magnetospheric substorms, and local time transitions of the Harang discontinuity can all lead to northward-to-southward transitions of the electric field in the midnight sector. Due to the interlaced phasing of each of these three causal mechanisms a highly complex temporal pattern of electric fields results

  9. Microstructure of the interplanetary magnetic field near 4 and 5 AU

    International Nuclear Information System (INIS)

    Parker, G.D.

    1980-01-01

    Seventy-two days of vector magnetic field measurements from Pioneer 10 and 11 are analyzed for information about magnetic field fluctuations in the quiet solar wind near 4 and 5 AU. Calculated as functions of frequency over the range 4 x 10 -5 to 9 x 10 -3 Hz, directional properties of magnetic field fluctuations are presented and are discussed with reference to theoretical predictions for MHD plane waves. The distributions of maximum variance directions computed from approx. =500 spectral matrices for each spacecraft are peaked along the normal to the plane of the minimum variance direction and the mean magnetic field. This orientation is expected for a planar, small-amplitude Alfven wave with a minimum variance direction close to the wave vector. Noting also that magnetic fluctuations tend to conserve field magnitude, as is required for Alfvenic fluctuations, we infer that single small-amplitude Alfven waves are occasionally present in the temporal and frequency bands analyzed. However, statistics of the relative spatial orientations of the mean field and the minimum and maximum variance directions permit that waves with wave vectors not well approximated by the minimum variance direction, Alfven wave ensembles, finite-amplitude waves, and nonplanar fluctuations may also be present. Assuming that the minimum variance direction approximates the wave vector when a small-amplitude wave is present, we note that (1) among those data in which the field fluctuations behave in accord with theoretical predictions for single, planar, small-amplitude MHD waves, observations suggest the predominance of the Alfven mode over the fast and slow modes and (2) there is a general lack of observational support for theoretical models of outward propagating plane Alfven waves of solar origin

  10. Non-Gaussianity and cross-scale coupling in interplanetary magnetic field turbulence during a rope-rope magnetic reconnection event

    Science.gov (United States)

    Miranda, Rodrigo A.; Schelin, Adriane B.; Chian, Abraham C.-L.; Ferreira, José L.

    2018-03-01

    In a recent paper (Chian et al., 2016) it was shown that magnetic reconnection at the interface region between two magnetic flux ropes is responsible for the genesis of interplanetary intermittent turbulence. The normalized third-order moment (skewness) and the normalized fourth-order moment (kurtosis) display a quadratic relation with a parabolic shape that is commonly observed in observational data from turbulence in fluids and plasmas, and is linked to non-Gaussian fluctuations due to coherent structures. In this paper we perform a detailed study of the relation between the skewness and the kurtosis of the modulus of the magnetic field |B| during a triple interplanetary magnetic flux rope event. In addition, we investigate the skewness-kurtosis relation of two-point differences of |B| for the same event. The parabolic relation displays scale dependence and is found to be enhanced during magnetic reconnection, rendering support for the generation of non-Gaussian coherent structures via rope-rope magnetic reconnection. Our results also indicate that a direct coupling between the scales of magnetic flux ropes and the scales within the inertial subrange occurs in the solar wind.

  11. The connection of the interplanetary magnetic field turbulence and rigidity spectrum of Forbush decrease of the galactic cosmic ray intensity

    International Nuclear Information System (INIS)

    Wawrzynczak, A; Alania, M V

    2015-01-01

    We analyze the temporal changes in the rigidity spectrum of Forbush decrease (Fd) of the galactic cosmic ray (GCR) intensity observed in November 2004. We compute the rigidity spectrum in two energy ranges based on the daily data from the worldwide network of neutron monitors and Nagoya ground muon telescope. We demonstrate that the changes in the rigidity spectrum of Fd are linked to the evolution/decay of the interplanetary magnetic field (IMF) turbulence during various phases of the Fd. We analyze the time-evolution of the state of the turbulence of the IMF in various frequency ranges during the Fd. Performed analysis show that the decrease of the exponent ν of the Power Spectral Density (PSD ∝ f −ν , where f is frequency) of the IMF turbulence with decreasing frequency lead to the soft rigidity spectrum of Fd for GCR particles with relatively higher energies. (paper)

  12. On a distribution of electric fields caused by the northern component of the interplanetary magnetic field in the absence of longitudinal currents in the winter polar cap

    International Nuclear Information System (INIS)

    Uvarov, V.M.

    1984-01-01

    Data on the distribution of electric fields, conditioned by the northern component of the interplanetary magnetic field Bsub(z), have been discussed. The problem of electric field excitation is reduced to the solution of equations of continuity for the current in three regions: northern and southern polar caps and region beyond the caps. At the values Bsub(z)>0 in the ranqe of latitudes phi >= 80 deg the localization of convection conversion effect is obtained in calculations for summer cap and it agrees with the data of direct measurements

  13. Using ACE Observations of Interplanetary Particles and Magnetic Fields as Possible Contributors to Variations Observed at Van Allen Probes during Major events in 2013

    Science.gov (United States)

    Armstrong, T. P.; Manweiler, J. W.; Gerrard, A. J.; Gkioulidou, M.; Lanzerotti, L. J.; Patterson, J. D.

    2013-12-01

    Observations from ACE EPAM including energy spectra of protons, helium, and oxygen will be prepared for coordinated use in estimating the direct and indirect access of energetic particles to inner and outer geomagnetic trapping zones. Complete temporal coverage from ACE at 12 seconds, 5 minutes, 17 minutes, hourly and daily cadences will be used to catalog interplanetary events arriving at Earth including interplanetary magnetic field sector boundaries, interplanetary shocks, and interplanetary coronal mass ejections, ICMEs. The first 6 months of 2013 have included both highly disturbed times, March 17 and May 22, and extended quiet periods of little or no variations. Among the specific questions that ACE and Van Allen Probes coordinated observations may aid in resolving are: 1. How much, if any, direct capture of interplanetary energetic particles occurs and what conditions account for it? 2. How much influence do interplanetary field and particle variations have on energization and/or loss of geomagnetically trapped populations? The poster will also present important links and describe methods and important details of access to numerically expressed ACE EPAM and Van Allen Probes RBSPICE observations that can be flexibly and easily accessed via the internet for student and senior researcher use.

  14. Theoretical interpretation of the observed interplanetary magnetic field radial variation in the outer solar system

    Science.gov (United States)

    Suess, S. T.; Thomas, B. T.; Nerney, S. F.

    1985-01-01

    Observations of the azimuthal component of the IMF are evaluated through the use of an MHD model which shows the effect of magnetic flux tubes opening in the outer solar system. It is demonstrated that the inferred meridional transport of magnetic flux is consistent with predictions by the MHD model. The computed azimuthal and radial magnetic flux deficits are almost identical to the observations. It is suggested that the simplest interpretation of the observations is that meridional flows are created by a direct body force on the plasma. This is consistent with the analytic model of Nerney and Suess (1975), in which such flux deficits in the IMF arise naturally from the meridional gradient in the spiralling field.

  15. A study of north-south asymmetry of interplanetary magnetic field plasma and some solar indices throughout four solar cycles

    International Nuclear Information System (INIS)

    El-Borie, M A; Bishara, A A; Abdel-halim, A A; El-Monier, S Y

    2017-01-01

    We provide a long epoch study of a set of solar and plasma parameters (sunspot number Rz, total solar irradiance TSI, solar radio flux SF, solar wind speed V , ion density n, dynamic pressure n V 2 , and ion temperature T) covering a temporal range of several decades corresponding to almost four solar cycles. Such data have been organized accordingly with the interplanetary magnetic field (IMF) polarity, i.e. away (A) if the azimuthal component of the IMF points away from the Sun and T if it points towards, to examine the N-S asymmetries between the northern and southern hemispheres. Our results displayed the sign of the N-S asymmetry in solar activity depends on the solar magnetic polarity state (qA>0 or qA<0). The solar flux component of toward field vector was larger in magnitude than those of away field vector during the negative polarity epochs (1986-88 and 2001-08). In addition, the solar wind speeds (SWS) are faster by about 22.11±4.5 km/s for away polarity days than for toward polarity days during the qA<0 epoch (2001-08), where the IMF points away from the Sun. Moreover, during solar cycles 21 st and 24 th the solar plasma is more dense, hotter, and faster south of the HCS. (paper)

  16. Interplanetary magnetic field according to measurements on the Fobos-1,-2 space vehicles. 3. Heliospheric substorm of August 5-7, 1988

    International Nuclear Information System (INIS)

    Ivanov, K.G.

    1995-01-01

    Three-phase disturbance of the interplanetary magnetic field was observed by FOBOS-1 and Fobos-2 space vehicles being at 10 million km distance from the Earth and by IMP-8 near-the-Earth satellite. Disturbance configuration and structure demonstrate that passing of nonstandard bend of heliospheric current layer is the reason of it. Structure, intensity and origination of disturbance enable to classify it as belonging to a category of heliospheric substorms. All three phases of interplanetary disturbance were represented in special near-the-Earth geomagnetic variations of polar cap. 9 refs

  17. Solar Wind Energy Input during Prolonged, Intense Northward Interplanetary Magnetic Fields: A New Coupling Function

    Science.gov (United States)

    Du, A. M.; Tsurutani, B. T.; Sun, W.

    2012-04-01

    Sudden energy release (ER) events in the midnight sector at auroral zone latitudes during intense (B > 10 nT), long-duration (T > 3 hr), northward (Bz > 0 nT = N) IMF magnetic clouds (MCs) during solar cycle 23 (SC23) have been examined in detail. The MCs with northward-then-southward (NS) IMFs were analyzed separately from MCs with southward-then-northward (SN) configurations. It is found that there is a lack of substorms during the N field intervals of NS clouds. In sharp contrast, ER events do occur during the N field portions of SN MCs. From the above two results it is reasonable to conclude that the latter ER events represent residual energy remaining from the preceding S portions of the SN MCs. We derive a new solar wind-magnetosphere coupling function during northward IMFs: ENIMF = α N-1/12V 7/3B1/2 + β V |Dstmin|. The first term on the right-hand side of the equation represents the energy input via "viscous interaction", and the second term indicates the residual energy stored in the magnetotail. It is empirically found that the magnetosphere/magnetotail can store energy for a maximum of ~ 4 hrs before it has dissipated away. This concept is defining one for ER/substorm energy storage. Our scenario indicates that the rate of solar wind energy injection into the magnetosphere/magnetotail determines the form of energy release into the magnetosphere/ionosphere. This may be more important than the dissipation mechanism itself (in understanding the form of the release). The concept of short-term energy storage is applied for the solar case. It is argued that it may be necessary to identify the rate of energy input into solar magnetic loop systems to be able to predict the occurrence of solar flares.

  18. The configuration of the auroral distribution for interplanetary magnetic field Bz northward. 2. Ionospheric convection consistent with Viking observations

    International Nuclear Information System (INIS)

    Jankowska, K.; Elphinstone, R.D.; Murphree, J.S.; Cogger, L.L.; Hearn, D.; Marklund, G.

    1990-01-01

    Views of the northern hemisphere auroral distribution obtained by the Viking satellite present a qualitative means of inferring the convective patterns which occur during interplanetary magnetic field (IMF) B z northward. The approach is taken whereby upward field-aligned currents are assumed to be coincident with large-scale discrete auroral features and on this basis possible convective patterns are deduced. While the patterns are not unique solutions, they are found to be consistent with merging theory predictions. That is, for B z northward the auroral observations support the possibility of three and/or four cell patterns. When the IMF azimuthal angle is 90 degree (270 degree), a clockwise (anticlockwise) cell is found to be located in the polar region between the two standard viscous cells. When IMF B x dominates and is in a toward orientation, convection stagnates, whereas if B x is negative, a four-cell pattern may form with sunward flow at very high latitudes. The concept of using global auroral images as an additional tool when developing convection models could prove to be necessary in order to extend beyond the few isolated measurements taken in situ by satellites

  19. Turbulence in a Global Magnetohydrodynamic Simulation of the Earth's Magnetosphere during Northward and Southward Interplanetary Magnetic Field

    Science.gov (United States)

    El-Alaoui, M.; Richard, R. L.; Ashour-Abdalla, M.; Walker, R. J.; Goldstein, M. L.

    2012-01-01

    We report the results of MHD simulations of Earth's magnetosphere for idealized steady solar wind plasma and interplanetary magnetic field (IMF) conditions. The simulations feature purely northward and southward magnetic fields and were designed to study turbulence in the magnetotail plasma sheet. We found that the power spectral densities (PSDs) for both northward and southward IMF had the characteristics of turbulent flow. In both cases, the PSDs showed the three scale ranges expected from theory: the energy-containing scale, the inertial range, and the dissipative range. The results were generally consistent with in-situ observations and theoretical predictions. While the two cases studied, northward and southward IMF, had some similar characteristics, there were significant differences as well. For southward IMF, localized reconnection was the main energy source for the turbulence. For northward IMF, remnant reconnection contributed to driving the turbulence. Boundary waves may also have contributed. In both cases, the PSD slopes had spatial distributions in the dissipative range that reflected the pattern of resistive dissipation. For southward IMF there was a trend toward steeper slopes in the dissipative range with distance down the tail. For northward IMF there was a marked dusk-dawn asymmetry with steeper slopes on the dusk side of the tail. The inertial scale PSDs had a dusk-dawn symmetry during the northward IMF interval with steeper slopes on the dawn side. This asymmetry was not found in the distribution of inertial range slopes for southward IMF. The inertial range PSD slopes were clustered around values close to the theoretical expectation for both northward and southward IMF. In the dissipative range, however, the slopes were broadly distributed and the median values were significantly different, consistent with a different distribution of resistivity.

  20. Effect of the Global Topology of the Interplanetary Magnetic Field on the Properties of Impulsive Acceleration Processes in Distant Regions of the Earth's Magnetospheric Tail

    International Nuclear Information System (INIS)

    Grigorenko, E.E.; Zelenyi, L.M.; Fedorov, A.O.; Sauvaud, J.-A.

    2005-01-01

    The paper is devoted to a statistical study of high-speed ion beams (beamlets) observed by the Interball-1 and Interball-2 satellites in the boundary region of the plasma sheet of the geomagnetic tail and in the high-latitude auroral regions of the Earth's magnetosphere. Beamlets result from nonlinear acceleration processes occurring in the current sheet in the distant regions of the geomagnetic tail. They propagate toward the Earth along the magnetic field lines and are detected in the boundary region of the plasma sheet and near the high-latitude boundary of the plasma sheet in the auroral region in the form of short (with a duration of 1-2 min) bursts of high-energy (with energies of about several tens of keV) ions. The sizes of the latitudinal zones where the beamlets are localized in the tail and in the auroral region are determined using the epoch superposition method. The relationship between the frequency of beamlet generation in the boundary region of the plasma sheet and the prehistory of the direction of the interplanetary magnetic field (the magnitude of a clock angle) is investigated. It was established that this direction exerts a global effect on the beamlet generation frequency; moreover, it was found that the beamlet generation frequency in the midnight local time sector of the tail and at the flanks depends differently on the direction of the interplanetary magnetic field. In the midnight sector, the beamlets are observed at almost all directions of the interplanetary field, whereas the frequency of their generation at the flanks is maximal only when the interplanetary magnetic field has a large y component

  1. On a role of the Bsub(z) component of interplanetary magnetic field in a force balance in the day time magnetopause

    International Nuclear Information System (INIS)

    Kuznetsova, T.V.

    1980-01-01

    The role of interplanetary magnetic field (IMF) in the force balance in the day time magnetopause is discussed. The effect of the circular DR-current on the balance of pressures in the magnetopause is taken into account in the calculations. It is shown that IMF plays a significant role in the balance of forces in the day time magnetopause. The ratio of magnetic pressure to the thermal pressure of solar wind in subsolar point is k=0.5. The field observed in magnetosphere near the neutral line is lower by the value of transition region field. All the conclusions are obtained for Bsub(z) [ru

  2. The Earth's passage of the April 11, 1997 coronal ejecta: geomagnetic field fluctuations at high and low latitude during northward interplanetary magnetic field conditions

    Directory of Open Access Journals (Sweden)

    S. Lepidi

    1999-10-01

    Full Text Available An analysis of the low frequency geomagnetic field fluctuations at an Antarctic (Terra Nova Bay and a low latitude (L'Aquila, Italy station during the Earth's passage of a coronal ejecta on April 11, 1997 shows that major solar wind pressure variations were followed at both stations by a high fluctuation level. During northward interplanetary magnetic field conditions and when Terra Nova Bay is close to the local geomagnetic noon, coherent fluctuations, at the same frequency (3.6 mHz and with polarization characteristics indicating an antisunward propagation, were observed simultaneously at the two stations. An analysis of simultaneous measurements from geosynchronous satellites shows evidence for pulsations at approximately the same frequencies also in the magnetospheric field. The observed waves might then be interpreted as oscillation modes, triggered by an external stimulation, extending to a major portion of the Earth's magnetosphere. Key words. Magnetospheric physics (MHD waves and instabilities; solar wind-magnetosphere interactions

  3. The control of auroral zone dynamics and thermodynamics by the interplanetary magnetic field dawn-dusk (Y) component

    International Nuclear Information System (INIS)

    Sica, R.J.; Hernandez, G.; Emery, B.A.; Roble, R.G.; Smith, R.W.; Rees, M.H.

    1989-01-01

    Previous theoretical and experimental studies have shown that the dawn-dusk component of the interplanetary magnetic field (IMF B y ) expands the classical symmetric two-cell convection pattern toward dusk (B y negative) or toward dawn (B y positive) in the northern hemisphere, altering the ion drag forcing on the neutral atmosphere. Measurements of the neutral dynamics associated with these convection patterns have been presented primarily at magnetic latitudes greater than 70 degree in the polar cap. In this study, nights with coincident IMF measurements have been selected from the extensive four-year auroral zone thermospheric wind and temperature data set derived from Fabry-Perot spectrometer measurements of the Doppler shifts and widths of the O( 1 D) 15,867 cm -1 (630.0 nm) emission from College, Alaska. Averages from 112 nights of measurements from College were also computed using a selection criterion that depended on the previous 2 hours of IMF measurements (case 2). This procedure yielded averages that differed at times from case 1. The wind and temperature averages for both cases show large variations with B y in the auroral zone. The wind averages for B y negative and positive are compared with National Center for Atmospheric Research thermospheric general circulation model predictions that use a B y -dependent model of ionospheric convection. The results for B y negative and positive are compared with National Center for Atmospheric Research thermospheric general circulation model predictions that use a B y -dependent model of ionospheric convection. The results for B y negative compare favorably with the averages, but there are significant differences between model calculations and averages for the B y positive case

  4. Winds in the high-latitude lower thermosphere: Dependence on the interplanetary magnetic field

    DEFF Research Database (Denmark)

    Richmond, A.D.; Lathuillere, C.; Vennerstrøm, Susanne

    2003-01-01

    -side cyclonic vortex that responds more strongly to B-z variations. The dependence of the wind on the IMF is nonlinear, especially with respect to IMF B-z. For positive B-z the difference winds are largely confined to the polar cap, while for negative B-z the difference winds extend to subauroral latitudes...... of similar to20 hours, a B-y-dependent magnetic-zonal-mean zonal wind generally exists, with maximum wind speeds at 80 magnetic latitude, typically 10 m/s at 105 km, increasing to about 60 m/s at 123 km and 80 m/s at 200 km. In the southern hemisphere the wind is cyclonic when the time-averaged B...

  5. Distribution of convection potential around the polar cap boundary as a function of the interplanetary magnetic field

    International Nuclear Information System (INIS)

    Lu, G.; Reiff, P.H.; Karty, J.L.; Hairston, M.R.; Heelis, R.A.

    1989-01-01

    Plasma flow data from the AE-C, AE-D and DE 2 satellites have been used to systematically study the distribution of the convection potential around the polar cap boundary under a variety of different interplanetary magnetic field (IMF) conditions. For either a garden hose (B x B y x B y >0) orientation of the IMF, the potential distribution is mainly affected by the sign of B y . In the northern hemisphere, the zero potential line (which separates the dusk convection cell from the dawn cell) on the dayside shifts duskward as B y changes from positive to negative. But in the southern hemisphere, a dawnward shift has been found, although the uncertainties are large. The typical range of displacement is about ±1.5 hours MLT. Note that this shift is in the opposite direction from most simple schematic models of ionospheric flow; this reflects the fact that the polar cap boundary is typically more poleward than the flow reversal associated with the region 1 current system, which shifts in the opposite direction. Thus the enhanced flow region typically crosses noon. In most cases a sine wave is an adequate representation of the distribution of potential around the boundary. However, in a few cases the data favors (at the 80% confidence level) a steeper gradient near noon, more indicative of a throat. The potential drop at the duskside boundary is almost greater than at the dawnside boundary. A slight duskward shift of the patterns observed as the IMF changes from garden hose to ortho-garden hose conditions. Analytic equipotential contours, given the potential function as a boundary condition, are constructed for several IMF conditions

  6. Factors controlling degree of correlation between ISEE 1 and ISEE 3 interplanetary magnetic field measurements

    International Nuclear Information System (INIS)

    Crooker, N.U.; Siscoe, G.L.; Russell, C.T.; Smith, E.J.

    1982-01-01

    The degree of correlation between ISEE 1 and ISEE 3 IMF measurements is highly variable. Approximately 200 two-hour periods when the correlation was good and 200 more when the correlation was poor are used to determine the relative control of several factors over the degree of correlation. Both IMF variance and spacecraft separation distance in the plane perpendicular to the earth-sun line exert substantial control. Good correlations are associated with high variance and distances less than 90 R/sub E/. During periods of highest variance, good correlations occur at distances beyond 90 R/sub E/ up to 120 R/sub E/, the maximum range of ISEE 1-ISEE 3 separation. Thus it appears that the scale size of magnetic features is larger when the variance is high. Abrupt changes in the correlation coefficient from poor to good or good to poor in adjacent two-hour intervals appear to be governed by the sense of change of IMF variance: changes in correlation from poor to good correspond to increasing variance and vice versa. The IMF orientation also exerts control over the degree of correlation. During periods of low variance, good correlations are most likely to occur when the distance between ISEE 1 and ISEE 3 perpendicular to the IMF is less than 20 R/sub E/. This scale size expands to approx.50 R/sub E/ during periods of high variance. Solar wind speed shows little control over the degree of correlation in the speed range 300--500 km/s

  7. Post sunset equatorial spread-F at Kwajalein and interplanetary magnetic field

    Science.gov (United States)

    Rastogi, R. G.; Chandra, H.; Janardhan, P.; Reinisch, B. W.; Bisoi, Susanta Kumar

    2017-10-01

    We connect the time sequence of changes in the IMF-Bz to the development of spread-F at an equatorial station Kwajalein on three different nights in November 2004, one during a geomagnetic quiet period and other two during geomagnetic disturbed periods. The chosen days show clear and smooth variations of IMF-Bz without any large fluctuations thereby enabling one to correlate changes in equatorial spread-F with corresponding changes in IMF-Bz. It is shown that a slow and continuous increase in the IMF-Bz over a duration of few hours has a similar effect on the equatorial ionosphere as of a sudden northward turning of the IMF-Bz in causing an electric field through the polar region and then to the equator. We conclude that the Spread-F at equatorial and low latitudes are due to echoes from ionization irregularities that arise due to the plasma instabilities generated by an eastward electric field on the large plasma density gradient in or below the base of the F-layer during any period of the night time along with the gravity driven Rayleigh-Taylor instability.

  8. Interplanetary sources of magnetic storms: A statistical study

    DEFF Research Database (Denmark)

    Vennerstrøm, Susanne

    2001-01-01

    Magnetic storms are mainly caused by the occurrence of intense southward magnetic fields in the interplanetary medium. These fields can be formed directly either by ejection of magnetic structures from the Sun or by stream interaction processes during solar wind propagation. In the present study we...... examine 30 years of satellite measurement of the solar wind during magnetic storms, with the aim of estimating the relative importance of these two processes. We use the solar wind proton temperature relative to the temperature expected from the empirical relation to the solar wind speed T......-p/T-exp, together with the speed gradient, and the interplanetary magnetic field azimuth in the ecliptic, in order to distinguish between the two processes statistically. We find that compression due to stream interaction is at least as important as the direct effect of ejection of intense fields, and probably more...

  9. Interplanetary sources to magnetic storms - A statistical study

    DEFF Research Database (Denmark)

    Vennerstrøm, Susanne

    2001-01-01

    Magnetic storms are mainly caused by the occurrence of intense southward magnetic fields in the interplanetary medium. These fields can be formed directly either by ejection of magnetic structures from the Sun or by stream interaction processes during solar wind propagation. In the present study we...... examine 30 years of satellite measurement of the solar wind during magnetic storms, with the aim of estimating the relative importance of these two processes. We use the solar wind proton temperature relative to the temperature expected from the empirical relation to the solar wind speed Tp/Texp, together...... with the speed gradient, and the interplanetary magnetic field azimuth in the ecliptic, in order to distinguish between the two processes statistically. We find that compression due to stream interaction is at least as important as the direct effect of ejection of intense fields, and probably more so. Only...

  10. Open solar flux estimates from near-Earth measurements of the interplanetary magnetic field: comparison of the first two perihelion passes of the Ulysses spacecraft

    Directory of Open Access Journals (Sweden)

    M. Lockwood

    2004-04-01

    Full Text Available Results from all phases of the orbits of the Ulysses spacecraft have shown that the magnitude of the radial component of the heliospheric field is approximately independent of heliographic latitude. This result allows the use of near-Earth observations to compute the total open flux of the Sun. For example, using satellite observations of the interplanetary magnetic field, the average open solar flux was shown to have risen by 29% between 1963 and 1987 and using the aa geomagnetic index it was found to have doubled during the 20th century. It is therefore important to assess fully the accuracy of the result and to check that it applies to all phases of the solar cycle. The first perihelion pass of the Ulysses spacecraft was close to sunspot minimum, and recent data from the second perihelion pass show that the result also holds at solar maximum. The high level of correlation between the open flux derived from the various methods strongly supports the Ulysses discovery that the radial field component is independent of latitude. We show here that the errors introduced into open solar flux estimates by assuming that the heliospheric field's radial component is independent of latitude are similar for the two passes and are of order 25% for daily values, falling to 5% for averaging timescales of 27 days or greater. We compare here the results of four methods for estimating the open solar flux with results from the first and second perehelion passes by Ulysses. We find that the errors are lowest (1–5% for averages over the entire perehelion passes lasting near 320 days, for near-Earth methods, based on either interplanetary magnetic field observations or the aa geomagnetic activity index. The corresponding errors for the Solanki et al. (2000 model are of the order of 9–15% and for the PFSS method, based on solar magnetograms, are of the order of 13–47%. The model of Solanki et al. is based on the continuity equation of open flux, and uses the

  11. INTERVALS OF RADIAL INTERPLANETARY MAGNETIC FIELDS AT 1 AU, THEIR ASSOCIATION WITH RAREFACTION REGIONS, AND THEIR APPARENT MAGNETIC FOOT POINTS AT THE SUN

    Energy Technology Data Exchange (ETDEWEB)

    Orlove, Steven T.; Smith, Charles W.; Vasquez, Bernard J.; Schwadron, Nathan A. [Physics Department and Space Science Center, Institute for the Study of Earth, Oceans, and Space, University of New Hampshire, Durham, NH (United States); Skoug, Ruth M. [Los Alamos National Laboratory, MS D466, Los Alamos, NM 87545 (United States); Zurbuchen, Thomas H.; Zhao Liang, E-mail: stx33@wildcats.unh.edu, E-mail: Charles.Smith@unh.edu, E-mail: Bernie.Vasquez@unh.edu, E-mail: N.Schwadron@unh.edu, E-mail: rskoug@lanl.gov, E-mail: thomasz@umich.edu, E-mail: lzh@umich.edu [Department of Atmospheric, Oceanic and Space Science, University of Michigan, Ann Arbor, MI (United States)

    2013-09-01

    We have examined 226 intervals of nearly radial interplanetary magnetic field orientations at 1 AU lasting in excess of 6 hr. They are found within rarefaction regions as are the previously reported high-latitude observations. We show that these rarefactions typically do not involve high-speed wind such as that seen by Ulysses at high latitudes during solar minimum. We have examined both the wind speeds and the thermal ion composition before, during and after the rarefaction in an effort to establish the source of the flow that leads to the formation of the rarefaction. We find that the bulk of the measurements, both fast- and slow-wind intervals, possess both wind speeds and thermal ion compositions that suggest they come from typical low-latitude sources that are nominally considered slow-wind sources. In other words, we find relatively little evidence of polar coronal hole sources even when we examine the faster wind ahead of the rarefaction regions. While this is in contrast to high-latitude observations, we argue that this is to be expected of low-latitude observations where polar coronal hole sources are less prevalent. As with the previous high-latitude observations, we contend that the best explanation for these periods of radial magnetic field is interchange reconnection between two sources of different wind speed.

  12. Interplanetary stream magnetism: Kinematic effects

    International Nuclear Information System (INIS)

    Burlaga, L.F.; Barouch, E.

    1976-01-01

    The particle density, and the magnetic field intensity and direction, are calculated for volume elements of the solar wind as a function of the initial magnetic field direction, Phi 0 , and the initial speed gradient, (deltaV/deltaR) 0 . It is assumed that the velocity is constant and radial. These assumptions are approximately valid between approx.0.1 and 1.0 AU for many streams. Time profiles of n, B, and V are calculated for corotating streams, neglecting effects of pressure gradients. The compression and rarefaction of B depend sensitively on Phi 0 . By averaging over a typical stream, it is found that approx.r -2 , whereas does not vary in a simple way, consistent with deep space observations. Changes of field direction may be very large, depending on the initial angle; but when the initial angle at 0.1 Au is such that the base of the field line corotates with the Sun, the spiral angle is the preferred direction at 1 AU. The theory is also applicable to nonstationary flows

  13. Stormtime and Interplanetary Magnetic Field Drivers of Wave and Particle Acceleration Processes in the Magnetosphere-Ionosphere Transition Region

    Science.gov (United States)

    Hatch, Spencer Mark

    The magnetosphere-ionosphere (M-I) transition region is the several thousand-kilometer stretch between the cold, dense and variably resistive region of ionized atmospheric gases beginning tens of kilometers above the terrestrial surface, and the hot, tenuous, and conductive plasmas that interface with the solar wind at higher altitudes. The M-I transition region is therefore the site through which magnetospheric conditions, which are strongly susceptible to solar wind dynamics, are communicated to ionospheric plasmas, and vice versa. We systematically study the influence of geomagnetic storms on energy input, electron precipitation, and ion outflow in the M-I transition region, emphasizing the role of inertial Alfven waves both as a preferred mechanism for dynamic (instead of static) energy transfer and particle acceleration, and as a low-altitude manifestation of high-altitude interaction between the solar wind and the magnetosphere, as observed by the FAST satellite. Via superposed epoch analysis and high-latitude distributions derived as a function of storm phase, we show that storm main and recovery phase correspond to strong modulations of measures of Alfvenic activity in the vicinity of the cusp as well as premidnight. We demonstrate that storm main and recovery phases occur during 30% of the four-year period studied, but together account for more than 65% of global Alfvenic energy deposition and electron precipitation, and more than 70% of the coincident ion outflow. We compare observed interplanetary magnetic field (IMF) control of inertial Alfven wave activity with Lyon-Fedder-Mobarry global MHD simulations predicting that southward IMF conditions lead to generation of Alfvenic power in the magnetotail, and that duskward IMF conditions lead to enhanced prenoon Alfvenic power in the Northern Hemisphere. Observed and predicted prenoon Alfvenic power enhancements contrast with direct-entry precipitation, which is instead enhanced postnoon. This situation

  14. Global observations of electromagnetic and particle energy flux for an event during northern winter with southward interplanetary magnetic field

    Directory of Open Access Journals (Sweden)

    H. Korth

    2008-06-01

    Full Text Available The response of the polar ionosphere–thermosphere (I-T system to electromagnetic (EM energy input is fundamentally different to that from particle precipitation. To understand the I-T response to polar energy input one must know the intensities and spatial distributions of both EM and precipitation energy deposition. Moreover, since individual events typically display behavior different from statistical models, it is important to observe the global system state for specific events. We present an analysis of an event in Northern Hemisphere winter for sustained southward interplanetary magnetic field (IMF, 10 January 2002, 10:00–12:00 UT, for which excellent observations are available from the constellation of Iridium satellites, the SuperDARN radar network, and the Far-Ultraviolet (FUV instrument on the IMAGE satellite. Using data from these assets we determine the EM and particle precipitation energy fluxes to the Northern Hemisphere poleward of 60° MLAT and examine their spatial distributions and intensities. The accuracy of the global estimates are assessed quantitatively using comparisons with in-situ observations by DMSP along two orbit planes. While the location of EM power input evaluated from Iridium and SuperDARN data is in good agreement with DMSP, the magnitude estimated from DMSP observations is approximately four times larger. Corrected for this underestimate, the total EM power input to the Northern Hemisphere is 188 GW. Comparison of IMAGE FUV-derived distributions of the particle energy flux with DMSP plasma data indicates that the IMAGE FUV results similarly locate the precipitation accurately while underestimating the precipitation input somewhat. The total particle input is estimated to be 20 GW, nearly a factor of ten lower than the EM input. We therefore expect the thermosphere response to be determined primarily by the EM input even under winter conditions, and accurate assessment of the EM energy input is therefore key

  15. Magnetohydrodynamic structure of an interplanetary flux according to measurements of plasma and magnetic field on the ''Prognoz-7'' satellite (VI STIP interval, April 25, 1979)

    International Nuclear Information System (INIS)

    Zastenker, G.N.; Omel'chenko, A.N.; Eroshenko, E.G.; Ivanov, K.G.; Styazhkin, B.A.

    1982-01-01

    MHD structure of an interplanetary flow on 25.04.1979 is studied using plasma and magnetic field measurements at the Prognoz 7 near-earth cosmic satellite. The main attention was paid to the interaction region between rapid flow (presumably from a low-latitudinal coronal hole) and slow solar wind. It is discovered that specific large break (flow boundary) divides the interaction region into a head shock wave with hot dense (β > 1) turbulent magnetoplasma and a back shock wave with a strong regular magnetic field and cold (β << 1) plasma. Ouantity of motion gained with slow wind in the head wave exceeds 4 times quantity of motion lost with rapid flow in a back wave. An additional quantity of motion to the acceleration region is suggested to go near the Sun at the expense of pulse of electrodynamic forces

  16. Energetic particle, solar wind plasma and magnetic field measurements on board Prognoz-6 during the large scale interplanetary disturbance of Jan. 3-4, 1978

    International Nuclear Information System (INIS)

    Kurt, V.G.; Stolpovskij, V.G.; Gombosi, T.I.; Kecskemety, K.; Somogyi, J.; Gringauz, K.I.; Kotova, G.A.; Verigin, M.I.; Styazhkin, V.A.

    1980-05-01

    The interplanetary shock, generated during the solar flare of Jan. 1, 1978 reached the Earth's orbit on January 3, 21sup(h) UT. Aboard Prognoz-6 satellite the fluxes and spectra of energetic electron (E>30 keV) and proton (E>500 keV) fluxes and energy spectra of solar wind ions up to 4.5 keV and magnetic field were measured, with a time resolution approximately 10 sec. Time variation of these characteristics are given including preshock and postshock frequency spectra of magnetic field fluctuations. Effective acceleration of protons in the oblique shock was observed. The mean free path of protons with E<6 MeV was determined by using the time interval of anisotropic particle flux observations as lambda approximately 0.2 a.u. (author)

  17. Anomalous aspects of magnetosheath flow and of the shape and oscillations of the magnetopause during an interval of strongly northward interplanetary magnetic field

    Science.gov (United States)

    Chen, Sheng-Hsien; Kivelson, Margaret G.; Gosling, Jack T.; Walker, Raymond T.; Lazarus, Allan J.

