Publications
177 results found
Mandt KE, Eriksson A, Edberg NJT, et al., 2016, RPC observation of the development and evolution of plasma interaction boundaries at 67P/ChuryumovGerasimenko, Monthly Notices of the Royal Astronomical Society, Vol: 462, Pages: S9-S22, ISSN: 1365-2966
One of the primary objectives of the Rosetta Plasma Consortium, a suite of five plasma instruments on-board the Rosetta spacecraft, is to observe the formation and evolution of plasma interaction regions at the comet 67P/Churyumov-Gerasimenko (67P/CG). Observations made between 2015 April and 2016 February show that solar wind–cometary plasma interaction boundaries and regions formed around 2015 mid-April and lasted through early 2016 January. At least two regions were observed, separated by an ion-neutral collisionopause boundary. The inner region was located on the nucleus side of the boundary and was characterized by low-energy water-group ions, reduced magnetic field pileup and enhanced electron densities. The outer region was located outside of the boundary and was characterized by reduced electron densities, water-group ions that are accelerated to energies above 100 eV and enhanced magnetic field pileup compared to the inner region. The boundary discussed here is outside of the diamagnetic cavity and shows characteristics similar to observations made on-board the Giotto spacecraft in the ion pileup region at 1P/Halley. We find that the boundary is likely to be related to ion-neutral collisions and that its location is influenced by variability in the neutral density and the solar wind dynamic pressure.
Richter I, Auster H-U, Berghofer G, et al., 2016, Two-point observations of low-frequency waves at 67P/Churyumov-Gerasimenko during descent of PHILAE: Comparison of RPCMAG and ROMAP, Annales Geophysicae, Vol: 34, Pages: 609-622, ISSN: 1432-0576
The European Space Agency’s spacecraft ROSETTA has reached its final destination,comet 67P/Churyumov-Gerasimenko. Whilst orbiting in the close vicinity of the nucleus theROSETTA magnetometers detected a new type of low-frequency waves possibly generated by across-field current instability due to freshly ionized cometary water group particles. During separation, descent and landing of the lander PHILAE on comet 67P/Churyumov-Gerasimenko, weused the unique opportunity to perform combined measurements with the magnetometers onboardROSETTA (RPCMAG) and its lander PHILAE (ROMAP). New details about the spatial distributionof wave properties along the connection line of the ROSETTA orbiter and the lander PHILAEare revealed. An estimation of the observed amplitude, phase and wavelength distribution will be presented as well as the measured dispersion relation, characterizing the new type of low-frequencywaves. The propagation direction and polarization features will be discussed using the results of aminimum variance analysis. Thoughts about the size of the wave source will complete our study
Soucek J, Ahlen L, Bale S, et al., 2016, EMC ASPECTS OF TURBULENCE HEATING OBSERVER (THOR) SPACECRAFT, ESA Workshop on Aerospace EMC (Aerospace EMC), Publisher: IEEE
Turbulence Heating ObserveR (THOR) is a spacecraft mission dedicated to the study of plasma turbulence in near-Earth space. The mission is currently under study for implementation as a part of ESA Cosmic Vision program. THOR will involve a single spinning spacecraft equipped with state of the art instruments capable of sensitive measurements of electromagnetic fields and plasma particles. The sensitive electric and magnetic field measurements require that the spacecraft-generated emissions are restricted and strictly controlled; therefore a comprehensive EMC program has been put in place already during the study phase. The THOR study team and a dedicated EMC working group are formulating the mission EMC requirements state of its EMC requirements.
