Opposite Magnetic Poles Research Articles

Waiting Time Distribution of Giant Pulses from the Crab Pulsar Modeled with a Non-stationary Poisson Process

We study the waiting time distribution of giant pulses from the Crab pulsar observed with the Nanshan 26-m radio telescope at a center frequency of 1556 MHz with 512 MHz bandwidth. The observations were performed over a duration of 12.6 hours with 32 μs sampling interval. Our analysis has led to the detection of 2097 giant pulses above a threshold of 10 σ, with flux density > 100 Jy. The occurrence rate of giant pulses is characterized by a highly intermittent giant pulse productivity in short clusters with high rates, separated by relatively long quiescent intervals with low occurrence rates, especially for the giant pulses associated with the interpulse emission. The distribution of waiting times between two subsequent giant pulses displays a power-law tail that can be modeled with a non-stationary Poisson process, which indicates that giant pulses are independent and random events. Distinct waiting time distributions between giant pulses in the main pulse and interpulse phases are presented, which implies that the giant pulse emission mechanisms maybe different in the opposite magnetic poles. The ramification for our understanding of the radio emission mechanisms is discussed.

Development of a circuit breaker system using a linear motor with opposite magnetic poles

AbstractThe high‐thrust linear motor with a lightweight and high‐strength mover was developed for operating circuit breakers. The linear motor is composed of a lightweight mover that has permanent magnets sandwiched between magnetic poles and an armature with a three‐dimensional magnetic circuit. The specifications and performance of the linear motor were determined to cut off current soundly. Then, a prototype of a fully electrically operated breaker using linear motor was investigated. The linear‐motor‐based operating mechanism designed for the circuit breaker reached the open‐pole position in 13.2 ms from the start of movement. However, the time from opening to 0.5 cycle was 9.0 ms. In addition, the variation in breaking operation time was within 1 ms, which was expected that stable controlled operation.

Development of an Circuit Breaker System Using a Linear Motor with Opposite Magnetic Poles

Development of an Circuit Breaker System Using a Linear Motor with Opposite Magnetic Poles

Improving the surface quality of 60/40 brass using flexible magnetic burnishing brush formed with permanent magnets

Herein, brass C274 was burnished by placing it between two opposite permanent magnetic poles on a vertical milling machine. The gap between the two magnets was filled with cylindrical stainless-steel pins, to form a newly flexible magnetic burnishing brush. The rotational speed and feed rate were varied at 500–1500 rpm and 6–16 mm min−1, respectively. The flexible magnetic burnishing brush improved the hardness for all feed rates by up to 40% as well as the roughness by 76% compared to the unburnished yellow brass. The corrosion resistance improved only for selected feed rates and burnishing speeds.

A piezoelectric energy harvester for broadband rotational excitation using buckled beam

This paper proposes a rotational energy harvester using a piezoelectric bistable buckled beam to harvest low-speed rotational energy. The proposed harvester consists of a piezoelectric buckled beam with a center magnet, and a rotary magnet pair with opposite magnetic poles mounted on a revolving host. The magnetic plucking is used to harvest the angular kinetic energy of the host. The nonlinear snap-through mechanism is utilized to improve the vibration displacement and output voltage of the piezoelectric layer over a wide rotation frequency range. Theoretical simulation and experimental results show that the proposed energy harvester can yield a stable average output power ranging between 6.91-48.01 μW over a rotation frequency range of 1-14 Hz across a resistance load of 110 kΩ. Furthermore, dual attraction magnets were employed to overcome the suppression phenomenon at higher frequencies, which yields a broadband and flat frequency response over 6-14 Hz with the output power reaching 42.19-65.44 μW, demonstrating the great potential of the bistable buckled beam for wideband rotation motion energy harvesting.