    1992-01-01

    On 15 Feb. 1978, the orientation of the interplanetary magnetic field (IMF) remained steadily northward for more than 12 hours. The ISEE 1 and 2 spacecraft were located near apogee on the dawn side flank of the magnetotail. IMP 8 was almost symmetrically located in the magnetosheath on the dusk flank and IMP 7 was upstream in the solar wind. Using plasma and magnetic field data, we show the following: (1) the magnetosheath flow speed on the flanks of the magnetotail steadily exceeded the solar wind speed by 20 percent; (2) surface waves with approximately a 5-min period and very non-sinusoidal waveform were persistently present on the dawn magnetopause and waves of similar period were present in the dusk magnetosheath; and (3) the magnetotail ceased to flare at an antisunward distance of 15 R(sub E). We propose that the acceleration of the magnetosheath flow is achieved by magnetic tension in the draped field configuration for northward IMF and that the reduction of tail flaring is consistent with a decreased amount of open magnetic flux and a larger standoff distance of the subsolar magnetopause. Results of a three-dimensional magnetohydrodynamic simulation support this phenomenological model.

  18. Wave properties near the subsolar magnetopause - Pc 3-4 energy coupling for northward interplanetary magnetic field

    Science.gov (United States)

    Song, P.; Russell, C. T.; Strangeway, R. J.; Wygant, J. R.; Cattell, C. A.; Fitzenreiter, R. J.; Anderson, R. R.

    1993-01-01

    Strong slow mode waves in the Pc 3-4 frequency range are found in the magnetosheath close to the magnetopause. We have studied these waves at one of the ISEE subsolar magnetopause crossings using the magnetic field, electric field, and plasma measurements. We use the pressure balance at the magnetopause to calibrate the Fast Plasma Experiment data versus the magnetometer data. When we perform such a calibration and renormalization, we find that the slow mode structures are not in pressure balance and small scale fluctuations in the total pressure still remain in the Pc 3-4 range. Energy in the total pressure fluctuations can be transmitted through the magnetopause by boundary motions. The Poynting flux calculated from the electric and magnetic field measurements suggests that a net Poynting flux is transmitted into the magnetopause. The two independent measurements show a similar energy transmission coefficient. The transmitted energy flux is about 18 percent of the magnetic energy flux of the waves in the magnetosheath. Part of this transmitted energy is lost in the sheath transition layer before it enters the closed field line region. The waves reaching the boundary layer decay rapidly. Little wave power is transmitted into the magnetosphere.

  19. An MHD simulation of the effects of the interplanetary magnetic field By component on the interaction of the solar wind with the earth's magnetosphere during southward interplanetary magnetic field

    Science.gov (United States)

    Ogino, T.; Walker, R. J.; Ashour-Abdalla, M.; Dawson, J. M.

    1986-01-01

    The interaction between the solar wind and the earth's magnetosphere has been studied by using a time-dependent three-dimensional MHD model in which the IMF pointed in several directions between dawnward and southward. When the IMF is dawnward, the dayside cusp and the tail lobes shift toward the morningside in the northern magnetosphere. The plasma sheet rotates toward the north on the dawnside of the tail and toward the south on the duskside. For an increasing southward IMF component, the plasma sheet becomes thinner and subsequently wavy because of patchy or localized tail reconnection. At the same time, the tail field-aligned currents have a filamentary layered structure. When projected onto the northern polar cap, the filamentary field-aligned currents are located in the same area as the region 1 currents, with a pattern similar to that associated with auroral surges. Magnetic reconnection also occurs on the dayside magnetopause for southward IMF.

  20. The Earth's magnetosphere is 165 R(sub E) long: Self-consistent currents, convection, magnetospheric structure, and processes for northward interplanetary magnetic field

    Science.gov (United States)

    Fedder, J. A.; Lyon, J. G.

    1995-01-01

    The subject of this paper is a self-consistent, magnetohydrodynamic numerical realization for the Earth's magnetosphere which is in a quasi-steady dynamic equilibrium for a due northward interplanetary magnetic field (IMF). Although a few hours of steady northward IMF are required for this asymptotic state to be set up, it should still be of considerable theoretical interest because it constitutes a 'ground state' for the solar wind-magnetosphere interaction. Moreover, particular features of this ground state magnetosphere should be observable even under less extreme solar wind conditions. Certain characteristics of this magnetosphere, namely, NBZ Birkeland currents, four-cell ionospheric convection, a relatively weak cross-polar potential, and a prominent flow boundary layer, are widely expected. Other characteristics, such as no open tail lobes, no Earth-connected magnetic flux beyond 155 R(sub E) downstream, magnetic merging in a closed topology at the cusps, and a 'tadpole' shaped magnetospheric boundary, might not be expected. In this paper, we will present the evidence for this unusual but interesting magnetospheric equilibrium. We will also discuss our present understanding of this singular state.

  1. Propagation of Solar Energetic Particles in Three-dimensional Interplanetary Magnetic Fields: Radial Dependence of Peak Intensities

    Science.gov (United States)

    He, H.-Q.; Zhou, G.; Wan, W.

    2017-06-01

    A functional form {I}\\max (R)={{kR}}-α , where R is the radial distance of a spacecraft, was usually used to model the radial dependence of peak intensities {I}\\max (R) of solar energetic particles (SEPs). In this work, the five-dimensional Fokker-Planck transport equation incorporating perpendicular diffusion is numerically solved to investigate the radial dependence of SEP peak intensities. We consider two different scenarios for the distribution of a spacecraft fleet: (1) along the radial direction line and (2) along the Parker magnetic field line. We find that the index α in the above expression varies in a wide range, primarily depending on the properties (e.g., location and coverage) of SEP sources and on the longitudinal and latitudinal separations between the sources and the magnetic foot points of the observers. Particularly, whether the magnetic foot point of the observer is located inside or outside the SEP source is a crucial factor determining the values of index α. A two-phase phenomenon is found in the radial dependence of peak intensities. The “position” of the break point (transition point/critical point) is determined by the magnetic connection status of the observers. This finding suggests that a very careful examination of the magnetic connection between the SEP source and each spacecraft should be taken in the observational studies. We obtain a lower limit of {R}-1.7+/- 0.1 for empirically modeling the radial dependence of SEP peak intensities. Our findings in this work can be used to explain the majority of the previous multispacecraft survey results, and especially to reconcile the different or conflicting empirical values of the index α in the literature.

  2. Excitation of transient lobe cell convection and auroral arc at the cusp poleward boundary during a transition of the interplanetary magnetic field from south to north

    Directory of Open Access Journals (Sweden)

    P. E. Sandholt

    2001-05-01

    Full Text Available We document the activation of transient polar arcs emanating from the cusp within a 15 min long intermediate phase during the transition from a standard two-cell convection pattern, representative of a strongly southward interplanetary magnetic field (IMF, to a "reverse" two-cell pattern, representative of strongly northward IMF conditions. During the 2–3 min lifetime of the arc, its base in the cusp, appearing as a bright spot, moved eastward toward noon by ~ 300 km. As the arc moved, it left in its "wake" enhanced cusp precipitation. The polar arc is a tracer of the activation of a lobe convection cell with clockwise vorticity, intruding into the previously established large-scale distorted two-cell pattern, due to an episode of localized lobe reconnection. The lobe cell gives rise to strong flow shear (converging electric field and an associated sheet of outflowing field-aligned current, which is manifested by the polar arc. The enhanced cusp precipitation represents, in our view, the ionospheric footprint of the lobe reconnection process.Key words. Magnetospheric physics (auroral phenomena; magnetopause, cusp, and boundary layers; plasma convection

  3. A theoretical and empirical study of the response of the high latitude thermosphere to the sense of the 'Y' component of the interplanetary magnetic field

    International Nuclear Information System (INIS)

    Rees, D.; Fuller-Rowell, T.J.; Gordon, R.

    1986-01-01

    The strength and direction of the Interplanetary Magnetic Field (IMF) controls the transfer of solar wind momentum and energy to the high latitude thermosphere in a direct fashion. The sense of ''Y'' component of the IMF (BY) creates a significant asymmetry of the magnetospheric convection pattern as mapped onto the high latitude thermosphere and ionosphere. The resulting response of the polar thermospheric winds during periods when BY is either positive or negative is quite distinct, with pronounced changes in the relative strength of thermospheric winds in the dusk-dawn parts of the polar cap and in the dawn part of the auroral oval. In a study of four periods when there was a clear signature of BY, observed by the ISEE-3 satellite, with observations of polar winds and electric fields from the Dynamics Explorer-2 satellite and with wind observations by a ground-based Fabry-Perot interferometer located in Kiruna, Northern Sweden, it is possible to explain features of the high latitude thermospheric circulation using three dimensional global models including BY dependent, asymmetric, polar convection fields. Anomalously zonal wind velocities are often observed, for BY positive and when BY is negative. These are matched by the observation of strong anti-sunward polar-cap wind jets from the DE-2 satellite, on the dusk side with BY negative, and on the dawn side with BY positive. (author)

  4. The configuration of the auroral distribution for interplanetary magnetic field Bz northward. 1. IMF Bx and By dependencies as observed by the Viking satellite

    International Nuclear Information System (INIS)

    Eliphinstone, R.D.; Jankowska, K.; Murphree, J.S.; Cogger, L.L.

    1990-01-01

    Viking images obtained throughout 1986 have been utilized in combination with IMP 8 satellite measurements of the interplanetary magnetic fields (IMF) to determine typical northern hemisphere auroral distributions for a variety of IMF B z positive conditions. Varying B y has an effect which is consistent with expected results. That is, B y positive implies high-latitude auroral arcs in the dusk sector while negative B y gives dawn sector polar arcs. A new result gives significant importance to the B x component of the IMF. B x toward the Sun (B y = 0) gives polar arcs on both dawn and dusk with comparatively weak UV emissions. With B x away from the Sun (B y = 0) a single Sun-aligned morning sector polar arc dominates the auroral distribution. Azimuthal angle changes to the IMF of only 45 degree seem to affect the global auroral distribution with time scales of less than 2-3 hours. Poleward boundaries of the aurora were found to have a strong dependence on the IMF azimuthal angle which varied according to the magnetic local time investigated

  5. Response of the ionospheric convection pattern to a rotation of the interplanetary magnetic field on January 14, 1988

    International Nuclear Information System (INIS)

    Cumnock, J.A.; Heelis, R.A.; Hairston, M.R.

    1992-01-01

    Ionospheric convection signatures observed over the polar regions are provided by the DMSP F8 satellite. The authors consider five passes over the southern summer hemisphere during a time when the z component of the interplantary magnetic field was stable and positive and the y component changed slowly from positive to negative. Large-scale regions of sunward flow are observed at very high latitudes consistent with a strong z component. When B y and B z are positive, but B y is greater than B z , strong evidence exists for dayside merging in a manner similar to that expected when B z is negative. This signature is diminished as B y decreases and becomes smaller than B z resulting in a four-cell convection pattern displaced toward the sunward side of the dawn-dusk meridian. In this case the sign of B y affects the relative sizes of the two highest-latitude cells. In the southern hemisphere the duskside high-latitude cell is dominant for B y positive and the dawnside high-latitude cell is dominant for B y negative. The relative importance of possible electric field sources in the low-latitude boundary layer, the dayside cusp, and the lobe all need to be considered to adequately explain the observed evolution of the convection pattern

  6. Analysis of Wind Vorticity and Divergence in the High-latitude Lower Thermosphere: Dependence on the Interplanetary Magnetic Field (IMF

    Directory of Open Access Journals (Sweden)

    Young-Sil Kwak

    2008-12-01

    Full Text Available To better understand the physical processes that control the high-latitude lower thermospheric dynamics, we analyze the divergence and vorticity of the high-latitude neutral wind field in the lower thermosphere during the southern summertime for different IMF conditions. For this study the National Center for Atmospheric Research Thermosphere-Ionosphere Electrodynamics General Circulation Model (NCAR-TIEG CM is used. The analysis of the large-scale vorticity and divergence provides basic understanding flow configurations to help elucidate the momentum sources that ultimately determine the total wind field in the lower polar thermosphere and provides insight into the relative strengths of the different sources of momentum responsible for driving winds. The mean neutral wind pattern in the high-latitude lower thermosphere is dominated by rotational flow, imparted primarily through the ion drag force, rather than by divergent flow, imparted primarily through Joule and solar heating. The difference vorticity, obtained by subtracting values with zero IMF from those with non-zero IMF, in the high-latitude lower thermosphere is much larger than the difference divergence for all IMF conditions, indicating that a larger response of the thermospheric wind system to enhancement in the momentum input generating the rotational motion with elevated IMF than the corresponding energy input generating the divergent motion. the difference vorticity in the high-latitude lower thermosphere depends on the direction of the IMF. The difference vorticity for negative and positive B_y shows positive and negative, respectively, at higher magnetic latitudes than -70°. For negative B_z, the difference vorticities have positive in the dusk sector and negative in the dawn sector. The difference vorticities for positive B_z have opposite sign. Negative IMF B_z has a stronger effect on the vorticity than does positive B_z.

  7. Source Regions of the Interplanetary Magnetic Field and Variability in Heavy-Ion Elemental Composition in Gradual Solar Energetic Particle Events

    Science.gov (United States)

    Ko, Yuan-Kuen; Tylka, Allan J.; Ng, Chee K.; Wang, Yi-Ming; Dietrich, William F.

    2013-01-01

    Gradual solar energetic particle (SEP) events are those in which ions are accelerated to their observed energies by interactions with a shock driven by a fast coronal mass-ejection (CME). Previous studies have shown that much of the observed event-to-event variability can be understood in terms of shock speed and evolution in the shock-normal angle. But an equally important factor, particularly for the elemental composition, is the origin of the suprathermal seed particles upon which the shock acts. To tackle this issue, we (1) use observed solar-wind speed, magnetograms, and the PFSS model to map the Sun-L1 interplanetary magnetic field (IMF) line back to its source region on the Sun at the time of the SEP observations; and (2) then look for correlation between SEP composition (as measured by Wind and ACE at approx. 2-30 MeV/nucleon) and characteristics of the identified IMF-source regions. The study is based on 24 SEP events, identified as a statistically-significant increase in approx. 20 MeV protons and occurring in 1998 and 2003-2006, when the rate of newly-emergent solar magnetic flux and CMEs was lower than in solar-maximum years and the field-line tracing is therefore more likely to be successful. We find that the gradual SEP Fe/O is correlated with the field strength at the IMF-source, with the largest enhancements occurring when the footpoint field is strong, due to the nearby presence of an active region. In these cases, other elemental ratios show a strong charge-to-mass (q/M) ordering, at least on average, similar to that found in impulsive events. These results lead us to suggest that magnetic reconnection in footpoint regions near active regions bias the heavy-ion composition of suprathermal seed ions by processes qualitatively similar to those that produce larger heavy-ion enhancements in impulsive SEP events. To address potential technical concerns about our analysis, we also discuss efforts to exclude impulsive SEP events from our event sample.

  8. Interplanetary spheromacs

    International Nuclear Information System (INIS)

    Ivanov, K.G.; Kharshiladze, A.F.

    1985-01-01

    The solution of Helmholtz's equation is used for the representation of force-free magnetic fields as series of spheroidal wave functions. It is assumed that these functions describe painly interplanetary hydromagnetic clouds in the shape of flattered and extended ellipsoids which are formed at the interaction of flare e ections with corona and interplanetary plasma

  9. Observations of interplanetary energetic ion enhancements near magnetic sector boundaries

    International Nuclear Information System (INIS)

    Briggs, P.R.; Armstrong, T.P.

    1984-01-01

    We have examined all energetic medium nuclei (carbon, nitrogen, and oxygen) flux increases observed all the satellites IMP 7 and IMP 8 at 1 AU during Bartels rotations 1906-1974. After removing flare-related increases, the remaining 14 ''events'' were compared to interplanetary magnetic field and solar wind parameters. We have discovered a class of flux enhancements in which the ion increases occur close to the onset of magnetic sector boundary crossings. We interpret this observation as a facilitated access to 1 AU of energetic ions from the corona or chromopshere via the magnetic sector structure. It appears that this access is more significant for medium than for lighter nuclei, ''suggesting a possible charge- or rigidity-dependent transport mechanism

  10. Solar flares associated coronal mass ejection accompanied with DH type II radio burst in relation with interplanetary magnetic field, geomagnetic storms and cosmic ray intensity

    Science.gov (United States)

    Chandra, Harish; Bhatt, Beena

    2018-04-01

    In this paper, we have selected 114 flare-CME events accompanied with Deca-hectometric (DH) type II radio burst chosen from 1996 to 2008 (i.e., solar cycle 23). Statistical analyses are performed to examine the relationship of flare-CME events accompanied with DH type II radio burst with Interplanetary Magnetic field (IMF), Geomagnetic storms (GSs) and Cosmic Ray Intensity (CRI). The collected sample events are divided into two groups. In the first group, we considered 43 events which lie under the CME span and the second group consists of 71 events which are outside the CME span. Our analysis indicates that flare-CME accompanied with DH type II radio burst is inconsistent with CSHKP flare-CME model. We apply the Chree analysis by the superposed epoch method to both set of data to find the geo-effectiveness. We observed different fluctuations in IMF for arising and decay phase of solar cycle in both the cases. Maximum decrease in Dst during arising and decay phase of solar cycle is different for both the cases. It is noted that when flare lie outside the CME span CRI shows comparatively more variation than the flare lie under the CME span. Furthermore, we found that flare lying under the CME span is more geo effective than the flare outside of CME span. We noticed that the time leg between IMF Peak value and GSs, IMF and CRI is on average one day for both the cases. Also, the time leg between CRI and GSs is on average 0 to 1 day for both the cases. In case flare lie under the CME span we observed high correlation (0.64) between CRI and Dst whereas when flare lie outside the CME span a weak correlation (0.47) exists. Thus, flare position with respect to CME span play a key role for geo-effectiveness of CME.

  11. An evaluation of the statistical significance of the association between northward turnings of the interplanetary magnetic field and substorm expansion onsets

    Science.gov (United States)

    Hsu, Tung-Shin; McPherron, R. L.

    2002-11-01

    An outstanding problem in magnetospheric physics is deciding whether substorms are always triggered by external changes in the interplanetary magnetic field (IMF) or solar wind plasma, or whether they sometimes occur spontaneously. Over the past decade, arguments have been made on both sides of this issue. In fact, there is considerable evidence that some substorms are triggered. However, equally persuasive examples of substorms with no obvious trigger have been found. Because of conflicting views on this subject, further work is required to determine whether there is a physical relation between IMF triggers and substorm onset. In the work reported here a list of substorm onsets was created using two independent substorm signatures: sudden changes in the slope of the AL index and the start of a Pi 2 pulsation burst. Possible IMF triggers were determined from ISEE-2 observations. With the ISEE spacecraft near local noon immediately upstream of the bow shock, there can be little question about propagation delay to the magnetopause or whether a particular IMF feature hits the subsolar magnetopause. Thus it eliminates the objections that the calculated arrival time is subject to a large error or that the solar wind monitor missed a potential trigger incident at the subsolar point. Using a less familiar technique, statistics of point process, we find that the time delay between substorm onsets and the propagated arrival time of IMF triggers are clustered around zero. We estimate for independent processes that the probability of this clustering by chance alone is about 10-11. If we take into account the requirement that the IMF must have been southward prior to the onset, then the probability of clustering is higher, ˜10-5, but still extremely unlikely. Thus it is not possible to ascribe the apparent relation between IMF northward turnings and substorm onset to coincidence.

  12. INTERPLANETARY MAGNETIC FLUX DEPLETION DURING PROTRACTED SOLAR MINIMA

    International Nuclear Information System (INIS)

    Connick, David E.; Smith, Charles W.; Schwadron, Nathan A.

    2011-01-01

    We examine near-Earth solar wind observations as assembled within the Omni data set over the past 15 years that constitute the latest solar cycle. We show that the interplanetary magnetic field continues to be depleted at low latitudes throughout the protracted solar minimum reaching levels below previously predicted minima. We obtain a rate of flux removal resulting in magnetic field reduction by 0.5 nT yr -1 at 1 AU when averaged over the years 2005-2009 that reduces to 0.3 nT yr -1 for 2007-2009. We show that the flux removal operates on field lines that follow the nominal Parker spiral orientation predicted for open field lines and are largely unassociated with recent ejecta. We argue that the field line reduction can only be accomplished by ongoing reconnection of nominally open field lines or very old closed field lines and we contend that these two interpretations are observationally equivalent and indistinguishable.

  13. An Alternative Method for Identifying Interplanetary Magnetic Cloud Regions

    Energy Technology Data Exchange (ETDEWEB)

    Ojeda-Gonzalez, A.; Prestes, A.; Klausner, V. [Laboratory of Physics and Astronomy, IP and D/Universidade do Vale do Paraíba—UNIVAP, São José dos Campos, SP (Brazil); Mendes, O. [Division of Space Geophysics, National Institute for Space Research, São José dos Campos, SP (Brazil); Calzadilla, A. [Department of Space Geophysics, Institute of Geophysics and Astronomy, Havana (Cuba); Domingues, M. O., E-mail: ojeda.gonzalez.a@gmail.com [Associate Laboratory of Applied Computing and Mathematics, National Institute for Space Research, São José dos Campos, SP (Brazil)

    2017-03-10

    Spatio-temporal entropy (STE) analysis is used as an alternative mathematical tool to identify possible magnetic cloud (MC) candidates. We analyze Interplanetary Magnetic Field (IMF) data using a time interval of only 10 days. We select a convenient data interval of 2500 records moving forward by 200 record steps until the end of the time series. For every data segment, the STE is calculated at each step. During an MC event, the STE reaches values close to zero. This extremely low value of STE is due to MC structure features. However, not all of the magnetic components in MCs have STE values close to zero at the same time. For this reason, we create a standardization index (the so-called Interplanetary Entropy, IE, index). This index is a worthwhile effort to develop new tools to help diagnose ICME structures. The IE was calculated using a time window of one year (1999), and it has a success rate of 70% over other identifiers of MCs. The unsuccessful cases (30%) are caused by small and weak MCs. The results show that the IE methodology identified 9 of 13 MCs, and emitted nine false alarm cases. In 1999, a total of 788 windows of 2500 values existed, meaning that the percentage of false alarms was 1.14%, which can be considered a good result. In addition, four time windows, each of 10 days, are studied, where the IE method was effective in finding MC candidates. As a novel result, two new MCs are identified in these time windows.

  14. Dependence of the Interplanetary Magnetic Field on Heliocentric Distance between 0.3 and 1.7 AU from MESSENGER, ACE and MAVEN data

    Science.gov (United States)

    Hanneson, C.; Johnson, C.; Al Asad, M.

    2017-12-01

    Magnetometer data from the MErcury Surface, Space ENvironment, GEochemistry and Ranging (MESSENGER), Advanced Composition Explorer (ACE) and Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft were used to characterize the variation of the interplanetary magnetic field (IMF) with heliocentric distance from 0.3 to 1.7 AU. MESSENGER and ACE data form a set of simultaneous observations that spans eight years, from March 2007 until April 2015, with ACE observations continuing until the present. MAVEN data have been collected since November 2014. Furthermore, for the period 2008-2015, MESSENGER and ACE observations were taken over the same range of heliocentric distances: 0.31-0.47 AU and 0.94-1.00 AU respectively. The IMF varies with the solar sunspot cycle, and so data taken simultaneously at different heliocentric distances allow solar-cycle effects to be decoupled from the radial evolution of the IMF. The data were averaged temporally by taking 1-hour means, and median values were then computed in 0.01-AU bins. For the time interval spanned by all observations, the median value of the magnitude of the IMF decreases steadily from 30.1 nT at 0.3 AU to 4.3 nT at 1.0 AU and 2.5 nT at 1.6 AU. The magnitude of the IMF was found to decay with heliocentric distance according to an inverse power law with an exponent equal to the adiabatic index for an ideal monatomic gas, 5/3, within 95% confidence limits. The magnitude of the radial component decays with distance as an inverse square law within 95% confidence limits. We also consider temporal variations of the heliocentric-dependence of the IMF over the current solar cycle by computing power law fits to the simultaneous MESSENGER and ACE observations using a moving window. Our study complements the recent study of Gruesbeck et al. (2017) that used Juno data to consider the variation in IMF properties over the heliocentric distance range 1 to 6 AU.

  15. The solar and interplanetary causes of the recent minimum in geomagnetic activity (MGA23: a combination of midlatitude small coronal holes, low IMF BZ variances, low solar wind speeds and low solar magnetic fields

    Directory of Open Access Journals (Sweden)

    B. T. Tsurutani

    2011-05-01

    Full Text Available Minima in geomagnetic activity (MGA at Earth at the ends of SC23 and SC22 have been identified. The two MGAs (called MGA23 and MGA22, respectively were present in 2009 and 1997, delayed from the sunspot number minima in 2008 and 1996 by ~1/2–1 years. Part of the solar and interplanetary causes of the MGAs were exceptionally low solar (and thus low interplanetary magnetic fields. Another important factor in MGA23 was the disappearance of equatorial and low latitude coronal holes and the appearance of midlatitude coronal holes. The location of the holes relative to the ecliptic plane led to low solar wind speeds and low IMF (Bz variances (σBz2 and normalized variances (σBz2/B02 at Earth, with concomitant reduced solar wind-magnetospheric energy coupling. One result was the lowest ap indices in the history of ap recording. The results presented here are used to comment on the possible solar and interplanetary causes of the low geomagnetic activity that occurred during the Maunder Minimum.

  16. The interaction of a very large interplanetary magnetic cloud with the magnetosphere and with cosmic rays

    International Nuclear Information System (INIS)

    Lepping, R.P.; Burlaga, L.F.; Ogilvie, K.W.; Tsurutani, B.T.; Lazarus, A.J.; Evans, D.S.; Klein, L.W.

    1991-01-01

    A large interplanetary magnetic cloud has been observed in the mid-December 1982 data from ISEE 3. It is estimated to have a heliocentric radial extent of approx-gt 0.4 AU, making it one of the largest magnetic clouds yet observed at 1 AU. The magnetic field measured throughout the main portion of the cloud was fairly tightly confined to a plane as it changed direction by 174 degree while varying only moderately in magnitude. Throughout nearly the entire duration of the cloud's passage, IMP 8 was located in the Earth's dawn magnetosheath providing observations of this cloud's interaction with the bow shock and magnetopause; the cloud is shown to maintain its solar wind characteristics during the interaction. Near the end of the cloud passage, at 0806 UT on December 17, ISEE 3 (and IMP 8 at nearly the same time) observed an oblique fast forward interplanetary shock closely coincident in time with a geomagnetic storm sudden commencement. The shock, moving much faster than the cloud (radial speeds of 700 and 390 km/s, respectively, on the average), was in the process of overtaking the cloud. The index Dst decreased monotonically by ∼ 130 nT during the 2-day cloud passage by the Earth and was well correlated with the B z component of the interplanetary magnetic field. There was no significant decrease in the cosmic ray intensity recorded by ground-based neutron monitors at this time of rather strong, smoothly changing fields. However, a Forbush decrease did occur immediately after the interplanetary shock, during a period of significant field turbulence. Thus a large, smooth, interplanetary helical magnetic field configuration engulfing the Earth does not necessarily deflect cosmic rays sufficiently to cause a Forbush decrease, but there is a suggestion that such a decrease may be caused by particle scattering by turbulent magnetic fields

  17. Linear Response of Field-Aligned Currents to the Interplanetary Electric Field

    DEFF Research Database (Denmark)

    Weimer, D. R.; R. Edwards, T.; Olsen, Nils

    2017-01-01

    Many studies that have shown that the ionospheric, polar cap electric potentials (PCEP) exhibit a “saturation” behavior in response to the level of the driving by the solar wind. As the magnitude of the interplanetary magnetic field (IMF) and electric field (IEF) increase, the PCEP response...... of the field-aligned currents (FAC) with the solar wind/magnetosphere/ionosphere system has a role. As the FAC are more difficult to measure, their behavior in response to the level of the IEF has not been investigated as thoroughly. In order to resolve the question of whether or not the FAC also exhibit...... saturation, we have processed the magnetic field measurements from the Ørsted, CHAMP, and Swarm missions, spanning more than a decade. As the amount of current in each region needs to be known, a new technique is used to separate and sum the current by region, widely known as R0, R1, and R2. These totals...

  18. Interplanetary magnetic field Bx component influence on horizontal and field‐aligned currents in the ionosphere

    DEFF Research Database (Denmark)

    Laundal, K. M.; Reistad, J. P.; Finlay, C. C.

    2018-01-01

    a detailed investigation of three different sets of magnetic field measurements, from the CHAMP and Swarm low‐Earth‐Orbit satellites, from the AMPERE products derived from the Iridium satellite constellation, and from the SuperMAG ground magnetometer network, each analyzed using different techniques, to test...

  19. Variations of ionospheric plasma concentration in the region of the main ionospheric through during the magnetic storm on 18-19.12, 1978 in relation to interplanetary magnetic field variations

    International Nuclear Information System (INIS)

    Gdalevich, G.L.; Eliseev, A.Yu.; Kolomijtsev, O.P.; Afonin, V.V.; Ozerov, V.D.; Soboleva, T.N.

    1986-01-01

    The variations of ion concentration in the region of the main ionospheric trough at the height approximately 500 km during the storm on 18-19, 12, 1978 are considered by data from ''Kosmos-900'' satellite. Three These changes in ion density are compared with variations of interplanetary medium parameters, in particular with Ey=-VBz, with the component of the interplanetary electric field. The comparison results are discussed. Exact correlation of ionospheric disturbance development with variations of interplanetary medium parameters is observed. This effect is expressed in the evening section both in the high and mean latitudes and it is obv ously caused by magnetosphere rearrangement in the region of the minimum pole trough, and on the equatorial wall - by convection field penetration to the mean latitude. The movement of the equatorial boundary of diffusion precipitations, which is much responsible for formation of the polar trough wall, corresponds to the boundary movement of corotating and convective plasma or to the last closed equipotentiality. But some delay of the precipitation boundary due to the responsiveness of precipitation processes is observed on the recovery phase

  20. Jovian electron bursts: Correlation with the interplanetary field direction and hydromagnetic waves

    International Nuclear Information System (INIS)

    Smith, E.J.; Tsurutani, B.T.; Chenette, D.L.; Conlon, T.F.; Simpson, J.A.

    1976-01-01

    The bursts of relativistic electrons detected on Pioneer 10 upstream from Jupiter and within 400r/subj/ of the planet have been found to be correlated with the interplanetary magnetic field. In the three examples upon which this study is based, during the month prior to the Pioneer 10 encounter, electrons with energies between 3 and 6 MeV escaping from Jupiter's magnetosphere were observed only when the interplanetary magnetic field was along the Jupiter-spacecraft line. In addition, large-amplitude interplanetary waves with characteristic periods of 10 min were observed and found to be well correlated with intervals during which the field was along the Jupiter-spacecraft line. Abrupt changes in the field away from the preferred direction caused equally abrupt terminations of the waves with an accompanying reduction in the electron flux. These results are consistent with propagation of the electrons from Jupiter to Pioneer along, rather than across, the magnetic field lines. The direction of the interplanetary magnetic field is apparently not affected by the electron bursts or by other particles from Jupiter. The average Parker spiral direction is clear with no enhancement in the Jupiter-spacecraft direction. Two alternative possibilities are considered for the origin of the waves. If they were generated near Jupiter, they would have to propagate to the spacecraft in the whistler mode. The expected attenuation of these waves over distances of several hundred r/subj/ an their long travel times make this explanation unattractive. Alternatively, hydromagnetic wave generation by Jovian charged particles, presumably the relativistic electrons themselves, as they travel upstream, appears to be an attractive explanation

  1. Interplanetary magnetic field rotations followed from L1 to the ground: the response of the Earth's magnetosphere as seen by multi-spacecraft and ground-based observations

    Directory of Open Access Journals (Sweden)

    M. Volwerk

    2011-09-01

    Full Text Available A study of the interaction of solar wind magnetic field rotations with the Earth's magnetosphere is performed. For this event there is, for the first time, a full coverage over the dayside magnetosphere with multiple (multispacecraft missions from dawn to dusk, combined with ground magnetometers, radar and an auroral camera, this gives a unique coverage of the response of the Earth's magnetosphere. After a long period of southward IMF Bz and high dynamic pressure of the solar wind, the Earth's magnetosphere is eroded and compressed and reacts quickly to the turning of the magnetic field. We use data from the solar wind monitors ACE and Wind and from magnetospheric missions Cluster, THEMIS, DoubleStar and Geotail to investigate the behaviour of the magnetic rotations as they move through the bow shock and magnetosheath. The response of the magnetosphere is investigated through ground magnetometers and auroral keograms. It is found that the solar wind magnetic field drapes over the magnetopause, while still co-moving with the plasma flow at the flanks. The magnetopause reacts quickly to IMF Bz changes, setting up field aligned currents, poleward moving aurorae and strong ionospheric convection. Timing of the structures between the solar wind, magnetosheath and the ground shows that the advection time of the structures, using the solar wind velocity, correlates well with the timing differences between the spacecraft. The reaction time of the magnetopause and the ionospheric current systems to changes in the magnetosheath Bz seem to be almost immediate, allowing for the advection of the structure measured by the spacecraft closest to the magnetopause.

  2. Counterstreaming electrons in small interplanetary magnetic flux ropes

    Science.gov (United States)

    Feng, H. Q.; Zhao, G. Q.; Wang, J. M.

    2015-12-01

    Small interplanetary magnetic flux ropes (SIMFRs) are commonly observed by spacecraft at 1 AU, and their origin still remains disputed. We investigated the counterstreaming suprathermal electron (CSE) signatures of 106 SIMFRs measured by Wind during 1995-2005. We found that 79 (75%) of the 106 flux ropes contain CSEs, and the percentages of counterstreaming vary from 8% to 98%, with a mean value of 51%. CSEs are often observed in magnetic clouds (MCs), and this indicates these MCs are still attached to the Sun at both ends. CSEs are also related to heliospheric current sheets (HCSs) and the Earth's bow shock. We divided the SIMFRs into two categories: The first category is far from HCSs, and the second category is in the vicinity of HCSs. The first category has 57 SIMFRs, and only 7 of 57 ropes have no CSEs. This ratio is similar to that of MCs. The second category has 49 SIMFRs; however, 20 of the 49 events have no CSEs. This ratio is larger than that of MCs. These two categories have different origins. One category originates from the solar corona, and most ropes are still connected to the Sun at both ends. The other category is formed near HCSs in the interplanetary space.

  3. Change in the F region structure of a polar ionosphere at the change of the Y component sighn of the interplanetary magnetic field. Svalgaard-Mansurov effect in the ionosphere

    International Nuclear Information System (INIS)

    Gal'perin, Yu.I.; Zosimova, A.G.; Larina, T.N.; Mozhaev, A.M.; Osipov, N.K.; Ponomarev, Yu.N.