Goetz C, Koenders C, Richter I, et al., 2016, First detection of a diamagnetic cavity at comet 67P/Churyumov-Gerasimenko, Astronomy & Astrophysics, Vol: 588, ISSN: 1432-0746
Context. The Rosetta magnetometer RPC-MAG has been exploring the plasma environment of comet 67P/Churyumov-Gerasimenko since August 2014. The first months were dominated by low-frequency waves which evolved into more complex features. However, at the end of July 2015, close to perihelion, the magnetometer detected a region that did not contain any magnetic field at all. Aims. These signatures match the appearance of a diamagnetic cavity as was observed at comet 1P/Halley in 1986. The cavity here is more extended than previously predicted by models and features unusual magnetic field configurations, which need to be explained. Methods. The onboard magnetometer data were analyzed in detail and used to estimate the outgassing rate. A minimum variance analysis was used to determine boundary normals. Results. Our analysis of the data acquired by the Rosetta Plasma Consortium instrumentation confirms the existence of a diamagnetic cavity. The size is larger than predicted by simulations, however. One possible explanation are instabilities that are propagating along the cavity boundary and possibly a low magnetic pressure in the solar wind. This conclusion is supported by a change in sign of the Sun-pointing component of the magnetic field. Evidence also indicates that the cavity boundary is moving with variable velocities ranging from 230-500 m/s.
Volwerk M, Richter I, Tsurutani B, et al., 2016, Mass-loading, pile-up, and mirror-mode waves at comet 67P/Churyumov-Gerasimenko, Annales Geophysicae, Vol: 34, Pages: 1-15, ISSN: 1432-0576
. The data from all Rosetta Plasma Consortium instruments and from the ROSINA COPSinstrument are used to study the interaction of the solar wind with the outgassing cometary nucleusof 67P/Churyumov-Gerasimenko. During 6 and 7 June 2015, the interaction was first dominatedby an increase in the solar wind dynamic pressure, caused by a higher solar wind ion density. Thispressure compressed the draped magnetic field around the comet, and the increase in solar windelectrons enhanced the ionization of the outflow gas through collisional ionization. The new ionsare picked up by the solar wind magnetic field, and create a ring/ring-beam distribution, which, in ahigh-β plasma, is unstable for mirror mode wave generation. Two different kinds of mirror modesare observed: one of small size generated by locally ionized water and one of large size generatedby ionization and pick-up farther away from the comet.
Edberg NJT, Eriksson AI, Odelstad E, et al., 2016, Solar wind interaction with comet 67P: impacts of corotating interaction regions, Journal of Geophysical Research: Space Physics, Vol: 121, Pages: 949-965, ISSN: 2169-9402
We present observations from the Rosetta Plasma Consortium of the effects of stormy solar wind on comet 67P/Churyumov-Gerasimenko. Four corotating interaction regions (CIRs), where the first event has possibly merged with a CME, are traced from Earth via Mars (using Mars Express and MAVEN) and to comet 67P from October to December 2014. When the comet is 3.1-2.7 AU from the Sun and the neutral outgassing rate ∼1025−1026 s−1 the CIRs significantly influence the cometary plasma environment at altitudes down to 10-30 km. The ionospheric low-energy (∼5 eV) plasma density increases significantly in all events, by a factor >2 in events 1-2 but less in events 3-4. The spacecraft potential drops below -20V upon impact when the flux of electrons increases. The increased density is likely caused by compression of the plasma environment, increased particle impact ionisation, and possibly charge exchange processes and acceleration of mass loaded plasma back to the comet ionosphere. During all events, the fluxes of suprathermal (∼10-100 eV) electrons increase significantly, suggesting that the heating mechanism of these electrons is coupled to the solar wind energy input. At impact the magnetic field strength in the coma increases by a factor of 2-5 as more interplanetary magnetic field piles up around of the comet. During two CIR impact events, we observe possible plasma boundaries forming, or moving past Rosetta, as the strong solar wind compresses the cometary plasma environment. We also discuss the possibility of seeing some signatures of the ionospheric response to tail disconnection events.