Synthesis of polishing fluid and novel approach for nanofinishing of copper using ball-end magnetorheological finishing process

ABSTRACTBall-end magnetorheological (MR) finishing process utilizes the magnetically controlled stiffened ball of an MR fluid for finishing purposes. Copper is a mechanically soft and chemically reactive material, so it is difficult to finish up to the nanometer-order level by traditional and most of the advanced finishing processes. In this research work, the problems associated with ball-end MR finishing of copper have been explored and a fluid composition suitable for the finishing of copper has been developed. A novel approach using two opposite magnetic poles has been used to enhance the magnetic flux density distribution between the tool tip and the copper workpiece surface. The same has been magnetically simulated and verified experimentally. The effect of fluid composition parameters has been analyzed by the statistical model developed by response surface. After 30 minutes of finishing time, a nano-finished surface with very few shallow scratches was achieved.

The Diagnosis and Treatment of Circadian Rhythm Disorders

Event Abstract Back to Event The Diagnosis and Treatment of Circadian Rhythm Disorders Leon C. Lack1* 1 Flinders University, Australia Sleepiness is determined biologically by two comparable but independent factors: homeostatic sleep drive and circadian rhythm sleep drive. The circadian sleepiness varies with a host of synchronised endogenous physiological and hormonal rhythms across the 24-hour period. Normal entrainment of this circadian system favours sleep at night (aprox. 2300-0700h) and alertness/productivity during the day. However, abnormalities of the circadian system in timing or amplitude can cause chronic or short term difficulties sleeping when desired and being alert when necessary. Delayed sleep phase disorder (DSPD) results from a 2-6 hour delay from normal of the circadian system making it impossible to initiate sleep before 0100h. Advanced sleep phase disorder (ASPD) results from an abnormally early timed circadian system making it impossible to maintain sleep past 0300h. Free-running rhythms do not remain stable in the 24-hour period but tend to drift later making night-time sleep and daytime alertness difficult for periods of days or weeks. Jet-lag and shiftwork usually produce short-lived sleep/wake problems. Since the most common disorders are from abnormal timing of the circadian system, tools to re-time circadian rhythms such as retinal light stimulation and exogenous melatonin administration can be used to treat these disorders. Light intensity, duration, and wavelength are important dimensions for treatment effect. However, the timing of light is critical for the effectiveness of these treatments. Bright light stimulation pushes the endogenous sleep period away from it like similar poles on a bar magnet (e.g. south/south) while the time of melatonin administration pulls the endogenous sleep period towards it like two opposite magnetic poles (e.g. north/south). The ‘push’ and ‘pull’ effects can be combined to shepherd the endogenous sleep period into the desired time (e.g. 2300-0700h). Other behavioural procedures and cognitive therapies can also be helpful in the treatment of these problematic circadian rhythm disorders. Keywords: Circadian Rhythm, Sleep, Sleep Disorders, delayed sleep phase syndrome, advanced sleep phase disorder, Circadian rhythm disorder Conference: ASP2016 - The 26th Annual Meeting of the Australasian Society for Psychophysiology, Adelaide Australia, Adelaide,SA, Australia, 12 Dec - 14 Dec, 2016. Presentation Type: Oral Presentation Topic: Abstract (general) Citation: Lack LC (2016). The Diagnosis and Treatment of Circadian Rhythm Disorders. Conference Abstract: ASP2016 - The 26th Annual Meeting of the Australasian Society for Psychophysiology, Adelaide Australia. doi: 10.3389/conf.fnhum.2016.221.00001 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 24 Nov 2016; Published Online: 05 Dec 2016. * Correspondence: Prof. Leon C Lack, Flinders University, Adelaide, Australia, leon.lack@flinders.edu.au Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Leon C Lack Google Leon C Lack Google Scholar Leon C Lack PubMed Leon C Lack Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Fabrication of aligned structure tissue engineering scaffold by electrospinning using magnetic field