    1980-01-01

    Model calculations of the planetary picture of the polar ionosphere characteristics taking into account modern models of magnetospheric convection are carried out. The results of direct measurements of the lateral component of the convection rate in the day polar cusp region obtained by the ''Kosmos-184'' satellite in 1967 indicative of rotation of the zonal convection component direction with tha change of the Bsub(y) component sign of the interplanetary magnetic field (IMF). It is shown that the change of the IMF Bsub(y) sign and the following change of the convection picture in the polar cap must cause a quick (10 3 s) change of the planetary picture of the polar ionosphere characteristics in the F region peak and higher, i.e. ''the Svalgard-Mansurov ionospheric effect''. The amplitude of the variations and their character are defined by the relation of the solar and auroral ionization, and, therefore, they strongly depend on the universal time, season and auroral activity, that hampers comparison of the calculations with the experiment. The experimental data obtained from satellites and indicative of the reality of the described ionospheric Bsub(y) effect are presented. Thus, the data of many years on the ionospheric measurements from the Earth and satellites parallel with the magnetic measurements can be used to specify parameters describing the magnetospheric convection picture [ru

  4. Numerical Simulation on a Possible Formation Mechanism of Interplanetary Magnetic Cloud Boundaries

    Science.gov (United States)

    Fan, Quan-Lin; Wei, Feng-Si; Feng, Xue-Shang

    2003-08-01

    The formation mechanism of the interplanetary magnetic cloud (MC) boundaries is numerically investigated by simulating the interactions between an MC of some initial momentum and a local interplanetary current sheet. The compressible 2.5D MHD equations are solved. Results show that the magnetic reconnection process is a possible formation mechanism when an MC interacts with a surrounding current sheet. A number of interesting features are found. For instance, the front boundary of the MCs is a magnetic reconnection boundary that could be caused by a driven reconnection ahead of the cloud, and the tail boundary might be caused by the driving of the entrained flow as a result of the Bernoulli principle. Analysis of the magnetic field and plasma data demonstrates that at these two boundaries appear large value of the plasma parameter β, clear increase of plasma temperature and density, distinct decrease of magnetic magnitude, and a transition of magnetic field direction of about 180 degrees. The outcome of the present simulation agrees qualitatively with the observational results on MC boundary inferred from IMP-8, etc. The project supported by National Natural Science Foundation of China under Grant Nos. 40104006, 49925412, and 49990450

  5. USING COORDINATED OBSERVATIONS IN POLARIZED WHITE LIGHT AND FARADAY ROTATION TO PROBE THE SPATIAL POSITION AND MAGNETIC FIELD OF AN INTERPLANETARY SHEATH

    Energy Technology Data Exchange (ETDEWEB)

    Xiong, Ming; Feng, Xueshang; Liu, Ying D. [State Key Laboratory of Space Weather, Center for Space Science and Applied Research, Chinese Academy of Sciences, Beijing (China); Davies, Jackie A.; Harrison, Richard A. [Rutherford-Appleton Laboratory (RAL) Space, Harwell Oxford (United Kingdom); Owens, Mathew J.; Davis, Chris J., E-mail: mxiong@spacweather.ac.cn [Reading University, Reading (United Kingdom)

    2013-11-01

    Coronal mass ejections (CMEs) can be continuously tracked through a large portion of the inner heliosphere by direct imaging in visible and radio wavebands. White light (WL) signatures of solar wind transients, such as CMEs, result from Thomson scattering of sunlight by free electrons and therefore depend on both viewing geometry and electron density. The Faraday rotation (FR) of radio waves from extragalactic pulsars and quasars, which arises due to the presence of such solar wind features, depends on the line-of-sight magnetic field component B{sub ∥} and the electron density. To understand coordinated WL and FR observations of CMEs, we perform forward magnetohydrodynamic modeling of an Earth-directed shock and synthesize the signatures that would be remotely sensed at a number of widely distributed vantage points in the inner heliosphere. Removal of the background solar wind contribution reveals the shock-associated enhancements in WL and FR. While the efficiency of Thomson scattering depends on scattering angle, WL radiance I decreases with heliocentric distance r roughly according to the expression I∝r {sup –3}. The sheath region downstream of the Earth-directed shock is well viewed from the L4 and L5 Lagrangian points, demonstrating the benefits of these points in terms of space weather forecasting. The spatial position of the main scattering site r{sub sheath} and the mass of plasma at that position M{sub sheath} can be inferred from the polarization of the shock-associated enhancement in WL radiance. From the FR measurements, the local B{sub ∥sheath} at r{sub sheath} can then be estimated. Simultaneous observations in polarized WL and FR can not only be used to detect CMEs, but also to diagnose their plasma and magnetic field properties.

  6. The effects of low solar activity upon the cosmic radiation and the interplanetary magnetic field over the past 10,000 years, and implications for the future. (Invited)

    Science.gov (United States)

    McCracken, K. G.; McDonald, F. B.; Beer, J.; Abreu, J.; Steinhilber, F.

    2009-12-01

    The paleo-cosmic ray records based on the radionuclides 10Be and 14 C show that the Sun has experienced twenty two extended periods of low activity (similar to, or longer than the Maunder Minimum) in the past 10,000 years, and many more periods of reduced activity for 2 or more solar cycles similar to the period 1880-1910. The 10,000 yr record shows that solar activity has exhibited three persistent periodicities that modulate the amplitude of the Hale (11/22 year) cycle. They are the Gleissberg (~85 yr); the de Vries (~208 yr); and the Hallstatt (~2200 yr) periodicities. It is possible that the Sun is entering a somewhat delayed Gleissberg repetition of the 1880-1910 period of reduced activity or a de Vries repetition of the Dalton Minimum of 1800-1820; or a combination of both. The historic record shows that the cosmic ray intensity at sunspot minimum increases substantially during periods of reduced solar activity- during the Dalton minimum it was twice the present-day sunspot minimum intensity at 2GeV/nucleon ; and 10 times greater at 100 MeV/nucleon. The Hale cycle of solar activity continued throughout the Spoerer (1420-1540) and Maunder Minima, and it appears possible that the local interstellar cosmic ray spectrum was occasionally incident on Earth. Using the cosmic ray transport equation to invert the paleo-cosmic ray record shows that the magnetic field was Dalton Minimum.

  7. Evidence linking coronal mass ejections with interplanetary magnetic clouds

    International Nuclear Information System (INIS)

    Wilson, R.M.; Hildner, E.

    1983-12-01

    Using proxy data for the occurrence of those mass ejections from the solar corona which are directed earthward, we investigate the association between the post-1970 interplanetary magnetic clouds of Klein and Burlaga and coronal mass ejections. The evidence linking magnetic clouds following shocks with coronal mass ejections is striking. Six of nine clouds observed at Earth were preceded an appropriate time earlier by meter-wave type II radio bursts indicative of coronal shock waves and coronal mass ejections occurring near central meridian. During the selected periods when no clouds were detected near Earth, the only type II bursts reported were associated with solar activity near the limbs. Where the proxy solar data to be sought are not so clearly suggested, that is, for clouds preceding interaction regions and clouds within cold magnetic enhancements, the evidence linking the clouds and coronal mass ejections is not as clear proxy data usually suggest many candidate mass-ejection events for each cloud. Overall, the data are consistent with and support the hypothesis suggested by Klein and Burlaga that magnetic clouds observed with spacecraft at 1 AU are manifestations of solar coronal mass ejection transients

  8. On the twists of interplanetary magnetic flux ropes observed at 1 AU

    Science.gov (United States)

    Wang, Yuming; Zhuang, Bin; Hu, Qiang; Liu, Rui; Shen, Chenglong; Chi, Yutian

    2016-10-01

    Magnetic flux ropes (MFRs) are one kind of fundamental structures in the solar/space physics and involved in various eruption phenomena. Twist, characterizing how the magnetic field lines wind around a main axis, is an intrinsic property of MFRs, closely related to the magnetic free energy and stableness. Although the effect of the twist on the behavior of MFRs had been widely studied in observations, theory, modeling, and numerical simulations, it is still unclear how much amount of twist is carried by MFRs in the solar atmosphere and in heliosphere and what role the twist played in the eruptions of MFRs. Contrasting to the solar MFRs, there are lots of in situ measurements of magnetic clouds (MCs), the large-scale MFRs in interplanetary space, providing some important information of the twist of MFRs. Thus, starting from MCs, we investigate the twist of interplanetary MFRs with the aid of a velocity-modified uniform-twist force-free flux rope model. It is found that most of MCs can be roughly fitted by the model and nearly half of them can be fitted fairly well though the derived twist is probably overestimated by a factor of 2.5. By applying the model to 115 MCs observed at 1 AU, we find that (1) the twist angles of interplanetary MFRs generally follow a trend of about 0.6l/R radians, where l/R is the aspect ratio of a MFR, with a cutoff at about 12π radians AU-1, (2) most of them are significantly larger than 2.5π radians but well bounded by 2l/R radians, (3) strongly twisted magnetic field lines probably limit the expansion and size of MFRs, and (4) the magnetic field lines in the legs wind more tightly than those in the leading part of MFRs. These results not only advance our understanding of the properties and behavior of interplanetary MFRs but also shed light on the formation and eruption of MFRs in the solar atmosphere. A discussion about the twist and stableness of solar MFRs are therefore given.

  9. Magnetic Field

    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...

  10. THREE-DIMENSIONAL FEATURES OF THE OUTER HELIOSPHERE DUE TO COUPLING BETWEEN THE INTERSTELLAR AND INTERPLANETARY MAGNETIC FIELDS. IV. SOLAR CYCLE MODEL BASED ON ULYSSES OBSERVATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Pogorelov, N. V.; Zank, G. P. [Department of Physics, University of Alabama in Huntsville, Huntsville, AL 35899 (United States); Suess, S. T. [National Space Science and Technology Center, Huntsville, AL 35805 (United States); Borovikov, S. N. [Center for Space Plasma and Aeronomic Research, University of Alabama in Huntsville, 320 Sparkman Dr., Huntsville, AL 35805 (United States); Ebert, R. W.; McComas, D. J., E-mail: np0002@uah.edu [Southwest Research Institute, San Antonio, TX 78227 (United States)

    2013-07-20

    The solar cycle has a profound influence on the solar wind (SW) interaction with the local interstellar medium (LISM) on more than one timescales. Also, there are substantial differences in individual solar cycle lengths and SW behavior within them. The presence of a slow SW belt, with a variable latitudinal extent changing within each solar cycle from rather small angles to 90 Degree-Sign , separated from the fast wind that originates at coronal holes substantially affects plasma in the inner heliosheath (IHS)-the SW region between the termination shock (TS) and the heliopause (HP). The solar cycle may be the reason why the complicated flow structure is observed in the IHS by Voyager 1. In this paper, we show that a substantial decrease in the SW ram pressure observed by Ulysses between the TS crossings by Voyager 1 and 2 contributes significantly to the difference in the heliocentric distances at which these crossings occurred. The Ulysses spacecraft is the source of valuable information about the three-dimensional and time-dependent properties of the SW. Its unique fast latitudinal scans of the SW regions make it possible to create a solar cycle model based on the spacecraft in situ measurements. On the basis of our analysis of the Ulysses data over the entire life of the mission, we generated time-dependent boundary conditions at 10 AU from the Sun and applied our MHD-neutral model to perform a numerical simulation of the SW-LISM interaction. We analyzed the global variations in the interaction pattern, the excursions of the TS and the HP, and the details of the plasma and magnetic field distributions in the IHS. Numerical results are compared with Voyager data as functions of time in the spacecraft frame. We discuss solar cycle effects which may be reasons for the recent decrease in the TS particles (ions accelerated to anomalous cosmic-ray energies) flux observed by Voyager 1.

  11. THREE-DIMENSIONAL FEATURES OF THE OUTER HELIOSPHERE DUE TO COUPLING BETWEEN THE INTERSTELLAR AND INTERPLANETARY MAGNETIC FIELDS. IV. SOLAR CYCLE MODEL BASED ON ULYSSES OBSERVATIONS

    International Nuclear Information System (INIS)

    Pogorelov, N. V.; Zank, G. P.; Suess, S. T.; Borovikov, S. N.; Ebert, R. W.; McComas, D. J.

    2013-01-01

    The solar cycle has a profound influence on the solar wind (SW) interaction with the local interstellar medium (LISM) on more than one timescales. Also, there are substantial differences in individual solar cycle lengths and SW behavior within them. The presence of a slow SW belt, with a variable latitudinal extent changing within each solar cycle from rather small angles to 90°, separated from the fast wind that originates at coronal holes substantially affects plasma in the inner heliosheath (IHS)—the SW region between the termination shock (TS) and the heliopause (HP). The solar cycle may be the reason why the complicated flow structure is observed in the IHS by Voyager 1. In this paper, we show that a substantial decrease in the SW ram pressure observed by Ulysses between the TS crossings by Voyager 1 and 2 contributes significantly to the difference in the heliocentric distances at which these crossings occurred. The Ulysses spacecraft is the source of valuable information about the three-dimensional and time-dependent properties of the SW. Its unique fast latitudinal scans of the SW regions make it possible to create a solar cycle model based on the spacecraft in situ measurements. On the basis of our analysis of the Ulysses data over the entire life of the mission, we generated time-dependent boundary conditions at 10 AU from the Sun and applied our MHD-neutral model to perform a numerical simulation of the SW-LISM interaction. We analyzed the global variations in the interaction pattern, the excursions of the TS and the HP, and the details of the plasma and magnetic field distributions in the IHS. Numerical results are compared with Voyager data as functions of time in the spacecraft frame. We discuss solar cycle effects which may be reasons for the recent decrease in the TS particles (ions accelerated to anomalous cosmic-ray energies) flux observed by Voyager 1.

  12. Interplanetary Magnetic Flux Ropes as Agents Connecting Solar Eruptions and Geomagnetic Activities

    Science.gov (United States)

    Marubashi, K.; Cho, K.-S.; Ishibashi, H.

    2017-12-01

    We investigate the solar wind structure for 11 cases that were selected for the campaign study promoted by the International Study of Earth-affecting Solar Transients (ISEST) MiniMax24 Working Group 4. We can identify clear flux rope signatures in nine cases. The geometries of the nine interplanetary magnetic flux ropes (IFRs) are examined with a model-fitting analysis with cylindrical and toroidal force-free flux rope models. For seven cases in which magnetic fields in the solar source regions were observed, we compare the IFR geometries with magnetic structures in their solar source regions. As a result, we can confirm the coincidence between the IFR orientation and the orientation of the magnetic polarity inversion line (PIL) for six cases, as well as the so-called helicity rule as regards the handedness of the magnetic chirality of the IFR, depending on which hemisphere of the Sun the IFR originated from, the northern or southern hemisphere; namely, the IFR has right-handed (left-handed) magnetic chirality when it is formed in the southern (northern) hemisphere of the Sun. The relationship between the orientation of IFRs and PILs can be taken as evidence that the flux rope structure created in the corona is in most cases carried through interplanetary space with its orientation maintained. In order to predict magnetic field variations on Earth from observations of solar eruptions, further studies are needed about the propagation of IFRs because magnetic fields observed at Earth significantly change depending on which part of the IFR hits the Earth.

  13. Effects of the interplanetary conditions on the magnetic activity observed in the southern auroral zone

    International Nuclear Information System (INIS)

    Cazeneuve, H.A.; Tabocchini, H.

    1981-01-01

    The relationship between the interplanetary conditions and the magnetic activity recorded at Belgrano is examined. H-component magnetograms, rheometer records and the concurrent interplanetary data are used. It is found that the geomagnetic activity is generated by the combined effect of a variety of interplanetary conditions. The data distinctly show that each physical entity of the interplanetary medium has a specific and precise role in the development of active periods. The reversal of the IMF polarity appears to be the critical step in the generation of geomagnetic activity. (author)

  14. GENESIS OF INTERPLANETARY INTERMITTENT TURBULENCE: A CASE STUDY OF ROPE–ROPE MAGNETIC RECONNECTION

    Energy Technology Data Exchange (ETDEWEB)

    Chian, Abraham C.-L.; Loew, Murray H. [Department of Biomedical Engineering, George Washington University, Washington, DC 20052 (United States); Feng, Heng Q. [Institute of Space Physics, Luoyang Normal University, Luoyang (China); Hu, Qiang [Department of Space Science and CSPAR, University of Alabama in Huntsville, Huntsville, AL 35805 (United States); Miranda, Rodrigo A. [UnB-Gama Campus, and Plasma Physics Laboratory, Institute of Physics, University of Brasília (UnB), Brasília DF 70910-900 (Brazil); Muñoz, Pablo R. [Department of Physics and Astronomy, University of La Serena, Av. Juan Cisternas 1200, La Serena (Chile); Sibeck, David G. [NASA Goddard Space Flight Center, Greenbelt, MD 20771 (United States); Wu, De J., E-mail: abraham.chian@gmail.com [Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing 210008 (China)

    2016-12-01

    In a recent paper, the relation between current sheet, magnetic reconnection, and turbulence at the leading edge of an interplanetary coronal mass ejection was studied. We report here the observation of magnetic reconnection at the interface region of two interplanetary magnetic flux ropes. The front and rear boundary layers of three interplanetary magnetic flux ropes are identified, and the structures of magnetic flux ropes are reconstructed by the Grad–Shafranov method. A quantitative analysis of the reconnection condition and the degree of intermittency reveals that rope–rope magnetic reconnection is the most likely site for genesis of interplanetary intermittency turbulence in this event. The dynamic pressure pulse resulting from this reconnection triggers the onset of a geomagnetic storm.

  15. Solar sources of interplanetary southward B/sub z/ events responsible for major magnetic storms (1978--1979)

    International Nuclear Information System (INIS)

    Tang, F.; Tsurutani, B.T.; Gonzalez, W.D.; Akasofu, S.I.; Smith, E.J.

    1989-01-01

    Tsurutani et al. [1988] analyzed the 10 intense interplanetary southward B/sub z/ events that led to major magnetic storms (Dst 3.0) are associated with prominence eruptions. For three of the five southward B/sub z/ events in which the driver gases are the causes of the intense southward field leading to magnetic storms, the photospheric fields of the solar sources have no dominant southward component, indicating the driver gas fields do not always result from a simple outward convection of solar magnetic fields. Finally we compare the solar events and their resulting interplanetary shocks and find that the standard solar parameters do not correlate with the strengths of the resulting shocks at 1 AU. The implications are discussed. copyright American Geophysical Union 1989

  16. Solar-diurnal variations of Cosmic rays (CR), connected with the passage of the Earth through the Neutral Layer of the Interplanetary Magnetic Fields (IMF) and the earthquake problem

    International Nuclear Information System (INIS)

    Khazaradze, N; Vanishvili, G; Bakradze, T; Bazerashvili, E; Kordzadze, L; Elizbarashvili, M

    2013-01-01

    Key explanation on effect of Fundamental Law of Momentum Conservation is given on the basis of Cosmo-Physical processes, which can be connected with all kinds of recently known geo-effective phenomena. Many works have been devoted to searches of extraterrestrial sources of generation of earthquake initiation preconditions. There is a direct indication on the fact in these works that all kinds of geo-active fluxes of plasma, which goes ahead of strong geomagnetic storms, concomitant to the earthquakes, may be served as favourable conditions for earthquake appearance. If in one group of works, the increase of seismic activity during geo-active solar flare is reported, then in the other group of works, there is the direct indication on the fact, that it is necessary to study the mechanism of generation of electro-magnetic emanation in the seismically active regions of Earth. Certain strong destructive earthquakes are putting in touch by some authors with the outburst of cosmic rays in distant regions of Universe during stellar explosion of supernovae. It's impossible to avoid our attention from announcement of 100% increase of hard component of cosmic radiation above Yerevan 30 minutes ahead of 1988 Spitak Earthquake. And finally, the data on article, in which is shown that about 75% of earthquakes with magnitude M≥6 takes place during traverse of neutral layer of Interplanetary Magnetic Field by the Earth, in the presence of good correlation with 11-years cycle of Solar Activity. Above mentioned geo-effective phenomena, with an increasable amount, can be reviewed in frame of the Law of Momentum Conservation, if we take into account the peculiarities of its development for a given specific cases.

  17. Criteria of interplanetary parameters causing intense magnetic storms (Dsub(st) < -100 nT)

    International Nuclear Information System (INIS)

    Gonzalez, W.D.; Tsurutani, B.T.

    1987-01-01

    Ten intense magnetic storms (Dsub(st) 5 mV m -1 , that last for intervals > 3 h. Because we find a one-to-one relationship between these interplanetary events and intense storms, we suggest that these criteria can, in the future, be used as predictors of intense storms by an interplanetary monitor such as ISEE-3. The close proximity of the Bsub(z) events and magnetic storms to the onset of high speed streams or density enhancement events is in sharp contrast to interplanetary Alfven waves and HILDCAA events previously reported and thus the two interplanetary features and corresponding geomagnetic responses can be thought of as being complementary in nature. An examination of opposite polarity (northward) Bsub(z) events with the same criteria shows that their occurrence is similar both in number as well as in their relationship to interplanetary disturbances, and that they lead to low levels of geomagnetic activity. (author)

  18. Structures of interplanetary magnetic flux ropes and comparison with their solar sources

    Energy Technology Data Exchange (ETDEWEB)

    Hu, Qiang [Department of Space Science/CSPAR, University of Alabama in Huntsville, Huntsville, AL 35805 (United States); Qiu, Jiong [Department of Physics, Montana State University, Bozeman, MT 59717-3840 (United States); Dasgupta, B.; Khare, A.; Webb, G. M., E-mail: qh0001@uah.edu, E-mail: qiu@physics.montana.edu [Center for Space Plasma and Aeronomic Research (CSPAR), University of Alabama in Huntsville, Huntsville, AL 35805 (United States)

    2014-09-20

    Whether a magnetic flux rope is pre-existing or formed in situ in the Sun's atmosphere, there is little doubt that magnetic reconnection is essential to release the flux rope during its ejection. During this process, the question remains: how does magnetic reconnection change the flux-rope structure? In this work, we continue with the original study of Qiu et al. by using a larger sample of flare-coronal mass ejection (CME)-interplanetary CME (ICME) events to compare properties of ICME/magnetic cloud (MC) flux ropes measured at 1 AU and properties of associated solar progenitors including flares, filaments, and CMEs. In particular, the magnetic field-line twist distribution within interplanetary magnetic flux ropes is systematically derived and examined. Our analysis shows that, similar to what was found before, for most of these events, the amount of twisted flux per AU in MCs is comparable with the total reconnection flux on the Sun, and the sign of the MC helicity is consistent with the sign of the helicity of the solar source region judged from the geometry of post-flare loops. Remarkably, we find that about half of the 18 magnetic flux ropes, most of them associated with erupting filaments, have a nearly uniform and relatively low twist distribution from the axis to the edge, and the majority of the other flux ropes exhibit very high twist near the axis, up to ≳ 5 turns per AU, which decreases toward the edge. The flux ropes are therefore not linearly force-free. We also conduct detailed case studies showing the contrast of two events with distinct twist distribution in MCs as well as different flare and dimming characteristics in solar source regions, and discuss how reconnection geometry reflected in flare morphology may be related to the structure of the flux rope formed on the Sun.

  19. Behaviour of the interplanetary and magnetospheric electric fields during very intense storms

    International Nuclear Information System (INIS)

    Wu, Lei; Gendrin, R.; Higel, B.

    1982-01-01

    A study is made of the role which a positive (northward) component of the interplanetary magnetic field (IMF) Bsub(z) may play in triggering large magnetic storms. The study is made over a 15 year period (1964-1978) by selecting storms with Ksub(p) >= 7 0 and which are preceded by a Sudden Commencement (Ssc). The correlation between the geomagnetic index Ksub(m) and the three-hourly averaged Bsub(z) is established both on a statistical basis and on a case-by-case study. Storms associated with Bsub(z) > 0 are found to be less intense than those associated with Bsub(z) < 0, but major storms can be also triggered by solar wind events associated with a northward IMF. The relation-ship between interplanetary electric field Esub(γ) and Ksub(m) is also given. By using this relation together with the one between Esub(M) and Ksub(m) which has been established in previous studies (where Esub(M) is the magnetospheric convection electric field), it is possible to study the transfer efficiency of the magnetosphere. It is found that the transfer coefficient ΔEsub(M)/ΔEsub(γ) is much smaller for intense storms than for moderate ones, the latter having been studied in a previous paper (Wu Lei et al., 1981)

  20. A Study on the Ionosphere and Thermosphere Interaction Based on NCAR-TIEGCM: Dependence of the Interplanetary Magnetic Field (IMF on the Momentum Forcing in the High-Latitude Lower Thermosphere

    Directory of Open Access Journals (Sweden)

    Young-Sil Kwak

    2005-06-01

    Full Text Available To understand the physical processes that control the high-latitude lower thermospheric dynamics, we quantify the forces that are mainly responsible for maintaining the high-latitude lower thermospheric wind system with the aid of the National Center for Atmospheric Research Thermosphere-Ionosphere Electrodynamics General Circulation Model (NCAR-TIEGCM. Momentum forcing is statistically analyzed in magnetic coordinates, and its behavior with respect to the magnitude and orientation of the interplanetary magnetic field (IMF is further examined. By subtracting the values with zero IMF from those with non-zero IMF, we obtained the difference winds and forces in the high-latitude lower thermosphere( 0.8 |bar{B}_z| or negative(B_y 0.3125 |bar{B}_y| or negative(B_z 125 km the primary forces that determine the variations of the neutral winds are the pressure gradient, Coriolis and rotational Pedersen ion drag forces; however, at various locations and times significant contributions can be made by the horizontal advection force. On the other hand, at lower altitudes(108-125 km the pressure gradient, Coriolis and non-rotational Hall ion drag forces determine the variations of the neutral winds. At lower altitudes(<108 km it tends to generate a geostrophic motion with the balance between the pressure gradient and Coriolis forces. The northward component of IMF bar{B}_y-dependent average momentum forces act more significantly on the neutral motion except for the ion drag. At lower altitudes(108-125 km for negative IMF-bar{B}_y condition the ion drag force tends to generate a warm clockwise circulation with downward vertical motion associated with the adiabatic compress heating in the polar cap region. For positive IMF-bar{B}_y condition it tends to generate a cold anticlockwise circulation with upward vertical motion associated with the adiabatic expansion cooling in the polar cap region. For negative IMF-bar{B}_z the ion drag force tends to generate a

  1. The interaction of a magnetic cloud with the Earth - Ionospheric convection in the Northern and Southern Hemispheres for a wide range of quasi-steady interplanetary magnetic field conditions

    Science.gov (United States)

    Freeman, M. P.; Farrugia, C. J.; Burlaga, L. F.; Hairston, M. R.; Greenspan, M. E.; Ruohoniemi, J. M.; Lepping, R. P.

    1993-01-01

    Observations are presented of the ionospheric convection in cross sections of the polar cap and auroral zone as part of the study of the interaction of the Earth's magnetosphere with the magnetic cloud of January 13-15, 1988. For strongly northward IMF, the convection in the Southern Hemisphere is characterized by a two-cell convection pattern comfined to high latitudes with sunward flow over the pole. The strength of the flows is comparable to that later seen under southward IMF. Superimposed on this convection pattern there are clear dawn-dusk asymmetries associated with a one-cell convection component whose sense depends on the polarity of the magnetic cloud's large east-west magnetic field component. When the cloud's magnetic field turns southward, the convection is characterized by a two-cell pattern extending to lower latitude with antisunward flow over the pole. There is no evident interhemispheric difference in the structure and strength of the convection. Superimposed dawn-dusk asymmetries in the flow patterns are observed which are only in part attributable to the east-west component of the magnetic field.

  2. Solar and interplanetary disturbances

    CERN Document Server

    Alurkar, S K

    1997-01-01

    Over the last three decades, a spate of solar wind observations have been made with sophisticated ground-based and space-borne instruments. Two highly successful space missions of the Skylab and the twin spacecraft Helios 1 and 2 have amassed an invaluable wealth of information on the large scale structure of the inner heliosphere, the solar and interplanetary magnetic field, coronal holes, interplanetary dust, solar windflows, etc.Solar and interplanetary propagating phenomena have been extensively studied during the last two decades. Very recently, a new simple model based on results from a

  3. Variation of Magnetic Field (By , Bz) Polarity and Statistical Analysis of Solar Wind Parameters during the Magnetic Storm Period

    OpenAIRE

    Ga-Hee Moon

    2011-01-01

    It is generally believed that the occurrence of a magnetic storm depends upon the solar wind conditions, particularly the southward interplanetary magnetic field (IMF) component. To understand the relationship between solar wind parameters and magnetic storms, variations in magnetic field polarity and solar wind parameters during magnetic storms are examined. A total of 156 storms during the period of 1997~2003 are used. According to the interplanetary driver, magnetic storms are ...

  4. Magnetic Field Calculator

    Data.gov (United States)

    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,...

  5. About the Las Acacias, Trelew and Vassouras Magnetic Observatories Monitoring the South Atlantic Magnetic Anomaly Region Response to an Interplanetary Coronal Mass Ejection

    Science.gov (United States)

    Gianibelli, J. C.; Quaglino, N. M.

    2007-05-01

    The South Atlantic Magnetic Anomaly (SAMA) Region presents evolutive characteristics very important as were observed by a variety of satelital sensors. Important Magnetic Observatories with digital record monitor the effects of the Sun-Earth interaction, such as San Juan de Puerto Rico (SJG), Kourou (KOU), Vassouras (VSS), Las Acacias (LAS), Trelew (TRW), Vernadsky (AIA), Hermanus (HER) and Huancayo (HUA). In the present work we present the features registered during the geomagnetic storm in January 21, 2005, produced by a geoeffective Coronal Mass Ejection (CME) whose Interplanetary Coronal Mass Ejection (ICME) was detected by the instrumental onboard the Advanced Composition Explorer (ACE) Sonde. We analize how the Magnetic Total Intensity records at VSS, TRW and LAS Observatories shows the effect of the entering particles to ionospherical dephts producing a field enhancement following the first Interplanetary Shock (IP) arrival of the ICME. This process manifest in the digital record as an increment over the magnetospheric Ring Current field effect and superinpossed effects over the Antarctic Auroral Electrojet. The analysis and comparison of the records demonstrate that the Ring Current effects are important in SJG and KOU but not in VSS, LAS and TRW observatories, concluding that SAMA region shows a enhancement of the ionospherical currents oposed to those generated at magnetospheric heighs. Moreover in TRW, 5 hours after the ICME shock arrival, shows the effect of the Antarctic Auroral Electrojet counteracting to fields generated by the Ring Current.

  6. A scheme for finding the front boundary of an interplanetary magnetic cloud

    Directory of Open Access Journals (Sweden)

    R. P. Lepping

    2009-03-01

    Full Text Available We develop a scheme for finding a "refined" front boundary-time (tB* of an interplanetary magnetic cloud (MC based on criteria that depend on the possible existence of any one or more of four specific solar wind features. The features that the program looks for, within ±2 h (i.e., the initial uncertainty interval of a preliminarily estimated front boundary time, are: (1 a sufficiently large directional discontinuity in the interplanetary magnetic field (IMF, (2 a significant proton plasma beta (βP drop, (3 a significant proton temperature drop, and (4 a marked increase in the IMF's intensity. Also we examine to see if the "MC-side" of the boundary has a MC-like value of βP. The scheme was tested using 5, 10, 15, and 20 min averages of the relevant physical quantities from WIND data, in order to find the optimum average to use. The 5 min average, initially based on analysis of N=26 carefully chosen MCs, turned out to be marginally the best average to use for our purposes. Other criteria, besides the four described above, such as the existence of a magnetic hole, plasma speed change, and/or field fluctuation level change, were examined and dismissed as not reliable enough, or usually associated with physical quantities that change too slowly around the boundary to be useful. The preliminarily estimated front boundary time, tB, and its initial ±2-h uncertainty interval are determined by either an automatic MC identification scheme or by visual inspection. The boundary-scheme was developed specifically for aiding in forecasting the strength and timing of a geomagnetic storm due to the passage of a MC in real-time, but can be used in post ground-data collection for imposing consistency when choosing front boundaries of MCs. This scheme has been extensively tested, first using 81 bona fide MCs, collected over about 8.6 years of WIND data (at 1 AU, and also by using

  7. A scheme for finding the front boundary of an interplanetary magnetic cloud

    Directory of Open Access Journals (Sweden)

    R. P. Lepping

    2009-03-01

    Full Text Available We develop a scheme for finding a "refined" front boundary-time (tB* of an interplanetary magnetic cloud (MC based on criteria that depend on the possible existence of any one or more of four specific solar wind features. The features that the program looks for, within ±2 h (i.e., the initial uncertainty interval of a preliminarily estimated front boundary time, are: (1 a sufficiently large directional discontinuity in the interplanetary magnetic field (IMF, (2 a significant proton plasma beta (βP drop, (3 a significant proton temperature drop, and (4 a marked increase in the IMF's intensity. Also we examine to see if the "MC-side" of the boundary has a MC-like value of βP. The scheme was tested using 5, 10, 15, and 20 min averages of the relevant physical quantities from WIND data, in order to find the optimum average to use. The 5 min average, initially based on analysis of N=26 carefully chosen MCs, turned out to be marginally the best average to use for our purposes. Other criteria, besides the four described above, such as the existence of a magnetic hole, plasma speed change, and/or field fluctuation level change, were examined and dismissed as not reliable enough, or usually associated with physical quantities that change too slowly around the boundary to be useful. The preliminarily estimated front boundary time, tB, and its initial ±2-h uncertainty interval are determined by either an automatic MC identification scheme or by visual inspection. The boundary-scheme was developed specifically for aiding in forecasting the strength and timing of a geomagnetic storm due to the passage of a MC in real-time, but can be used in post ground-data collection for imposing consistency when choosing front boundaries of MCs. This scheme has been extensively tested, first using 81 bona fide MCs, collected over about 8.6 years of WIND data (at 1 AU, and also by using 122 MC-like structures as defined by Lepping et al. (2005 over about the same

  8. 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

  9. The Galactic magnetic fields

    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

  10. Magnetic superstorm on August 4-5, 1972 in connection with a hydromagnetic structure of the interplanetary plasma stream from a powerful flare

    International Nuclear Information System (INIS)

    Ivanov, K.G.; Mikerina, N.V.

    1977-01-01

    A comparison is made between the hydromagnetic structure of the interplanetary plasma flux from the powerful solar flare occurred on 4.08.1972 and the magnetic storm of 4-5.08.1972. The geomagnetic effects of the head impact layer of the interplanetary flux are being considered. The world-wide disturbances being most intensive in the Polar regions corresponded to the elements of the substructure of the impact layer. These disturbances are interpreted as the superposition of magnetic fields from reconnection currents on the magnetopause and in the neutral layer of the magnetosphere trail. The qualitative description of the effects under investigation has been made on the assumption that the magnetopause is a rotational impact wave

  11. Magnetic Field Grid Calculator

    Data.gov (United States)

    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...

  12. Cross-field diffusion of energetic (100 keV to 2 MeV) protons in interplanetary space

    Energy Technology Data Exchange (ETDEWEB)

    Costa Jr, Edio da [Instituto Federal de Minas Gerais-IFMG, Ouro Preto, MG, 35400-000 (Brazil); Tsurutani, Bruce T. [Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109 (United States); Alves, Maria Virgínia; Echer, Ezequiel [Instituto Nacional de Pesquisas Espaciais-INPE, São José dos Campos, SP, 12227-010 (Brazil); Lakhina, Gurbax S., E-mail: edio.junior@ifmg.edu.br, E-mail: costajr.e@gmail.com [Indian Institute for Geomagnetism, Navi Mumbai 410 218 (India)

    2013-12-01

    Magnetic field magnitude decreases (MDs) are observed in several regions of the interplanetary medium. In this paper, we characterize MDs observed by the Ulysses spacecraft instrumentation over the solar south pole by using magnetic field data to obtain the empirical size, magnetic field MD, and frequency of occurrence distribution functions. The interaction of energetic (100 keV to 2 MeV) protons with these MDs is investigated. Charged particle and MD interactions can be described by a geometrical model allowing the calculation of the guiding center shift after each interaction. Using the distribution functions for the MD characteristics, Monte Carlo simulations are used to obtain the cross-field diffusion coefficients as a function of particle kinetic energy. It is found that the protons under consideration cross-field diffuse at a rate of up to ≈11% of the Bohm rate. The same method used in this paper can be applied to other space regions where MDs are observed, once their local features are well known.

  13. Omnigenous magnetic fields

    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)

  14. Cosmic Magnetic Fields

    Science.gov (United States)

    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.

  15. Strong Magnetic Field Characterisation

    Science.gov (United States)

    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

  16. 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 ...

  17. 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 ...

  18. Organic magnetic field sensor

    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).

  19. Are interplanetary magnetic clouds manifestations of coronal transients at 1 AU

    International Nuclear Information System (INIS)

    Wilson, R.M.; Hildner, E.

    1984-01-01

    Using proxy data for the occurrence of those mass ejections from the solar corona which are directed earthward, we investigate the association between the post-1970 interplanetary magnetic clouds of Klein and Burlaga (1982) and coronal mass ejections. The evidence linking magnetic clouds following shocks with coronal mass ejections is striking; six of nine clouds observed at Earth were preceded an appropriate time earlier by meter-wave type II radio bursts indicative of coronal shock waves and coronal mass ejections occurring near central meridian. During the selected control periods when no clouds were detected near Earth, the only type II bursts reported were associated with solar activity near the limbs. Where the proxy solar data to be sought are not so clearly suggested, that is, for clouds preceding interaction regions and clouds within cold magnetic enhancements, the evidence linking the clouds and coronal mass ejections is not as clear; proxy data usually suggest many candidate mass-ejection events for each cloud. Overall, the data are consistent with and support the hypothesis suggested by Klein and Burlaga that magnetic clouds observed with spacecraft at 1 AU are manifestations of solar coronal mass ejection transients. (orig.)

  20. Magnetic field on board

    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)

  1. 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

  2. MAGNETIC FIELDS OF STARS

    OpenAIRE

    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.

