Magnetic Field Change Research Articles

Low-temperature magnetic and magnetocaloric properties of orthorhombic DyNiSn

In this work, magnetic and magnetocaloric properties of antiferromagnetic (AFM) DyNiSn compounds which shows complex magnetic behavior at low-temperatures are investigated. Performed magnetic and specific heat measurements showed that except transition to the antiferromagnetic state at TN = 7.7(1) K, there are two more changes in the magnetic structure at T1 = 5.6(1) K = and T2 = 2.6(1) K. The magnetocaloric properties of the DyNiSn were determined indirectly from magnetic and specific heat measurements. DyNiSn shows normal and inverse magnetocaloric effect peaks at ∼9 K and ∼5 K, respectively. The maximum values of the magnetic entropy change (ΔSm), relative cooling power (RCP), and temperature averaged entropy change (TEC(5)) evaluated from magnetic measurements and for magnetic field change of 5 T are −8.0(1) Jkg−1K−1, 130(9) Jkg−1, and 8.7(1) Jkg−1K−1, respectively.

The terahertz isolator and switch based on the nonreciprocal feature of magnetized InSb layered photonic structure

In this paper, a multifunctional device based on a one-dimensional (1-D) magnetized InSb layered photonic structure (LPS) that can achieve the function of a magnetic-controlled isolator and switch is proposed, with the advantages of multi-function. The external conditions for realizing the LPS function are temperature 303 K, magnetic field B1 = 0–0.3 T, B2 = 0 T, which are easier to obtain through an applied magnetic field device. B1 and B2 differ only in intensity. Both B1 and B2 are applied magnetic fields parallel to the positive y-axis. The change of magnetic field can influence the the cyclotron frequency of the electron which affect the dielectric constant of the tensor form, and finally lead to the change of refractive index (RI), resulting in interesting electromagnetic phenomena. Temporal inversion symmetry and spatial inversion symmetry could be easily broken to actualize nonreciprocal phenomena because of the magneto-optic effect of Indium antimonide (InSb) and an asymmetric arrangement of quasi-periodic media. For the isolator, the transmittance of forwarding propagation arrives at 0.994 and the backward scale is much closer to 0. The isolation and insertion loss achieves 34 dB and 0.0269 dB, and the range of the angle stabilization is from 17° to 31°. For the switch operating, just changing the value of B1 from 0.3 T to 0 T, can realize the function of the switch operating instead of an isolator. This shift is easier to reach by turning off the magnetic field. The extinction ratio attains 99.8 % and angle stabilization is between 9° and 31°. This magnetic-structure multifunctional LPS can play a vital constructive role in medicine, computing, and other fields.

Magnetohydrodynamic Shocks Revisited: Magnetically Constraining the Upstream Solar Wind Condition

Magnetohydrodynamic (MHD) shocks are commonly found in various space and astrophysical systems. One often encounters the problem that only the magnetic field data are available when studying interplanetary shocks and planetary bow shocks in the solar system, and not the plasma data due to instrumental and/or telemetry limitations. We aim to reveal the mathematical structure of the MHD Rankine–Hugoniot relation under the condition that magnetic field changes across the shock are known, which can be devised into a diagnosis tool to constrain the shock parameters. The perturbative solution is already known for the Rankine–Hugoniot equation. The solution is combined with the condition of the de Hoffmann–Teller frame for the vanishing convective electric field, and we obtain a two-dimensional matrix equation for the density jump and the Alfvén Mach number. The lesson is that the shock parameters (density jump and Alfvén Mach number) are analytically obtained by inverting the MHD Rankine–Hugoniot equation under the condition that the plasma beta is either a priori set or known. Further numerical studies indicate that the presented shock jump estimation works particularly well for quasi-perpendicular shocks. Moreover, a test case with the Earth bow shock crossing data supports our theoretical development. The presented method opens the door to determining or constraining the shock parameters even if the data are limited to the magnetic field only.