Event Abstract Back to Event Fabrication of aligned structure tissue engineering scaffold by electrospinning using magnetic field Zhen Li1*, Lei Zhang1* and Feng Lin1* 1 Tsinghua University, Department of Mechanical Engineering, China Introduction: The technology of electrospinning is an important method in fabrication of the tissue engineering scaffold, having the superiority of small diameter, high porosity and so on. Especially, the structure of aligned fiber has many advantages, such as it is good for the adhesion and proliferation of cells. But the random non-woven fabric structure is got using the ordinary method of electrospinning, and that how to fabricate aligned fiber is one of the hot issues in this field. The purpose of this study is to fabricate the aligned fiber using the mothed of electrospinning in the static magnetic field and analyze the influence of the magnetic field. Materials and Methods: In this study, we fabricated fibers by electrospinning using the PLGA and 1,4-dioxide solution. In order to verify the effect of the static magnetic field in the process of electrospinning, different kinds of materials of magnets (ferrite and NdFeB, we also used plastic block as contrast) and different magnetic field distribution were used in this experiment. And in order to analyze the theoretic effect of the magnetic field, the scale of the force and the movement effect on the fiber were analyzed and estimated by establishing a model of fiber’s deposition. Result and Discussion: In the experiment, some good experimental parameter was found in the electrospinning of the PLGA and 1,4-dioxide solution. But it is shown that we got the same aligned fibers whether the same magnetic poles is opposite or different magnetic poles is opposite. It illustrated that the main factors of the aligned structure are physic structure of the receiver and the electric field distribution instead of the magnetic field. The model calculating result showed that the direction of the force couldn’t make the fiber despite along the magnetic field between the two magnets. And the force is too small to control the movement of the fiber. Conclusions: According to the experimental and theoretical results, the influence of the fiber structure by magnetic field is small and this conclusion is opposite to many study in this field. In this study, some extra experiment made the conclusions before not valid any more and the theory of the magnetic electrospinning needs further researches.​ Keywords: Tissue Engineering, Structure, nanofiber, Scaffold Conference: 10th World Biomaterials Congress, Montréal, Canada, 17 May - 22 May, 2016. Presentation Type: Poster Topic: Synthetic scaffolds as extracellular matrices Citation: Li Z, Zhang L and Lin F (2016). Fabrication of aligned structure tissue engineering scaffold by electrospinning using magnetic field. Front. Bioeng. Biotechnol. Conference Abstract: 10th World Biomaterials Congress. doi: 10.3389/conf.FBIOE.2016.01.01791 Copyright: The abstracts in this collection have not been subject to any Frontiers peer review or checks, and are not endorsed by Frontiers. They are made available through the Frontiers publishing platform as a service to conference organizers and presenters. The copyright in the individual abstracts is owned by the author of each abstract or his/her employer unless otherwise stated. Each abstract, as well as the collection of abstracts, are published under a Creative Commons CC-BY 4.0 (attribution) licence (https://creativecommons.org/licenses/by/4.0/) and may thus be reproduced, translated, adapted and be the subject of derivative works provided the authors and Frontiers are attributed. For Frontiers’ terms and conditions please see https://www.frontiersin.org/legal/terms-and-conditions. Received: 27 Mar 2016; Published Online: 30 Mar 2016. * Correspondence: Dr. Zhen Li, Tsinghua University, Department of Mechanical Engineering, Beijing, China, zhen-li15@mails.tsinghua.edu.cn Dr. Lei Zhang, Tsinghua University, Department of Mechanical Engineering, Beijing, China, stoneszhang@mail.tsinghua.edu.cn Dr. Feng Lin, Tsinghua University, Department of Mechanical Engineering, Beijing, China, Email1 Login Required This action requires you to be registered with Frontiers and logged in. To register or login click here. Abstract Info Abstract The Authors in Frontiers Zhen Li Lei Zhang Feng Lin Google Zhen Li Lei Zhang Feng Lin Google Scholar Zhen Li Lei Zhang Feng Lin PubMed Zhen Li Lei Zhang Feng Lin Related Article in Frontiers Google Scholar PubMed Abstract Close Back to top Javascript is disabled. Please enable Javascript in your browser settings in order to see all the content on this page.

Experimental Research on the Transmission of the Eccentric Magnetic Gear with Few Pole Difference

Used for reference the transmission principle of few teeth difference planetary gear for reference, it is presented the drive principle with coupled magnetic-field and tow concrete structures of eccentric magnetic gear pair with few poles difference. Based on the nature that opposite rare-earth magnetic poles attract each other, this mechanism transforms the revolution inputted in eccentric planetary rotor into the outputted rotation of the planetary rotor, with the result that realizing the high torque of few poles difference magnetic gears transferred variably without mechanical contact and friction. It is analyzed the structure with axial and radial coupled magnetic-field in the method of equivalent magnetic path, brought in the magnetic-field coupling coefficient of permanent magnetic poles to simplify the analysis and operation, and gotten the related dynamic behaviors of the new type of magnetic gear. According to theoretical analysis, a set of 110 N·m speed reducer used for the industry, is manufactured. And the results, obtained from the experiments on the prototype, proved the correctness of the results analyzed by the theory of magnetic-field.