  3. 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

  4. Relationship between Interplanetary (IP) Parameters and ...

    Indian Academy of Sciences (India)

    3SITAA-SAC, Indian Space Research Organisation, Ahmedabad, Gujarat 380 015, India. 4Indian Space Research Organisation-Head Quarters, Bangalore, Karnataka, India. Abstract. In the present study, .... Lepping, R. P., Jones, J. A., Burlaga, L. F. 1990, Magnetic field structure of Interplanetary. Magnetic Clouds at 1 A.U; ...

  5. Magnetic fields at Neptune

    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

  6. Magnetic fields in cosmology

    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)

  7. A model of the magnetosheath magnetic field during magnetic clouds

    Directory of Open Access Journals (Sweden)

    L. Turc

    2014-02-01

    Full Text Available Magnetic clouds (MCs are huge interplanetary structures which originate from the Sun and have a paramount importance in driving magnetospheric storms. Before reaching the magnetosphere, MCs interact with the Earth's bow shock. This may alter their structure and therefore modify their expected geoeffectivity. We develop a simple 3-D model of the magnetosheath adapted to MCs conditions. This model is the first to describe the interaction of MCs with the bow shock and their propagation inside the magnetosheath. We find that when the MC encounters the Earth centrally and with its axis perpendicular to the Sun–Earth line, the MC's magnetic structure remains mostly unchanged from the solar wind to the magnetosheath. In this case, the entire dayside magnetosheath is located downstream of a quasi-perpendicular bow shock. When the MC is encountered far from its centre, or when its axis has a large tilt towards the ecliptic plane, the MC's structure downstream of the bow shock differs significantly from that upstream. Moreover, the MC's structure also differs from one region of the magnetosheath to another and these differences vary with time and space as the MC passes by. In these cases, the bow shock configuration is mainly quasi-parallel. Strong magnetic field asymmetries arise in the magnetosheath; the sign of the magnetic field north–south component may change from the solar wind to some parts of the magnetosheath. We stress the importance of the Bx component. We estimate the regions where the magnetosheath and magnetospheric magnetic fields are anti-parallel at the magnetopause (i.e. favourable to reconnection. We find that the location of anti-parallel fields varies with time as the MCs move past Earth's environment, and that they may be situated near the subsolar region even for an initially northward magnetic field upstream of the bow shock. Our results point out the major role played by the bow shock configuration in modifying or keeping the

  8. 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

  9. Nonlinear Alfvén waves, discontinuities, proton perpendicular acceleration, and magnetic holes/decreases in interplanetary space and the magnetosphere: intermediate shocks?

    Directory of Open Access Journals (Sweden)

    B. T. Tsurutani

    2005-01-01

    Full Text Available Alfvén waves, discontinuities, proton perpendicular acceleration and magnetic decreases (MDs in interplanetary space are shown to be interrelated. Discontinuities are the phase-steepened edges of Alfvén waves. Magnetic decreases are caused by a diamagnetic effect from perpendicularly accelerated (to the magnetic field protons. The ion acceleration is associated with the dissipation of phase-steepened Alfvén waves, presumably through the Ponderomotive Force. Proton perpendicular heating, through instabilities, lead to the generation of both proton cyclotron waves and mirror mode structures. Electromagnetic and electrostatic electron waves are detected as well. The Alfvén waves are thus found to be both dispersive and dissipative, conditions indicting that they may be intermediate shocks. The resultant 'turbulence' created by the Alfvén wave dissipation is quite complex. There are both propagating (waves and nonpropagating (mirror mode structures and MDs byproducts. Arguments are presented to indicate that similar processes associated with Alfvén waves are occurring in the magnetosphere. In the magnetosphere, the 'turbulence' is even further complicated by the damping of obliquely propagating proton cyclotron waves and the formation of electron holes, a form of solitary waves. Interplanetary Alfvén waves are shown to rapidly phase-steepen at a distance of 1AU from the Sun. A steepening rate of ~35 times per wavelength is indicated by Cluster-ACE measurements. Interplanetary (reverse shock compression of Alfvén waves is noted to cause the rapid formation of MDs on the sunward side of corotating interaction regions (CIRs. Although much has been learned about the Alfvén wave phase-steepening processfrom space plasma observations, many facets are still not understood. Several of these topics are discussed for the interested researcher. Computer simulations and theoretical developments will be particularly useful in making further progress in

  10. 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

  11. Magnetic Fields Versus Gravity

    Science.gov (United States)

    Hensley, Kerry

    2018-04-01

    Deep within giant molecular clouds, hidden by dense gas and dust, stars form. Unprecedented data from the Atacama Large Millimeter/submillimeter Array (ALMA) reveal the intricate magnetic structureswoven throughout one of the most massive star-forming regions in the Milky Way.How Stars Are BornThe Horsehead Nebulasdense column of gas and dust is opaque to visible light, but this infrared image reveals the young stars hidden in the dust. [NASA/ESA/Hubble Heritage Team]Simple theory dictates that when a dense clump of molecular gas becomes massive enough that its self-gravity overwhelms the thermal pressure of the cloud, the gas collapses and forms a star. In reality, however, star formation is more complicated than a simple give and take between gravity and pressure. Thedusty molecular gas in stellar nurseries is permeated with magnetic fields, which are thought to impede the inward pull of gravity and slow the rate of star formation.How can we learn about the magnetic fields of distant objects? One way is by measuring dust polarization. An elongated dust grain will tend to align itself with its short axis parallel to the direction of the magnetic field. This systematic alignment of the dust grains along the magnetic field lines polarizes the dust grains emission perpendicular to the local magnetic field. This allows us to infer the direction of the magnetic field from the direction of polarization.Magnetic field orientations for protostars e2 and e8 derived from Submillimeter Array observations (panels a through c) and ALMA observations (panels d and e). Click to enlarge. [Adapted from Koch et al. 2018]Tracing Magnetic FieldsPatrick Koch (Academia Sinica, Taiwan) and collaborators used high-sensitivity ALMA observations of dust polarization to learn more about the magnetic field morphology of Milky Way star-forming region W51. W51 is one of the largest star-forming regions in our galaxy, home to high-mass protostars e2, e8, and North.The ALMA observations reveal

  12. Solar cycle effect on geomagnetic storms caused by interplanetary magnetic clouds

    Directory of Open Access Journals (Sweden)

    C.-C. Wu

    2006-12-01

    Full Text Available We investigated geomagnetic activity which was induced by interplanetary magnetic clouds during the past four solar cycles, 1965–1998. We have found that the intensity of such geomagnetic storms is more severe in solar maximum than in solar minimum. In addition, we affirm that the average solar wind speed of magnetic clouds is faster in solar maximum than in solar minimum. In this study, we find that solar activity level plays a major role on the intensity of geomagnetic storms. In particular, some new statistical results are found and listed as follows. (1 The intensity of a geomagnetic storm in a solar active period is stronger than in a solar quiet period. (2 The magnitude of negative Bzmin is larger in a solar active period than in a quiet period. (3 Solar wind speed in an active period is faster than in a quiet period. (4 VBsmax in an active period is much larger than in a quiet period. (5 Solar wind parameters, Bzmin, Vmax and VBsmax are correlated well with geomagnetic storm intensity, Dstmin during a solar active period. (6 Solar wind parameters, Bzmin, and VBsmax are not correlated well (very poorly for Vmax with geomagnetic storm intensity during a solar quiet period. (7 The speed of the solar wind plays a key role in the correlation of solar wind parameters vs. the intensity of a geomagnetic storm. (8 More severe storms with Dstmin≤−100 nT caused by MCs occurred in the solar active period than in the solar quiet period.

  13. Shear-induced inflation of coronal magnetic fields

    International Nuclear Information System (INIS)

    Klimchuk, J.A.

    1990-01-01

    Using numerical models of force-free magnetic fields, the shearing of footprints in arcade geometries leading to an inflation of the coronal magnetic field was examined. For each of the shear profiles considered, all of the field lines become elevated compared with the potential field. This includes cases where the shear is concentrated well away from the arcade axis, such that B(sub z), the component of field parallel to the axis, increases outward to produce an inward B(sub z) squared/8 pi magnetic pressure gradient force. These results contrast with an earlier claim, shown to be incorrect, that field lines can sometimes become depressed as a result of shear. It is conjectured that an inflation of the entire field will always result from the shearing of simple arcade configurations. These results have implications for prominence formation, the interplanetary magnetic flux, and possibly also coronal holes. 38 refs

  14. ISR Radial Field Magnet

    CERN Multimedia

    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

  15. Influence of the interplanetary driver type on the durations of main and recovery phases of magnetic storms

    OpenAIRE

    Yermolaev, Yu. I.; Lodkina, I. G.; Nikolaeva, N. S.; Yermolaev, M. Yu.

    2013-01-01

    We study durations of main and recovery phases of magnetic storms induced by different types of large-scale solar-wind streams (Sheath, magnetic cloud (MC), Ejecta and CIR) on the basis of OMNI data base during 1976-2000. Durations of both main and recovery phases depend on types of interplanetary drivers. On the average, duration of main phase of storms induced by compressed regions (CIR and Sheath) is shorter than by MC and Ejecta while duration of recovery phase of CIR- and Sheath-induced ...

  16. Cosmic magnetic fields

    CERN Document Server

    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.

  17. Modelling interplanetary CMEs using magnetohydrodynamic simulations

    Directory of Open Access Journals (Sweden)

    P. J. Cargill

    Full Text Available The dynamics of Interplanetary Coronal Mass Ejections (ICMEs are discussed from the viewpoint of numerical modelling. Hydrodynamic models are shown to give a good zero-order picture of the plasma properties of ICMEs, but they cannot model the important magnetic field effects. Results from MHD simulations are shown for a number of cases of interest. It is demonstrated that the strong interaction of the ICME with the solar wind leads to the ICME and solar wind velocities being close to each other at 1 AU, despite their having very different speeds near the Sun. It is also pointed out that this interaction leads to a distortion of the ICME geometry, making cylindrical symmetry a dubious assumption for the CME field at 1 AU. In the presence of a significant solar wind magnetic field, the magnetic fields of the ICME and solar wind can reconnect with each other, leading to an ICME that has solar wind-like field lines. This effect is especially important when an ICME with the right sense of rotation propagates down the heliospheric current sheet. It is also noted that a lack of knowledge of the coronal magnetic field makes such simulations of little use in space weather forecasts that require knowledge of the ICME magnetic field strength.

    Key words. Interplanetary physics (interplanetary magnetic fields Solar physics, astrophysics, and astronomy (flares and mass ejections Space plasma physics (numerical simulation studies

  18. Ring current and auroral electrojets in connection with interplanetary medium parameters during magnetic storm

    Directory of Open Access Journals (Sweden)

    Y. I. Feldstein

    1994-06-01

    Full Text Available The relationship between the auroral electrojet indices (AE and the ring current magnetic field (DR was investigated by observations obtained during the magnetic storm on 1-3 April 1973. During the storm main phase the DR development is accompanied by a shift of the auroral electrojets toward the equator. As a result, the standard AE indices calculated on the basis of data from auroral observatories was substantially lower than the real values (AE'. To determine AE' during the course of a storm main phase data from subauroral magnetic observatories should be used. It is shown that the intensity of the indices (AE' which take into account the shift of the electrojets is increased substantially relative to the standard indices during the storm main phase. AE' values are closely correlated with geoeffective solar wind parameters. A high correlation was obtained between AE' and the energy flux into the ring current during the storm main phase. Analysis of magnetic field variations during intervals with intense southward IMF components demonstrates a decrease of the saturation effect of auroral electrojet currents if subauroral stations magnetic field variations are taken into account. This applies both to case studies and statistical data. The dynamics of the electrojets in connection with the development of the ring current and of magnetospheric substorms can be described by the presence (absence of saturation for minimum (maximum AE index values during a 1-h interval. The ring current magnetic field asymmetry (ASY was calculated as the difference between the maximum and minimum field values along a parallel of latitude at low latitudes. The ASY value is closely correlated with geoeffective solar wind parameters and simultaneously is a more sensitive indicator of IMF Bz variations than the symmetric ring current. ASY increases (decreases faster during the main phase (the recovery phase than DR. The magnetic field decay at low latitudes in the

  19. High field superconducting magnets

    Science.gov (United States)

    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.

  20. 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.)

  1. Magnetic field of Mercury

    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

  2. On the twists of interplanetary magnetic flux ropes observed at 1 AU

    OpenAIRE

    Wang, Yuming; Zhuang, Bin; Hu, Qiang; Liu, Rui; Shen, Chenglong; Chi, Yutian

    2016-01-01

    Magnetic flux ropes (MFRs) are one kind of fundamental structures in the solar physics, and involved in various eruption phenomena. Twist, characterizing how the magnetic field lines wind around a main axis, is an intrinsic property of MFRs, closely related to the magnetic free energy and stableness. So far it is unclear how much amount of twist is carried by MFRs in the solar atmosphere and in heliosphere and what role the twist played in the eruptions of MFRs. Contrasting to the solar MFRs,...

  3. On a forecast of geomagnetic activity according to magnetic fields on the Sun

    International Nuclear Information System (INIS)

    Ponyavin, D.I.; Pudovkin, M.I.

    1988-01-01

    Technique for tracking the current layer orientation in the solar corona and solar wind high-velocity flux sources is suggested according to the observation of large-scale magnetic fields at the Sun. Ionospheric magnetic fields in potential approximation are extrapolated to the Sun atmosphere high layers - in the region of probable formation of solar wind and interplanetary magnetic field. The chart of isocline-lines of field vector even inclination to the surface of R=1.8R sun radius sphere is plotted according to the calculated magnetic field. Daily plotting of such charts allows to continuosly track the large-scale structure and evolution of solar wind and interplanetary magnetic field. Th comparison of isoclinic charts with geomagnetic activity for October 1982 has shown the principal possibility to use this technique for the purposes of geomagnetic activity forecasting

  4. 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.

  5. 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)

  6. 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

  7. The earth's magnetic field

    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)

  8. Magnetic field screens

    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)

  9. Magnetic fields in diffuse media

    CERN Document Server

    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.

  10. Using Statistical Multivariable Models to Understand the Relationship Between Interplanetary Coronal Mass Ejecta and Magnetic Flux Ropes

    Science.gov (United States)

    Riley, P.; Richardson, I. G.

    2012-01-01

    In-situ measurements of interplanetary coronal mass ejections (ICMEs) display a wide range of properties. A distinct subset, "magnetic clouds" (MCs), are readily identifiable by a smooth rotation in an enhanced magnetic field, together with an unusually low solar wind proton temperature. In this study, we analyze Ulysses spacecraft measurements to systematically investigate five possible explanations for why some ICMEs are observed to be MCs and others are not: i) An observational selection effect; that is, all ICMEs do in fact contain MCs, but the trajectory of the spacecraft through the ICME determines whether the MC is actually encountered; ii) interactions of an erupting flux rope (PR) with itself or between neighboring FRs, which produce complex structures in which the coherent magnetic structure has been destroyed; iii) an evolutionary process, such as relaxation to a low plasma-beta state that leads to the formation of an MC; iv) the existence of two (or more) intrinsic initiation mechanisms, some of which produce MCs and some that do not; or v) MCs are just an easily identifiable limit in an otherwise corntinuous spectrum of structures. We apply quantitative statistical models to assess these ideas. In particular, we use the Akaike information criterion (AIC) to rank the candidate models and a Gaussian mixture model (GMM) to uncover any intrinsic clustering of the data. Using a logistic regression, we find that plasma-beta, CME width, and the ratio O(sup 7) / O(sup 6) are the most significant predictor variables for the presence of an MC. Moreover, the propensity for an event to be identified as an MC decreases with heliocentric distance. These results tend to refute ideas ii) and iii). GMM clustering analysis further identifies three distinct groups of ICMEs; two of which match (at the 86% level) with events independently identified as MCs, and a third that matches with non-MCs (68 % overlap), Thus, idea v) is not supported. Choosing between ideas i) and

  11. Ring current and auroral electrojets in connection with interplanetary medium parameters during magnetic storm

    Directory of Open Access Journals (Sweden)

    Y. I. Feldstein

    Full Text Available The relationship between the auroral electrojet indices (AE and the ring current magnetic field (DR was investigated by observations obtained during the magnetic storm on 1-3 April 1973. During the storm main phase the DR development is accompanied by a shift of the auroral electrojets toward the equator. As a result, the standard AE indices calculated on the basis of data from auroral observatories was substantially lower than the real values (AE'. To determine AE' during the course of a storm main phase data from subauroral magnetic observatories should be used. It is shown that the intensity of the indices (AE' which take into account the shift of the electrojets is increased substantially relative to the standard indices during the storm main phase. AE' values are closely correlated with geoeffective solar wind parameters. A high correlation was obtained between AE' and the energy flux into the ring current during the storm main phase. Analysis of magnetic field variations during intervals with intense southward IMF components demonstrates a decrease of the saturation effect of auroral electrojet currents if subauroral stations magnetic field variations are taken into account. This applies both to case studies and statistical data. The dynamics of the electrojets in connection with the development of the ring current and of magnetospheric substorms can be described by the presence (absence of saturation for minimum (maximum AE index values during a 1-h interval. The ring current magnetic field asymmetry (ASY was calculated as the difference between the maximum and minimum field values along a parallel of latitude at low latitudes. The ASY value is closely correlated with geoeffective solar wind parameters and simultaneously is a more sensitive indicator of IMF Bz variations than the symmetric ring current.

  12. Earth's Magnetic Field

    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....

  13. Manifestation of interplanetary medium parameters in development of a geomagnetic storm initial phase

    International Nuclear Information System (INIS)

    Chkhetiya, A.M.

    1988-01-01

    The role of solar wind plasma parameters in formation of a geomagnetic storm initial phase is refined. On the basis of statistical analysis an empirical formula relating the interplanetary medium parameters (components of interplanetary magnetic field, proton velocity and concentration) and D st -index during the geomagnetic storm initial phase is proposed

  14. 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

  15. Diffusion of charged particles in strong large-scale random and regular magnetic fields

    International Nuclear Information System (INIS)

    Mel'nikov, Yu.P.

    2000-01-01

    The nonlinear collision integral for the Green's function averaged over a random magnetic field is transformed using an iteration procedure taking account of the strong random scattering of particles on the correlation length of the random magnetic field. Under this transformation the regular magnetic field is assumed to be uniform at distances of the order of the correlation length. The single-particle Green's functions of the scattered particles in the presence of a regular magnetic field are investigated. The transport coefficients are calculated taking account of the broadening of the cyclotron and Cherenkov resonances as a result of strong random scattering. The mean-free path lengths parallel and perpendicular to the regular magnetic field are found for a power-law spectrum of the random field. The analytical results obtained are compared with the experimental data on the transport ranges of solar and galactic cosmic rays in the interplanetary magnetic field. As a result, the conditions for the propagation of cosmic rays in the interplanetary space and a more accurate idea of the structure of the interplanetary magnetic field are determined

  16. Magnetic Field Topology in Jets

    Science.gov (United States)

    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.

  17. Low field magnetic resonance imaging

    Science.gov (United States)

    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.

  18. Interplanetary Alfvenic fluctuations: A stochastic model

    International Nuclear Information System (INIS)

    Barnes, A.

    1981-01-01

    The strong alignment of the average directions of minimum magnetic variance and mean magnetic field in interplanetary Alfvenic fluctuations is inconsistent with the usual wave-propagation models. We investigate the concept of minimum variance for nonplanar Alfvenic fluctuations in which the field direction varies stochastically. It is found that the tendency of the minimum variance and mean field directions to be aligned may be purely a consequence of the randomness of the field direction. In particular, a well-defined direction of minimum variance does not imply that the fluctuations are necessarily planar. The fluctuation power spectrum is a power law for frequencies much higher than the inverse of the correlation time. The probability distribution of directions a randomly fluctuating field of constant magnitude is calculated. A new approach for observational studies of interplanetary fluctuations is suggested

  19. The Capacitive Magnetic Field Sensor

    Science.gov (United States)

    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.

  20. Possible mechanism of the interplanetary medium effect on the diurnal rotation rate of the Earth

    International Nuclear Information System (INIS)

    Krymskij, P.F.

    1993-01-01

    Mechanism is proposed for effect of the solar wind and interplanetary magnetic field on the Earth rotation. In the mechanism base is Hall current generation in the plasma layer of the magnetosphere tail

  1. Study of the magnetic turbulence in a corotating interaction region in the interplanetary medium

    Directory of Open Access Journals (Sweden)

    J. F. Valdés-Galicia

    Full Text Available We study the geometry of magnetic fluctuations in a CIR observed by Pioneer 10 at 5 AU between days 292 and 295 in 1973. We apply the methodology proposed by Bieber et al. to make a comparison of the relative importance of two geometric arrays of vector propagation of the magnetic field fluctuations: slab and two-dimensional (2D. We found that inside the studied CIR this model is not applicable due to the restrictions imposed on it. Our results are consistent with Alfvenic fluctuations propagating close to the radial direction, confirming Mavromichalaki et al.'s findings. A mixture of isotropic and magnetoacoustic waves in the region before the front shock would be consistent with our results, and a mixture of slab/2D and magnetoacoustic waves in a region after the reverse shock. We base the latter conclusions on the theoretical analysis made by Kunstmann. We discuss the reasons why the composite model can not be applied in the CIR studied although the fluctuations inside it are two dimensional.

    Key words. Solar physics · astrophysics and astronomy (magnetic fields · Space plasma physics (turbulence; waves and instabilities

  2. Study of the magnetic turbulence in a corotating interaction region in the interplanetary medium

    Directory of Open Access Journals (Sweden)

    J. F. Valdés-Galicia

    1999-11-01

    Full Text Available We study the geometry of magnetic fluctuations in a CIR observed by Pioneer 10 at 5 AU between days 292 and 295 in 1973. We apply the methodology proposed by Bieber et al. to make a comparison of the relative importance of two geometric arrays of vector propagation of the magnetic field fluctuations: slab and two-dimensional (2D. We found that inside the studied CIR this model is not applicable due to the restrictions imposed on it. Our results are consistent with Alfvenic fluctuations propagating close to the radial direction, confirming Mavromichalaki et al.'s findings. A mixture of isotropic and magnetoacoustic waves in the region before the front shock would be consistent with our results, and a mixture of slab/2D and magnetoacoustic waves in a region after the reverse shock. We base the latter conclusions on the theoretical analysis made by Kunstmann. We discuss the reasons why the composite model can not be applied in the CIR studied although the fluctuations inside it are two dimensional.Key words. Solar physics · astrophysics and astronomy (magnetic fields · Space plasma physics (turbulence; waves and instabilities

  3. Relationships between interplanetary quantities and the global auroral electrojet index

    International Nuclear Information System (INIS)

    Meloni, A.; Wolfe, A.; Lanzerotti, L.J.

    1982-01-01

    We have studied, using linear cross correlation and multilinear regression analyses, statistical relations between the magnetospheric auroral electrojet intensity index AE and various parameters characterizing the interplanetary plasma and magnetic field. We also consider the recently proposed epsilon parameter as an independent variable. The analyses were carried out separately for twenty-eight days in mid 1975 and for each of five individual magnetic storm intervals that have been previously discussed extensively in the literature. We find that when the interplanetary data set is not distinguished as to the direction of the north-south component B/sub z/, the interplanetary electric field -VB/sub z/ carried to the front of the magnetosphere correlates with AE substantially better than does epsilon. Considering only data during which B/sub z/ is negative gives a slightly better correlation of epsilon with AE than of the electric field with AE. The correlations are valid for the specific storm periods as well as for the unrestricted twenty-eight days of data. Our results suggest that the physical processes involved in energy transfer to the nightside magnetosphere depend upon the direction of the north-south component of the interplanetary magnetic field: the interplanetary electric field plays an important role during northward B/sub z/ and the epsilon parameter and the electric field both provide an indication of energy transfer and substorm activity during southward B/sub z/

  4. 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.

  5. Dynamics of interplanetary dust grains

    International Nuclear Information System (INIS)

    Lamy, P.L.

    1975-01-01

    The interaction of spherical grains of various materials-three silicates (quartz, obsidian and andesite), water-ice and iron - whose radii lie in the micronic and submicronic range with the interplanetary medium is solved. This includes: the interaction with the solar radiation field which is solved using Mie scattering theory and taking into account the precise dependence of the optical properties of the five materials upon wavelength; the interaction with the solar wind: corpuscular tangential drag is found to be always important and may even be larger than the Poynting-Robertson drag; the interaction with the interplanetary magnetic field is investigated in terms of a diffusion or random walk through a series of electromagnetic scatterings, leading to a Chapman-Komolgorov equation (i.e., a generalized Liouville equation). Numerical results are presented for these interactions spanning the entire solar system with circularity of elliptical orbits, direct or retrograde, with grains of various materials and sizes and giving -probably for the first time - a clear global picture of the interaction of dust grains with the interplanetary medium. The dynamics of the grains is then investigated using the theory of general perturbations and the numerical integration of trajectories of circum-solar grains

  6. 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

  7. Tempered Lévy walk of charged particles in turbulent magnetic field

    International Nuclear Information System (INIS)

    Sibatov, R T; Uchaikin, V V; Byzykchi, A N

    2017-01-01

    Recently, various diffusion regimes of ions and electrons in interplanetary magnetic field have been recognized from the data collected by different spacecrafts. Particularly for protons, superdiffusion and normal diffusion parallel to the mean magnetic field were declared, simulation also predicts transient superdiffusive behavior. We interpret parallel motion in terms of the one-dimensional tempered Lévy walk process and show that this representation is consistent with the experimental and simulated results. (paper)

  8. Fast superconducting magnetic field switch

    Science.gov (United States)

    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.

  9. 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

  10. Patterns of magnetic field merging sites on the magnetopause

    International Nuclear Information System (INIS)

    Luhmann, J.G.; Walker, R.J.; Russell, C.T.; Crooker, N.U.; Spreiter, J.R.; Stahara, S.S.

    1984-01-01

    Several years ago, Crooker presented a qualitative picture of the merging sites on the magnetopause defined as the points where the magnetospheric and magnetosheath field are antiparallel. However, Cowley pointed out that merging can also occur where these fields are not exactly antiparallel, but merely have antiparallel components. Using realistic models of the magnetosphere and magnetosheath magnetic fields, the angles between the fields at the magnetopause boundary were determined for different interplanetary field orientations, including radial field and Parker spiral field. The results are summarized in Figure 1, which displays contours on the dayside magnetopause (viewed from the sun, i.e., the GSE Y-Z plane projection) of equal value of the cosine of the angle between the magnetospheric and magnetosheath model fields. Only contours with negative values, implying some antiparallel component, are shown. Values at the contours, starting with the contour filled with shading, are -.98, -.95, -.9, -.8, -.7, -.6, -.5, -.4, -.3, -.2, -.1, -.0. The interplanetary field orientations are indicated in vector notation in the lower right corners. In particular, the pattern for a 45 0 cone angle is shown in the fourth diagram in the right hand column and patterns for northward and southward fields occupy the first position in the first column and the second position in the right hand column. These results can be used for comparisons with observed distribution of flux transfer events and for studies of magnetospheric particle leakage

  11. Magnetic field modification of optical magnetic dipoles.

    Science.gov (United States)

    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.

  12. Tracing magnetic fields with aligned grains

    International Nuclear Information System (INIS)

    Lazarian, A.

    2007-01-01

    Magnetic fields play a crucial role in various astrophysical processes, including star formation, accretion of matter, transport processes (e.g., transport of heat), and cosmic rays. One of the easiest ways to determine the magnetic field direction is via polarization of radiation resulting from extinction or/and emission by aligned dust grains. Reliability of interpretation of the polarization maps in terms of magnetic fields depends on how well we understand the grain-alignment theory. Explaining what makes grains aligned has been one of the big issues of the modern astronomy. Numerous exciting physical effects have been discovered in the course of research undertaken in this field. As both the theory and observations matured, it became clear that the grain-alignment phenomenon is inherent not only in diffuse interstellar medium or molecular clouds but also is a generic property of the dust in circumstellar regions, interplanetary space and cometary comae. Currently the grain-alignment theory is a predictive one, and its results nicely match observations. Among its predictions is a subtle phenomenon of radiative torques. This phenomenon, after having stayed in oblivion for many years after its discovery, is currently viewed as the most powerful means of alignment. In this article, I shall review the basic physical processes involved in grain alignment, and the currently known mechanisms of alignment. I shall also discuss possible niches for different alignment mechanisms. I shall dwell on the importance of the concept of grain helicity for understanding of many properties of grain alignment, and shall demonstrate that rather arbitrarily shaped grains exhibit helicity when they interact with gaseous and radiative flows

  13. 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

  14. 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.

  15. 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.)

  16. Heliomagnetic cycle of magneto-ionospheric and interplanetary activities

    International Nuclear Information System (INIS)

    Zaretskij, N.S.; Krymskij, P.F.; Maksimov, Ya.Ya.

    1983-01-01

    The difference in frequency distributions of geomagnetic- and ionospheric disturbance levels are revealed within generalized intervals: odd-even- and even-odd 11-year solar activity cycles. The interplanetary medium of the first half of the 20th cycle (before reversal of the general heliomagnetic field polarity) is characterized by the background vertical component of the interplanetary magnetic field (IMF) in the north direction, rather small variability of the interplanetary field and low solar wind velocity. The south field component, higher field dispersion and high-velocity corpuscular fluxes are characteristic of the second half of the cycle. The 22-year variation in the number of small and moderate values of the geomagnetic activity within the limits of the 20th cycle is satisfactorily described by the behaviour of the quantities of the corresponding values of the IMF north-south component, field variability and solar wind velocity

  17. Magnetic field overshoots in the Venus blow shock

    International Nuclear Information System (INIS)

    Tatrallyay, M.; Luhmann, J.G.; Russell, C.T.

    1984-01-01

    An examination of Pioneer Venus Orbiter fluxgate magnetometer data has shown that magnetic field overshoots occur not only behind quasi-perpendicular bow shocks but also behind quasi-parallel shocks. Overshoots are assocciated only with supercritical shocks. Their amplitudes increase with increasing fast Mach number. Solar wind beta has a lesser effect. The thickness of the overshoot increases with decreasing Theta-BN. The thickness of apparent overshoots detected behind 4 strong fast interplanetary shocks (M greater than M/crit) is about 3 orders of magnitude larger. Multiple crossings of the Venus bow shock were observed mainly at turbulent shocks. Their occurence is not influenced by Theta-BN. 15 references

  18. 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

  19. On a Correlation between the Ionospheric Electric Field and the Time Derivative of the Magnetic Field

    Directory of Open Access Journals (Sweden)

    R. R. Ilma

    2012-01-01

    Full Text Available A correlation of the ionospheric electric field and the time derivative of the magnetic field was noticed over thirty years ago and has yet to be explained. Here we report on another set of examples during the superstorm of November 2004. The electric field in the equatorial ionosphere, measured with the Jicamarca incoherent scatter radar, exhibited a 3 mV/m electric field pulse that was not seen in the interplanetary medium. It was, however, accompanied by a correlation with the time derivative of the magnetic field measured at two points in Peru. Our inclination was to assume that the field was inductive. However, the time scale of the pulse was too short for the magnetic field to penetrate the crust of the Earth. This means that the area threaded by ∂B/∂t was too small to create the observed electric field by induction. We suggest that the effect was caused by a modulation of the ring current location relative to the Earth due to the electric field. This electric field is required, as the magnetic field lines are considered frozen into the plasma in the magnetosphere. The closer location of the ring current to the Earth in turn increased the magnetic field at the surface.

  20. NMR in pulsed magnetic field

    KAUST Repository

    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.

  1. NMR in pulsed magnetic field

    KAUST Repository

    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.

  2. Sector boundary distortion in the interplanetary medium

    International Nuclear Information System (INIS)

    Suess, S.T.; Feynman, J.

    1977-01-01

    We address the theoretical problem of the effect of a solar wind meridional velocity gradient on the orientation, or tipping, of a line embedded within the interplanetary plasma. We find that rotations of from 30degree to 75degree, between 1.5 solar radii and I AU, are produced when observed values for the solar wind velocity and its meridional gradient are used. This is not a small effect, nor is it difficult to calculate: it is a natural consequence of any meridional velocity gradient in the interplanetary medium. In relating this result to observed sector boundaries we note that the latitude dependence of the width of interplanetary magnetic sectors (dominant polarity or Rosenberg-Coleman effect) implies that sector boundaries at I AU are generally inclined at an angle of from 10degree to 20degree to the solar equatorial plane. Conversely, studies of photospheric magnetic fields have led to the conclusion that sector boundaries near the sun are, on the average, at large angles (approx.90degree) to the solar equatorial plane. If the dominant polarity effect were to be produced by rotation in the interplanetary medium, the sign of the solar wind meridional velocity gradient must not change at the equator, but the gradient does have to change sign for +/- boundary crossings in comparison to -/+ boundary crossings

  3. Magnetic field of the magnetospheric ring current and its dynamics during magnetic storms

    International Nuclear Information System (INIS)

    Feldstein, Y.I.; Grafe, A.; Pisarsky, V.Yu.; Prigansova, A.; Sumaruk, P.V.

    1990-01-01

    This review examines models existing in the literature which describe the magnetic field produced by the ring current (DR) at the Earth's surface based on the energy balance equation. The parameters of this equation, the injection function F and decay parameter τ are considered to depend on parameters of the interplanetary medium and the DR intensity. The existing models are shown to be able to describe the DR variations with sufficient accuracy (r.m.s. deviation δ between the experimental and modelled values of DR for 170 magnetic storms is 5 < δ < 15 nT, and the correlation coefficient between the two is 0.85 < r < 1). The models describe that part of the geomagnetic field variation at low latitudes during a magnetic storm that is controlled by the geoeffective characteristics of the interplanetary medium and which thus responds immediately to its variations (the driven part). The values of τ are significantly less during the main phase of a magnetic storm than during the recovery phase. This reflects the difference in the main mechanisms of ion loss from the ring current during the two phases of the storm. These are the interaction of ions with hydromagnetic waves during the main phase of the storm with its intervals of intense plasma injection into the inner magnetosphere, and charge exchange with the cold hydrogen geocorona during the recovery phase. (author)

  4. Magnetic Field Measurements in Beam Guiding Magnets

    CERN Document Server

    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.

  5. Positive and negative sudden impulses caused by fast forward and reverse interplanetary shocks

    Energy Technology Data Exchange (ETDEWEB)

    Andrioli, Vania Fatima; Savian, Jairo Francisco, E-mail: vaniafatima@gmail.com, E-mail: savian@lacesm.ufsm.br [Space Science Laboratory of Santa Maria - LACESM/CT - UFSM, Universidade Federal de Santa Maria - UFSM, Centro Tecnologico, Santa Maria, RS (Brazil); Echer, Ezequiel, E-mail: eecher@dge.inpe.br [National Institute for Space Research - INPE - MCT, Sao Jose dos Campos, SP (Brazil); Schuch, Nelson Jorge, E-mail: njschuch@lacesm.ufsm.br [Southern Regional Space Research Center - CRSPE/INPE - MCT, Universidade Federal de Santa Maria - UFSM, Santa Maria, RS (Brazil)

    2007-07-01

    Fast forward interplanetary shocks (FFS) are characterized by positive jump in all interplanetary plasma parameters (solar wind speed, temperature and density) and interplanetary magnetic field. However the fast reverse interplanetary shocks (FRS) are characterized by negative jump in all mentioned parameters except solar wind speed. Observations show that FFS cause positive sudden impulses (SI) while FRS cause negative SI in the H-component of the geomagnetic field. In this work we investigate the SI caused by interplanetary shocks. We use the observed plasma parameters, upstream and downstream, to calculate the variation of dynamic pressure. We observe that the SI amplitude is larger for positive SI than for negative ones, as a consequence of the fact that FFS have larger dynamic pressure variations as compared to FRS. (author)

  6. 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)

  7. 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

  8. 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...

  9. Geomagnetic response of interplanetary coronal mass ejections in the Earth's magnetosphere

    Science.gov (United States)

    Badruddin; Mustajab, F.; Derouich, M.