Sigsbee K, Kletzing CA, Smith CW, et al., 2016, Van Allen Probes, THEMIS, GOES, and Cluster Observations of EMIC waves, ULF pulsations, and an electron flux dropout, Journal of Geophysical Research: Space Physics, Vol: 121, Pages: 1990-2008, ISSN: 2169-9402
We examined an electron flux dropout during the 12–14 November 2012 geomagnetic storm using observations from seven spacecraft: the two Van Allen Probes, THEMIS-A (P5), Cluster 2, and Geostationary Operational Environmental Satellite (GOES) 13, 14, and 15. The electron fluxes for energies greater than 2.0 MeV observed by GOES 13, 14, and 15 at geosynchronous orbit and by the Van Allen Probes remained at or near instrumental background levels for more than 24 hours from 12–14 November. For energies of 0.8 MeV, the GOES satellites observed two shorter intervals of reduced electron fluxes. The first interval of reduced 0.8 MeV electron fluxes on 12–13 November was associated with an interplanetary shock and a sudden impulse. Cluster, THEMIS, and GOES observed intense He+ EMIC waves from just inside geosynchronous orbit out to the magnetopause across the dayside to the dusk flank. The second interval of reduced 0.8 MeV electron fluxes on 13–14 November was associated with a solar sector boundary crossing and development of a geomagnetic storm with Dst < −100 nT. At the start of the recovery phase, both the 0.8 and 2.0 MeV electron fluxes finally returned to near pre-storm values, possibly in response to strong ultra-low frequency (ULF) waves observed by the Van Allen Probes near dawn. A combination of adiabatic effects, losses to the magnetopause, scattering by EMIC waves, and acceleration by ULF waves can explain the observed electron behavior.
Odelstad E, Eriksson AI, Edberg NJT, et al., 2015, Evolution of the plasma environment of comet 67P from spacecraft potential measurements by the Rosetta Langmuir probe instrument, Geophysical Research Letters, Vol: 42, Pages: 10126-10134, ISSN: 1944-8007
We study the evolution of the plasma environment of comet 67P using measurements of the spacecraft potential from early September 2014 (heliocentric distance 3.5 AU) to late March 2015 (2.1 AU) obtained by the Langmuir probe (RPC-LAP) instrument. The low collision rate keeps the electron temperature high (~ 5 eV), resulting in a negative spacecraft potential whose magnitude depends on the electron density. This potential is more negative in the northern (summer) hemisphere, particularly over sunlit parts of the neck region on the nucleus, consistent with neutral gas measurements by ROSINA-COPS. Assuming constant electron temperature, the spacecraft potential traces the electron density. This increases as the comet approaches the Sun, most clearly in the southern hemisphere by a factor possibly as high as 20 - 44 between September 2014 and January 2015. The northern hemisphere plasma density increase stays around a factor of around or below 8 - 12, consistent with seasonal insolation change.
Walker SN, Balikhin MA, Shklyar DR, et al., 2015, Experimental determination of the dispersion relation of magnetosonic waves, Journal of Geophysical Research: Space Physics, Vol: 120, Pages: 9632-9650, ISSN: 2169-9402
Magnetosonic waves are commonly observed in the vicinity of the terrestrial magnetic equator. It has been proposed that within this region they may interact with radiation belt electrons, accelerating some to high energies. These wave-particle interactions depend upon the characteristic properties of the wave mode. Hence determination of the wave properties is a fundamental part of understanding these interaction processes. Using data collected during the Cluster Inner Magnetosphere Campaign, this paper identifies an occurrence of magnetosonic waves, discusses their generation and propagation properties from a theoretical perspective, and utilises multispacecraft measurements to experimentally determine their dispersion relation. Their experimental dispersion is found to be in accordance with that based on cold plasma theory.