A three-band frequency hopping high power microwave oscillator based on magnetic field tuning

The frequency hopping technology is one of the most significant research directions for high-power microwave (HPM) devices. This paper presented a novel HPM oscillator with frequency hopping across C, X, and Ku bands based on magnetic field tuning. A coaxial transit time oscillator (TTO) is nested onto the outer conductor of the hollow relativistic Cherenkov microwave oscillator, which forms a dual electromagnetic structure with a single-annular cathode. When the electron beam is guided by gradient magnetic fields, it interacts with TTO to produce Ku-band HPMs. If the gradient magnetic field changes into the uniform magnetic field, the electron beam would enter the relativistic Cherenkov microwave oscillator, and the frequency of generated microwaves decreases, which are decided by the strength of the magnetic fields according to the cyclotron resonance absorption theory. In the particle-in-cell simulation, when the diode voltage and gradient magnetic field are 580 kV and 0.5 T, respectively, a Ku-band HPM output with a frequency of 13.9 GHz and a power of 2.09 GW is obtained, corresponding to power efficiency of 42%. When the magnetic field transforms into uniform, the device produces an X-band HPM output with a frequency of 9 GHz and a power of 2.4 GW at a diode voltage of 683 kV and a magnetic field of 0.7 T. When the voltage and magnetic field strength are increased to 699 kV and 1.5 T, respectively, the device generates a C-band HPM output with a frequency of 4.5 GHz and a power of 2.1 GW. The corresponding conversion efficiency of the X-band and C-band Cherenkov microwave oscillators is 35% and 30.7%, respectively.

Assessing the Effects of a Minor CIR‐HSS Geomagnetic Storm on the Brazilian Low‐Latitude Ionosphere: Ground and Space‐Based Observations

AbstractThis paper investigates the effects of a minor G1 Co‐rotating Interaction Region (CIR)/High‐Speed Stream (HSS)‐driven geomagnetic storm that occurred on (13–14 October 2018), during deep solar minimum. We used simultaneous observations from multiple instruments, namely; ground‐based Global Navigation Satellite Systems (GNSS) receivers, a Digisonde, ground magnetometers, and space‐based observations from the National Aeronautics and Space Administration Global‐scale Observations of Limb and Disk (GOLD) and SWARM missions. This study presents a detailed picture of the low‐latitude ionosphere response over the Brazilian sector during a minor storm. Our results showed that the minor CIR/HSS‐driven storm caused a positive ionospheric storm of over ∼20 TECU in magnitude. For the first time, periodic post‐sunset irregularities and Equatorial Plasma Bubbles, equatorial plasma bubbles, were analyzed using GOLD FUV OI 135.6 nm emission, Total Electron Content (TEC) maps, Rate of TEC index, ROTI, and TEC gradients. Fluctuations in the interplanetary magnetic field Bz and changes in the thermospheric column density ratio (∑O/N2) are discussed as the main sources of ionospheric changes during the storm. This paper highlights the importance of monitoring and understanding the impact of Sun‐Earth interactions and provides insight into the behavior of the low‐latitude ionosphere during minor geomagnetic storms.

Borderline first-order phase transition and large cryogenic magnetocaloric effect in PrNdIn

We report a large cryogenic magnetocaloric effect stemming from an unconventional borderline first-order magnetic phase transition with negligibly small thermomagnetic hysteresis in a rare-earth-based intermetallic compound PrNdIn. The sample exhibits maximum magnetic field-induced entropy change as large as −10 J/Kg K (for 20 kOe magnetic field change) near the boiling point of oxygen. Magnetocaloric properties of PrNdIn are comparable to those of other known potential magnetocaloric materials with operating temperatures ranging between 50 and 125 K. The magnetic properties of the present sample are qualitatively reminiscent of those of the binary Pr2In and Nd2In, including the emergence of a second low-temperature anomaly in the temperature dependence of magnetization.