    2018-05-01

    A coronal mass ejections (CME) is the huge mass of plasma with embedded magnetic field ejected abruptly from the Sun. These CMEs propagate into interplanetary space with different speed. Some of them hit the Earth's magnetosphere and create many types of disturbances; one of them is the disturbance in the geomagnetic field. Individual geomagnetic disturbances differ not only in their magnitudes, but the nature of disturbance is also different. It is, therefore, desirable to understand these differences not only to understand the physics of geomagnetic disturbances but also to understand the properties of solar/interplanetary structures producing these disturbances of different magnitude and nature. In this work, we use the spacecraft measurements of CMEs with distinct magnetic properties propagating in the interplanetary space and generating disturbances of different levels and nature. We utilize their distinct plasma and field properties to search for the interplanetary parameter(s) playing important role in influencing the geomagnetic response of different coronal mass ejections.

  10. Measuring Earth's Magnetic Field Simply.

    Science.gov (United States)

    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)

  11. ISR split-field magnet

    CERN Multimedia

    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.

  12. The Juno Magnetic Field Investigation

    Science.gov (United States)

    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

  13. Interplanetary matter

    International Nuclear Information System (INIS)

    Ceplecha, Z.; Pecina, P.

    1987-01-01

    Of the total number of 57 presented papers 56 have been submitted to INIS. One paper was out of INIS scope. List of sessions (in brackets is the number of papers presented in the respective session and incorporated in the INIS): Preface (2), Comets (17), Asteroids (7), Meteors (19), Interplanetary dust (9), Other bodies (2). (Z.S.). 155 figs., 68 tabs., 1140 refs

  14. 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

  15. 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

  16. ENERGETIC PARTICLE TRANSPORT ACROSS THE MEAN MAGNETIC FIELD: BEFORE DIFFUSION

    International Nuclear Information System (INIS)

    Laitinen, T.; Dalla, S.

    2017-01-01

    Current particle transport models describe the propagation of charged particles across the mean field direction in turbulent plasmas as diffusion. However, recent studies suggest that at short timescales, such as soon after solar energetic particle (SEP) injection, particles remain on turbulently meandering field lines, which results in nondiffusive initial propagation across the mean magnetic field. In this work, we use a new technique to investigate how the particles are displaced from their original field lines, and we quantify the parameters of the transition from field-aligned particle propagation along meandering field lines to particle diffusion across the mean magnetic field. We show that the initial decoupling of the particles from the field lines is slow, and particles remain within a Larmor radius from their initial meandering field lines for tens to hundreds of Larmor periods, for 0.1–10 MeV protons in turbulence conditions typical of the solar wind at 1 au. Subsequently, particles decouple from their initial field lines and after hundreds to thousands of Larmor periods reach time-asymptotic diffusive behavior consistent with particle diffusion across the mean field caused by the meandering of the field lines. We show that the typical duration of the prediffusive phase, hours to tens of hours for 10 MeV protons in 1 au solar wind turbulence conditions, is significant for SEP propagation to 1 au and must be taken into account when modeling SEP propagation in the interplanetary space.

  17. ENERGETIC PARTICLE TRANSPORT ACROSS THE MEAN MAGNETIC FIELD: BEFORE DIFFUSION

    Energy Technology Data Exchange (ETDEWEB)

    Laitinen, T.; Dalla, S., E-mail: tlmlaitinen@uclan.ac.uk [Jeremiah Horrocks Institute, University of Central Lancashire, Preston (United Kingdom)

    2017-01-10

    Current particle transport models describe the propagation of charged particles across the mean field direction in turbulent plasmas as diffusion. However, recent studies suggest that at short timescales, such as soon after solar energetic particle (SEP) injection, particles remain on turbulently meandering field lines, which results in nondiffusive initial propagation across the mean magnetic field. In this work, we use a new technique to investigate how the particles are displaced from their original field lines, and we quantify the parameters of the transition from field-aligned particle propagation along meandering field lines to particle diffusion across the mean magnetic field. We show that the initial decoupling of the particles from the field lines is slow, and particles remain within a Larmor radius from their initial meandering field lines for tens to hundreds of Larmor periods, for 0.1–10 MeV protons in turbulence conditions typical of the solar wind at 1 au. Subsequently, particles decouple from their initial field lines and after hundreds to thousands of Larmor periods reach time-asymptotic diffusive behavior consistent with particle diffusion across the mean field caused by the meandering of the field lines. We show that the typical duration of the prediffusive phase, hours to tens of hours for 10 MeV protons in 1 au solar wind turbulence conditions, is significant for SEP propagation to 1 au and must be taken into account when modeling SEP propagation in the interplanetary space.

  18. Magnetic field induced dynamical chaos.

    Science.gov (United States)

    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.

  19. 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

  20. Magnetic field effects in proteins

    Science.gov (United States)

    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.

  1. 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.

  2. 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

  3. Indoor localization using magnetic fields

    Science.gov (United States)

    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

  4. Magnetic field of the Earth

    Science.gov (United States)

    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

  5. 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.)

  6. 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

  7. 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

  8. Search Coil vs. Fluxgate Magnetometer Measurements at Interplanetary Shocks

    Science.gov (United States)

    Wilson, L.B., III

    2012-01-01

    We present magnetic field observations at interplanetary shocks comparing two different sample rates showing significantly different results. Fluxgate magnetometer measurements show relatively laminar supercritical shock transitions at roughly 11 samples/s. Search coil magnetometer measurements at 1875 samples/s, however, show large amplitude (dB/B as large as 2) fluctuations that are not resolved by the fluxgate magnetometer. We show that these fluctuations, identified as whistler mode waves, would produce a significant perturbation to the shock transition region changing the interpretation from laminar to turbulent. Thus, previous observations of supercritical interplanetary shocks classified as laminar may have been under sampled.

  9. Satellite to study earth's magnetic field

    Science.gov (United States)

    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.

  10. 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)

  11. 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.

  12. 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

  13. Variations of interplanetary parameters and cosmic-ray intensities

    International Nuclear Information System (INIS)

    Geranios, A.

    1980-01-01

    Observations of cosmic ray intensity depressions by earth bound neutron monitors and measurements of interplanetary parameter's variations aboard geocentric satellites in the period January 1972-July 1974 are analysed and grouped according to their correlation among them. From this analysis of about 30 cases it came out that the majority of the depressions correlates with the average propagation speed of interplanetary shocks as well as with the amplitude of the interplanetary magnetic field after the eruption of a solar flare. About one fourth of the events correlates with corotating fast solar wind streams. As the recovery time of the shock-related depressions depends strongly on the heliographic longitude of the causitive solar flare, it seems that the cosmic ray modulation region has a corotative-like feature. (Auth.)

  14. Galactic and intergalactic magnetic fields

    CERN Document Server

    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

  15. 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)

  16. 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

  17. A variation of the Davis-Smith method for in-flight determination of spacecraft magnetic fields.

    Science.gov (United States)

    Belcher, J. W.

    1973-01-01

    A variation of a procedure developed by Davis and Smith (1968) is presented for the in-flight determination of spacecraft magnetic fields. Both methods take statistical advantage of the observation that fluctuations in the interplanetary magnetic field over short periods of time are primarily changes in direction rather than in magnitude. During typical solar wind conditions between 0.8 and 1.0 AU, a statistical analysis of 2-3 days of continuous interplanetary field measurements yields an estimate of a constant spacecraft field with an uncertainty of plus or minus 0.25 gamma in the direction radial to the sun and plus or minus 15 gammas in the directions transverse to the radial. The method is also of use in estimating variable spacecraft fields with gradients of the order of 0.1 gamma/day and less and in other special circumstances.

  18. Diagnostics of vector magnetic fields

    Science.gov (United States)

    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.

  19. Latitudinal Dependence of the Radial IMF Component - Interplanetary Imprint

    Science.gov (United States)

    Suess, S. T.; Smith, E. J.; Phillips, J.; Goldstein, B. E.; Nerney, S.

    1996-01-01

    Ulysses measurements have confirmed that there is no significant gradient with respect to heliomagnetic latitude in the radial component, B(sub r,), of the interplanetary magnetic field. There are two processes responsible for this observation. In the corona, the plasma beta is much less than 1, except directly above streamers, so both longitudinal and latitudinal (meridional) gradients in field strength will relax, due to the transverse magnetic pressure gradient force, as the solar wind carries magnetic flux away from the Sun. This happens so quickly that the field is essentially uniform by 5 solar radius. Beyond 10 solar radius, beta is greater than 1 and it is possible for a meridional thermal pressure gradient to redistribute magnetic flux - an effect apparently absent in Ulysses and earlier ICE and Interplanetary Magnetic Physics (IMP) data. We discuss this second effect here, showing that its absence is mainly due to the perpendicular part of the anisotropic thermal pressure gradient in the interplanetary medium being too small to drive significant meridional transport between the Sun and approx. 4 AU. This is done using a linear analytic estimate of meridional transport. The first effect was discussed in an earlier paper.

  20. 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.)

  1. 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.

  2. 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

  3. 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.

  4. Influence of the Interplanetary Convective Electric Field on the Distribution of Heavy Pickup Ions Around Mars

    Science.gov (United States)

    Johnson, B. C.; Liemohn, M. W.; Fränz, M.; Ramstad, R.; Stenberg Wieser, G.; Nilsson, H.

    2018-01-01

    This study obtains a statistical representation of 2-15 keV heavy ions outside of the Martian-induced magnetosphere and depicts their organization by the solar wind convective electric field (ESW). The overlap in the lifetime of Mars Global Surveyor (MGS) and Mars Express (MEX) provides a period of nearly three years during which magnetometer data from MGS can be used to estimate the direction of ESW in order to better interpret MEX ion data. In this paper we use MGS estimates of ESW to express MEX ion measurements in Mars-Sun-Electric field (MSE) coordinates. A new methodological technique used in this study is the limitation of the analysis to a particular instrument mode for which the overlap between proton contamination and plume observations is rare. This allows for confident energetic heavy ion identification outside the induced magnetosphere boundary. On the dayside, we observe high count rates of 2-15 keV heavy ions more frequently in the +ESW hemisphere (+ZMSE) than in the -ESW hemisphere, but on the nightside the reverse asymmetry was found. The results are consistent with planetary origin ions being picked up by the solar wind convective electric field. Though a field of view hole hinders quantification of plume fluxes and velocity space, this new energetic heavy ion identification technique means that Mars Express should prove useful in expanding the time period available to assess general plume loss variation with drivers.

  5. 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

  6. 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.

  7. 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

  8. 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

  9. The magnetic field of Mars according to data of Mars-3 and Mars-5 space vehicles

    International Nuclear Information System (INIS)

    Dolginov, Sh.Sh.; Eroshenko, E.G.; Zhuzgov, L.N.

    1975-01-01

    Magnitograms obtained by the space probe ''Mars-5'' on the evening and day sides as well as those from the ''Mars-3'' obtained earlier suggest the following: In the vicinity of Mars there exists a shock front and its disposition is tracked at various angles to the direction to the sun. Magnetometers have registered a region in space where magnetic field features the properties of a magnetosphere field in its topology and action on plasma. The magnetic field in the region of the ''magnitosphere'' does not change its sign when the interplanetary field does shile in adjacent boundary regions the regular part of the field changes its sign when that of the interplanetary field does. The configuration and dimensions of the ''magnitosphere'' depend on thesolar wind intensity. On the day side (''Mars-3'') the magnitospheric field ceases to be registered at an altitude of 2200km, whereas on the night side (''Mars-5'') the regular field is traced up to 7500-9500km from the planet surface. All the above unambiguously suggests that the planet Mars has its own magnetic field. Under the influence of the solar wind the field takes the characteristic form: it is limited on the day side and elongated on the night one. The topology oif force lines is explicable if one assumes that the axis of the Mars magnetic dipole is inclined to the rotation axis at an abgle of 15-20deg. The northern magnetic pole of the dipole is licated in the northern hemisphere, i.e. the Mars fields in their regularity are opposite to the geomagnetic field. The magnetic moment of the Mars dipole is equal to M=2.5x10 22 Gauss.cm 3 . (author)

  10. Measurements of Solar Vector Magnetic Fields

    Science.gov (United States)

    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.

  11. Shaped superconductor cylinder retains intense magnetic field

    Science.gov (United States)

    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.

  12. 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

  13. 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

  14. Correlation of variations of charged particle fluxes in the flare on 3 November, 1973 with change of parameters of interplanetary medium according to the data of the ''Mars-7'' automatic interplanetary station and ''Prognoz-3'' artificial Earth's satellite

    International Nuclear Information System (INIS)

    Kuzhevskij, B.M.; Mineev, Yu.V.; Savenko, I.A.; Spir'kova, E.S.; Surova, G.M.; ShestopaloV, I.P.

    1979-01-01

    The experimental data on the charged particle fluxes in the flare on the 3d of November, 1973 are analyzed. The experiments were carried out at the ''Prognoz-3'' artificial Earth satellite and ''Mars-7'' automatic interplanetary station with the help of devices recorded Esub(e) >= 30 keV energy electrons, 1 <= Esub(p) <= 5 MeV energy protons and 1-150 MeV energy protons. Presented are the data on variations of the intensity of cosmic ray particles which are compared with the data on interplanetary magnetic fields. The character of proton and electron intensity variations is explained by the change of interplanetary medium parameters. It is supposed that the electron splashes and proton intensity variations recorded at the satellites are conditioned by the sign change of the interplanetary magnetic field

  15. The cause of high-intensity long-duration continuous AE activity (HILDCAAS): interplanetary Alfven wave trains

    International Nuclear Information System (INIS)

    Tsurutani, B.T.; Gonzalez, W.D.

    1987-01-01

    It is shown that high intensity (AE > 1,000 nT), long duration (T > 2 d) continuous auroral activity (HILDCAA) events are caused by outward (from the sun) propagating interplanetary Alfven wave trains. The Alfven waves are often (but not always) detected several days after major interplanetary events, such as shocks and solar wind density enhancements. Presumably magnetic reconnection between the southward components of the Alfven wave magnetic fields and magnetospheric fields is the mechanism for transfer of solar wind energy to the magnetosphere. If the stringent requirements for HILDCAA events are relaxed, there are many more AE events of this type. A brief inspection indicates that these are also related to interplanetary Alfvenic fluctuations. We therefore suggest that most auroral activity may be caused by reconnection associated with Alfven waves in the interplanetary medium. (author)

  16. 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.

  17. 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.)

  18. 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.

  19. 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

  20. 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.

  1. 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)

  2. 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

  3. Magnetic field fluctuations across the Earth’s bow shock

    Directory of Open Access Journals (Sweden)

    A. Czaykowska

    Full Text Available We present a statistical analysis of 132 dayside (LT 0700-1700 bow shock crossings of the AMPTE/IRM spacecraft. We perform a superposed epoch analysis of low frequency, magnetic power spectra some minutes up-stream and downstream of the bow shock. The events are devided into categories depending on the angle θBn between bow shock normal and interplanetary magnetic field, and on plasma-β. In the foreshock upstream of the quasi-parallel bow shock, the power of the magnetic fluctuations is roughly 1 order of magnitude larger (δB ~ 4 nT for frequencies 0.01–0.04 Hz than upstream of the quasi-perpendicular shock. There is no significant difference in the magnetic power spectra upstream and downstream of the quasi-parallel bow shock; only at the shock itself, is the magnetic power enhanced by a factor of 4. This enhancement may be due to either an amplification of convecting upstream waves or to wave generation at the shock interface. On the contrary, downstream of the quasi-perpendicular shock, the magnetic wave activity is considerably higher than upstream. Down-stream of the quasi-perpendicular low-β bow shock, we find a dominance of the left-hand polarized component at frequencies just below the ion-cyclotron frequency, with amplitudes of about 3 nT. These waves are identified as ion-cyclotron waves, which grow in a low-β regime due to the proton temperature anisotropy. We find a strong correlation of this anisotropy with the intensity of the left-hand polarized component. Downstream of some nearly perpendicular (θBn ≈ 90° high-β crossings, mirror waves are identified. However, there are also cases where the conditions for mirror modes are met downstream of the nearly perpendicular shock, but no mirror waves are observed.

    Key words. Interplanetary physics (plasma waves and turbulence – Magnetospheric physics (magnetosheath; plasma waves and

  4. Magnetic field fluctuations across the Earth’s bow shock

    Directory of Open Access Journals (Sweden)

    A. Czaykowska

    2001-03-01

    Full Text Available We present a statistical analysis of 132 dayside (LT 0700-1700 bow shock crossings of the AMPTE/IRM spacecraft. We perform a superposed epoch analysis of low frequency, magnetic power spectra some minutes up-stream and downstream of the bow shock. The events are devided into categories depending on the angle θBn between bow shock normal and interplanetary magnetic field, and on plasma-β. In the foreshock upstream of the quasi-parallel bow shock, the power of the magnetic fluctuations is roughly 1 order of magnitude larger (δB ~ 4 nT for frequencies 0.01–0.04 Hz than upstream of the quasi-perpendicular shock. There is no significant difference in the magnetic power spectra upstream and downstream of the quasi-parallel bow shock; only at the shock itself, is the magnetic power enhanced by a factor of 4. This enhancement may be due to either an amplification of convecting upstream waves or to wave generation at the shock interface. On the contrary, downstream of the quasi-perpendicular shock, the magnetic wave activity is considerably higher than upstream. Down-stream of the quasi-perpendicular low-β bow shock, we find a dominance of the left-hand polarized component at frequencies just below the ion-cyclotron frequency, with amplitudes of about 3 nT. These waves are identified as ion-cyclotron waves, which grow in a low-β regime due to the proton temperature anisotropy. We find a strong correlation of this anisotropy with the intensity of the left-hand polarized component. Downstream of some nearly perpendicular (θBn ≈ 90° high-β crossings, mirror waves are identified. However, there are also cases where the conditions for mirror modes are met downstream of the nearly perpendicular shock, but no mirror waves are observed.Key words. Interplanetary physics (plasma waves and turbulence – Magnetospheric physics (magnetosheath; plasma waves and instabilities

  5. MODELING THE SUN’S SMALL-SCALE GLOBAL PHOTOSPHERIC MAGNETIC FIELD

    Energy Technology Data Exchange (ETDEWEB)

    Meyer, K. A. [Division of Computing and Mathematics, Abertay University, Kydd Building, Dundee, Bell Street, DD1 1HG, Scotland (United Kingdom); Mackay, D. H., E-mail: k.meyer@abertay.ac.uk [School of Mathematics and Statistics, University of St Andrews, North Haugh, St Andrews, KY16 9SS, Scotland (United Kingdom)

    2016-10-20

    We present a new model for the Sun’s global photospheric magnetic field during a deep minimum of activity, in which no active regions emerge. The emergence and subsequent evolution of small-scale magnetic features across the full solar surface is simulated, subject to the influence of a global supergranular flow pattern. Visually, the resulting simulated magnetograms reproduce the typical structure and scale observed in quiet Sun magnetograms. Quantitatively, the simulation quickly reaches a steady state, resulting in a mean field and flux distribution that are in good agreement with those determined from observations. A potential coronal magnetic field is extrapolated from the simulated full Sun magnetograms to consider the implications of such a quiet photospheric magnetic field on the corona and inner heliosphere. The bulk of the coronal magnetic field closes very low down, in short connections between small-scale features in the simulated magnetic network. Just 0.1% of the photospheric magnetic flux is found to be open at 2.5 R {sub ⊙}, around 10–100 times less than that determined for typical Helioseismic and Magnetic Imager synoptic map observations. If such conditions were to exist on the Sun, this would lead to a significantly weaker interplanetary magnetic field than is currently observed, and hence a much higher cosmic ray flux at Earth.

  6. 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

  7. 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)

  8. Laser-fusion rocket for interplanetary propulsion

    International Nuclear Information System (INIS)

    Hyde, R.A.

    1983-01-01

    A rocket powered by fusion microexplosions is well suited for quick interplanetary travel. Fusion pellets are sequentially injected into a magnetic thrust chamber. There, focused energy from a fusion Driver is used to implode and ignite them. Upon exploding, the plasma debris expands into the surrounding magnetic field and is redirected by it, producing thrust. This paper discusses the desired features and operation of the fusion pellet, its Driver, and magnetic thrust chamber. A rocket design is presented which uses slightly tritium-enriched deuterium as the fusion fuel, a high temperature KrF laser as the Driver, and a thrust chamber consisting of a single superconducting current loop protected from the pellet by a radiation shield. This rocket can be operated with a power-to-mass ratio of 110 W gm -1 , which permits missions ranging from occasional 9 day VIP service to Mars, to routine 1 year, 1500 ton, Plutonian cargo runs

  9. 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

  10. 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.

  11. 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

  12. 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....

  13. Strong and superstrong pulsed magnetic fields generation

    CERN Document Server

    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.

  14. On interplanetary coronal mass ejection identification at 1 AU

    International Nuclear Information System (INIS)

    Mulligan, T.; Russell, C.T.; Gosling, J.T.

    1999-01-01

    Coronal mass ejections are believed to be produced in the corona from closed magnetic regions not previously participating in the solar wind expansion. At 1 AU their interplanetary counterparts (ICMEs) generally have a number of distinct plasma and field signatures that distinguish them from the ambient solar wind. These include heat flux dropouts, bi-directional streaming, enhanced alpha particle events, times of depressed proton temperatures, intervals of distorted or enhanced magnetic field, and times of large magnetic field rotations characteristic of magnetic clouds. The first three of these signatures are phenomena that occur at some point within the ICME, but do not necessarily persist throughout the entire ICME. The large scale magnetic field rotations, distortions and enhancements, and the proton temperature depressions tend to mark more accurately the beginning and end of the ICME proper. We examine herein the reliability with which each of these markers identifies ICMEs utilizing ISEE-3 data from 1978 - 1980. copyright 1999 American Institute of Physics

  15. In situ magnetic field measurements during AMPTE solar wind Li+ releases

    International Nuclear Information System (INIS)

    Luehr, H.; Southwood, D.J.; Kloecker, N.; Acuna, M.; Haeusler, B.; Dunlop, M.W.; Mier-Jedrzejowicz, W.A.C.; Rijnbeek, R.P.; Six, M.

    1986-01-01

    Data recorded by the magnetometers on the German (IRM) and British (UKS) spacecraft of the Active Magnetospheric Particle Tracer Explorers (AMPTE) spacecraft mission are described during the immediate period following the two releases of lithium from the IRM during September. Ions created in the first seconds of the release form a coherent obstacle to solar wind flow. A cavity from which the interplanetary magnetic field is excluded is detected. Outside the cavity the field is compressed, and subsequently the cavity is convected downstream. We compare what is observed with other relevant natural interactions but also emphasize the unique features of this experiment

  16. 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

  17. 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)

  18. Remarks on transport theories of interplanetary fluctuations

    International Nuclear Information System (INIS)

    Ye Zhou; Matthaeus, W.H.

    1990-01-01

    The structure of approximate transport theories for the radial behavior of interplanetary fluctuations is reconsidered. The emphasis is on theories derived under the assumption of scale separation; i.e., the correlation length of the fluctuations is much less than the scale of large inhomogeneities. In these cases the zero-wavelength limit provides a first approximation to the spectral evolution equations for the radial dependence of interplanetary fluctuation spectra. The goal here is to investigate the structure of a recently presented (Zhou and Matthaeus, 1989) transport theory, in which coupling of inward- and outward-type fluctuations appears in the leading order, an effect the authors call mixing. In linear theory, mixing-type couplings of inward-type and outward-type waves are formally a nonresonant effect. However, leading order mixing terms do not vanish at zero wavelength for fluctuations that vary nearly perpendicular to the local magnetic field, or when the mean magnetic field is weak. Leading order mixing terms also survive when the dispersion relation fails and there is a nonunique relationship between frequency and wave number. The former case corresponds to nearly two-dimensional structures; these are included, for example, in isotropic models of turbulence. The latter instance occurs when wave-wave couplings are sufficiently strong. Thus there are a variety of situations in which leading order mixing effects are expected to be present

  19. 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

  20. 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.

  1. Investigations on magnetic field induced optical transparency in magnetic nanofluids

    Science.gov (United States)

    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.

  2. The dynamic behavior of magnetic fluid adsorbed to small permanent magnet in alternating magnetic field

    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.

  3. 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.

  4. Magnetic field of mars from data of simultaneous measurements in the planet's magnetosphere and in the solar wind

    International Nuclear Information System (INIS)

    Dolginov, S.S.; Shkol'nikova, S.I.; Zhuzgov, L.N.

    1985-01-01

    This paper examines the parameters of the magnetic dipole of Mars according to measurements by the Mars-2 probe on February 23-24, 1972. In all components there were observed fields of marked intensity in the components; however, at the second pass of the pericenter no field of marked intensity was observed. The passage through zero and change of polarity of the radial component Y /sub m/ of the field was also revealed in the magnetogram. The results of simultaneous measurements of interplanetary magnetic fields near Mars on its day and night sides and data on the dynamic pressure of the solar wind (IMP-6) are compared. The existence of a Martian magnetic field with a magnetic moment that is an effective obstacle to the solar wind is demonstrated. It is estimated that, with the width of the polar cap of Mars ca 45 degrees, the magnetic tail of the Martian magnetosphere can reach as far as 90R /sub M/

  5. Tripolar electric field Structure in guide field magnetic reconnection

    OpenAIRE

    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...

  6. 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

  7. 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.

  8. 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.

  9. 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)

  10. 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

  11. Geomagnetic Field Variation during Winter Storm at Localized ...

    Indian Academy of Sciences (India)

    that transports plasma and magnetic flux which create the geomagnetic field variation. Key words. Dst—vertical component of interplanetary magnetic field and geomagnetic field components. 1. Introduction. The magnetic field is one of the important properties of the earth. The main magnetic field originates from ...

  12. 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

  13. Magnetic field dependent atomic tunneling in non-magnetic glasses

    Science.gov (United States)

    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.

  14. Correlation of ICME Magnetic Fields at Radially Aligned Spacecraft

    Science.gov (United States)

    Good, S. W.; Forsyth, R. J.; Eastwood, J. P.; Möstl, C.

    2018-03-01

    The magnetic field structures of two interplanetary coronal mass ejections (ICMEs), each observed by a pair of spacecraft close to radial alignment, have been analysed. The ICMEs were observed in situ by MESSENGER and STEREO-B in November 2010 and November 2011, while the spacecraft were separated by more than 0.6 AU in heliocentric distance, less than 4° in heliographic longitude, and less than 7° in heliographic latitude. Both ICMEs took approximately two days to travel between the spacecraft. The ICME magnetic field profiles observed at MESSENGER have been mapped to the heliocentric distance of STEREO-B and compared directly to the profiles observed by STEREO-B. Figures that result from this mapping allow for easy qualitative assessment of similarity in the profiles. Macroscale features in the profiles that varied on timescales of one hour, and which corresponded to the underlying flux rope structure of the ICMEs, were well correlated in the solar east-west and north-south directed components, with Pearson's correlation coefficients of approximately 0.85 and 0.95, respectively; microscale features with timescales of one minute were uncorrelated. Overall correlation values in the profiles of one ICME were increased when an apparent change in the flux rope axis direction between the observing spacecraft was taken into account. The high degree of similarity seen in the magnetic field profiles may be interpreted in two ways. If the spacecraft sampled the same region of each ICME ( i.e. if the spacecraft angular separations are neglected), the similarity indicates that there was little evolution in the underlying structure of the sampled region during propagation. Alternatively, if the spacecraft observed different, nearby regions within the ICMEs, it indicates that there was spatial homogeneity across those different regions. The field structure similarity observed in these ICMEs points to the value of placing in situ space weather monitors well upstream of the

  15. Swarm: ESA's Magnetic Field Mission

    Science.gov (United States)

    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.

  16. Strongly interacting matter in magnetic fields

    CERN Document Server

    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...

  17. High magnetic fields science and technology

    CERN Document Server

    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

  18. 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.

  19. 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.

  20. 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....

  1. 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.

  2. Effect of magnetic field on food freezing

    OpenAIRE

    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...

  3. Magnetic field sensor for isotropically sensing an incident magnetic field in a sensor plane

    Science.gov (United States)

    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.

  4. Novel Electrochemical Phenomena in Magnetic Fields(Research in High Magnetic Fields)

    OpenAIRE

    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.

  5. Magnetic field measurements and mapping techniques

    CERN Multimedia

    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.

  6. 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.

  7. 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

  8. 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.)

  9. Magnetic vector field tag and seal

    Science.gov (United States)

    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.

  10. 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

  11. 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

  12. 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

  13. The strongest magnetic fields in the universe

    CERN Document Server

    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.

  14. 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)

  15. Magnetic Fields of the Earth and Mars a Comparison and Discussion

    Science.gov (United States)

    Taylor, Patrick T.

    2004-01-01

    In several aspects the magnetic fields of the Earth and Mars are similar but also different. In the past both bodies had planetary magnetic fields but while they Earth's field remains today the Martian ceased to operate, at some unknown time in the past, leaving this planet without a main or core field. This fact resulted in the interaction between the solar and interplanetary magnetic fields with the surfaces of these planets being very different. In addition, Mars has large crustal magnetic anomalies, nearly ten times larger than those on the Earth. Since crustal magnetic anomalies are the product of the thickness of the layer of magnetization, both the magnetizing material and the thickness of the layer of this material must be very different on Mars than Earth. Furthermore, the martian anomalies can only be produced by remanent or fossil magnetization, in contrast with the Earth where both induced and remanent magnetization are producing these anomalies. Crustal magnetic anomalies on the Earth are mainly produced by single-domain, irontitanium oxides, in the form of magnetite being the most common on Mars the main magnetic mineral(s) are unknown. The thickness of the martian magnetized layer in comparison with the Earth remains a major area for research. Determining the paleopole position for the Earth has been done by some of the earliest paleomagnetic researchers. Since we do not have oriented martian rock samples determining the paleopoles for Mars has been done by fitting a magnetization vector to individual magnetic anomalies. Several groups have worked on this problem with somewhat differing results.

  16. Reducing Field Distortion in Magnetic Resonance Imaging

    Science.gov (United States)

    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

  17. 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)

  18. 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

  19. Erratum to "Solar Sources and Geospace Consequences of Interplanetary Magnetic Clouds Observed During Solar Cycle 23-Paper 1" [J. Atmos. Sol.-Terr. Phys. 70(2-4) (2008) 245-253

    Science.gov (United States)

    Gopalswamy, N.; Akiyama, S.; Yashiro, S.; Michalek, G.; Lepping, R. P.

    2009-01-01

    One of the figures (Fig. 4) in "Solar sources and geospace consequences of interplanetary magnetic Clouds observed during solar cycle 23 -- Paper 1" by Gopalswamy et al. (2008, JASTP, Vol. 70, Issues 2-4, February 2008, pp. 245-253) is incorrect because of a software error in t he routine that was used to make the plot. The source positions of various magnetic cloud (MC) types are therefore not plotted correctly.

  20. 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

  1. 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.

  2. Recent perspectives in solar physics - Elemental composition, coronal structure and magnetic fields, solar activity

    Science.gov (United States)

    Newkirk, G., Jr.

    1975-01-01

    Elemental abundances in the solar corona are studied. Abundances in the corona, solar wind and solar cosmic rays are compared to those in the photosphere. The variation in silicon and iron abundance in the solar wind as compared to helium is studied. The coronal small and large scale structure is investigated, emphasizing magnetic field activity and examining cosmic ray generation mechanisms. The corona is observed in the X-ray and EUV regions. The nature of coronal transients is discussed with emphasis on solar-wind modulation of galactic cosmic rays. A schematic plan view of the interplanetary magnetic field during sunspot minimum is given showing the presence of magnetic bubbles and their concentration in the region around 4-5 AU by a fast solar wind stream.

  3. 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

  4. 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.)

  5. 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

  6. The Evolution of the Earth's Magnetic Field.

    Science.gov (United States)

    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)

  7. Outer Radiation Belt Dropout Dynamics Following the Arrival of Two Interplanetary Coronal Mass Ejections

    Science.gov (United States)

    Alves, L. R.; Da Silva, L. A.; Souza, V. M.; Sibeck, D. G.; Jauer, P. R.; Vieira, L. E. A.; Walsh, B. M.; Silveira, M. V. D.; Marchezi, J. P.; Rockenbach, M.; hide

    2016-01-01

    Magnetopause shadowing and wave-particle interactions are recognized as the two primary mechanisms for losses of electrons from the outer radiation belt. We investigate these mechanisms, sing satellite observations both in interplanetary space and within the magnetosphere and particle drift modeling. Two interplanetary shocks sheaths impinged upon the magnetopause causing a relativistic electron flux dropout. The magnetic cloud (C) and interplanetary structure sunward of the MC had primarily northward magnetic field, perhaps leading to a concomitant lack of substorm activity and a 10 day long quiescent period. The arrival of two shocks caused an unusual electron flux dropout. Test-particle simulations have shown 2 to 5 MeV energy, equatorially mirroring electrons with initial values of L 5.5can be lost to the magnetosheath via magnetopause shadowing alone. For electron losses at lower L-shells, coherent chorus wave-driven pitch angle scattering and ULF wave-driven radial transport have been shownto be viable mechanisms.

  8. Tripolar electric field Structure in guide field magnetic reconnection

    Science.gov (United States)

    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.

  9. 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.

  10. Observing Interstellar and Intergalactic Magnetic Fields

    Science.gov (United States)

    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.

  11. Propagation Characteristics of Two Coronal Mass Ejections from the Sun Far into Interplanetary Space

    Energy Technology Data Exchange (ETDEWEB)

    Zhao, Xiaowei; Liu, Ying D.; Hu, Huidong; Wang, Rui, E-mail: liuxying@spaceweather.ac.cn [State Key Laboratory of Space Weather, National Space Science Center, Chinese Academy of Sciences, Beijing 100190 (China)

    2017-03-01

    Propagation of coronal mass ejections (CMEs) from the Sun far into interplanetary space is not well understood, due to limited observations. In this study we examine the propagation characteristics of two geo-effective CMEs, which occurred on 2005 May 6 and 13, respectively. Significant heliospheric consequences associated with the two CMEs are observed, including interplanetary CMEs (ICMEs) at the Earth and Ulysses , interplanetary shocks, a long-duration type II radio burst, and intense geomagnetic storms. We use coronagraph observations from SOHO /LASCO, frequency drift of the long-duration type II burst, in situ measurements at the Earth and Ulysses , and magnetohydrodynamic propagation of the observed solar wind disturbances at 1 au to track the CMEs from the Sun far into interplanetary space. We find that both of the CMEs underwent a major deceleration within 1 au and thereafter a gradual deceleration when they propagated from the Earth to deep interplanetary space, due to interactions with the ambient solar wind. The results also reveal that the two CMEs interacted with each other in the distant interplanetary space even though their launch times on the Sun were well separated. The intense geomagnetic storm for each case was caused by the southward magnetic fields ahead of the CME, stressing the critical role of the sheath region in geomagnetic storm generation, although for the first case there is a corotating interaction region involved.

  12. Simultaneous observations of solar MeV particles in a magnetic cloud and in the earth's northern tail lobe - Implications for the global field line topology of magnetic clouds and for the entry of solar particles into the magnetosphere during cloud passage

    Science.gov (United States)

    Farrugia, C. J.; Richardson, I. G.; Burlaga, L. F.; Lepping, R. P.; Osherovich, V. A.

    1993-01-01

    Simultaneous ISEE 3 and IMP 8 spacecraft observations of magnetic fields and flow anisotropies of solar energetic protons and electrons during the passage of an interplanetary magnetic cloud show various particle signature differences at the two spacecraft. These differences are interpretable in terms of the magnetic line topology of the cloud, the connectivity of the cloud field lines to the solar surface, and the interconnection between the magnetic fields of the magnetic clouds and of the earth. These observations are consistent with a magnetic cloud model in which these mesoscale configurations are curved magnetic flux ropes attached at both ends to the sun's surface, extending out to 1 AU.

  13. 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

  14. Magnetic field errors tolerances of Nuclotron booster

    Science.gov (United States)

    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.