Yan GQ, Mozer FS, Phan T, et al., 2015, Quasi-continuous reconnection accompanied by FTEs during IMF Bz≈0 nT observed by Double Star TC-1 at the dawnside magnetopause, Advances in Space Research, Vol: 58, Pages: 208-217, ISSN: 0273-1177
During a one-hour interval of interplanetary magnetic field (IMF) Bz≈0 nT, the equatorialspacecraft Double Star TC-1 encountered the dawn flank magnetopause many times at the magnetic localtime (MLT) of about 08:00 and the latitude of about -27°. During each encounter, reconnection jets wereobserved with their velocities up to more than 500 km/s, significantly higher than the background flow inthe magnetosheath. The fast flows match the theoretical prediction of Alfvénic acceleration well. Themedium temperature and density of ions in the boundary layer indicate the open magnetic field topologyinside this layer. The mainly southward and tailward flows of the plasma jets alongside with the negativeslopes of the Walén test indicate that the spacecraft was located south of the reconnection site, consistentwith both anti-parallel and component reconnection models. The accelerated flows were observed lastingfor about one hour, with some modulations by the oscillations of the magnetopause, but no reversals inthe direction of Vz were found during the interval. The significantly enhanced flows in the boundary layercompared to the adjacent magnetosheath indicate that the reconnection was quasi-continuously active atthe magnetopause northward of the spacecraft under such IMF conditions. At the same time, the bipolarsignatures in BN with enhancements of the magnetic field indicate the occurrence of the Flux TransferEvents (FTEs). The observed reconnection was quasi-continuous, whereas the simultaneouslyaccompanied FTEs were time-dependent under the IMF Bz≈0 nT. For this event, however, it is notpossible to identify whether the reconnection was anti-parallel or component because the TC-1 was faraway from the reconnection site.
Richter I, Koenders C, Auster H-U, et al., 2015, Observation of a new type of low frequency waves at comet 67P/Churyumov-Gerasimenko, Annales Geophysicae, Vol: 33, Pages: 1031-1036, ISSN: 1432-0576
We report on magnetic field measurements madein the innermost coma of 67P/Churyumov-Gerasimenkoin its low activity state. Quasi-coherent, large-amplitude(δB/B ∼ 1), compressional magnetic field oscillations at5 ∼ 40 mHz dominate the immediate plasma environmentof the nucleus. This differs from previously studied cometinteractionregions where waves at the cometary ion gyrofrequenciesare the main feature. Thus classical pick-up iondriven instabilities are unable to explain the observations. We10 propose a cross-field current instability associated with newborncometary ion currents as a possible source mechanism
Auster H-U, Apathy I, Berghofer G, et al., 2015, The nonmagnetic nucleus of comet 67P/Churyumov-Gerasimenko, Science, Vol: 349, ISSN: 0036-8075
<jats:p> Knowledge of the magnetization of planetary bodies constrains their origin and evolution, as well as the conditions in the solar nebular at that time. On the basis of magnetic field measurements during the descent and subsequent multiple touchdown of the Rosetta lander Philae on the comet 67P/Churyumov-Gerasimenko (67P), we show that no global magnetic field was detected within the limitations of analysis. The Rosetta Magnetometer and Plasma Monitor (ROMAP) suite of sensors measured an upper magnetic field magnitude of less than 2 nanotesla at the cometary surface at multiple locations, with the upper specific magnetic moment being <3.1 × 10 <jats:sup>−5</jats:sup> ampere–square meters per kilogram for meter-size homogeneous magnetized boulders. The maximum dipole moment of 67P is 1.6 × 10 <jats:sup>8</jats:sup> ampere–square meters. We conclude that on the meter scale, magnetic alignment in the preplanetary nebula is of minor importance. </jats:p>
Balikhin MA, Shprits YY, Walker SN, et al., 2015, Observations of discrete harmonics emerging from equatorial noise, Nature Communications, Vol: 6, ISSN: 2041-1723
A number of modes of oscillations of particles and fields can exist in space plasmas. Since the early 1970s, space missions have observed noise-like plasma waves near the geomagnetic equator known as 'equatorial noise'. Several theories were suggested, but clear observational evidence supported by realistic modelling has not been provided. Here we report on observations by the Cluster mission that clearly show the highly structured and periodic pattern of these waves. Very narrow-banded emissions at frequencies corresponding to exact multiples of the proton gyrofrequency (frequency of gyration around the field line) from the 17th up to the 30th harmonic are observed, indicating that these waves are generated by the proton distributions. Simultaneously with these coherent periodic structures in waves, the Cluster spacecraft observes 'ring' distributions of protons in velocity space that provide the free energy for the waves. Calculated wave growth based on ion distributions shows a very similar pattern to the observations.