Effect of annealing on magnetic and magnetocaloric properties of SmCo3B2 thin films

In this study, SmCo3B2 ternary thin films of manifold thickness were fabricated via e-beam evaporation technique. All the as-deposited SmCo3B2 thin films were subjected to electron beam rapid thermal annealing (ERTA). The X-ray diffraction studies showed amorphous nature for all the as deposited thin films and a highly crystalline hexagonal structure for all ERTA subjected thin films. The elemental composition, purity and surface morphology of the samples were analyzed using energy-dispersive x-ray spectroscopy (EDS) and High-resolution Scanning Electron Microscopy (HR-SEM). Furthermore, the study investigates the magnetocaloric properties of SmCo3B2 thin films, with significant changes depending on the thickness and annealing time. The thin films exhibited a magnetic phase transition around the Curie temperature (Tc) within the range of 40–46 K, attributed to the indirect exchange coupling of Sm–Sm sublattice interactions. Moreover, a significant shift in Tc towards higher temperatures with respect to thickness and annealing were observed in both as deposited and ERTA subjected thin films. The Arrot plots in the positive quadrant suggested the second order magnetic phase transition (SOPT) for all the films. The maximum magnetic entropy change (−ΔSm) of 1.172 Jkg−1K−1 accompanied by a relative cooling power of 5.33 Jkg-1 was achieved for 240 nm ERTA subjected thin film under a change in magnetic field of 5T. The study reveals the effect of ERTA and thickness dependent magnetic and magnetocaloric properties of SmCo3B2 thin films.

A non-destructive method for detecting turn-to-turn resistivity distribution in NI REBCO coils

A non-destructive method is proposed for detecting the turn-to-turn resistivity distribution (TTRD) of non-insulation (NI) coils made of REBCO tapes. In conventional designs, TTRD is often estimated to be a constant, while it is actually non-uniform. It is crucial to detect the TTRD of NI coils more accurately as it determines the behaviour of NI coils and may lead to peculiar phenomena such as local reverse currents. The proposed approach involves acquiring the temporal change of voltage distribution during an excitation/demagnetization process, which is subsequently incorporated into a system of ordinary differential equations derived from an equivalent circuit model. A genetic algorithm (GA) is then employed to fit the collected time-varying voltage data and generate the results of the ‘measured’ TTRD. The system of equations can actually be numerically solved. The solved time-varying TTRD results are averaged over the measuring period, which serve as the initial value of GA fitting, and accelerates the fitting process. Virtual measurements were performed on an artificially established mock coil, demonstrating high accuracy in reproducing the predetermined TTRD. Furthermore, an actual measurement was also conducted on a single-pancake coil, however with unknown TTRD, using eight voltage measurement points during the demagnetization process. The measured TTRD was incorporated into the equivalent circuit model to predict the temporal changes in voltage and magnetic field of the coil under additional excitation/demagnetization conditions. By comparing the predicted results with the experimental data, a high level of agreement was observed, thus confirming the potential application of the proposed method.

Martian Bow Shock Oscillations Driven by Solar Wind Variations: Simultaneous Observations From Tianwen‐1 and MAVEN

AbstractThe Martian bow shock stands as the first defense against the solar wind and shapes the Martian magnetosphere. Previous studies showed the correlation between the Martian bow shock location and solar wind parameters. Here we present direct evidence of solar wind effects on the Martian bow shock by analyzing Tianwen‐1 and MAVEN data. We examined three cases where Tianwen‐1 data show rapid oscillations of the bow shock, while MAVEN data record changes in solar wind plasma and magnetic field. The results indicate that the bow shock is rapidly compressed and then expanded during the dynamic pressure pulse in the solar wind, and is also oscillated during the IMF rotation. The superposition of variations in multiple solar wind parameters leads to more intensive bow shock oscillation. This study emphasizes the importance of joint observations by Tianwen‐1 and MAVEN for studying the real‐time response of the Martian magnetosphere to the solar wind.