  15. Science objectives of the magnetic field experiment onboard Aditya-L1 spacecraft

    Science.gov (United States)

    Yadav, Vipin K.; Srivastava, Nandita; Ghosh, S. S.; Srikar, P. T.; Subhalakshmi, Krishnamoorthy

    2018-01-01

    The Aditya-L1 is first Indian solar mission scheduled to be placed in a halo orbit around the first Lagrangian point (L1) of Sun-Earth system in the year 2018-19. The approved scientific payloads onboard Aditya-L1 spacecraft includes a Fluxgate Digital Magnetometer (FGM) to measure the local magnetic field which is necessary to supplement the outcome of other scientific experiments onboard. The in-situ vector magnetic field data at L1 is essential for better understanding of the data provided by the particle and plasma analysis experiments, onboard Aditya-L1 mission. Also, the dynamics of Coronal Mass Ejections (CMEs) can be better understood with the help of in-situ magnetic field data at the L1 point region. This data will also serve as crucial input for the short lead-time space weather forecasting models. The proposed FGM is a dual range magnetic sensor on a 6 m long boom mounted on the Sun viewing panel deck and configured to deploy along the negative roll direction of the spacecraft. Two sets of sensors (tri-axial each) are proposed to be mounted, one at the tip of boom (6 m from the spacecraft) and other, midway (3 m from the spacecraft). The main science objective of this experiment is to measure the magnitude and nature of the interplanetary magnetic field (IMF) locally and to study the disturbed magnetic conditions and extreme solar events by detecting the CME from Sun as a transient event. The proposed secondary science objectives are to study the impact of interplanetary structures and shock solar wind interaction on geo-space environment and to detect low frequency plasma waves emanating from the solar corona at L1 point. This will provide a better understanding on how the Sun affects interplanetary space. In this paper, we shall give the main scientific objectives of the magnetic field experiment and brief technical details of the FGM onboard Aditya-1 spacecraft.

  16. 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)

  17. 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

  18. 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

  19. 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

  20. Earth magnetism a guided tour through magnetic fields

    CERN Document Server

    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

  1. 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 )

  2. Classical theory of electric and magnetic fields

    CERN Document Server

    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

  3. 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.

  4. 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)

  5. 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.

  6. Orienting Paramecium with intense static magnetic fields

    Science.gov (United States)

    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).

  7. 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.)

  8. Bats Respond to Very Weak Magnetic Fields

    Science.gov (United States)

    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

  9. Cluster magnetic field observations of the bowshock: Orientation, motion and structure

    Directory of Open Access Journals (Sweden)

    T. S. Horbury

    Full Text Available Four spacecraft Cluster magnetic field observations of the low quasi-perpendicular terrestrial bowshock are presented for the first time. Multiple quasi-perpendicular crossings on 25 December 2000 are analysed. By combining data from the four spacecraft, bowshock orientations and velocities can be calculated. It is shown that, even while in rapid motion, the bowshock normal direction remains remarkably constant, and that coplanarity estimates are accurate to, typically, around 20°. Magnetic field magnitude profiles are shown to be very well correlated between spacecraft although downstream waves with fluctuations perpendicular to the local field, while statistically similar at all four spacecraft, are poorly correlated on separation scales of several hundred km. Examples are shown of a number of bowshock phenomena, including non-standing fluctuations in the shock foot and the shock interacting with changing solar wind conditions.

    Key words. Interplanetary physics (planetary bow shocks Space plasma physics (shock waves; waves and instabilities

  10. Cluster magnetic field observations of the bowshock: Orientation, motion and structure

    Directory of Open Access Journals (Sweden)

    T. S. Horbury

    2001-09-01

    Full Text Available Four spacecraft Cluster magnetic field observations of the low quasi-perpendicular terrestrial bowshock are presented for the first time. Multiple quasi-perpendicular crossings on 25 December 2000 are analysed. By combining data from the four spacecraft, bowshock orientations and velocities can be calculated. It is shown that, even while in rapid motion, the bowshock normal direction remains remarkably constant, and that coplanarity estimates are accurate to, typically, around 20°. Magnetic field magnitude profiles are shown to be very well correlated between spacecraft although downstream waves with fluctuations perpendicular to the local field, while statistically similar at all four spacecraft, are poorly correlated on separation scales of several hundred km. Examples are shown of a number of bowshock phenomena, including non-standing fluctuations in the shock foot and the shock interacting with changing solar wind conditions.Key words. Interplanetary physics (planetary bow shocks Space plasma physics (shock waves; waves and instabilities

  11. 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.)

  12. Suprathermal protons in the interplanetary solar wind

    Science.gov (United States)

    Goodrich, C. C.; Lazarus, A. J.

    1976-01-01

    Using the Mariner 5 solar wind plasma and magnetic field data, we present observations of field-aligned suprathermal proton velocity distributions having pronounced high-energy shoulders. These observations, similar to the interpenetrating stream observations of Feldman et al. (1974), are clear evidence that such proton distributions are interplanetary rather than bow shock associated phenomena. Large Alfven speed is found to be a requirement for the occurrence of suprathermal proton distribution; further, we find the proportion of particles in the shoulder to be limited by the magnitude of the Alfven speed. It is suggested that this last result could indicate that the proton thermal anisotropy is limited at times by wave-particle interactions

  13. Magnetic fields of HgMn stars

    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...

  14. 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.

  15. Magnetic fields in noninvasive brain stimulation.

    Science.gov (United States)

    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.

  16. Field Mapping System for Solenoid Magnet

    Science.gov (United States)

    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.

  17. 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}.

  18. 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.

  19. 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

  20. Magnetic Field Measurements In Magnetized Plasmas Using Zeeman Broadening Diagnostics

    Science.gov (United States)

    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.

  1. 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.

  2. 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

  3. 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)

  4. Lightning magnetic field measuring system in Bogota

    OpenAIRE

    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 ...

  5. 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

  6. 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)

  7. 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

  8. Neutron stars velocities and magnetic fields

    Science.gov (United States)

    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.

  9. Magnetization of dense neutron matter in a strong magnetic field

    International Nuclear Information System (INIS)

    Isaev, A.A.; Yang, J.

    2010-01-01

    Spin polarized states in neutron matter at a strong magnetic field up to 1018 G are considered in the model with the Skyrme effective interaction. Analyzing the self consistent equations at zero temperature, it is shown that a thermodynamically stable branch of solutions for the spin polarization parameter as a function of the density corresponds to the negative spin polarization when the majority of neutron spins are oriented oppositely to the direction of the magnetic field. In addition, beginning from some threshold density dependent on the magnetic field strength, the self-consistent equations have also two other branches of solutions for the spin polarization parameter with the positive spin polarization. The free energy corresponding to one of these branches turns out to be very close to the free energy corresponding to the thermodynamically preferable branch with the negative spin polarization. As a consequence, at a strong magnetic field, the state with the positive spin polarization can be realized as a metastable state at the high density region in neutron matter which changes into a thermodynamically stable state with the negative spin polarization with decrease in the density at some threshold value. The calculations of the neutron spin polarization parameter, energy per neutron, and chemical potentials of spin-up and spin-down neutrons as functions of the magnetic field strength show that the influence of the magnetic field remains small at the field strengths up to 1017 G.

  10. Tuning bacterial hydrodynamics with magnetic fields

    Science.gov (United States)

    Pierce, C. J.; Mumper, E.; Brown, E. E.; Brangham, J. T.; Lower, B. H.; Lower, S. K.; Yang, F. Y.; Sooryakumar, R.

    2017-06-01

    Magnetotactic bacteria are a group of motile prokaryotes that synthesize chains of lipid-bound, magnetic nanoparticles called magnetosomes. This study exploits their innate magnetism to investigate previously unexplored facets of bacterial hydrodynamics at surfaces. Through use of weak, uniform, external magnetic fields and local, micromagnetic surface patterns, the relative strength of hydrodynamic, magnetic, and flagellar force components is tuned through magnetic control of the bacteria's orientation. The resulting swimming behaviors provide a means to experimentally determine hydrodynamic parameters and offer a high degree of control over large numbers of living microscopic entities. The implications of this controlled motion for studies of bacterial motility near surfaces and for micro- and nanotechnology are discussed.

  11. Solar cycle variation of cosmic ray intensity along with interplanetary and solar wind plasma parameters

    International Nuclear Information System (INIS)

    Mishra, R.K.; Tiwari, S.; Agarwal, R.

    2008-01-01

    Galactic cosmic rays are modulated at their propagation in the heliosphere by the effect of the large-scale structure of the interplanetary medium. A comparison of the variations in the cosmic ray intensity data obtained by neutron monitoring stations with those in geomagnetic disturbance, solar wind velocity (V), interplanetary magnetic field (B), and their product (V , B) near the Earth for the period 1964-2004 has been presented so as to establish a possible correlation between them. We used the hourly averaged cosmic ray counts observed with the neutron monitor in Moscow. It is noteworthy that a significant negative correlation has been observed between the interplanetary magnetic field, product (V , B) and cosmic ray intensity during the solar cycles 21 and 22. The solar wind velocity has a good positive correlation with cosmic ray intensity during solar cycle 21, whereas it shows a weak correlation during cycles 20, 22 and 23. The interplanetary magnetic field shows a weak negative correlation with cosmic rays for solar cycle 20, and a good anti-correlation for solar cycles 21-23 with the cosmic ray intensity, which, in turn, shows a good positive correlation with disturbance time index (Dst) during solar cycles 21 and 22, and a weak correlation for cycles 20 and 23. (Authors)

  12. Magnetic Fields in the Early Universe

    CERN Document Server

    Grasso, D; Grasso, D

    2001-01-01

    This review concerns the origin and the possible effects of magnetic fields in the early Universe. We start by providing to the reader with a short overview of the current state of art of observations of cosmic magnetic fields. We then illustrate the arguments in favour of a primordial origin of magnetic fields in the galaxies and in the clusters of galaxies. We argue that the most promising way to test this hypothesis is to look for possible imprints of magnetic fields on the temperature and polarization anisotropies of the cosmic microwave background radiation (CMBR). With this purpose in mind, we provide a review of the most relevant effects of magnetic fields on the CMBR. A long chapter of this review is dedicated to particle physics inspired models which predict the generation of magnetic fields during the early Universe evolution. Although it is still unclear if any of these models can really explain the origin of galactic and intergalactic magnetic fields, we show that interesting effects may arise any...

  13. The characterisation of magnetic pigment dispersions using pulsed magnetic fields

    International Nuclear Information System (INIS)

    Blackwell, J.J.; O'Grady, K.; Nelson, N.K.; Sharrock, M.P.

    2003-01-01

    In this work, we describe the application of pulsed field magnetometry techniques for the characterisation of magnetic pigment dispersions. Magnetic pigment dispersions are important technological materials as in one form they are the material which are used to coat base film in order to make magnetic recording tape. It is these materials that have been evaluated. In this work, we describe the use of two pulsed field magnetometers, one being a low-field instrument with a maximum field of 750 Oe and the other a high-field instrument with a maximum field of 4.1 kOe. Using inductive sensing, the magnetisation is monitored in real time as the pulse is applied. We find that using these techniques we can successfully monitor the progress of the dispersion process, the effects of different resin systems and the effect of different processing conditions. We find that our results are consistent with rheological and other measurements

  14. The characterisation of magnetic pigment dispersions using pulsed magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Blackwell, J.J.; O' Grady, K. E-mail: kog1@york.ac.uk; Nelson, N.K.; Sharrock, M.P

    2003-10-01

    In this work, we describe the application of pulsed field magnetometry techniques for the characterisation of magnetic pigment dispersions. Magnetic pigment dispersions are important technological materials as in one form they are the material which are used to coat base film in order to make magnetic recording tape. It is these materials that have been evaluated. In this work, we describe the use of two pulsed field magnetometers, one being a low-field instrument with a maximum field of 750 Oe and the other a high-field instrument with a maximum field of 4.1 kOe. Using inductive sensing, the magnetisation is monitored in real time as the pulse is applied. We find that using these techniques we can successfully monitor the progress of the dispersion process, the effects of different resin systems and the effect of different processing conditions. We find that our results are consistent with rheological and other measurements.

  15. Geometrical Relationship Between Interplanetary Flux Ropes and Their Solar Sources

    Science.gov (United States)

    Marubashi, K.; Akiyama, S.; Yashiro, S.; Gopalswamy, N.; Cho, K.-S.; Park, Y.-D.

    2015-05-01

    We investigated the physical connection between interplanetary flux ropes (IFRs) near Earth and coronal mass ejections (CMEs) by comparing the magnetic field structures of IFRs and CME source regions. The analysis is based on the list of 54 pairs of ICMEs (interplanetary coronal mass ejections) and CMEs that are taken to be the most probable solar source events. We first attempted to identify the flux rope structure in each of the 54 ICMEs by fitting models with a cylinder and torus magnetic field geometry, both with a force-free field structure. This analysis determined the possible geometries of the identified flux ropes. Then we compared the flux rope geometries with the magnetic field structure of the solar source regions. We obtained the following results: (1) Flux rope structures are seen in 51 ICMEs out of the 54. The result implies that all ICMEs have an intrinsic flux rope structure, if the three exceptional cases are attributed to unfavorable observation conditions. (2) It is possible to find flux rope geometries with the main axis orientation close to the orientation of the magnetic polarity inversion line (PIL) in the solar source regions, the differences being less than 25°. (3) The helicity sign of an IFR is strongly controlled by the location of the solar source: flux ropes with positive (negative) helicity are associated with sources in the southern (northern) hemisphere (six exceptions were found). (4) Over two-thirds of the sources in the northern hemisphere are concentrated along PILs with orientations of 45° ± 30° (measured clockwise from the east), and over two-thirds in the southern hemisphere along PILs with orientations of 135° ± 30°, both corresponding to the Hale boundaries. These results strongly support the idea that a flux rope with the main axis parallel to the PIL erupts in a CME and that the erupted flux rope propagates through the interplanetary space with its orientation maintained and is observed as an IFR.

  16. Design of integral magnetic field sensor

    International Nuclear Information System (INIS)

    Ma Liang; Cheng Yinhui; Wu Wei; Li Baozhong; Zhou Hui; Li Jinxi; Zhu Meng

    2010-01-01

    Magnetic field is one of the important physical parameters in the measuring process of pulsed EMP. We researched on anti-interference and high-sensitivity measurement technique of magnetic field in this report. Semi rigid cables were to bent into ringed antenna so that the antenna was shielded from electric-field interference and had little inductance; In order to have high sensitivity, operational transconductance amplifier was used to produce an active integrator; We designed an optical-electronic transferring module to upgrade anti-interference capability of the magnetic-field measurement system. A measurement system of magnetic field was accomplished. The measurement system was composed of antenna, integrator, and optical-electric transferring module and so on. We calibrated the measurement system in coaxial TEM cell. It indicates that, the measurement system's respondence of rise time is up to 2.5 ns, and output width at 90%-maximum of the pulse is wider than 200 ns. (authors)

  17. Magnetic field aberration induced by cycle stress

    International Nuclear Information System (INIS)

    Yang En; Li Luming; Chen Xing

    2007-01-01

    Magneto-mechanical effect has been causing people's growing interest because of its relevance to several technology problems. One of them is the variation of surface magnetic field induced by stress concentration under the geomagnetic field. It can be used as an innovative, simple and convenient potential NDE method, called as magnetic memory method. However, whether and how this can be used as a quantitative measurement method, is still a virginal research field where nobody sets foot in. In this paper, circle tensile stress within the elastic region was applied to ferromagnetic sample under geomagnetic field. Experiment results on the relation between surface magnetic field and elastic stress were presented, and a simple model was derived. Simulation of the model was reconciled with the experimental results. This can be of great importance for it provides a brighter future for the promising Magnetic Memory NDE method-the potential possibility of quantitative measurement

  18. Graphene spin capacitor for magnetic field sensing

    OpenAIRE

    Semenov, Y. G.; Zavada, J. M.; Kim, K. W.

    2010-01-01

    An analysis of a novel magnetic field sensor based on a graphene spin capacitor is presented. The proposed device consists of graphene nanoribbons on top of an insulator material connected to a ferromagnetic source/drain. The time evolution of spin polarized electrons injected into the capacitor can be used for an accurate determination at room temperature of external magnetic fields. Assuming a spin relaxation time of 100 ns, magnetic fields on the order of $\\sim 10$ mOe may be detected at r...

  19. Dissipative charged fluid in a magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Abbasi, Navid; Davody, Ali, E-mail: davody.phy@gmail.com

    2016-05-10

    We study the collective excitations in a dissipative charged fluid at zero chemical potential when an external magnetic field is present. While in the absence of magnetic field, four collective excitations appear in the fluid, we find five hydrodynamic modes here. This implies that the magnetic field splits the degeneracy between the transverse shear modes. Using linear response theory, we then compute the retarded response functions. In particular, it turns out that the correlation between charge and the energy fluctuations will no longer vanish, even at zero chemical potential. By use of the response functions, we also derive the relevant Kubo formulas for the transport coefficients.

  20. Relativistic stars with purely toroidal magnetic fields

    International Nuclear Information System (INIS)

    Kiuchi, Kenta; Yoshida, Shijun

    2008-01-01

    We investigate the effects of the purely toroidal magnetic field on the equilibrium structures of the relativistic stars. The basic equations for obtaining equilibrium solutions of relativistic rotating stars containing purely toroidal magnetic fields are derived for the first time. To solve these basic equations numerically, we extend the Cook-Shapiro-Teukolsky scheme for calculating relativistic rotating stars containing no magnetic field to incorporate the effects of the purely toroidal magnetic fields. By using the numerical scheme, we then calculate a large number of the equilibrium configurations for a particular distribution of the magnetic field in order to explore the equilibrium properties. We also construct the equilibrium sequences of the constant baryon mass and/or the constant magnetic flux, which model the evolution of an isolated neutron star as it loses angular momentum via the gravitational waves. Important properties of the equilibrium configurations of the magnetized stars obtained in this study are summarized as follows: (1) For the nonrotating stars, the matter distribution of the stars is prolately distorted due to the toroidal magnetic fields. (2) For the rapidly rotating stars, the shape of the stellar surface becomes oblate because of the centrifugal force. But, the matter distribution deep inside the star is sufficiently prolate for the mean matter distribution of the star to be prolate. (3) The stronger toroidal magnetic fields lead to the mass shedding of the stars at the lower angular velocity. (4) For some equilibrium sequences of the constant baryon mass and magnetic flux, the stars can spin up as they lose angular momentum.

  1. Conductance of auroral magnetic field lines

    International Nuclear Information System (INIS)

    Weimer, D.R.; Gurnett, D.A.; Goertz, C.K.

    1986-01-01

    DE-1 high-resolution double-probe electric-field data and simultaneous magnetic-field measurements are reported for two 1981 events with large electric fields which reversed over short distances. The data are presented graphically and analyzed in detail. A field-line conductance of about 1 nmho/sq m is determined for both upward and downward currents, and the ionospheric conductivity is shown, in the short-wavelength limit, to have little effect on the relationship between the (N-S) electric and (E-W) magnetic fields above the potential drop parallel to the magnetic-field lines. The results are found to be consistent with a linear relationship between the field-aligned current density and the parallel potential drop. 14 references

  2. Magnetic fields in the early solar system

    International Nuclear Information System (INIS)

    Strangway, D.W.

    1980-01-01

    Most of the terrestrial planets and the meteorites contain records of early magnetic fields. In the Allende meteorite some of the chondrules were magnetized in fields of about 10 Oe. When assembled into the meteorite, they remained randomly oriented but were partially remagnetized in a field of 1 Oe at temperatures of 200-300 0 C. They present dipole moment of Mercury and the weak dipole moment of Mars may be due to the cooling of a crust in the presence of early magnetic fields. The Earth on the other hand, has had an active dynamo for at least 3 Ga and probably longer, although there is no discernible record of earlier fields due to extensive reheating of the magnetic carriers. Venus has no dynamo field and its surface temperature is too high to carry a crustal remanence. The Moon has no dipole, but local islands of magnetization are believed to be the results of breccias cooling in the presence of an early field, possibly in itself a crustal memory. As we learn about the fields of the planets and the magnetic record contained in their samples we may be able to put sharp constraints on the earliest history of planet formation and evolution. (Auth.)

  3. Magnetic field decay in black widow pulsars

    Science.gov (United States)

    Mendes, Camile; de Avellar, Marcio G. B.; Horvath, J. E.; Souza, Rodrigo A. de; Benvenuto, O. G.; De Vito, M. A.

    2018-04-01

    We study in this work the evolution of the magnetic field in `redback-black widow' pulsars. Evolutionary calculations of these `spider' systems suggest that first the accretion operates in the redback stage, and later the companion star ablates matter due to winds from the recycled pulsar. It is generally believed that mass accretion by the pulsar results in a rapid decay of the magnetic field when compared to the rate of an isolated neutron star. We study the evolution of the magnetic field in black widow pulsars by solving numerically the induction equation using the modified Crank-Nicolson method with intermittent episodes of mass accretion on to the neutron star. Our results show that the magnetic field does not fall below a minimum value (`bottom field') in spite of the long evolution time of the black widow systems, extending the previous conclusions for much younger low-mass X-ray binary systems. We find that in this scenario, the magnetic field decay is dominated by the accretion rate, and that the existence of a bottom field is likely related to the fact that the surface temperature of the pulsar does not decay as predicted by the current cooling models. We also observe that the impurity of the pulsar crust is not a dominant factor in the decay of magnetic field for the long evolution time of black widow systems.

  4. Electromagnetic fields of rotating magnetized NUT stars

    International Nuclear Information System (INIS)

    Ahmedov, B.J.; Khugaev, A.V.; Ahmedov, B.J.

    2004-01-01

    Full text: Analytic general relativistic expressions for the electromagnetic fields external to a slowly-rotating magnetized NUT star with nonvanishing gravitomagnetic charge have been presented. Solutions for the electric and magnetic fields have been found after separating the Maxwell equations in the external background spacetime of a slowly rotating NUT star into angular and radial parts in the lowest order approximation. The star is considered isolated and in vacuum, with different models for stellar magnetic field: i) monopolar magnetic field and II) dipolar magnetic field aligned with the axis of rotation. We have shown that the general relativistic corrections due to the dragging of reference frames and gravitomagnetic charge are not present in the form of the magnetic fields but emerge only in the form of the electric fields. In particular, we have shown that the frame-dragging and gravitomagnetic charge provide an additional induced electric field which is analogous to the one introduced by the rotation of the star in the flat spacetime limit

  5. Generation of high magnetic fields using superconducting magnets

    International Nuclear Information System (INIS)

    Kiyoshi, T.; Otsuka, A.; Kosuge, M.; Yuyama, M.; Nagai, H.; Matsumoto, F.

    2006-01-01

    High-field superconducting magnets have opened new frontiers for several kinds of applications, such as fusion reactors, particle accelerators, and nuclear magnetic resonance (NMR) spectrometers. The present record for the highest field in a fully superconducting state is 23.4 T. It was achieved with a combination of NbTi, Nb 3 Sn, and Bi-2212 conductors in 1999. Since high T c (critical temperature) superconductors (HTS) have sufficiently high critical current density even in excess of 30 T, they are promising for use as high-field superconducting magnets. However, several problems still remain to be resolved for practical applications, and the use of HTS coils will be limited to the inner part of a high-field magnet system in the near future. The required technologies to develop a high-field superconducting magnet with a field of up to 28 T have already been established. Such a magnet is certain to provide information to all leading research areas

  6. Working in the magnetic field of ultrahigh field MRI

    International Nuclear Information System (INIS)

    Leitgeb, N.; Gombotz, H.

    2013-01-01

    Development of magnetic resonance imaging (MRI) device technology continues to increase the static magnetic flux densities applied and consequently leads to considerably increased occupational exposure. This has already made it necessary to review limits of occupational exposure and to postpone European legal regulations for occupational exposure to electromagnetic fields. This raises the question whether and if so which adverse health effects and health risks might be associated with occupational exposure to MRI ultra-high static magnetic fields. Based on a survey on interaction mechanisms recommendations and safety rules are presented to help minimize adverse health effects of emerging ultra-high field MRI. (orig.) [de

  7. Relaxed plasmas in external magnetic fields

    International Nuclear Information System (INIS)

    Spies, G.O.; Li, J.

    1991-08-01

    The well-known theory of relaxed plasmas (Taylor states) is extended to external magnetic fields whose field lines intersect the conducting toroidal boundary. Application to an axially symmetric, large-aspect-ratio torus with circular cross section shows that the maximum pinch ratio, and hence the phenomenon of current saturation, is independent of the external field. The relaxed state is explicitly given for an external octupole field. In this case, field reversal is inhibited near parts of the boundary if the octupole generates magnetic x-points within the plasma. (orig.)

  8. Field simulations for large dipole magnets

    International Nuclear Information System (INIS)

    Lazzaro, A.; Cappuzzello, F.; Cunsolo, A.; Cavallaro, M.; Foti, A.; Khouaja, A.; Orrigo, S.E.A.; Winfield, J.S.

    2007-01-01

    The problem of the description of magnetic field for large bending magnets is addressed in relation to the requirements of modern techniques of trajectory reconstruction. The crucial question of the interpolation and extrapolation of fields known at a discrete number of points is analysed. For this purpose a realistic field model of the large dipole of the MAGNEX spectrometer, obtained with finite elements three dimensional simulations, is used. The influence of the uncertainties in the measured field to the quality of the trajectory reconstruction is treated in detail. General constraints for field measurements in terms of required resolutions, step sizes and precisions are thus extracted

  9. Evolution and interaction of large interplanetary streams

    International Nuclear Information System (INIS)

    Whang, Y.C.; Burlaga, L.F.

    1985-02-01

    A computer simulation for the evolution and interaction of large interplanetary streams based on multi-spacecraft observations and an unsteady, one-dimensional MHD model is presented. Two events, each observed by two or more spacecraft separated by a distance of the order of 10 AU, were studied. The first simulation is based on the plasma and magnetic field observations made by two radially-aligned spacecraft. The second simulation is based on an event observed first by Helios-1 in May 1980 near 0.6 AU and later by Voyager-1 in June 1980 at 8.1 AU. These examples show that the dynamical evolution of large-scale solar wind structures is dominated by the shock process, including the formation, collision, and merging of shocks. The interaction of shocks with stream structures also causes a drastic decrease in the amplitude of the solar wind speed variation with increasing heliocentric distance, and as a result of interactions there is a large variation of shock-strengths and shock-speeds. The simulation results shed light on the interpretation for the interaction and evolution of large interplanetary streams. Observations were made along a few limited trajectories, but simulation results can supplement these by providing the detailed evolution process for large-scale solar wind structures in the vast region not directly observed. The use of a quantitative nonlinear simulation model including shock merging process is crucial in the interpretation of data obtained in the outer heliosphere

  10. The CMS Magnetic Field Map Performance

    CERN Document Server

    Klyukhin, V.I.; Andreev, V.; Ball, A.; Cure, B.; Herve, A.; Gaddi, A.; Gerwig, H.; Karimaki, V.; Loveless, R.; Mulders, M.; Popescu, S.; Sarycheva, L.I.; Virdee, T.

    2010-04-05

    The Compact Muon Solenoid (CMS) is a general-purpose detector designed to run at the highest luminosity at the CERN Large Hadron Collider (LHC). Its distinctive featuresinclude a 4 T superconducting solenoid with 6 m diameter by 12.5 m long free bore, enclosed inside a 10000-ton return yoke made of construction steel. Accurate characterization of the magnetic field everywhere in the CMS detector is required. During two major tests of the CMS magnet the magnetic flux density was measured inside the coil in a cylinder of 3.448 m diameter and 7 m length with a specially designed field-mapping pneumatic machine as well as in 140 discrete regions of the CMS yoke with NMR probes, 3-D Hall sensors and flux-loops. A TOSCA 3-D model of the CMS magnet has been developed to describe the magnetic field everywhere outside the tracking volume measured with the field-mapping machine. A volume based representation of the magnetic field is used to provide the CMS simulation and reconstruction software with the magnetic field ...

  11. A method simulating random magnetic field in interplanetary space by an autoregressive method

    International Nuclear Information System (INIS)

    Kato, Masahito; Sakai, Takasuke

    1985-01-01

    With an autoregressive method, we tried to generate the random noise fitting in with the power spectrum which can be analytically Fouriertransformed into an autocorrelation function. Although we can not directly compare our method with FFT by Owens (1978), we can only point out the following; FFT method should determine at first the number of data points N, or the total length to be generated and we cannot generate random data more than N. Because, beyond the NΔy, the generated data repeats the same pattern as below NΔy, where Δy = minimum interval for random noise. So if you want to change or increase N after generating the random noise, you should start the generation from the first step. The characteristic of the generated random number may depend upon the number of N, judging from the generating method. Once the prediction error filters are determined, our method can produce successively the random numbers, that is, we can possibly extend N to infinite without any effort. (author)

  12. Mercury's magnetosphere-solar wind interaction for northward and southward interplanetary magnetic field: Hybrid simulation results

    Czech Academy of Sciences Publication Activity Database

    Trávníček, Pavel M.; Schriver, D.; Hellinger, Petr; Herčík, David; Anderson, B.J.; Sarantos, M.; Slavin, J.A.

    2010-01-01

    Roč. 209, č. 1 (2010), s. 11-22 ISSN 0019-1035 R&D Projects: GA AV ČR IAA300030805; GA MŠk ME09009 Grant - others:ESA(XE) ESA-PECS project No. 98068; NASA (US) NNX09AD41G; NASA (US) NNX07AR62G Institutional research plan: CEZ:AV0Z10030501; CEZ:AV0Z30420517 Keywords : MESSENGERS 1ST FLYBY * substorms * instability Subject RIV: BN - Astronomy, Celestial Mechanics, Astrophysics Impact factor: 3.813, year: 2010

  13. Reliability of prediction of the magnetosheath Bz component from interplanetary magnetic field observations

    Czech Academy of Sciences Publication Activity Database

    Šafránková, J.; Hayosh, Mykhaylo; Gutynska, O.; Němeček, Z.; Přech, L.

    2009-01-01

    Roč. 114, - (2009), A12213/1-A12213/7 ISSN 0148-0227 R&D Projects: GA ČR GA205/09/0170 Grant - others:GA ČR(CZ) GA205/09/0112 Institutional research plan: CEZ:AV0Z30420517 Keywords : IMF * magnetosheath Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 3.082, year: 2009

  14. Field quality of LHC superconducting dipole magnets

    International Nuclear Information System (INIS)

    Mishra, R.K.

    2003-01-01

    The author reports here the main results of field measurements performed so far on the LHC superconducting dipoles at superfluid helium temperature. The main field strength at injection, collision conditions and higher order multipoles are discussed. Superconducting magnets exhibit additional field imperfections due to diamagnetic properties of superconducting cables, apart from geometric error, saturation of iron yoke and eddy currents error. Dynamic effects on field harmonics, such as field decay at injection and subsequent snap back are also discussed. (author)

  15. Observations of the interplanetary sector structure up to heliographic latitudes of 160: Pioneer 11

    International Nuclear Information System (INIS)

    Smith, E.J.; Tsurutani, B.T.; Rosenberg, R.L.

    1978-01-01

    A study of the interplanetary sector structure at heliographic latitudes up to 16 0 N is reported. The study is based on magnetic field measurements made on board Pioneer 11 as the spacecraft traveled along the post-Jupiter-encounter trajectory. Preliminary measurements are used to determine the dominant polarity of the interplanetary magnetic field during 43 successive solar rotations including Pioneer's ascent to its maximum latitude and motion inward from 5 to 3.7 AU. As the latitude of Pioneer increased, the dominant polarity became continually more positive, corresponding to an outward-directed solar interplanetary field. When the spacecraft reached the highest latitude, the usual sector structure had essentially disappeared. A histogram of the field longitude angle, based on data acquired during 1 month at 16 0 latitude, shows an almost total absence of inward-directed fields. A comparison with interplanetary field polarities in the ecliptic, as inferred from geomagnetic field variations, rules out the possibility that a time variation rather than a latitude dependence is responsible. The Pioneer 11 observations imply that the boundary between adjacent sectors corresponds physically to a current sheet surrounding the sun and lying near parallel to the solar equatorial plane. Above this current sheet, in the northern hemisphere, the field polarity at this phase of the solar cycle is outward, and below the current sheet, in the southern hemisphere, it is inward. The Pioneer observations confirm earlier theoretical suggestions regarding the existence and equatorial orientation of this current sheet. The properties of the current sheet and some major implications and questions associated with it are discussed. It is shown that the radial component of the sheet current is compensated by the distributed currents in the northern and southern hemispheres associated with the spiraled interplanetary field

  16. Open magnetic fields in active regions

    International Nuclear Information System (INIS)

    Svestka, Z.; Solodyna, C.V.; Levine, R.H.

    1977-01-01

    Soft X-ray observations confirm that some of the dark gaps seen between interconnecting loops and inner cores of active regions may be loci of open fields, as it has been predicted by global potential extrapolation of photospheric magnetic fields. It seems that the field lines may open only in a later state of the active region development. (Auth.)

  17. Magnetic monopoles in field theory and cosmology.

    Science.gov (United States)

    Rajantie, Arttu

    2012-12-28

    The existence of magnetic monopoles is predicted by many theories of particle physics beyond the standard model. However, in spite of extensive searches, there is no experimental or observational sign of them. I review the role of magnetic monopoles in quantum field theory and discuss their implications for particle physics and cosmology. I also highlight their differences and similarities with monopoles found in frustrated magnetic systems.

  18. Calculation of magnetic fields for engineering devices

    International Nuclear Information System (INIS)

    Colonias, J.S.

    1976-06-01

    The methodology of magnet technology and its application to various engineering devices are discussed. Magnet technology has experienced a rigid growth in the past few years as a result of the advances made in superconductivity, numerical methods and computational techniques. Included are discussions on: (1) mathematical models for solving magnetic field problems; (2) the applicability, usefulness, and limitations of computer programs that utilize these models; (3) examples of application in various engineering disciplines; and (4) areas where further contributions are needed

  19. Comparison of adjustable permanent magnetic field sources

    DEFF Research Database (Denmark)

    Bjørk, Rasmus; Bahl, Christian Robert Haffenden; Smith, Anders

    2010-01-01

    be altered are analyzed using numerical simulations, and compared based on the generated magnetic flux density in a sample volume and the amount of magnet material used. The designs are the concentric Halbach cylinder, the two half Halbach cylinders, the two linear Halbach arrays and the four and six rod...... and the direction of the magnetic field are measured and compared with numerical simulation and a good agrement is found....

  20. Magnetic field considerations in fusion power plant environs

    International Nuclear Information System (INIS)

    Liemohn, H.B.; Lessor, D.L.; Duane, B.H.

    1976-09-01

    A summary of magnetic field production mechanisms and effects is given. Discussions are included on the following areas: (1) stray magnetic and electric fields from tokamaks, (2) methods for reducing magnetic fields, (3) economics of magnetic field reductions, (4) forces on magnetizable objects near magnetic confinement fusion reactors, (5) electric field transients in tokamaks, (6) attenuation and decay of electromagnetic fields, and (7) magnetic field transients from tokamak malfunctions

  1. Pulsed magnetic field generation suited for low-field unilateral nuclear magnetic resonance systems

    Science.gov (United States)

    Gaunkar, Neelam Prabhu; Selvaraj, Jayaprakash; Theh, Wei-Shen; Weber, Robert; Mina, Mani

    2018-05-01

    Pulsed magnetic fields can be used to provide instantaneous localized magnetic field variations. In presence of static fields, pulsed field variations are often used to apply torques and in-effect to measure behavior of magnetic moments in different states. In this work, the design and experimental performance of a pulsed magnetic field generator suited for low static field nuclear magnetic resonance (NMR) applications is presented. One of the challenges of low bias field NMR measurements is low signal to noise ratio due to the comparable nature of the bias field and the pulsed field. Therefore, a circuit is designed to apply pulsed currents through an inductive load, leading to generation of pulsed magnetic fields which can temporarily overpower the effect of the bias field on magnetic moments. The designed circuit will be tuned to operate at the precession frequency of 1H (protons) placed in a bias field produced by permanent magnets. The designed circuit parameters may be tuned to operate under different bias conditions. Therefore, low field NMR measurements can be performed for different bias fields. Circuit simulations were used to determine design parameters, corresponding experimental measurements will be presented in this work.

  2. On the helicity of open magnetic fields

    International Nuclear Information System (INIS)

    Prior, C.; Yeates, A. R.

    2014-01-01

    We reconsider the topological interpretation of magnetic helicity for magnetic fields in open domains, and relate this to the relative helicity. Specifically, our domains stretch between two parallel planes, and each of these ends may be magnetically open. It is demonstrated that, while the magnetic helicity is gauge-dependent, its value in any gauge may be physically interpreted as the average winding number among all pairs of field lines with respect to some orthonormal frame field. In fact, the choice of gauge is equivalent to the choice of reference field in the relative helicity, meaning that the magnetic helicity is no less physically meaningful. We prove that a particular gauge always measures the winding with respect to a fixed frame, and propose that this is normally the best choice. For periodic fields, this choice is equivalent to measuring relative helicity with respect to a potential reference field. However, for aperiodic fields, we show that the potential field can be twisted. We prove by construction that there always exists a possible untwisted reference field.