The Effect of Cyclic Movement of Magnets on the Sedimentation of Magnetic Nanoparticles in Magnetofection Devices: Computer Simulation

A computer model of sedimentation of magnetic nanoparticles in a magnetic field of a set of moving permanent magnets is developed. It is shown that the magnets’ motion leads not only to more uniform distribution of the nanoparticles over sedimentation plane, but sufficiently accelerates the process. It is shown that the orientation of the magnets poles significantly affects the characteristics of sedimentation, and the optimal condition—both for the most uniform distribution of nanoparticles and the acceleration of process—is when opposite magnetic poles are located next to each other. This model is used to calculate the characteristics of the magnetofection device.

Magnetic Equipped Wire Device-for Closed Interlocking Intramedullary Femoral Nailing: A Method That Avoids Exposure to Ionizing Radiations

Background: Intramedullary nailing is probably the best procedure for treating the long bone fractures in the lower limb. Such operation is guided by fluoroscopy for the guide-wire insertion like fracture reduction and distal locking. Radiation exposure during interlocked nailing continues a matter of challenge. Objectives: The aim of this experimental study was to design and test the new aiming device for closed intramedullary nailing and to reduce the radiation exposure and the operation time during the procedure. Materials and Methods: A stainless steel femoral intramedullary guide wire equipped with a small magnet on its end was designed; and also an exchange tube that would enter into the bone canal upon the guide wire to maintain the alignment. Besides these mentioned parts, we applied the standard classic interamedullary nailing set. Pin guide was inserted in the femoral intramedullary canal from periformis fossa. Another equipped magnetic guide wire was inserted from distal portal which was created in the lateral epicondyle. Two opposite magnetic poles supposed to find each other in the fracture site. After replacing the guide-wire with guide pine; the alignment would be checked by a C-arm. The study has been designed in 4 phases including moulage phase, animal phase on young cows, and a human cadaveric phase. The last step of the study is under design and it consists of a randomized controlled clinical trial on the elective patients. Results: Outcomes of applying the new system on 15 fiberglass artificial femurs and 20 bovine femurs as well as 10 human cadaveric femurs were successful. Conclusions: We found the magnetic field assistant device to be an accurate, radiation-independent jig for close passing of guide wire after close reduction of femoral fracture. It can reduce the need for radiation during placement of guide wire for closed intramedullary nailing of the long bones. More studies are required to improve and evaluate the technique and equipment.

One, two, or three stars? An investigation of an unusual eclipsing binary candidate undergoing dramatic period changes

We report our investigation of 1SWASP J234401.81-212229.1, a variable with a 18461.6 s period. After identification in a 2011 search of the SuperWASP archive for main-sequence eclipsing binary candidates near the distribution's short-period limit of approx. 0.20 d, it was measured to be undergoing rapid period decrease in our earlier work, though later observations supported a cyclic variation in period length. Spectroscopic data obtained in 2012 with the Southern African Large Telescope did not, however, support the interpretation of the object as a normal eclipsing binary. Here, we consider three possible explanations consistent with the data: a single-star oblique rotator model in which variability results from stable cool spots on opposite magnetic poles; a two-star model in which the secondary is a brown dwarf; and a three-star model involving a low-mass eclipsing binary in a hierarchical triple system. We conclude that the latter is the most likely model.