Study on tide characteristics and mechanism of PSP in buried pipeline along the lake

The fluctuations of the Pipe-to-Soil Potential (PSP) in buried pipes are influenced by the geoelectric field induced by changes in the Earth's magnetic field, which can accelerate pipeline corrosion. Monitoring data of PSP along China's West–East Gas Pipeline near the lake indicates obvious tidal changes. This study proposes that the periodic movement of the conductivity boundary of the seepage area near the lake shore caused by tides is the fundamental cause of the tidal changes in PSP. The movement of the boundary changes the range of the H polarization of the geoelectric field, resulting in periodic changes in the PSP of the pipeline outside the seepage area. To investigate this mechanism, a dynamic boundary model of conductivity in the seepage area of Sailimu Lake in Xinjiang was established, and the characteristics of PSP at different distances from the boundary were analyzed using electromagnetic field finite element method and DSTL pipeline model. The study compared the simulation results of the model with the PSP data of the cathodic protection station and PSP monitoring station near Sailimu Lake, during a geomagnetic disturbance on September 23–24, 2016. The results of the study, as well as the corrosion of the test strips along the lake, verified the validity of the boundary change mechanism and model of the seepage zone. This study provides a theoretical basis for corrosion protection of pipelines near the lake’s edge.

Effect of Interface Defects on the Harmonic Currents in Distribution Cable Accessories under Damp Conditions

Dampness is one of the most important factors leading to the degradation of the insulation performance of cable accessories; it may easily lead to interface defects of composite insulation. In this paper, an electromagnetic field defect model of the cable composite insulation interface is established, and the effects of the defect degree and the defect type on the magnetic flux and the harmonic current are studied. The results show that the magnetic field is uniformly distributed with a decreasing trend when the cable is in good condition, and the grounding current has no obvious harmonic component. For different defects, the magnetic field changes at the defect location are notably different; for water droplets and the water film, the magnetic field distortion is obvious at the location of the defect and sheath, and for water tree defects, the distortion of the magnetic field is significant. In addition, the degree of distortion caused by the same defect at different positions is also different, and the magnetic field contrast is not obvious at different degrees of moisture exposure. The distortion of the grounding current caused by the water tree is higher than that of the water droplet and the water film, and the characteristics of the harmonic components of the grounding current caused by different defects have obvious distinctions. The type of cable defect can be judged by the proportion of harmonic components. This work can be used as a reference for the assessment of the cable insulation defect status.

A Performance Improvement for Indoor Positioning Systems Using Earth's Magnetic Field.

Although most indoor positioning systems use radio waves, such as Wi-Fi, Bluetooth, or RFID, for application in department stores, exhibition halls, stations, and airports, the accuracy of such technology is easily affected by human shadowing and multipath propagation delay. This study combines the earth's magnetic field strength and Wi-Fi signals to obtain the indoor positioning information with high availability. Wi-Fi signals are first used to identify the user's area under several kinds of environment partitioning methods. Then, the signal pattern comparison is used for positioning calculations using the strength change in the earth's magnetic field among the east-west, north-south, and vertical directions at indoor area. Finally, the k-nearest neighbors (KNN) method and fingerprinting algorithm are used to calculate the fine-grained indoor positioning information. The experiment results show that the average positioning error is 0.57 m in 12-area partitioning, which is almost a 90% improvement in relation to that of one area partitioning. This study also considers the positioning error if the device is held at different angles by hand. A rotation matrix is used to convert the magnetic sensor coordinates from a mobile phone related coordinates into the geographic coordinates. The average positioning error is decreased by 68%, compared to the original coordinates in 12-area partitioning with a 30-degree pitch. In the offline procedure, only the northern direction data are used, which is reduced by 75%, to give an average positioning error of 1.38 m. If the number of reference points is collected every 2 m for reducing 50% of the database requirement, the average positioning error is 1.77 m.