Nilsson H, Wieser GS, Behar E, et al., 2015, Evolution of the ion environment of comet 67P/Churyumov-Gerasimenko - Observations between 3.6 and 2.0 AU, Astronomy & Astrophysics, Vol: 583, ISSN: 0004-6361
Context. The Rosetta spacecraft is escorting comet 67P/Churyumov-Gerasimenko from a heliocentric distance of >3.6 AU, wherethe comet activity was low, until perihelion at 1.24 AU. Initially, the solar wind permeates the thin comet atmosphere formed fromsublimation.Aims. Using the Rosetta Plasma Consortium Ion Composition Analyzer (RPC-ICA), we study the gradual evolution of the comet ionenvironment, from the first detectable traces of water ions to the stage where cometary water ions accelerated to about 1 keV energyare abundant. We compare ion fluxes of solar wind and cometary origin.Methods. RPC-ICA is an ion mass spectrometer measuring ions of solar wind and cometary origins in the 10 eV–40 keV energyrange.Results. We show how the flux of accelerated water ions with energies above 120 eV increases between 3.6 and 2.0 AU. The 24 haverage increases by 4 orders of magnitude, mainly because high-flux periods become more common. The water ion energy spectraalso become broader with time. This may indicate a larger and more uniform source region. At 2.0 AU the accelerated water ion fluxis frequently of the same order as the solar wind proton flux. Water ions of 120 eV–few keV energy may thus constitute a significantpart of the ions sputtering the nucleus surface. The ion density and mass in the comet vicinity is dominated by ions of cometary origin.The solar wind is deflected and the energy spectra broadened compared to an undisturbed solar wind.Conclusions. The flux of accelerated water ions moving from the upstream direction back toward the nucleus is a strongly nonlinearfunction of the heliocentric distance.
Carr CM, Edberg NJT, Eriksson AI, et al., 2015, Spatial distribution of low-energy plasma around 2 comet 67P/CG from Rosetta measurements, Geophysical Research Letters, Vol: 42, Pages: 4263-4269, ISSN: 1944-8007
We use measurements from the Rosetta plasma consortium Langmuir probe and mutual impedance probe to study the spatial distribution of low-energy plasma in the near-nucleus coma of comet 67P/Churyumov-Gerasimenko. The spatial distribution is highly structured with the highest density in the summer hemisphere and above the region connecting the two main lobes of the comet, i.e., the neck region. There is a clear correlation with the neutral density and the plasma to neutral density ratio is found to be ∼1–2·10−6, at a cometocentric distance of 10 km and at 3.1 AU from the Sun. A clear 6.2 h modulation of the plasma is seen as the neck is exposed twice per rotation. The electron density of the collisionless plasma within 260 km from the nucleus falls off with radial distance as ∼1/r. The spatial structure indicates that local ionization of neutral gas is the dominant source of low-energy plasma around the comet.
Dunlop MW, Yang J-Y, Yang Y-Y, et al., 2015, Simultaneous field-aligned currents at Swarm and Cluster satellites, Geophysical Research Letters, Vol: 42, Pages: 3683-3691, ISSN: 1944-8007
We show for the first time, with direct, multispacecraft calculations of electric current density, and other methods, matched signatures of field-aligned currents (FACs) sampled simultaneously near the ionosphere at low (~500 km altitude) orbit and in the magnetosphere at medium (~2.5 RE altitude) orbits using a particular Swarm and Cluster conjunction. The Cluster signatures are interpreted and ordered through joint mapping of the ground/magnetospheric footprints and estimation of the auroral zone boundaries (taken as indication of the boundaries of Region 1 and Region 2 currents). We find clear evidence of both small-scale and large-scale FACs and clear matching of the behavior and structure of the large-scale currents at both Cluster and Swarm. The methodology is made possible through the joint operations of Cluster and Swarm, which contain, in the first several months of Swarm operations, a number of close three-spacecraft configurations.