  3. The magnetic field in the pile-up region at Mars, and its variation with the solar wind

    DEFF Research Database (Denmark)

    Vennerstrøm, Susanne; Olsen, Nils; Purucker, M.

    2003-01-01

    [1] The magnetic measurements from the Mars Global Surveyor satellite are used to study the magnetic field on the Martian dayside, and its variation with the solar wind. Because of the lack of solar wind measurements near Mars, solar wind measurements near Earth during a period centered on a Mars......-Earth conjunction are used. Concurrent variations at Mars and Earth related to the interplanetary sector-structure and dynamic pressure variations are demonstrated. The study is confined to the northern hemisphere of Mars in regions where the crustal anomalies are weak. Here we find a close association between...

  4. High-field superconducting nested coil magnet

    Science.gov (United States)

    Laverick, C.; Lobell, G. M.

    1970-01-01

    Superconducting magnet, employed in conjunction with five types of superconducting cables in a nested solenoid configuration, produces total, central magnetic field strengths approaching 70 kG. The multiple coils permit maximum information on cable characteristics to be gathered from one test.

  5. Deformable nematic droplets in a magnetic field

    NARCIS (Netherlands)

    Otten, R.H.J.; van der Schoot, P. P. A. M.

    2012-01-01

    We present a Frank-Oseen elasticity theory for the shape and structure of deformable nematic droplets with homeotropic surface anchoring in the presence of a magnetic field. Inspired by recent experimental observations, we focus on the case where the magnetic susceptibility is negative, and find

  6. Magnetic fields in laser heated plasmas

    International Nuclear Information System (INIS)

    Amiranoff, F.; Brackbill, J.; Colombant, D.; Grandjouan, N.

    1984-01-01

    With a fixed-ion code for the study of self-generated magentic fields in laser heated plasmas, the inhibition of thermal transport and the effect of the Nernst term are modeled for a KrF laser. For various values of the flux limiter, the response of a foil to a focused laser is calculated without a magnetic field and compared with the response calculated with a magnetic field. The results are: The Nernst term convects the magnetic field to densities above critical as found by Nishiguchi et al. (1984), but the field does not strongly inhibit transport into the foil. The field is also transported to sub-critical densities, where it inhibits thermal diffusion and enhance lateral transport by convection

  7. External magnetic field configurations for EXTRAP

    International Nuclear Information System (INIS)

    Bonnevier, B.

    1982-08-01

    The strongly inhomogeneous magnetic field for stabilization of a pinch in an Extrap configuration can be created in various ways. Some possibilities both for the linear case and for the toroidal case are discussed. (author)

  8. Hydrogen atoms in a strong magnetic field

    International Nuclear Information System (INIS)

    Santos, R.R. dos.

    1975-07-01

    The energies and wave functions of the 14 lowest states of a Hydrogen atom in a strong magnetic field are calculated, using a variational scheme. The equivalence between the atomic problem and the problems related with excitons and impurities in semiconductors in the presence of a strong magnetic field are shown. The calculations of the energies and wave functions have been divided in two regions: the first, for the magnetic field ranging between zero and 10 9 G; in the second the magnetic field ranges between 10 9 and 10 11 G. The results have been compared with those obtained by previous authors. The computation time necessary for the calculations is small. Therefore this is a convenient scheme to obtain the energies and wave functions for the problem. Transition probabilities, wavelengths and oscillator strengths for some allowed transitions are also calculated. (Author) [pt

  9. The significance of vector magnetic field measurements

    Science.gov (United States)

    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.

  10. Magnetic Field Strength Evaluation Yu. S. Yefimov

    Indian Academy of Sciences (India)

    physical task is to evaluate the strength and topology of magnetic field in blazars and related ... polarization, spectral index of radiation, ratio of apparent velocity of the motion of matter along .... A detailed analysis of the evaluation of physical.

  11. Compact muon solenoid magnet reaches full field

    CERN Multimedia

    2006-01-01

    Scientist of the U.S. Department of Energy in Fermilab and collaborators of the US/CMS project announced that the world's largest superconducting solenoid magnet has reached full field in tests at CERN. (1 apge)

  12. Split-Field Magnet facility upgraded

    CERN Multimedia

    CERN PhotoLab

    1977-01-01

    The Split Field Magnet (SFM) was the largest spectrometer for particles from beam-beam collisions in the ISR. It could determine particle momenta in a large solid angle, but was designed mainly for the analysis of forward travelling particles.As the magnet was working on the ISR circulating beams, its magnetic field had to be such as to restore the correct proton orbit.The SFM, therefore, produced zero field at the crossing point and fields of opposite signs upstream and downstream of it and was completed by 2 large and 2 small compensator magnets. The gradient effects were corrected by magnetic channels equipped with movable flaps. The useful magnetic field volume was 28 m3, the induction in the median plane 1.14 T, the gap heigth 1.1 m, the length 10.5 m, the weight about 1000 ton. Concerning the detectors, the SFM was the first massive application of multiwire proportional chambers (about 70000 wires) which filled the main and the large compensator magnets. In 1976 an improved programme was started with tw...

  13. Ehrenfest force in inhomogeneous magnetic field

    International Nuclear Information System (INIS)

    Sisakyan, A.N.; Shevchenko, O.Yu.; Samojlov, V.N.

    2000-01-01

    The Ehrenfest force in an inhomogeneous magnetic field is calculated. It is shown that there exist such (very rare) topologically nontrivial physical situations when the Gauss theorem in its classic formulation fails and, as a consequence, apart from the usual Lorentz force an additional, purely imaginary force acts on the charged particle. This force arises only in inhomogeneous magnetic fields of special configurations, has a purely quantum origin, and disappears in the classical limit

  14. Core Processes: Earth's eccentric magnetic field

    DEFF Research Database (Denmark)

    Finlay, Chris

    2012-01-01

    Earth’s magnetic field is characterized by a puzzling hemispheric asymmetry. Calculations of core dynamo processes suggest that lopsided growth of the planet’s inner core may be part of the cause.......Earth’s magnetic field is characterized by a puzzling hemispheric asymmetry. Calculations of core dynamo processes suggest that lopsided growth of the planet’s inner core may be part of the cause....

  15. Neutron oscillations and the primordial magnetic field

    International Nuclear Information System (INIS)

    Sarkar, S.

    1988-01-01

    It has been claimed that a primordial magnetic field must exist in order to suppress possible oscillations of neutrons into antineutrons which would otherwise affect the cosmological synthesis of helium. We demonstrate that such oscillations, even if they do occur, have a negligible effect on primordial nucleosynthesis, thus refuting the above claim. Hence the possible existence of a primordial magnetic field, relevant to current speculations concerning superconducting 'cosmic strings', remains an open question. (author)

  16. Wake field in matched kicker magnet

    International Nuclear Information System (INIS)

    Miyahara, Y.

    1979-01-01

    Coherent transverse instability observed in KEK booster proton synchrotron has been reported previously. This instability is induced by the interaction of the beam with kicker magnet for the fast beam extraction. To understand the mechanism completely, it is necessary to know the wake field in detail. Here, the wake field or induced current in the kicker magnet which is terminated with matched resistance is considered

  17. Magnetic fields and massive star formation

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Qizhou; Keto, Eric; Ho, Paul T. P.; Ching, Tao-Chung; Chen, How-Huan [Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138 (United States); Qiu, Keping [School of Astronomy and Space Science, Nanjing University, 22 Hankou Road, Nanjing 210093 (China); Girart, Josep M.; Juárez, Carmen [Institut de Ciències de l' Espai, (CSIC-IEEC), Campus UAB, Facultat de Ciències, C5p 2, E-08193 Bellaterra, Catalonia (Spain); Liu, Hauyu; Tang, Ya-Wen; Koch, Patrick M.; Rao, Ramprasad; Lai, Shih-Ping [Academia Sinica Institute of Astronomy and Astrophysics, P.O. Box 23-141, Taipei 106, Taiwan (China); Li, Zhi-Yun [Department of Astronomy, University of Virginia, P.O. Box 400325, Charlottesville, VA 22904 (United States); Frau, Pau [Observatorio Astronómico Nacional, Alfonso XII, 3 E-28014 Madrid (Spain); Li, Hua-Bai [Department of Physics, The Chinese University of Hong Kong, Hong Kong (China); Padovani, Marco [Laboratoire de Radioastronomie Millimétrique, UMR 8112 du CNRS, École Normale Supérieure et Observatoire de Paris, 24 rue Lhomond, F-75231 Paris Cedex 05 (France); Bontemps, Sylvain [OASU/LAB-UMR5804, CNRS, Université Bordeaux 1, F-33270 Floirac (France); Csengeri, Timea, E-mail: qzhang@cfa.harvard.edu [Max Planck Institute for Radioastronomy, Auf dem Hügel 69, D-53121 Bonn (Germany)

    2014-09-10

    Massive stars (M > 8 M {sub ☉}) typically form in parsec-scale molecular clumps that collapse and fragment, leading to the birth of a cluster of stellar objects. We investigate the role of magnetic fields in this process through dust polarization at 870 μm obtained with the Submillimeter Array (SMA). The SMA observations reveal polarization at scales of ≲0.1 pc. The polarization pattern in these objects ranges from ordered hour-glass configurations to more chaotic distributions. By comparing the SMA data with the single dish data at parsec scales, we found that magnetic fields at dense core scales are either aligned within 40° of or perpendicular to the parsec-scale magnetic fields. This finding indicates that magnetic fields play an important role during the collapse and fragmentation of massive molecular clumps and the formation of dense cores. We further compare magnetic fields in dense cores with the major axis of molecular outflows. Despite a limited number of outflows, we found that the outflow axis appears to be randomly oriented with respect to the magnetic field in the core. This result suggests that at the scale of accretion disks (≲ 10{sup 3} AU), angular momentum and dynamic interactions possibly due to close binary or multiple systems dominate over magnetic fields. With this unprecedentedly large sample of massive clumps, we argue on a statistical basis that magnetic fields play an important role during the formation of dense cores at spatial scales of 0.01-0.1 pc in the context of massive star and cluster star formation.

  18. Explosion of soliton in a magnetic field

    International Nuclear Information System (INIS)

    Nishinari, K.; Abe, K.; Satsuma, J.

    1994-01-01

    A dynamics of a solitary pulse of the electrostatic ion cyclotron wave that propagates perpendicular to an applied magnetic field is considered. It is shown that the solitary wave will be singular in some range of parameters in the system, such as the plasma density and the magnitude of an applied magnetic field. This fact shows that there is a possibility of controlling the place where explosion of the solitary wave occurs

  19. Particle acceleration in the interplanetary space

    International Nuclear Information System (INIS)

    Tverskoj, B.A.

    1983-01-01

    A review on the problem of particle acceleration in the interplanetary space is given. The main lationship attention is paid to the problem of the re/ between the impact- and turbulent acceleration when an undisturbed magnetic field forms not too small angle THETA > 10 deg with the shock wave front. The following conclusions are drawn. Particle acceleration at the shock wave front is manifested in the explicit form, if the shock wave propagates along a homogeneous (in the 11 cm range) solar wind. The criterion of such an acceleration is the exponential distribution function F approximately vsup(-ν) (v is the particle velocity and ν is the accelerated particle spectrum index) in the low energy range and the conservation of this function at considerable distances behind the front. The presence of an additional turbulent acceleration behind the front is manifested in decreasing ν down to approximately 3.5 in the low energy range and in the spectrum evolution behind the front

  20. The Strongest Magnetic Field in Sunspots

    Science.gov (United States)

    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.

  1. 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

  2. Magnetic field transfer device and method

    Science.gov (United States)

    Wipf, S.L.

    1990-02-13

    A magnetic field transfer device includes a pair of oppositely wound inner coils which each include at least one winding around an inner coil axis, and an outer coil which includes at least one winding around an outer coil axis. The windings may be formed of superconductors. The axes of the two inner coils are parallel and laterally spaced from each other so that the inner coils are positioned in side-by-side relation. The outer coil is outwardly positioned from the inner coils and rotatable relative to the inner coils about a rotational axis substantially perpendicular to the inner coil axes to generate a hypothetical surface which substantially encloses the inner coils. The outer coil rotates relative to the inner coils between a first position in which the outer coil axis is substantially parallel to the inner coil axes and the outer coil augments the magnetic field formed in one of the inner coils, and a second position 180[degree] from the first position, in which the augmented magnetic field is transferred into the other inner coil and reoriented 180[degree] from the original magnetic field. The magnetic field transfer device allows a magnetic field to be transferred between volumes with negligible work being required to rotate the outer coil with respect to the inner coils. 16 figs.

  3. THE POSSIBLE IMPACT OF L5 MAGNETOGRAMS ON NON-POTENTIAL SOLAR CORONAL MAGNETIC FIELD SIMULATIONS

    Energy Technology Data Exchange (ETDEWEB)

    Weinzierl, Marion; Yeates, Anthony R. [Department of Mathematical Sciences, Durham University South Road, Durham DH1 3LE (United Kingdom); Mackay, Duncan H. [School of Mathematics and Statistics, University of St. Andrews North Haugh, St. Andrews, Fife KY16 9SS (United Kingdom); Pevtsov, Alexei A., E-mail: marion.weinzierl@durham.ac.uk [National Solar Observatory 3010 Coronal Loop, sunspot NM 88349 (United States)

    2016-09-10

    The proposed Carrington-L5 mission would bring instruments to the L5 Lagrange point to provide us with crucial data for space weather prediction. To assess the importance of including a magnetograph, we consider the possible differences in non-potential solar coronal magnetic field simulations when magnetograph observations are available from the L5 point, compared with an L1-based field of view (FOV). A timeseries of synoptic radial magnetic field maps is constructed to capture the emergence of two active regions from the L5 FOV. These regions are initially absent in the L1 magnetic field maps, but are included once they rotate into the L1 FOV. Non-potential simulations for these two sets of input data are compared in detail. Within the bipolar active regions themselves, differences in the magnetic field structure can exist between the two simulations once the active regions are included in both. These differences tend to reduce within 5 days of the active region being included in L1. The delayed emergence in L1 can, however, lead to significant persistent differences in long-range connectivity between the active regions and the surrounding fields, and also in the global magnetic energy. In particular, the open magnetic flux and the location of open magnetic footpoints, are sensitive to capturing the real-time of emergence. These results suggest that a magnetograph at L5 could significantly improve predictions of the non-potential corona, the interplanetary magnetic field, and of solar wind source regions on the Sun.

  4. Measurement of the magnetic field coefficients of particle accelerator magnets

    International Nuclear Information System (INIS)

    Herrera, J.; Ganetis, G.; Hogue, R.; Rogers, E.; Wanderer, P.; Willen, E.

    1989-01-01

    An important aspect in the development of magnets to be used in particle accelerators is the measurement of the magnetic field in the beam aperture. In general it is necessary to measure the harmonic multipoles in the dipole, quadrupole, and sextupole magnets for a series of stationary currents (plateaus). This is the case for the Superconducting Super Collider (SSC) which will be ramped to high field over a long period (/approximately/1000 sec.) and then remain on the flat top for the duration of the particle collision phase. In contrast to this mode of operation, the Booster ring being constructed for the Brookhaven AGS, will have a fast ramp rate of approximately 10 Hz. The multipole fields for these Booster magnets must therefore be determined ''on the ramp.'' In this way the effect of eddy currents will be taken into account. The measurement system which we will describe in this paper is an outgrowth of that used for the SSC dipoles. It has the capability of measuring the field multipoles on both a plateau or during a fast ramp. In addition, the same basic coil assembly is used to obtain the magnetic multipoles in dipole, quadrupole, and sextupole magnets. 2 refs., 3 figs., 1 tab

  5. Cooling Curve of Strange Star in Strong Magnetic Field

    Institute of Scientific and Technical Information of China (English)

    WANG Xiao-Qin; LUO Zhi-Quan

    2008-01-01

    In this paper, firstly, we investigate the neutrino emissivity from quark Urca process in strong magnetic field. Then, we discuss the heat capacity of strange stars in strong magnetic field. Finally, we give the cooling curve in strong magnetic field. In order to make a comparison, we also give the corresponding cooling curve in the case of null magnetic field. It turns out that strange stars cool faster in strong magnetic field than that without magnetic field.

  6. Nuclear resonance apparatus including means for rotating a magnetic field

    International Nuclear Information System (INIS)

    Sugimoto, H.

    1983-01-01

    A nuclear magnetic resonance apparatus including magnet apparatus for generating a homogeneous static magnetic field between its magnetic poles, shims of a magnetic substance mounted on the magnetic poles to apply a first gradient magnetic field intensity distribution in a direction orthogonal as to the direction of line of magnetic force of the static magnetic field, gradient magnetic field generating electromagnetic apparatus for generating a second gradient magnetic field having a gradient magnetic field intensity distribution in superimposition with the static magnetic field and for changing the magnetic field gradient of the first gradient magnetic field, an oscillator for generating an oscillating output having a frequency corresponding to the nuclear magnetic resonance condition of an atomic nucleus to be measured, a coil wound around a body to be examined for applying the output of said oscillator as electromagnetic waves upon the body, a receiver for detecting the nuclear magnetic resonance signals received by the coil, a gradient magnetic field controller making a magnetic field line equivalent to the combined gradient magnetic fields and for rotating the line along the section of the body to be examined by controlling said gradient magnetic field generating electromagnetic apparatus and devices for recording the nuclear magnetic resonance signals, for reconstructing the concentration distribution of the specific atomic nuclei in the section of the body, and a display unit for depicting the result of reconstruction

  7. High-magnetic field atomic physics

    International Nuclear Information System (INIS)

    Gay, J.C.

    1984-01-01

    This chapter discusses both the traditional developments of Zeeman techniques at strong fields and the fundamental concepts of diamagnetism. Topics considered include historical aspects, the production of high fields, the atom in a magnetic field (Hamiltonian and symmetries, the various magnetic regimes in atomic spectra), applications of the Zeeman effect at strong B fields, the Landau regime for loosely bound particles, theoretical concepts of atomic diamagnetism, and the ultra-high-field regime and quantum electrodynamics. It is concluded that the wide implications of the problem of the strongly magnetized hydrogen atom in various domains of physics and its conceptual importance concerning theoretical methods of classical and quantum mechanics justify the experimental and theoretical efforts in atomic physics

  8. Superconductivity in Strong Magnetic Field (Greater Than Upper Critical Field)

    International Nuclear Information System (INIS)

    Tessema, G.X.; Gamble, B.K.; Skove, M.J.; Lacerda, A.H.; Mielke, C.H.

    1998-01-01

    The National High Magnetic Field Laboratory, funded by the National Science Foundation and other US federal Agencies, has in recent years built a wide range of magnetic fields, DC 25 to 35 Tesla, short pulse 50 - 60 Tesla, and quasi-continuous 60 Tesla. Future plans are to push the frontiers to 45 Tesla DC and 70 to 100 Tesla pulse. This user facility, is open for national and international users, and creates an excellent tool for materials research (metals, semiconductors, superconductors, biological systems ..., etc). Here we present results of a systematic study of the upper critical field of a novel superconducting material which is considered a promising candidate for the search for superconductivity beyond H c2 as proposed by several new theories. These theories predict that superconductors with low carrier density can reenter the superconducting phase beyond the conventional upper critical field H c2 . This negates the conventional thinking that superconductivity and magnetic fields are antagonistic

  9. TANGLED MAGNETIC FIELDS IN SOLAR PROMINENCES

    International Nuclear Information System (INIS)

    Van Ballegooijen, A. A.; Cranmer, S. R.

    2010-01-01

    Solar prominences are an important tool for studying the structure and evolution of the coronal magnetic field. Here we consider so-called hedgerow prominences, which consist of thin vertical threads. We explore the possibility that such prominences are supported by tangled magnetic fields. A variety of different approaches are used. First, the dynamics of plasma within a tangled field is considered. We find that the contorted shape of the flux tubes significantly reduces the flow velocity compared to the supersonic free fall that would occur in a straight vertical tube. Second, linear force-free models of tangled fields are developed, and the elastic response of such fields to gravitational forces is considered. We demonstrate that the prominence plasma can be supported by the magnetic pressure of a tangled field that pervades not only the observed dense threads but also their local surroundings. Tangled fields with field strengths of about 10 G are able to support prominence threads with observed hydrogen density of the order of 10 11 cm -3 . Finally, we suggest that the observed vertical threads are the result of Rayleigh-Taylor instability. Simulations of the density distribution within a prominence thread indicate that the peak density is much larger than the average density. We conclude that tangled fields provide a viable mechanism for magnetic support of hedgerow prominences.

  10. Neutrino oscillations in strong magnetic fields

    International Nuclear Information System (INIS)

    Likhachev, G.G.; Studenikin, A.I.

    1994-07-01

    Neutrino conversion processes between two neutrino species and the corresponding oscillations induced by strong magnetic fields are considered. The value of the critical strength of magnetic field B cr as a function of characteristics of neutrinos in vacuum (Δm 2 ν , mixing angle θ), effective particle density of matter n eff , neutrino (transition) magnetic moment μ-tilde and energy E is introduced. It is shown that the neutrino conversion and oscillations effects induced by magnetic fields B ≥ B cr are important and may result in the depletion of the initial type of ν's in the bunch. A possible increase of these effects in the case when neutrinos pass through a sudden decrease of density of matter (''cross-boundary effect'') and applications to neutrinos from neutron stars and supernova are discussed. (author). 25 refs

  11. On the absorbing force of magnetic fields acting on magnetic particle under magnetic particle examination

    International Nuclear Information System (INIS)

    Maeda, N.

    1988-01-01

    During the magnetic particle examination, magnetic particles near defects are deposited by an absorbing force of magnetic fields acting on the magnetic particles. Therefore, a quantitative determination of this absorbing force is a theoretical and experimental basis for solving various problems associated with magnetic particle examinations. The absorbing force is formulated based on a magnetic dipole model, and a measuring method of the absorbing force using magnetic fields formed around linear current is proposed. Measurements according to this method produced appropriate results, verifying the validation of the concept and the measuring method

  12. Magnetic fields of Jupiter and Saturn

    International Nuclear Information System (INIS)

    Ness, N.F.

    1981-01-01

    The magnetic fields of Jupiter and Saturn and the characteristics of their magnetospheres, formed by interaction with the solar wind, are discussed. The origins of both magnetic fields are associated with a dynamo process deep in the planetary interior. The Jovian magnetosphere is analogous to that of a pulsar magnetosphere: a massive central body with a rapid rotation and an associated intense magnetic field. Its most distinctive feature is its magnetodisk of concentrated plasma and particle flux, and reduced magnetic field intensity. The magnetopause near the subsolar point has been observed at radial distances ranging over 50 to 100 Jovian radii, implying a relatively compressible obstacle to solar wind flow. The composition of an embedded current sheet within the magnetic tail is believed to be influenced by volcanic eruptions and emissions from Io. Spectral troughs of the Jovian radiation belts have been interpreted as possible ring particles. The Saturnian magnetosphere appears to be more like the earth in its topology. It is mainly characterized by a dipole axis parallel to the rotational axis of the planet and a magnetic field intensity much less than expected

  13. Electron Dropout Echoes Induced by Interplanetary Shock: A Statistical Study

    Science.gov (United States)

    Liu, Z.; Zong, Q.; Hao, Y.; Zhou, X.; Ma, X.; Liu, Y.

    2017-12-01

    "Electron dropout echo" as indicated by repeated moderate dropout and recovery signatures of the flux of energetic electron in the out radiation belt region has been investigated systematically. The electron dropout and its echoes are usually found for higher energy (> 300 keV) channels fluxes, whereas the flux enhancements are obvious for lower energy electrons simultaneously after the interplanetary shock arrives at the Earth's geosynchronous orbit. 104 dropout echo events have been found from 215 interplanetary shock events from 1998 to 2007 based on LANL satellite data. In analogy to substorm injections, these 104 events could be naturally divided into two categories: dispersionless (49 events) or dispersive (55 events) according to the energy dispersion of the initial dropout. It is found that locations of dispersionless events are distributed mainly in the duskside magnetosphere. Further, the obtained locations derived from dispersive events with the time-of-flight technique of the initial dropout regions are mainly located at the duskside as well. Statistical studies have shown that the effect of shock normal, interplanetary magnetic field Bz and solar wind dynamic pressure may be insignificant to these electron dropout events. We suggest that the electric field impulse induced by the IP shock produces a more pronounced inward migration of electrons at the dusk side, resulting in the observed dusk-side moderate dropout of electron flux and its consequent echoes.

  14. Understanding the Internal Magnetic Field Configurations of ICMEs Using More than 20 Years of Wind Observations

    Science.gov (United States)

    Nieves-Chinchilla, T.; Vourlidas, A.; Raymond, J. C.; Linton, M. G.; Al-haddad, N.; Savani, N. P.; Szabo, A.; Hidalgo, M. A.

    2018-02-01

    The magnetic topology, structure, and geometry of the magnetic obstacles embedded within interplanetary coronal mass ejections (ICMEs) are not yet fully and consistently described by in situ models and reconstruction techniques. The main goal of this work is to better understand the status of the internal magnetic field of ICMEs and to explore in situ signatures to identify clues to develop a more accurate and reliable in situ analytical models. We take advantage of more than 20 years of Wind observations of transients at 1 AU to compile a comprehensive database of ICMEs through three solar cycles, from 1995 to 2015. The catalog is publicly available at wind.gsfc.nasa.gov and is fully described in this article. We identify and collect the properties of 337 ICMEs, of which 298 show organized magnetic field signatures. To allow for departures from idealized magnetic configurations, we introduce the term "magnetic obstacle" (MO) to signify the possibility of more complex configurations. To quantify the asymmetry of the magnetic field strength profile within these events, we introduce the distortion parameter (DiP) and calculate the expansion velocity within the magnetic obstacle. Circular-cylindrical geometry is assumed when the magnetic field strength displays a symmetric profile. We perform a statistical study of these two parameters and find that only 35% of the events show symmetric magnetic profiles and a low enough expansion velocity to be compatible with the assumption of an idealized cylindrical static flux rope, and that 41% of the events do not show the expected relationship between expansion and magnetic field compression in the front, with the maximum magnetic field closer to the first encounter of the spacecraft with the magnetic obstacle; 18% show contractions ( i.e. apparent negative expansion velocity), and 30% show magnetic field compression in the back. We derive an empirical relation between DiP and expansion velocity that is the first step toward

  15. Neutron stars, magnetic fields, and gravitational waves

    International Nuclear Information System (INIS)

    Lamb, F.K.

    2001-01-01

    The r-modes of rapidly spinning young neutron stars have recently attracted attention as a promising source of detectable gravitational radiation. These neutron stars are expected to have magnetic fields ∼ 10 12 G. The r-mode velocity perturbation causes differential motion of the fluid in the star; this is a kinematic effect. In addition, the radiation-reaction associated with emission of gravitational radiation by r-waves drives additional differential fluid motions; this is a dynamic effect. These differential fluid motions distort the magnetic fields of neutron stars and may therefore play an important role in determining the structure of neutron star magnetic fields. If the stellar field is ∼ 10 16 (Ω/Ω B ) G or stronger, the usual r-modes are no longer normal modes of the star; here Ω and Ω B are the angular velocities of the star and at which mass shedding occurs. Much weaker magnetic fields can prevent gravitational radiation from amplifying the r-modes or damp existing r-mode oscillations on a relatively short timescale by extracting energy from the modes faster than gravitational wave emission can pump energy into them. The onset of proton superconductivity in the cores of newly formed magnetic neutron stars typically increases the effect on the r-modes of the magnetic field in the core by many orders of magnitude. Once the core has become superconducting, magnetic fields of the order of 10 12 G or greater are usually sufficient to damp r-modes that have been excited by emission of gravitational radiation and to suppress any further emission. A rapid drop in the strength of r-mode gravitational radiation from young neutron stars may therefore signal the onset of superconductivity in the core and provide a lower bound on the strength of the magnetic field there. Hence, measurements of r-mode gravitational waves from newly formed neutron stars may provide valuable diagnostic information about magnetic field strengths, cooling processes, and the

  16. Magnetization relaxation of single molecule magnets after field cooling

    Science.gov (United States)

    Fernandez, Julio F.; Alonso, Juan J.

    2004-03-01

    Magnetic clusters, such as Fe8 and Mn_12, behave at low temperatures as large single spins S. In crystals, anisotropy energies U allow magnetic relaxation only through tunneling at k_BTstackrelspins with dipolar interactions. To mimic tunneling effects, a spin on a lattice site where h is within some tunnel window -h_wmagnetic dipole field drift.

  17. Energy of magnetic moment of superconducting current in magnetic field

    International Nuclear Information System (INIS)

    Gurtovoi, V.L.; Nikulov, A.V.

    2015-01-01

    Highlights: • Quantization effects observed in superconducting loops are considered. • The energy of magnetic moment in magnetic field can not be deduced from Hamiltonian. • This energy is deduced from a history of the current state in the classical case. • It can not be deduced directly in the quantum case. • Taking this energy into account demolishes agreement between theory and experiment. - Abstract: The energy of magnetic moment of the persistent current circulating in superconducting loop in an externally produced magnetic field is not taken into account in the theory of quantization effects because of identification of the Hamiltonian with the energy. This identification misleads if, in accordance with the conservation law, the energy of a state is the energy expended for its creation. The energy of magnetic moment is deduced from a creation history of the current state in magnetic field both in the classical and quantum case. But taking this energy into account demolishes the agreement between theory and experiment. Impartial consideration of this problem discovers the contradiction both in theory and experiment

  18. Two dimensional magnetic field calculations for the SSC dipole magnets

    International Nuclear Information System (INIS)

    Krefta, M.P.; Pavlik, D.

    1991-01-01

    In this work two-dimensional methods are used to calculate the magnetic fields throughout the cross section of a SSC dipole magnet. Analytic techniques, which are based on closed form solutions to the defining field equations, are used to calculate the multipole content for any specified conductor positioning. The method is extended to investigate the effects of radial slots or keyways in the iron yoke. The multipole components of field, directly attributable to the slots or keyways, are examined as a function of size and location. It is shown that locating the slots or keyways at the magnet pole centers has a large effect on the multipole components; whereas, locating the keyways between the magnet poles has little effect on any of the multipoles. The investigation of nonlinear effects such as ferromagnetic saturation or superconductor magnetization relies on the use of numerical methods such as the finite element method. The errors associated with these codes are explained in terms of numerical round-off, spatial discretization error and the representation of distant boundaries. A method for increasing the accuracy of the multipole calculation from finite element solutions is set forth. It is shown that calculated multipole coefficients are sensitive to boundary conditions external to the cold mass during conditions of magnetic saturation

  19. UNDERSTANDING THE GEOMETRY OF ASTROPHYSICAL MAGNETIC FIELDS

    Energy Technology Data Exchange (ETDEWEB)

    Broderick, Avery E [Canadian Institute for Theoretical Astrophysics, 60 St. George St., Toronto, ON M5S 3H8 (Canada); Blandford, Roger D., E-mail: aeb@cita.utoronto.c [Kavli Institute for Particle Astrophysics and Cosmology, 2575 Sand Hill Rd., Menlo Park, CA 94309 (United States)

    2010-08-01

    Faraday rotation measurements have provided an invaluable technique for probing the properties of astrophysical magnetized plasmas. Unfortunately, typical observations provide information only about the density-weighted average of the magnetic field component parallel to the line of sight. As a result, the magnetic field geometry along the line of sight, and in many cases even the location of the rotating material, is poorly constrained. Frequently, interpretations of Faraday rotation observations are dependent upon underlying models of the magnetic field being probed (e.g., uniform, turbulent, equipartition). However, we show that at sufficiently low frequencies, specifically below roughly 13(RM/1 rad m{sup -2}){sup 1/4}(B/1 G){sup 1/2} MHz, the character of Faraday rotation changes, entering what we term the 'super-adiabatic regime' in which the rotation measure (RM) is proportional to the integrated absolute value of the line-of-sight component of the field. As a consequence, comparing RMs at high frequencies with those in this new regime provides direct information about the geometry of the magnetic field along the line of sight. Furthermore, the frequency defining the transition to this new regime, {nu}{sub SA}, depends directly upon the local electron density and magnetic field strength where the magnetic field is perpendicular to the line of sight, allowing the unambiguous distinction between Faraday rotation within and in front of the emission region. Typical values of {nu}{sub SA} range from 10 kHz (below the ionospheric cutoff, but above the heliospheric cutoff) to 10 GHz, depending upon the details of the Faraday rotating environment. In particular, for resolved active galactic nuclei, including the black holes at the center of the Milky Way (Sgr A*) and M81, {nu}{sub SA} ranges from roughly 10 MHz to 10 GHz, and thus can be probed via existing and up-coming ground-based radio observatories.

  20. UNDERSTANDING THE GEOMETRY OF ASTROPHYSICAL MAGNETIC FIELDS

    International Nuclear Information System (INIS)

    Broderick, Avery E.; Blandford, Roger D.

    2010-01-01

    Faraday rotation measurements have provided an invaluable technique for probing the properties of astrophysical magnetized plasmas. Unfortunately, typical observations provide information only about the density-weighted average of the magnetic field component parallel to the line of sight. As a result, the magnetic field geometry along the line of sight, and in many cases even the location of the rotating material, is poorly constrained. Frequently, interpretations of Faraday rotation observations are dependent upon underlying models of the magnetic field being probed (e.g., uniform, turbulent, equipartition). However, we show that at sufficiently low frequencies, specifically below roughly 13(RM/1 rad m -2 ) 1/4 (B/1 G) 1/2 MHz, the character of Faraday rotation changes, entering what we term the 'super-adiabatic regime' in which the rotation measure (RM) is proportional to the integrated absolute value of the line-of-sight component of the field. As a consequence, comparing RMs at high frequencies with those in this new regime provides direct information about the geometry of the magnetic field along the line of sight. Furthermore, the frequency defining the transition to this new regime, ν SA , depends directly upon the local electron density and magnetic field strength where the magnetic field is perpendicular to the line of sight, allowing the unambiguous distinction between Faraday rotation within and in front of the emission region. Typical values of ν SA range from 10 kHz (below the ionospheric cutoff, but above the heliospheric cutoff) to 10 GHz, depending upon the details of the Faraday rotating environment. In particular, for resolved active galactic nuclei, including the black holes at the center of the Milky Way (Sgr A*) and M81, ν SA ranges from roughly 10 MHz to 10 GHz, and thus can be probed via existing and up-coming ground-based radio observatories.

  1. Improved magnetic field line design for TMX

    International Nuclear Information System (INIS)

    Logan, B.G.; Baldwin, D.E.; Foote, J.H.; Chargin, A.K.; Hinkle, R.E.; Hussung, R.O.; Damm, C.C.

    1977-01-01

    Optimization of the currents in the TMX magnet set leads to a field line configuration which has a central solenoidal region uniform in parallel B parallel to within 10 percent over a 2m length. The field design has sufficient flexibility to meet all three physics objectives of the TMX experiment

  2. Surface Magnetic Fields on Giants and Supergiants

    Science.gov (United States)

    Lebre, Agnès

    2018-04-01

    After a short introduction to spectropolarimetry and the tecnics allowing for the detection of surface fields, I will review the numerous and various detections of magnetic fields at the surface of giant and supergiant stars. On Betelgeuse, the prototype of Red Supergiants, I will present recent results collected after a 10 years long spectropolarimetric survey.

  3. The Ring Current Response to Solar and Interplanetary Storm Drivers

    Science.gov (United States)

    Mouikis, C.; Kistler, L. M.; Bingham, S.; Kronberg, E. A.; Gkioulidou, M.; Huang, C. L.; Farrugia, C. J.