Influence of uncertainty factors on the dynamic characteristics of magnetorheological damper

The magnetorheological damper (MRD) is a kind of energy dissipation device, which converts vibration mechanical energy into self-heat energy during operation. The dynamic performance of MRD is affected by uncertain factors such as temperature and external magnetic field. In this paper, basing on the temperature rise theory and external magnetic field interference theory of MRD, it analyses the influence of temperature effect and external magnetic field on the dynamic performance of MRD. Under sinusoidal excitation, the internal temperature field and magnetic field distribution of MRD are simulated by COMSOL, and it calculates the changes of temperature and magnetic field in MRD by the conditions of input current of 0.4A, 0.8A and 1.2A. The temperature rise and external magnetic field test are carried out. Under the same input current, the temperature rise of the outer wall of the cylinder is measured. The results show that the input current increases, the temperature rise of MRD increases, and the temperature of MRD increases, the output damping force decreases obviously. When the input current is 0.4A, the temperature of MRD rises to 40℃, the maximum output damping force decreases by 11.2%, and the current is 1.2A, the maximum output damping force decreases by 18.6%. When external magnetic field is applied, the output damping force of MRD increases. The magnetic induction intensity of the external magnetic field increases from 10mT to 30mT, when the incoming current is 0.4A, the maximum output damping force increases by 5.9%, and the current is 1.2A, the maximum output damping force increases by 5.1%. Therefore, applying external magnetic field to compensate the decreasing value of output damping force caused by temperature rise effect has a certain effect. The results show that the variation trend of theoretical analysis, simulation calculation and experimental verification is consistent.

Role of 5 mol% rare earth (La3+) on the structural, microstructural, and magnetic properties of cobalt chromite ceramics

Spinel oxides, which have the structure AB2O4 and are distinguished by their exceptional magnetic, electric, and multiferroic properties and exhibit a wide range of functional responses in the category of oxides. The cobalt chromate (CoCr2O4) is well-known as a multiferroic-magnetoelctric (ME) material. It belongs to the magnetic spinal oxide family and is noted for its complicated spiral ferromagnetic(FM) orderings. To enhance the magnetic properties of the CoCr2O4, in this work we have chosen Lanthanum (La3+) 0.05 mol% doped cobalt chromites (CoCr2O4) nanoparticles. The solution combustion method was utilized to synthesize the nanomaterial, where urea and glucose were used as fuels. The Structural exploration of the Co0.95La0.05 Cr2O4 nanoparticles were clarified using powder X-ray diffraction. To understand the microstructure properties we have carried out high-resolution electron microscopy and it reveals highly porous nature. In FTIR spectra the two main absorption bands at 507 cm−1 and 616 cm−1 were observed which confirm the formation of spinal chromates. The TGA results revealed a slow thermal degradation, and the sample has a thermal stability that is greater than the temperature range tested. Researchers have examined the changes in temperature and magnetic field affected the magnetic properties of materials over time (ZFC & FC). In comparison to the bulk sample, the Curie temperature at which samples transition from a paramagnetic (PM) state to a collinear short-range ferromagnetic (FM) state is significantly lower. This temperature is denoted as TC-98 K deteriorated with time in terms of quality. At low temperatures, there is no magnetic transition that can be identified between the short-range FM order and the long-range spiral spin structure. This is in contrast to the magnetic transitions that can be discovered in bulk. What gives rise to all of the intriguing qualities that have been described above is the presence of weak magnetic frustration, which is very much connected to super-exchange interactions and is found along different paths such as A-O-A, B–O–B, and A-O-B. This presence is what gives rise to all of the intriguing characteristics that have been described above.