Carr CM, Erikksson S, Lapenta G, et al., 2015, On Multiple Reconnection X-lines and Tripolar Perturbations of Strong Guide Magnetic Fields, The Astrophysical Journal, Vol: 805, ISSN: 0004-637X
We report new multi-spacecraft Cluster observations of tripolar guide magnetic field perturbations at a solar windreconnection exhaust in the presence of a guide field BM which is almost four times as strong as the reversing fieldBL. The novel tripolar field consists of two narrow regions of depressed BM, with an observed 7%–14% ΔBMmagnitude relative to the external field, which are found adjacent to a wide region of enhanced BM within theexhaust. A stronger reversing field is associated with each BM depression. A kinetic reconnection simulation forrealistic solar wind conditions and the observed strong guide field reveals that tripolar magnetic fields preferentiallyform across current sheets in the presence of multiple X-lines as magnetic islands approach one another and mergeinto fewer and larger islands. The simulated ΔBM/ΔXN over the normal width ΔXN between a BM minimum andthe edge of the external region agree with the normalized values observed by Cluster. We propose that a tripolarguide field perturbation may be used to identify candidate regions containing multiple X-lines and interactingmagnetic islands at individual solar wind current sheets with a strong guide field.
Nilsson H, Wieser GS, Behar E, et al., 2015, Birth of a comet magnetosphere: A spring of water ions, Science, Vol: 347, ISSN: 0036-8075
The Rosetta mission shall accompany comet 67P/Churyumov-Gerasimenko from a heliocentric distance of >3.6 astronomical units through perihelion passage at 1.25 astronomical units, spanning low and maximum activity levels. Initially, the solar wind permeates the thin comet atmosphere formed from sublimation, until the size and plasma pressure of the ionized atmosphere define its boundaries: A magnetosphere is born. Using the Rosetta Plasma Consortium ion composition analyzer, we trace the evolution from the first detection of water ions to when the atmosphere begins repelling the solar wind (~3.3 astronomical units), and we report the spatial structure of this early interaction. The near-comet water population comprises accelerated ions (<800 electron volts), produced upstream of Rosetta, and lower energy locally produced ions; we estimate the fluxes of both ion species and energetic neutral atoms.
Leitner S, Valavanoglou A, Brown P, et al., 2015, Design of the Magnetoresistive Magnetometer for ESA's SOSMAG Project, IEEE TRANSACTIONS ON MAGNETICS, Vol: 51, ISSN: 0018-9464
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Forsyth C, Watt CEJ, Rae IJ, et al., 2014, Increases in plasma sheet temperature with solar wind driving during substorm growth phases, GEOPHYSICAL RESEARCH LETTERS, Vol: 41, Pages: 8713-8721, ISSN: 0094-8276
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Brown P, Whiteside BJ, Beek TJ, et al., 2014, Space magnetometer based on an anisotropic magnetoresistive hybrid sensor, Review of Scientific Instruments, Vol: 85, ISSN: 1089-7623
Varsani A, Owen CJ, Fazakerley AN, et al., 2014, Cluster observations of the substructure of a flux transfer event: analysis of high-time-resolution particle data, ANNALES GEOPHYSICAE, Vol: 32, Pages: 1093-1117, ISSN: 0992-7689
Yang YY, Shen C, Zhang YC, et al., 2014, The force-free configuration of flux ropes in geomagnetotail: Cluster observations, Journal of Geophysical Research: Space Physics, Vol: 119, Pages: 6327-6341, ISSN: 2169-9402
Unambiguous knowledge of magnetic field structure and the electric current distribution is critical for understanding the origin, evolution, and related dynamic properties of magnetic flux ropes (MFRs). In this paper, a survey of 13 MFRs in the Earth's magnetotail are conducted by Cluster multipoint analysis, so that their force-free feature, i.e., the kind of magnetic field structure satisfying J × B = 0, can be probed directly. It is showed that the selected flux ropes with the bipolar signature of the south-north magnetic field component generally lie near the equatorial plane, as expected, and that the magnetic field gradient is rather weak near the axis center, where the curvature radius is large. The current density (up to several tens of nA/m2) reaches their maximum values as the center is approached. It is found that the stronger the current density, the smaller the angles between the magnetic field and current in MFRs. The direct observations show that only quasi force-free structure is observed, and it tends to appear in the low plasma beta regime (in agreement with the theoretic results). The quasi force-free region is generally found to be embedded in the central portion of the MFRs, where the current is approximately field aligned and proportional to the strength of core field. It is shown that ~60% of surveyed MFRs can be globally approximated as force free. The force-free factor α is found to be nonconstantly varied through the quasi force-free MFR, suggesting that the force-free structure is nonlinear.