    2014-12-01

    The ring current responds differently to the different solar and interplanetary storm drivers such as coronal mass injections, (CME's), corotating interaction regions (CIR's), high-speed streamers and other structures. The resulting changes in the ring current particle pressure, in turn, change the global magnetic field, controlling the transport of the radiation belts. To quantitatively determine the field changes during a storm throughout the magnetosphere, it is necessary to understand the transport, sources and losses of the particles that contribute to the ring current. Because the measured ring current energy spectra depend not only on local processes, but also on the history of the ions along their entire drift path, measurements of ring current energy spectra at two or more locations can be used to strongly constrain the time dependent magnetic and electric fields. In this study we use data predominantly from the Cluster and the Van Allen Probes, covering more than a full solar cycle (from 2001 to 2014). For the period 2001-2012, the Cluster CODIF and RAPID measurements of the inner magnetosphere are the primary data set used to monitor the storm time ring current variability. After 2012, the Cluster data set complements the data from the Van Allen Probes HOPE and RBSPICE instruments, providing additional measurements from different MLT and L shells. Selected storms from this periods, allow us to study the ring current dynamics and pressure changes, as a function of L shell, magnetic local time, and the type of interplanetary disturbances.

  4. Calculation of the Initial Magnetic Field for Mercury's Magnetosphere Hybrid Model

    Science.gov (United States)

    Alexeev, Igor; Parunakian, David; Dyadechkin, Sergey; Belenkaya, Elena; Khodachenko, Maxim; Kallio, Esa; Alho, Markku

    2018-03-01

    Several types of numerical models are used to analyze the interactions of the solar wind flow with Mercury's magnetosphere, including kinetic models that determine magnetic and electric fields based on the spatial distribution of charges and currents, magnetohydrodynamic models that describe plasma as a conductive liquid, and hybrid models that describe ions kinetically in collisionless mode and represent electrons as a massless neutralizing liquid. The structure of resulting solutions is determined not only by the chosen set of equations that govern the behavior of plasma, but also by the initial and boundary conditions; i.e., their effects are not limited to the amount of computational work required to achieve a quasi-stationary solution. In this work, we have proposed using the magnetic field computed by the paraboloid model of Mercury's magnetosphere as the initial condition for subsequent hybrid modeling. The results of the model have been compared to measurements performed by the Messenger spacecraft during a single crossing of the magnetosheath and the magnetosphere. The selected orbit lies in the terminator plane, which allows us to observe two crossings of the bow shock and the magnetopause. In our calculations, we have defined the initial parameters of the global magnetospheric current systems in a way that allows us to minimize paraboloid magnetic field deviation along the trajectory of the Messenger from the experimental data. We have shown that the optimal initial field parameters include setting the penetration of a partial interplanetary magnetic field into the magnetosphere with a penetration coefficient of 0.2.

  5. Magnetic Field Fluctuations in the High Ionosphere at Polar Latitudes: Impact of the IMF Conditions

    Science.gov (United States)

    De Michelis, P.; Consolini, G.; Tozzi, R.

    2016-12-01

    The characterization of ionospheric turbulence plays an important role for all those communication systems affected by the ionospheric medium. For instance, independently of geomagnetic latitude, ionospheric turbulence represents a considerable issue for all Global Navigation Satellite Systems (GNSS). Swarm constellation measurements of the Earth's magnetic field allow a precise characterization of ionospheric turbulence. This is possible using a range of indices derived from the analysis of the scaling properties of the geomagnetic field. In particular, by the scaling properties of the 1st order structure function, a scale index can be obtained, with a consequent characterization of the degree of persistence of the fluctuations and of their spectral properties. The knowledge of this index provides a global characterization of the nature and level of ionospheric turbulence on a local scale, which can be displayed along a single satellite orbit or through maps over the region of interest. The present work focuses on the analysis of the scaling properties of the 1st order structure function of magnetic field fluctuations measured by Swarm constellation at polar latitudes in the Northern Hemisphere. They are studied according to different interplanetary magnetic field conditions and Earth's seasons to characterize the possible drivers of magnetic field variability. The obtained results are discussed in the framework of Sun-Earth relationship and ionospheric polar convection. This work is supported by the Italian National Program for Antarctic Research (PNRA) Research Project 2013/AC3.08

  6. Opening the cusp. [using magnetic field topology

    Science.gov (United States)

    Crooker, N. U.; Toffoletto, F. R.; Gussenhoven, M. S.

    1991-01-01

    This paper discusses the magnetic field topology (determined by the superposition of dipole, image, and uniform fields) for mapping the cusp to the ionosphere. The model results are compared to both new and published observations and are then used to map the footprint of a flux transfer event caused by a time variation in the merging rate. It is shown that the cusp geometry distorts the field lines mapped from the magnetopause to yield footprints with dawn and dusk protrusions into the region of closed magnetic flux.

  7. Plasma heating in a variable magnetic field

    Energy Technology Data Exchange (ETDEWEB)

    Kichigin, G. N., E-mail: king@iszf.irk.ru [Russian Academy of Sciences, Institute of Solar-Terrestrial Physics (Russian Federation)

    2013-05-15

    The problem of particle acceleration in a periodically variable magnetic field that either takes a zero value or passes through zero is considered. It is shown that, each time the field [0]passes through zero, the particle energy increases abruptly. This process can be regarded as heating in the course of which plasma particles acquire significant energy within one field period. This mechanism of plasma heating takes place in the absence of collisions between plasma particles and is analogous to the mechanism of magnetic pumping in collisional plasma considered by Alfven.

  8. Measurement of gradient magnetic field temporal characteristics

    International Nuclear Information System (INIS)

    Bartusek, K.; Jflek, B.

    1994-01-01

    We describe a technique of measuring the time dependence and field distortions of magnetic fields due to eddy currents (EC) produced by time-dependent magnetic field gradients. The EC measuring technique makes use of a large volume sample and selective RF excitation pulses and free induction decay (FID) (or a spin or gradient echo) to measure the out-of-phase component of the FID, which is proportional to γδB, i.e. the amount the signal is off resonance. The measuring technique is sensitive, easy to implement and interpret, and used for determining pre-emphasis compensation parameters

  9. IMAGINE: Interstellar MAGnetic field INference Engine

    Science.gov (United States)

    Steininger, Theo

    2018-03-01

    IMAGINE (Interstellar MAGnetic field INference Engine) performs inference on generic parametric models of the Galaxy. The modular open source framework uses highly optimized tools and technology such as the MultiNest sampler (ascl:1109.006) and the information field theory framework NIFTy (ascl:1302.013) to create an instance of the Milky Way based on a set of parameters for physical observables, using Bayesian statistics to judge the mismatch between measured data and model prediction. The flexibility of the IMAGINE framework allows for simple refitting for newly available data sets and makes state-of-the-art Bayesian methods easily accessible particularly for random components of the Galactic magnetic field.

  10. Acceleration of superparamagnetic particles with magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Stange, R., E-mail: Robert.stange@tu-dresden.de; Lenk, F.; Bley, T.; Boschke, E.

    2017-04-01

    High magnetic capture efficiency in the context of Biomagnetic Separation (BMS) using superparamagnetic particles (SMPs) requires efficient mixing and high relative velocities between cellular and other targets and SMPs. For this purpose, batch processes or microfluidic systems are commonly used. Here, we analyze the characteristics of an in-house developed batch process experimental setup, the Electromagnetic Sample Mixer (ESM) described earlier. This device uses three electromagnets to increase the relative velocity between SMPs and targets. We carry out simulations of the magnetic field in the ESM and in a simpler paradigmatic setup, and thus were able to calculate the force field acting on the SMPs and to simulate their relative velocities and fluid dynamics due to SMP movement. In this way we were able to show that alternate charging of the magnets induces a double circular stream of SMPs in the ESM, resulting in high relative velocities of SMPs to the targets. Consequently, due to the conservation of momentum, the fluid experiences an acceleration induced by the SMPs. We validated our simulations by microscopic observation of the SMPs in the magnetic field, using a homemade apparatus designed to accommodate a long working-distance lens. By comparing the results of modeling this paradigmatic setup with the experimental observations, we determined that the velocities of the SMPs corresponded to the results of our simulations. - Highlights: • Investigation of a batch process setup for complex forming at Biomagnetic Separation. • Simulation of fluid flow characteristics in this Electro Magnetic Samplemixer. • Simulation of relative velocities between magnetic particles and fluid in the setup. • Simulation of fluid flow induced by the acceleration of magnet particles. • Validation of magnetic fields and flow characteristics in paradigmatic setups. • Reached relative velocity is higher than the sedimentation velocity of the particles • Alternating

  11. Electric arc behaviour in dynamic magnetic fields

    International Nuclear Information System (INIS)

    Put'ko, V.F.

    2000-01-01

    The behaviour of an electric arc in different time-dependent (dynamic) magnetic fields was investigated. New possibilities were found for spatial and energy stabilisation of a discharge, for intensifying heat exchange, extending the electric arc and distributed control of electric arc plasma. Rotating, alternating and travelling magnetic fields were studied. It was found that under the effect of a relatively low frequency of variations of dynamic magnetic fields (f 1000 Hz) the arc stabilised at the axis of the discharge chamber, the pulsation level decreased and discharge stability increased. The borders between these two arc existence modes were formed by a certain critical field variation frequency the period of which was determined by the heat relaxation time of the discharge. (author)

  12. Magnetic droplet soliton nucleation in oblique fields

    Science.gov (United States)

    Mohseni, Morteza; Hamdi, M.; Yazdi, H. F.; Banuazizi, S. A. H.; Chung, S.; Sani, S. R.; Åkerman, Johan; Mohseni, Majid

    2018-05-01

    We study the auto-oscillating magnetodynamics in orthogonal spin-torque nano-oscillators (STNOs) as a function of the out-of-plane (OOP) magnetic-field angle. In perpendicular fields and at OOP field angles down to approximately 50°, we observe the nucleation of a droplet. However, for field angles below 50°, experiments indicate that the droplet gives way to propagating spin waves, in agreement with our micromagnetic simulations. Theoretical calculations show that the physical mechanism behind these observations is the sign changing of spin-wave nonlinearity (SWN) by angle. In addition, we show that the presence of a strong perpendicular magnetic anisotropy free layer in the system reverses the angular dependence of the SWN and dynamics in STNOs with respect to the known behavior determined for the in-plane magnetic anisotropy free layer. Our results are of fundamental interest in understanding the rich dynamics of nanoscale solitons and spin-wave dynamics in STNOs.

  13. Assessment of inhomogeneous ELF magnetic field exposures

    International Nuclear Information System (INIS)

    Leitgeb, N.; Cech, R.; Schroettner, J.

    2008-01-01

    In daily life as well as at workplaces, exposures to inhomogeneous magnetic fields become very frequent. This makes easily applicable compliance assessment methods increasingly important. Reference levels have been defined linking basic restrictions to levels of homogeneous fields at worst-case exposure conditions. If reference levels are met, compliance with basic restrictions can be assumed. If not, further investigations could still prove compliance. Because of the lower induction efficiency, inhomogeneous magnetic fields such as from electric appliances could be allowed exceeding reference levels. To easily assess inhomogeneous magnetic fields, a quick and flexible multi-step assessment procedure is proposed. On the basis of simulations with numerical, anatomical human models reference factors were calculated elevating reference levels to link hot-spot values measured at source surfaces to basic limits and allowing accounting for different source distance, size, orientation and position. Compliance rules are proposed minimising assessment efforts. (authors)

  14. Neutron Scattering and High Magnetic Fields

    Energy Technology Data Exchange (ETDEWEB)

    Winn, Barry L. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States); Stone, Matthew B. [Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)

    2014-11-01

    The workshop “Neutron Scattering and High Magnetic Fields” was held September 4-5, 2014 at the Oak Ridge National Laboratory (ORNL). The workshop was held in response to a recent report by the National Research Council of the National Academy of Sciences entitled “High Magnetic Field Science and Its Application in the United States: Current Status and Future Directions.”1 This report highlights the fact that neutron scattering measurements carried out in high magnetic fields provide important opportunities for new science. The workshop explored the range of the scientific discoveries that could be enabled with neutron scattering measurements at high fields (25 Tesla or larger), the various technologies that might be utilized to build specialized instruments and sample environment equipment to enable this research at ORNL, and possible routes to funding and constructing these facilities and portable high field sample environments.

  15. Field measurement of dipole magnets for TARN

    International Nuclear Information System (INIS)

    Hori, T.; Noda, A.; Hattori, T.; Fujino, T.; Yoshizawa, M.

    1980-05-01

    Eight dipole magnets of window-frame type with zero field gradient have been fabricated for TARN. Various characteristics of the field were examined by a measuring system with a Hall and an NMR probes. The accuracy of the measurement was better than 1 x 10 -4 at the maximum field strength of --9 kG, and the uniformity of the field in the radial direction was better than +-2 x 10 -4 over the whole useful aperture. The deviations both of the field strengths and of the effective lengths among the eight magnets are smaller than +-2 x 10 -3 . The sextupole component of the field and the variation of the effective length over the beam orbits contribute to chromaticities of the ring as the amount of -1.59 and 0.93 in the horizontal and vertical directions, respectively. (author)

  16. Magnetic Fields in the Interstellar Medium

    Science.gov (United States)

    Clark, Susan

    2017-01-01

    The Milky Way is magnetized. Invisible magnetic fields thread the Galaxy on all scales and play a vital but still poorly understood role in regulating flows of gas in the interstellar medium and the formation of stars. I will present highlights from my thesis work on magnetic fields in the diffuse interstellar gas and in accretion disks. At high Galactic latitudes, diffuse neutral hydrogen is organized into an intricate network of slender linear features. I will show that these neutral hydrogen “fibers” are extremely well aligned with the ambient magnetic field as traced by both starlight polarization (Clark et al. 2014) and Planck 353 GHz polarized dust emission (Clark et al. 2015). The structure of the neutral interstellar medium is more tightly coupled to the magnetic field than previously known. Because the orientation of neutral hydrogen is an independent predictor of the local dust polarization angle, our work provides a new tool in the search for inflationary gravitational wave B-mode polarization in the cosmic microwave background, which is currently limited by dust foreground contamination. Magnetic fields also drive accretion in astrophysical disks via the magnetorotational instability (MRI). I analytically derive the behavior of this instability in the weakly nonlinear regime and show that the saturated state of the instability depends on the geometry of the background magnetic field. The analytical model describes the behavior of the MRI in a Taylor-Couette flow, a set-up used by experimentalists in the ongoing quest to observe MRI in the laboratory (Clark & Oishi 2016a, 2016b).

  17. Electrically induced magnetic fields; a consistent approach

    Science.gov (United States)

    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.

  18. Upper critical magnetic field of superconducting films with magnetic impurities

    International Nuclear Information System (INIS)

    Lemberger, T.R.

    1978-01-01

    The upper critical magnetic field, H/sub c2/(T), of In-Mn and Pb-Mn alloy films was measured. H/sub c2/ was determined from the resistance of the films. The results were compared with the theory of Fulde and Maki. This theory assumes that the electron-phonon coupling is weak, and that the interaction between the impurity spins and the conduction electron spins is weak. The theory predicts that the pair-breaking effect of the magnetic impurities is temperature-independent, and that the pair-breaking effects of the magnetic impurities and the applied magnetic field are additive. Furthermore, it predicts explicitly the temperature dependence of H/sub c2/. The temperature dependence of H/sub c2/ for the In-Mn alloy films is well described by the Fulde-Maki theory, despite the moderately strong electron-phonon coupling and the strong interaction between the impurity spins and the conduction electron spins. The temperature dependence of H/sub c2/ for the Pb-Mn alloy films is not well described by the Fulde-Maki theory, probably due to the strong electron-phonon coupling in Pb. However, even without a quantitatively correct theory, one can conclude from the Pb-Mn data that the pair-breaking effect of the magnetic impurities is temperature independent, and that the pair-breaking effects of the magnetic impurities and the applied magnetic field are additive. For some of the Pb-Mn alloy films, there was a region of positive curvature in H/sub c2/(T) near the zero-field transition temperature. This positive curvature is not understood

  19. Measurements of the Magnetic Field of the Upper Chromosphere with Polarimetry

    Science.gov (United States)

    Rachmeler, Laurel; Mckenzie, David; Winebarger, Amy; Kobayashi, Ken; Ishikawa, Ryohko; Kubo, Masahito; Narukage, Noriyuki; Bueno, Trujillo, Javier; Auchere, Frederic

    2017-01-01

    A major remaining challenge for heliophysics is to decipher the magnetic structure of the chromosphere. The chromosphere is the critical interface between the Sun's photosphere and corona: it contains more mass than the entire interplanetary heliosphere, requires a heating rate that is larger than that of the corona, and mediates all the energy driving the solar wind, solar atmospheric heating and solar eruptions. While measurements of the magnetic field in the photosphere are routine, the chromosphere poses several extra challenges. The magnetically sensitive lines formed in the upper chromosphere are in the ultraviolet, so space-based observations are required. The lines are often formed over a range of heights, sampling different plasma which complicates the inversion process. These lines are sensitive to the magnetic field via polarized light that is created or modified through the Hanle and Zeeman effects. There are a few observations of these lines, and a significant challenge remains in extracting the magnetic field from the polarization measurements, as detailed model atmospheres with advanced radiative transfer physics are needed. Real progress is obtained by a simultaneous improvement in both the observational side and the modeling side. We present information on the CLASP (Chromospheric LAyer Spectro-Polarimeter) sounding rocket program, and future prospects for these types of measurements.

  20. Magnetic Field Response Measurement Acquisition System

    Science.gov (United States)

    Woodard, Stanley E.; Taylor,Bryant D.; Shams, Qamar A.; Fox, Robert L.

    2007-01-01

    This paper presents a measurement acquisition method that alleviates many shortcomings of traditional measurement systems. The shortcomings are a finite number of measurement channels, weight penalty associated with measurements, electrical arcing, wire degradations due to wear or chemical decay and the logistics needed to add new sensors. Wire degradation has resulted in aircraft fatalities and critical space launches being delayed. The key to this method is the use of sensors designed as passive inductor-capacitor circuits that produce magnetic field responses. The response attributes correspond to states of physical properties for which the sensors measure. Power is wirelessly provided to the sensing element by using Faraday induction. A radio frequency antenna produces a time-varying magnetic field used to power the sensor and receive the magnetic field response of the sensor. An interrogation system for discerning changes in the sensor response frequency, resistance and amplitude has been developed and is presented herein. Multiple sensors can be interrogated using this method. The method eliminates the need for a data acquisition channel dedicated to each sensor. The method does not require the sensors to be near the acquisition hardware. Methods of developing magnetic field response sensors and the influence of key parameters on measurement acquisition are discussed. Examples of magnetic field response sensors and the respective measurement characterizations are presented. Implementation of this method on an aerospace system is discussed.

  1. Magnetic field measurements in xi Bootis A

    International Nuclear Information System (INIS)

    Boesgaard, A.M.; Chesley, D.; Preston, G.W.

    1975-01-01

    Four Zeeman spectrograms from Lick Observatory of xi Boo A and two of iota Peg at 2 A mm -1 have been measured to determine if a weak magnetic field is present in xi Boo A. The results indicate that the field is too weak to be measured by this technique on these spectrograms, although remeasurements of spectrograms from Mauna Kea at 3.4 A mm -1 still give a positive field of 170 gauss. (U.S.)

  2. Magnetic Thermometer: Thermal effect on the Agglomeration of Magnetic Nanoparticles by Magnetic field

    Science.gov (United States)

    Jin, Daeseong; Kim, Hackjin

    2018-03-01

    We have investigated the agglomeration of magnetite nanoparticles in the aqueous solution under magnetic field by measuring temporal change of magnetic weight. The magnetic weight corresponds to the force due to the magnetization of magnetic materials. Superparamagnetic magnetite nanoparticles are synthesized and used in this work. When the aqueous solution of magnetite nanoparticle is placed under magnetic field, the magnetic weight of the sample jumps instantaneously by Neel and Brown mechanisms and thereafter increases steadily following a stretched exponential function as the nanoparticles agglomerate, which results from the distribution of energy barriers involved in the dynamics. Thermal motions of nanoparticles in the agglomerate perturb the ordered structure of the agglomerate to reduce the magnetic weight. Fluctuation of the structural order of the agglomerate by temperature change is much faster than the formation of agglomerate and explained well with the Boltzmann distribution, which suggests that the magnetic weight of the agglomerate works as a magnetic thermometer.

  3. Plasma diffusion due to magnetic field fluctuations

    International Nuclear Information System (INIS)

    Okuda, H.; Lee, W.W.; Lin, A.T.

    1979-01-01

    Plasma diffusion due to magnetic field fluctuations has been studied in two dimensions for a plasma near thermal equilibrium and when the fluctuations are suprathermal. It is found that near thermal equilibrium electron diffusion varies as B -2 when the collisionless skin depth is greater than the thermal electron gyroradius and is generally smaller than the diffusion due to collisions or electrostatic fluctuations for a low-β plasma. When the suprathermal magnetic fluctuation exists because of macroscopic plasma currents, electron diffusion is enhanced due to the coalescence of current filaments and magnetic islands. Magnetic field energy is found to condense to the longest wavelength available in the system and stays there longer than the electron diffusion time scale

  4. Exploring Magnetic Fields with a Compass

    Science.gov (United States)

    Lunk, Brandon; Beichner, Robert

    2011-01-01

    A compass is an excellent classroom tool for the exploration of magnetic fields. Any student can tell you that a compass is used to determine which direction is north, but when paired with some basic trigonometry, the compass can be used to actually measure the strength of the magnetic field due to a nearby magnet or current-carrying wire. In this paper, we present a series of simple activities adapted from the Matter & Interactions textbook for doing just this. Interestingly, these simple measurements are comparable to predictions made by the Bohr model of the atom. Although antiquated, Bohr's atom can lead the way to a deeper analysis of the atomic properties of magnets. Although originally developed for an introductory calculus-based course, these activities can easily be adapted for use in an algebra-based class or even at the high school level.

  5. Magnetic Field Effects on Plasma Plumes

    Science.gov (United States)

    Ebersohn, F.; Shebalin, J.; Girimaji, S.; Staack, D.

    2012-01-01

    Here, we will discuss our numerical studies of plasma jets and loops, of basic interest for plasma propulsion and plasma astrophysics. Space plasma propulsion systems require strong guiding magnetic fields known as magnetic nozzles to control plasma flow and produce thrust. Propulsion methods currently being developed that require magnetic nozzles include the VAriable Specific Impulse Magnetoplasma Rocket (VASIMR) [1] and magnetoplasmadynamic thrusters. Magnetic nozzles are functionally similar to de Laval nozzles, but are inherently more complex due to electromagnetic field interactions. The two crucial physical phenomenon are thrust production and plasma detachment. Thrust production encompasses the energy conversion within the nozzle and momentum transfer to a spacecraft. Plasma detachment through magnetic reconnection addresses the problem of the fluid separating efficiently from the magnetic field lines to produce maximum thrust. Plasma jets similar to those of VASIMR will be studied with particular interest in dual jet configurations, which begin as a plasma loops between two nozzles. This research strives to fulfill a need for computational study of these systems and should culminate with a greater understanding of the crucial physics of magnetic nozzles with dual jet plasma thrusters, as well as astrophysics problems such as magnetic reconnection and dynamics of coronal loops.[2] To study this problem a novel, hybrid kinetic theory and single fluid magnetohydrodynamic (MHD) solver known as the Magneto-Gas Kinetic Method is used.[3] The solver is comprised of a "hydrodynamic" portion based on the Gas Kinetic Method and a "magnetic" portion that accounts for the electromagnetic behaviour of the fluid through source terms based on the resistive MHD equations. This method is being further developed to include additional physics such as the Hall effect. Here, we will discuss the current level of code development, as well as numerical simulation results

  6. Trapped field recovery of bulk superconductor magnets by static field magnetization

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Z., E-mail: zigang@kaiyodai.ac.jp [Laboratory of Applied Physics, Department of Marine Electronics and Mechanical Engineering, Tokyo University of Marine Science and Technology, Tokyo 135-8533 (Japan); Tsuzuki, K.; Miki, M.; Felder, B.; Hara, S.; Izumi, M. [Laboratory of Applied Physics, Department of Marine Electronics and Mechanical Engineering, Tokyo University of Marine Science and Technology, Tokyo 135-8533 (Japan)

    2011-11-15

    A series of initial trapped fields after ZFC or FC magnetization are used to simulate the attenuated trapped field. It is possible and easy to recover the lost trapped field and regain the best trapped field performance as before. In the re-magnetization process, the initial magnetic flux inside the bulk magnets will help to recover the trapped field. The optimum recovery field is recommended to be 2.5 times the saturation field of the bulk at LN2 temperature. Thanks to the trapped field of bulk high-temperature superconductors, they can be used as field-pole magnets in the high temperature superconducting (HTS) rotating machines. For example, an output power of 10 kW at 720 rpm was realized by an average trapped field of 0.56 T of eight melt-textured GdBa{sub 2}Cu{sub 3}O{sub y} (Gd-123) bulks at liquid nitrogen temperature in TUMSAT in 2004. Similarly to the HTS machines involving 1G or 2G wires, the trapped field of the bulk is possibly sensitive and even can be attenuated by the AC component field during the operation. Hence, it is necessary to recover the trapped field once being decreased to some extent in the practical application. From this point, we have investigated the trapped field recovery of HTS bulk magnets by static field magnetization in the paper. A series of different initial trapped fields after zero-field-cooling or field-cooling magnetization are used to simulate the attenuated trapped field. By comparing the trapped field peak and its distribution, the trapped field was found to be able to recover by the static field magnetization method with a stronger excitation field and the initial trapped flux inside the bulk also has an influence on the recovery process. The optimum recovery field was found to be about 2.5 times the saturated trapped field of the bulk at liquid nitrogen temperature, by which the bulk can regain the former best trapped field performance.

  7. High magnetic field magnetization of a new triangular lattice antiferromagnet

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, H. D. [Univ. of Tennessee, Knoxville, TN (United States); Los Alamos National Lab. (LANL), Los Alamos, NM (United States). National High Magnetic Field Lab. (MagLab); Stritzinger, Laurel Elaine Winter [Los Alamos National Lab. (LANL), Los Alamos, NM (United States); Harrison, Neil [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)

    2017-03-23

    In CsV(MoO4)2, the magnetic V3+ ions with octahedral oxygen-coordination form a geometrically frustrated triangular lattice. So fare, there is no magnetic properties reported on it. Recently, we successfully grew single crystals of CsV(MoO4)2 by using flux method. The susceptibility shows a sharp drop around 24 K, representing a long range magnetic ordering. To understand the physical properties of this new triangular lattice antiferromagnet (TLAF), we pursued high field magnetization measurements to answer two questions: (i) what is the saturation field, which will be very useful to calculate the exchange interaction of the system? (ii) Will it exhibit spin state transition, such as the up up down phase with 1/3-saturation moment as other TLAFs? Recently, we performed VSM measurements in Cell 8, Tallahassee, NHMFL, the results show that the magnetization reaches 0.38 MuB at 34 T, which is just 19% of the full moment of 2 MuB for V3+ (3d2) ions. Apparently we need higher field to reach 1/3 value or full moment.

  8. Magnetic resonance signal moment determination using the Earth's magnetic field

    KAUST Repository

    Fridjonsson, Einar Orn; Creber, Sarah A.; Vrouwenvelder, Johannes S.; Johns, Michael L.

    2015-01-01

    We demonstrate a method to manipulate magnetic resonance data such that the moments of the signal spatial distribution are readily accessible. Usually, magnetic resonance imaging relies on data acquired in so-called k-space which is subsequently Fourier transformed to render an image. Here, via analysis of the complex signal in the vicinity of the centre of k-space we are able to access the first three moments of the signal spatial distribution, ultimately in multiple directions. This is demonstrated for biofouling of a reverse osmosis (RO) membrane module, rendering unique information and an early warning of the onset of fouling. The analysis is particularly applicable for the use of mobile magnetic resonance spectrometers; here we demonstrate it using an Earth's magnetic field system.

  9. Magnetic resonance signal moment determination using the Earth's magnetic field

    KAUST Repository

    Fridjonsson, Einar Orn

    2015-03-01

    We demonstrate a method to manipulate magnetic resonance data such that the moments of the signal spatial distribution are readily accessible. Usually, magnetic resonance imaging relies on data acquired in so-called k-space which is subsequently Fourier transformed to render an image. Here, via analysis of the complex signal in the vicinity of the centre of k-space we are able to access the first three moments of the signal spatial distribution, ultimately in multiple directions. This is demonstrated for biofouling of a reverse osmosis (RO) membrane module, rendering unique information and an early warning of the onset of fouling. The analysis is particularly applicable for the use of mobile magnetic resonance spectrometers; here we demonstrate it using an Earth\\'s magnetic field system.

  10. The ARASE (ERG) magnetic field investigation

    Science.gov (United States)

    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.

  11. Diffusive processes in a stochastic magnetic field

    International Nuclear Information System (INIS)

    Wang, H.; Vlad, M.; Vanden Eijnden, E.; Spineanu, F.; Misguich, J.H.; Balescu, R.

    1995-01-01

    The statistical representation of a fluctuating (stochastic) magnetic field configuration is studied in detail. The Eulerian correlation functions of the magnetic field are determined, taking into account all geometrical constraints: these objects form a nondiagonal matrix. The Lagrangian correlations, within the reasonable Corrsin approximation, are reduced to a single scalar function, determined by an integral equation. The mean square perpendicular deviation of a geometrical point moving along a perturbed field line is determined by a nonlinear second-order differential equation. The separation of neighboring field lines in a stochastic magnetic field is studied. We find exponentiation lengths of both signs describing, in particular, a decay (on the average) of any initial anisotropy. The vanishing sum of these exponentiation lengths ensures the existence of an invariant which was overlooked in previous works. Next, the separation of a particle's trajectory from the magnetic field line to which it was initially attached is studied by a similar method. Here too an initial phase of exponential separation appears. Assuming the existence of a final diffusive phase, anomalous diffusion coefficients are found for both weakly and strongly collisional limits. The latter is identical to the well known Rechester-Rosenbluth coefficient, which is obtained here by a more quantitative (though not entirely deductive) treatment than in earlier works

  12. Consistency relation for cosmic magnetic fields

    DEFF Research Database (Denmark)

    Jain, R. K.; Sloth, M. S.

    2012-01-01

    If cosmic magnetic fields are indeed produced during inflation, they are likely to be correlated with the scalar metric perturbations that are responsible for the cosmic microwave background anisotropies and large scale structure. Within an archetypical model of inflationary magnetogenesis, we show...... that there exists a new simple consistency relation for the non-Gaussian cross correlation function of the scalar metric perturbation with two powers of the magnetic field in the squeezed limit where the momentum of the metric perturbation vanishes. We emphasize that such a consistency relation turns out...... to be extremely useful to test some recent calculations in the literature. Apart from primordial non-Gaussianity induced by the curvature perturbations, such a cross correlation might provide a new observational probe of inflation and can in principle reveal the primordial nature of cosmic magnetic fields. DOI...

  13. Magnetic field effects on electrochemical metal depositions

    Directory of Open Access Journals (Sweden)

    Andreas Bund, Adriana Ispas and Gerd Mutschke

    2008-01-01

    Full Text Available This paper discusses recent experimental and numerical results from the authors' labs on the effects of moderate magnetic (B fields in electrochemical reactions. The probably best understood effect of B fields during electrochemical reactions is the magnetohydrodynamic (MHD effect. In the majority of cases it manifests itself in increased mass transport rates which are a direct consequence of Lorentz forces in the bulk of the electrolyte. This enhanced mass transport can directly affect the electrocrystallization. The partial currents for the nucleation of nickel in magnetic fields were determined using an in situ micro-gravimetric technique and are discussed on the basis of the nucleation model of Heerman and Tarallo. Another focus of the paper is the numerical simulation of MHD effects on electrochemical metal depositions. A careful analysis of the governing equations shows that many MHD problems must be treated in a 3D geometry. In most cases there is a complex interplay of natural and magnetically driven convection.

  14. Magnetic field coils for a thermonuclear device

    International Nuclear Information System (INIS)

    Oosaki, Osamu; Sanada, Yoshinao.

    1984-01-01

    Purpose: To generate magnetic fields with an excellent axis symmetry by reducing the error magnetic field, as well as improve the mechanical strength. Constitution: Pan cakes in which the radial innermost conductor is formed spirally and a conductor is successively wound around the outer radial side of the conductor are laminated in plurality, and a spacer having a generally circular inner radial configuration and a spiral outer radial configuration corresponding to the radial innermost conductor is disposed to the inner radial side of the radial inner most conductor. Accordingly, transfer portions between the turns are uniformly dispersed in the circumferential direction to improve the axial symmetry of the magnetic fields. Furthermore, disposition of the spacer can eliminate the gap within the coils and make the inner radial side circular to improve the mechanical strength. (Yoshino, Y.)

  15. Generation of intense transient magnetic fields

    International Nuclear Information System (INIS)

    Benjamin, R.F.

    1983-01-01

    In a laser system, the return current of a laser generated plasma is conducted near a target to subject that target to a magnetic field. The target may be either a small non-fusion object for testing under the magnetic field or a laser-fusion pellet. In the laser-fusion embodiment, the laser-fusion pellet is irradiated during the return current flow and the intense transient magnetic field is used to control the hot electrons thereof to hinder them from striking and heating the core of the irradiated laser-fusion pellet. An emitter, e.g. a microballoon of glass, metal or plastics, is subjected to a laser pulse to generate the plasma from which the return current flows into a wire cage or a coil and then to earth. (author)

  16. Chiral battery, scaling laws and magnetic fields

    Energy Technology Data Exchange (ETDEWEB)

    Anand, Sampurn; Bhatt, Jitesh R.; Pandey, Arun Kumar, E-mail: sampurn@prl.res.in, E-mail: jeet@prl.res.in, E-mail: arunp@prl.res.in [Physical Research Laboratory, Ahmedabad, 380009 (India)

    2017-07-01

    We study the generation and evolution of magnetic field in the presence of chiral imbalance and gravitational anomaly which gives an additional contribution to the vortical current. The contribution due to gravitational anomaly is proportional to T {sup 2} which can generate seed magnetic field irrespective of plasma being chirally charged or neutral. We estimate the order of magnitude of the magnetic field to be 10{sup 30} G at T ∼ 10{sup 9} GeV, with a typical length scale of the order of 10{sup −18} cm, which is much smaller than the Hubble radius at that temperature (10{sup −8} cm). Moreover, such a system possess scaling symmetry. We show that the T {sup 2} term in the vorticity current along with scaling symmetry leads to more power transfer from lower to higher length scale as compared to only chiral anomaly without scaling symmetry.

  17. Field flattening in superconducting beam transport magnets

    International Nuclear Information System (INIS)

    Morgan, G.H.

    1994-01-01

    Dipoles in which the beam traverses the midplane well away from tie magnet axis may benefit from flattening of the vertical field on the midplane. A procedure is described for doing so, making use of Chebyshev polynomials. In the case of the large aperture ''DX'' magnets located immediately on each side of the six intersection regions of the Relativistic Heavy Ion Powder (RHIC), a comparison is made of the field of coils optimized in this way and of coils optimized in the more common way by minimizing the leading coefficients of the Fourier expansion about the magnet axis. The comparison is of the integrated Fourier coefficients of the field expanded locally along the beam trajectory

  18. Vertical gradients of sunspot magnetic fields

    Science.gov (United States)

    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.

  19. Superconductor shields test chamber from ambient magnetic fields

    Science.gov (United States)

    Hildebrandt, A. F.

    1965-01-01

    Shielding a test chamber for magnetic components enables it to maintain a constant, low magnetic field. The chamber is shielded from ambient magnetic fields by a lead foil cylinder maintained in a superconducting state by liquid helium.

  20. Streaming flows produced by oscillating interface of magnetic fluid adsorbed on a permanent magnet in alternating magnetic field

    Science.gov (United States)

    Sudo, S.; Ito, M.; Ishimoto, Y.; Nix, S.

    2017-04-01

    This paper describes microstreaming flows generated by oscillating interface of magnetic fluid adsorbed on a circular cylindrical permanent magnet in alternating magnetic field. The interface of magnetic fluid adsorbed on the NdFeB magnet responds to the external alternating magnetic flied as harmonic oscillation. The directions of alternating magnetic field are parallel and antiparallel to the magnetic field of permanent magnet. The oscillation of magnetic fluid interface generates streaming flow around the magnet-magnetic fluid element in water. Microstreaming flows are observed with a high-speed video camera analysis system. The flow pattern generated by magnetic fluid motion depends on the Keulegan-Carpenter number and the Reynolds number.