Magnetic control of spin switches in a graphene quantum dot and two-electron spin qubit

To get a magnetically controllable spin qubit based on carbon materials, we study the energy spectra of a triangular graphene quantum dot with two electrons occupying the degenerate shell. The total spin of the system can be either 0 or 1 and thus provides a possible realization for a spin qubit. The spin-phase diagrams are employed to show the evolution of the spin with the change of external magnetic and electric fields. The spin switches can be achieved by changing the magnetic field strength in the realistic range. In addition, from the perspective of manipulating spin qubits, we present some typical control models of spin switches. Our findings support the possibility to realize a carbon-based spin qubit controlled by an external magnetic field.

Functional drug-delivery hydrogels for oral and maxillofacial wound healing.

The repair process for oral and maxillofacial injuries involves hemostasis, inflammation, proliferation, and remodeling. Injury repair involves a variety of cells, including platelets, immune cells, fibroblasts, and various cytokines. Rapid and adequate healing of oral and maxillofacial trauma is a major concern to patients. Functional drug-delivery hydrogels play an active role in promoting wound healing and have shown unique advantages in wound dressings. Functional hydrogels promote wound healing through their adhesive, anti-inflammatory, antioxidant, antibacterial, hemostatic, angiogenic, and re-epithelialization-promoting properties, effectively sealing wounds and reducing inflammation. In addition, functional hydrogels can respond to changes in temperature, light, magnetic fields, pH, and reactive oxygen species to release drugs, enabling precise treatment. Furthermore, hydrogels can deliver various cargos that promote healing, including nucleic acids, cytokines, small-molecule drugs, stem cells, exosomes, and nanomaterials. Therefore, functional drug-delivery hydrogels have a positive impact on the healing of oral and maxillofacial injuries. This review describes the oral mucosal structure and healing process and summarizes the currently available responsive hydrogels used to promote wound healing.

Magnetic Discontinuities in the Inner Heliosphere: Do Intermediate Shocks Exist?

Magnetic discontinuities are fundamental structures in space and laboratory plasmas where the changes in magnetic and velocity fields are constrained by Rankine–Hugoniot relations. Due to the absence of precise measurements for particles, some issues therein are hardly investigated. The nature of discontinuities driven by the magnetohydrodynamics (MHD) turbulence, and the intermediate shock are two puzzles to be solved. The MHD turbulence generates numerous discontinuities with both small normal magnetic fields and nearly constant magnetic field magnitudes in statistics. By utilizing the data from the Parker Solar Probe, we identify among the turbulence-driven discontinuities two components that exhibit diverse statistical characteristics of the plasma density, and reveal that these discontinuities comprise 80.2% rotational and 19.8% tangential discontinuities. Then, we note a special class of discontinuities within 0.35 au that have jump conditions similar to that of the rotational discontinuity and the shock simultaneously, including (1) positively correlated jumps in the plasma density and temperature, (2) a small change in the magnetic field magnitude, and (3) opposite tangential magnetic fields on two sides. These features conform to the theoretical intermediate shock, which previous studies have found to not practically exist due to the breakdown of the evolutionary condition. By the conservation law of the mass flux across a boundary, we calculate their propagation speeds and find three intermediate shock candidates with super-Alfvénic upstream and sub-Alfvénic downstream flows. This work can improve our understanding of plasma intermittencies and suggests reassessing conclusions based on ideal MHD Rankine–Hugoniot relations.

Basic Research on a Magnetic Refrigeration System for Cooling to Liquid Hydrogen Temperature

Magnetic refrigeration technology is expected to be a highly efficient process at a temperature of around 20 K, which is the hydrogen liquefaction temperature. In magnetic refrigeration, a magnetic field change is applied to a magnetocaloric material (MCM) to obtain a magnetocaloric effect. In addition, since the greater the magnetic field change, the better the cooling characteristics, the magnetic field strength of permanent magnets is insufficient, and the use of superconducting coils that can generate strong magnetic fields with low power consumption is essential. We are researching and developing a static magnetic refrigeration system (SMRS) that does not have moving parts to obtain magnetic field changes, and generates them by altering the energizing current to the coil. The key to devising this system is an AC loss of the superconducting coil. In this study, we measured the AC loss under energization conditions of multiple palm-sized REBCO coils at liquid nitrogen temperature, and calculated the efficiency of the SMRS by improving the accuracy of the analysis method for evaluating the AC loss, based on the results. We report the results and discuss the technical feasibility of SMRS.