Reveret V, de la Broise X, Fermon C, et al., 2014, CESAR: Cryogenic Electronics for Space Applications, JOURNAL OF LOW TEMPERATURE PHYSICS, Vol: 176, Pages: 446-452, ISSN: 0022-2291
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Alconcel LNS, Fox P, Brown P, et al., 2014, An initial investigation of the long-term trends in the fluxgate magnetometer (FGM) calibration parameters on the four Cluster spacecraft, GEOSCIENTIFIC INSTRUMENTATION METHODS AND DATA SYSTEMS, Vol: 3, Pages: 95-109, ISSN: 2193-0856
Shen C, Yang YY, Rong ZJ, et al., 2014, Direct calculation of the ring current distribution and magnetic structure seen by Cluster during geomagnetic storms, JOURNAL OF GEOPHYSICAL RESEARCH-SPACE PHYSICS, Vol: 119, Pages: 2458-2465, ISSN: 2169-9380
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Alconcel LNS, Fox P, Brown P, et al., 2014, An initial investigation of the long-term trends in the fluxgate magnetometer (FGM) calibration parameters on the four Cluster spacecraft, GEOSCIENTIFIC INSTRUMENTATION METHODS AND DATA SYSTEMS, Vol: 4, Pages: 43-84, ISSN: 2193-0856
Nakamura R, Plaschke F, Teubenbacher R, et al., 2014, Interinstrument calibration using magnetic field data from the flux-gate magnetometer (FGM) and electron drift instrument (EDI) onboard Cluster, GEOSCIENTIFIC INSTRUMENTATION METHODS AND DATA SYSTEMS, Vol: 3, Pages: 1-11, ISSN: 2193-0856
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Whiteside BJ, Brown P, Beek TJ, et al., 2014, TID Response of a Hybrid AMR Vector Magnetometer, IEEE Radiation Effects Data Workshop (REDW) is part of the Nuclear and Space Radiation Effect Conference (NSREC), Publisher: IEEE
Pudney MA, Carr CM, Schwartz SJ, et al., 2013, Near-magnetic-field scaling for verification of spacecraft equipment, Geoscientific Instrumentation, Methods and Data Systems, Vol: 2, Pages: 249-255, ISSN: 2193-0864
Magnetic-field measurements are essential tothe success of many scientific space missions. Outside ofthe earth’s magnetic field the biggest potential source ofmagnetic-field contamination of these measurements is emittedby the spacecraft. Spacecraft magnetic cleanliness is enforcedthrough the application of strict ground verificationrequirements for spacecraft equipment and instruments. Dueto increasingly strict AC magnetic-field requirements, manyspacecraft units cannot be verified on the ground using existingtechniques. These measurements must instead be takenclose to the equipment under test (EUT) and then extrapolated.A traditional dipole power law of −3 (with a fieldfall-off proportional to r−3) cannot be applied at these closedistances without risk of underestimating the field emitted bythe EUT, but we demonstrate that a power law of −2 is tooconservative. We propose a compromise that uses a powerlaw of −2 up to a distance equal to 3 times the unit size, beyondwhich a dipole power law can be applied. When extrapolatingfrom a distance of 0.20 m to 1.00 m from the centre ofa 0.20 m wide EUT, we demonstrate that this method avoidsan under prediction of the field, and is at least twice as accurateas performing the extrapolation with a fixed power lawof −2.
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