Maglev for Dark Matter: Dark-photon and axion dark matter sensing with levitated superconductors

Ultraprecise mechanical sensors offer an exciting avenue for testing new physics. While many of these sensors are tailored to detect inertial forces, magnetically levitated (Maglev) systems are particularly interesting, in that they are also sensitive to electromagnetic forces. In this work, we propose the use of magnetically levitated superconductors to detect dark-photon and axion dark matter through their couplings to electromagnetism. Several existing laboratory experiments search for these dark-matter candidates at high frequencies, but few are sensitive to frequencies below $\mathrm{1\,kHz}$ (corresponding to dark-matter masses $m_\mathrm{DM}\lesssim10^{-12}\,\mathrm{eV}$). As a mechanical resonator, magnetically levitated superconductors are sensitive to lower frequencies, and so can probe parameter space currently unexplored by laboratory experiments. Dark-photon and axion dark matter can source an oscillating magnetic field that drives the motion of a magnetically levitated superconductor. This motion is resonantly enhanced when the dark matter Compton frequency matches the levitated superconductor's trapping frequency. We outline the necessary modifications to make magnetically levitated superconductors sensitive to dark matter, including specifications for both broadband and resonant schemes. We show that in the $\mathrm{Hz}\lesssim f_\mathrm{DM}\lesssim\mathrm{kHz}$ frequency range our technique can achieve the leading sensitivity amongst laboratory probes of both dark-photon and axion dark matter.Comment: 24 pages, 7 figure

Comparison of Neural Network Based Controllers for Nonlinear EMS Magnetic Levitation Train

Magnetic levitation system is operated primarily based at the principle of magnetic attraction and repulsion to levitate the passengers and the train. However, magnetic levitation trains are rather nonlinear and open loop unstable which makes it hard to govern. In this paper, investigation, design and control of a nonlinear Maglev train based on NARMA-L2, model reference and predictive controllers. The response of the Maglev train with the proposed controllers for the precise role of a Magnetic levitation machine have been as compared for a step input signal. The simulation consequences prove that the Maglev teach system with NARMA-L2 controller suggests the quality performance in adjusting the precise function of the system and the device improves the experience consolation and street managing criteria

Magnetic Levitation for Long-Life Space Mechanisms: Technology Assessment and Remaining Challenges

Spacecraft mechanisms and mechanical systems must operate reliably and without failure to enable successful, long-term space missions. Such requirements place demands upon the tribological elements, especially bearings, which are frequently difficult or impossible to satisfy. Several recent, high-profile bearing failures in coolant fluid pumps and attitude control system (ACS) momentum wheels provided the impetus to assess the state-of-the-art non-contacting magnetic levitation-based, rotor support technologies.Magnetic levitation technology continues to gain acceptance for terrestrial applications and has been spaceflight demonstrated in mechanical systems such as reaction wheels (RWs) but is not in widespread use. The specific reasons inhibiting this new technology are not readily clear but include cost, weight, performance, and perceived risk. These reasons arise from a variety of real and perceived technical limitations in areas like materials, controls, sensors, thermal management and others. This white paper seeks to determine, define, and quantify the technical hurdles and gaps that must be overcome to enable the broad adoption of non-contacting bearings for long-life space mechanisms. It is anticipated that a better understanding of this complex topic may guide resource investments and clear the path to improved performance mechanical systems for spacecraft

Effects of diamagnetic levitation on bacterial growth in liquid

Diamagnetic levitation is a technique that uses a strong, spatially-varying magnetic field to levitate diamagnetic materials, such as water and biological cells. This technique has the potential to simulate aspects of weightlessness, on the Earth. In common with all ground-based techniques to simulate weightlessness, however, there are effects introduced by diamagnetic levitation that are not present in space. Since there have been few studies that systematically investigate these differences, diamagnetic levitation is not yet being fully exploited. For the first time, we critically assess the effect of diamagnetic levitation on a bacterial culture in liquid. We used a superconducting magnet to levitate growing bacterial cultures for up to 18 hours, in a series of experiments to determine the effect of diamagnetic levitation on all phases of the bacterial growth cycle. We find that diamagnetic levitation increases the rate of population growth in a liquid culture. The speed of sedimentation of the bacterial cells to the bottom of the container is considerably reduced. Further experiments and microarray gene analysis show that the growth enhancement is due to greater oxygen availability in the magnetically levitated sample. We demonstrate that the magnetic field that levitates the cells also induces convective stirring in the liquid, an effect not present in microgravity. We present a simple theoretical model, showing how the paramagnetic force on dissolved oxygen can cause the liquid to become unstable to convection when the consumption of oxygen by the bacteria generates an oxygen concentration gradient. We propose that this convection enhances oxygen availability by transporting oxygen around the sample. Since convection is absent in space, these results are of significant importance and timeliness to researchers considering using diamagnetic levitation to explore weightless effects on living organisms and a broad range of other topics in the physical and life sciences

Quantum Spin Stabilized Magnetic Levitation

We theoretically show that, despite Earnshaw's theorem, a non-rotating single magnetic domain nanoparticle can be stably levitated in an external static magnetic field. The stabilization relies on the quantum spin origin of magnetization, namely the gyromagnetic effect. We predict the existence of two stable phases related to the Einstein--de Haas effect and the Larmor precession. At a stable point, we derive a quadratic Hamiltonian that describes the quantum fluctuations of the degrees of freedom of the system. We show that in the absence of thermal fluctuations, the quantum state of the nanomagnet at the equilibrium point contains entanglement and squeezing.Comment: Published version. 5 pages, 2 figure

Generalised Design Models For EMS Maglev

The paper presents a generic modelling approach for electro-magnetic suspension (EMS) systems which brings together both fundamental principles and specific design factors to provide generalised models that can be adapted for any application. Key system parameters and typical electro-magnetic design factors are used to produce practical models for EMS controller design

Magnetically levitated mesenchymal stem cell spheroids cultured with a collagen gel maintain phenotype and quiescence

Multicellular spheroids are an established system for three-dimensional cell culture. Spheroids are typically generated using hanging drop or non-adherent culture; however, an emerging technique is to use magnetic levitation. Herein, mesenchymal stem cell spheroids were generated using magnetic nanoparticles and subsequently cultured within a type I collagen gel, with a view towards developing a bone marrow niche environment. Cells were loaded with magnetic nanoparticles, and suspended beneath an external magnet, inducing self-assembly of multicellular spheroids. Cells in spheroids were viable and compared to corresponding monolayer controls, maintained stem cell phenotype and were quiescent. Interestingly, core spheroid necrosis was not observed, even with increasing spheroid size, in contrast to other commonly used spheroid systems. This mesenchymal stem cell spheroid culture presents a potential platform for modelling in vitro bone marrow stem cell niches, elucidating interactions between cells, as well as a useful model for drug delivery studies

EMS control system design for a Maglev vehicle - a critical system

For the effective operation of a magnetically levitated (maglev) vehicle using electro-magnetic suspension, it is necessary that the airgap between the guideway and the levitating magnets is maintained. Such systems, where the output is required to remain strictly within bounds, are known as critical systems. This paper describes the design of the suspension system for a high-speed maglev vehicle which ensures that the airgap is maintained