Statistical and polarization properties of giant pulses of the millisecond pulsar B1937+21

We have studied the statistical and polarization properties of giant pulses (GPs) emitted by the millisecond pulsar B1937+21, with high sensitivity and time resolution. The observations were made in June 2005 with the 100-m Robert C. Byrd Green Bank Telescope at S-band (2052-2116 MHz) using the Mk5A VLBI recording system, with formal time resolution of 16 ns. The total observing time was about 4.5 hours; the rate of detection of GPs was about 130 per hour at the average longitudes of the main pulse (MPGPs) and 60 per hour at the interpulse (IPGPs). While the average profile shows well-defined polarization behavior, with regular evolution of the linear polarization position angle (PA), GPs exhibit random properties, occasionally having high linear or circular polarization. Neither MPGPs nor IPGPs show a preferred PA. The cumulative probability distribution (CPD) of GP pulse energy was constructed down to the level where GPs merge with regular pulses and noise. For both MPGPs and IPGPs, the CPD follows a power law with a break, the power index changing from -2.4 at high energy to -1.6 for low energy. Pulse smearing due to scattering masks the intrinsic shape and duration of the detected GPs. The smearing time varied during the observing session within a range of a few hundred nanoseconds. The measured polarization and statistical properties of GPs impose strong constraints on physical models of GPs. Some of these properties support a model in which GPs are generated by the electric discharge caused by magnetic reconnection of field lines connecting the opposite magnetic poles of a neutron star.

The Faraday rotation in the pulsar magnetosphere

The magnetosphere of a pulsar is composed of relativistic plasmas streaming along the magnetic field lines and corotating with the pulsar. We study the intrinsic Faraday rotation in the pulsar magnetosphere by critically examining the wave modes and the variations of polarization properties for the circularly polarized natural modes under various assumptions about the magnetosphere plasma properties. Since it is difficult to describe analytically the Faraday rotation effect in such a plasma, we use numerical integrations to study the wave propagation effects in the corotating magnetosphere. Faraday rotation effect is identified among other propagation effects, such as wave mode coupling and the cyclotron absorption. In a highly symmetrical electron-positron pair plasma, the Faraday rotation effect is found to be negligible. Only for asymmetrical plasmas, such as the electron-ion streaming plasma, can the Faraday rotation effect become significant, and the Faraday rotation angle is found to be approximately proportional to $\lambda^{0.5}$ instead of the usual $\lambda^2$-law. For such electrons-ion plasma of pulsar magnetosphere, the induced rotation measure becomes larger at higher frequencies, and should have opposite signs for the emissions from opposite magnetic poles.

Reply to “Comment on ‘Frustrated magnetization in Co nanowires: Competition between crystal anisotropy and demagnetization energy’ ”

In contrast to our analytic model neither of the two magnetic structure simulations by Lebecki and Donahue [preceding Comment, Phys. Rev. B 82, 096401 (2010)] for Co nanowires agrees with the experimental results of Liu et al. [Adv. Funct. Mater. 18, 1573 (2008)]. Simulations with the same OOMMF software by Vila et al. [Phys. Rev. B 79, 172410 (2009)] for equivalent Co nanowires yield quite a different structure that shows opposite magnetic poles at the ends and periodic north and south poles on the sides of the wire in agreement with the experimental results.

Experimental investigation on possibility of oxygen enrichment by using gradient magnetic fields

This paper presents a novel method that uses the interception effect of gradient magnetic field on oxygen molecules to realize enrichment. The use of two opposite magnetic poles of two magnets at a certain distance forms a magnetic space having a field intensity gradient near its borders. When air injected into the magnetic space outflows from the magnetic space via its borders, oxygen molecules in the air will experience the interception effect of the gradient magnetic field, but nitrogen molecules will outflow from the magnetic space without hindrance. Thus, continuous oxygen enrichment is realized. The enrichment degree of oxygen reaches 0.65% when the inlet and outlet air flows are 40 mL/min and 20 mL/min, respectively, and the gas temperature is 298 K and the maximal product of magnetic flux density and its gradient is 563 T2/m (the distance between two magnetic poles is 1 mm). When the gas temperature rises to 343 K, the enrichment degree drops to 0.32%; and when the maximal product of magnetic flux density and field intensity gradient drops to 101 T2/m (the distance between two magnetic poles is 4 mm), the enrichment degree drops to 0.23%. The experimental results show that there is an optimal ratio between the inlet air flow and the outlet air flow. Under the experimental conditions in this paper, the value is about 2.0. It is demonstrated that the method presented in this paper can continuously enrich oxygen and has a higher enrichment degree than other oxygen-enrichment methods using magnetic separation.