Magnetic field fluctuations in the shocked umbral chromosphere

Context. Umbral chromospheric observations show the presence of magnetoacoustic shocks. Several recent studies have reported magnetic field fluctuations associated with these shock waves. The mechanism behind these periodic magnetic field changes is still an unresolved question. Aims. We aim to study the properties and origin of magnetic field fluctuations in the umbral chromosphere. Methods. Temporal series of spectropolarimetric observations were acquired with the GREGOR telescope on 2017 June 18. The chromospheric and photospheric conditions, including the temporal evolution of the magnetic field, were derived from simultaneous inversions of the He I 10 830 Å triplet and the Si I 10 827 Å line using the HAZEL2 code. The oscillations were interpreted using wavelet analysis and context information from ultraviolet observations acquired with the Atmospheric Imaging Assembly on board the Solar Dynamics Observatory (SDO/AIA) and the Interface Region Imaging Spectrograph (IRIS). Results. The chromospheric magnetic field shows strong fluctuations in the sunspot umbra, with peak field strengths of up to 2900 G. This inferred field strength is comparable to the magnetic field strength in the upper photosphere. Magnetic field and velocity umbral oscillations exhibit a strong coherence, with the magnetic field lagging the shock fronts detected in the velocity fluctuations. This points to a common origin of the fluctuations in both parameters, and the analysis of the phase shift between photospheric and chromospheric velocity is consistent with upward wave propagation. These results suggest that the strong inferred magnetic field fluctuations are caused by changes in the response height of the He I 10 830 Å line to the magnetic field, which is sensitive to the high photosphere during and right after the shock. The analysis of extreme ultraviolet data shows a weak brightening in a coronal loop rooted in the umbra around the time of the measured magnetic field fluctuations. This coronal activity could possibly have some impact on the inferred fluctuations, but it is not the main driver of the magnetic field oscillations since they are found before the extreme ultraviolet event takes place. Conclusions. Chromospheric magnetic field fluctuations measured with the He I 10 830 Å triplet arise due to variations in the opacity of the line. After strong shocks are produced by the propagation of slow magnetoacoustic waves, the response of the line to the magnetic field can be shifted down to the upper photosphere. This is seen as remarkably large fluctuations in the line-of-sight magnetic field strength.

Partially Erupted Prominence Material as a Diagnostic of Coronal Mass Ejection Trajectory

AbstractCoronal mass ejections (CMEs) are energetic releases of large‐scale magnetic structures from the Sun. CMEs can have impacts on spacecraft and at Earth. This trajectory is typically assumed to be radial, but often the CME moves outward with some spatial offset from the source region where the eruption initially occurred. A CME is frequently accompanied by a prominence eruption, a movement of cool, dense material up into the corona that can be ejected or fall back down. We investigate eruptions in which some portion of the prominence material falls back to the Sun along field lines which have reconfigured in the eruption, rather than draining back to the source or escaping with the CME. Using a method called persistence mapping, 304 Å images from the Solar Dynamics Observatory (SDO), and coronagraph images from the Solar and Heliospheric Observatory, we measure and compare the offsets in latitude of 20 CMEs and their respective prominences with respect to the source region. The 20 events were chosen to sample over the first 10 years of the SDO mission. We find that the offsets are correlated. We find no difference between eruptions offset toward the equator or the poles, suggesting that the offset is a result of local changes in the eruptive field, rather than of the Sun's global magnetic field structure. These findings help us contextualize individual eruptions and highlight changes in the local magnetic field associated with the prominence eruption.