A novel magnetic separation oxygen-enriched method and the influence of temperature and magnetic field on enrichment

A novel oxygen-enriched method is presented. Using two opposite magnetic poles of two magnets with certain distance forms a magnetic space having a field intensity gradient near its borders. When air injected into the magnetic space outflows from the magnetic space via its borders, oxygen molecules in air will experience the interception effect of the gradient magnetic field, but nitrogen molecules will outflow without hindrance. Thereby the continuous oxygen enrichment is realized. The results show that the maximum increment of oxygen concentration reaches 0.49% at 298 K when the maximum product of magnetic flux density and field intensity gradient is 563T2/m. The enrichment level is significantly influenced by the gas temperature and the magnetic field. The maximum increment of oxygen concentration drops to 0.16% when the gas temperature rises to 343 K, and drops to 0.09% when the maximum product of magnetic flux density and gradient is reduced to 101 T2/m from 563 T2/m.

Origin of Giant Radio Pulses

A model for the origin of giant radio pulses is suggested. Radio emission is generated by the electric discharge taking place due to the magnetic reconnection of field lines connecting the opposite magnetic poles. The reconnection occurs in the region of the light cylinder near the zero line of the magnetic field. The coherent mechanism of radiation is pure maser amplification of Alfvén waves. The radiated frequencies are found.

Emission Beam Geometry of Selected Pulsars Derived from Average Pulse Polarization Data

By fitting the classical rotating vector model (RVM) to high-quality polarization data for selected radio pulsars, we find the inclination of the magnetic axis to the spin axis, α, as well as the minimum angle between the line of sight and the magnetic axis, β, for 10 objects. We give a full treatment of statistical errors in the fitting process. We also present a dictionary and conversion table of various investigators' geometric definitions to facilitate future comparisons. We compare our results with other RVM fits and with empirical/geometrical (E/G) approaches, and we examine the strengths and weaknesses of RVM fits and E/G investigations for the determination of pulsar emission beam geometry. Our fits to B0950+08 show that it is an orthogonal rotator with the main and interpulse radiation emitted from opposite magnetic poles, whereas earlier RVM fits indicated that it is an almost-aligned, single-magnetic pole emitter. We demonstrate that low-level emission across a wide longitude range, when properly weighted in the RVM fit, conclusively favors the former scenario. B0823+26 is also an orthogonal rotator. We find that B1929+10 emits into its wide observed range of longitudes from portions of a single cone that is almost aligned with the spin axis. This result agrees with other RVM fits but conflicts with the E/G findings of Rankin & Rathnasree. We determine that convergent RVM solutions can be found only for a minority of pulsars: generally those having emission over a relatively wide longitude range, and especially those pulsars having interpulse emission. In pulsar B0823+26, our preferred fit to data at all longitudes yields a solution differing by several σ from a fit to the main pulse/postcursor combination alone. For pulsar B0950+08, separate fits to the main pulse region, the interpulse region, and our preferred fit to almost all longitudes, converge to results differing by several times the formal uncertainties. These results indicate that RVM fits are easily perturbed by systematic effects in polarized position angles and that the formal uncertainties significantly underestimate the actual errors.

RX J2115-5840: confirmation of a new near-synchronous polar

Following the suggestion of Schwope et al that the magnetic cataclysmic variable RX J2115-5840 maybe a near-synchronous polar, we obtained optical polarimetry of this system over a 2 week period. From a power spectrum of the circular polarimetry data we determine that the spin period of the white dwarf and the binary orbital period which differ by 1.2%. RX J2115-5840 is thus the fourth near synchronous polar and has the shortest spin-orbit beat period: 6.3 days. By folding the data on spin, beat and orbital periods we find evidence that the accretion stream is directed towards opposite magnetic poles as the stream precesses around the white dwarf on the spin-orbit beat period. The phasing requires that the accretion flow must be directed onto the same magnetic field line at all spin-orbit beat phases implying that at some phases the flow must follow a path around the white dwarf before accreting. This is difficult to reconcile with simple views of how the accretion stream attaches onto the magnetic field of the white dwarf.