Diamagnetic Plates Research Articles

Modeling Development of a Diamagnetically Stabilized Magnetically Levitated Gravimeter.

The aim of this work is to create a new type of gravimeter that can function effectively in the challenging conditions of space, specifically on the surfaces of planets and moons. The proposed device, called a diamagnetically stabilized magnetically levitated gravimeter (DSMLG), uses magnetic forces to balance a test mass against the force of gravity, allowing for accurate measurements. A diamagnetically stabilized levitation structure comprises a floating magnet, diamagnetic material, and a lifting magnet. The floating magnet levitates between two diamagnetic plates without the need for external energy input due to the interaction between the magnetic forces of the floating magnet and the stabilizing force of the diamagnetic material. This structure allows for stable levitation of the floating magnet without requiring additional energy. The goal is to design a gravimeter that is lightweight, requires minimal power, can withstand extreme temperatures and shocks, and has a low data rate. The authors envision this gravimeter being used on various robotic spacecraft, such as landers and rovers, to study the interiors of rocky and icy celestial bodies. This paper reports on the results of a finite element model analysis of the DSMLG and the strength of the resulting diamagnetic spring. The findings contribute to the understanding of the levitation characteristics of diamagnetically stabilized structures and provide valuable insights for their practical applications, including in the development of the proposed DSMLG.

Levitation Characteristics Analysis of a Diamagnetically Stabilized Levitation Structure.

A diamagnetically stabilized levitation structure is composed of a floating magnet, diamagnetic material, and a lifting magnet. The floating magnet is freely levitated between two diamagnetic plates without any external energy input. In this paper, the levitation characteristics of a floating magnet were firstly studied through simulation. Three different levitation states were found by adjusting the gap between the two diamagnetic plates, namely symmetric monostable levitation, bistable levitation, and asymmetric monostable levitation. Then, according to experimental comparison, it was found that the stability of the symmetric monostable levitation system is better than that of the other two. Lastly, the maximum moving space that allows the symmetric monostable levitation state is investigated by Taguchi method. The key factors affecting the maximum gap were determined as the structure parameters of the floating magnet and the thickness of highly oriented pyrolytic graphite (HOPG) sheets. According to the optimal parameters, work performance was obtained by an experiment with an energy harvester based on the diamagnetic levitation structure. The effective value of voltage is 250.69 mV and the power is 86.8 An LED light is successfully lit on when the output voltage is boosted with a Cockcroft–Walton cascade voltage doubler circuit. This work offers an effective method to choose appropriate parameters for a diamagnetically stabilized levitation structure.

A bi-stable horizontal diamagnetic levitation based low frequency vibration energy harvester

A new form of bi-stable system based on the passive friction-free horizontal diamagnetic levitation mechanism is proposed in this article. The system is comprised of twelve magnets which create a bi-stable potential well for a centrally located floating magnet. The levitation is stabilized in the horizontal direction by the diamagnetic repulsion from pyrolytic graphite plates which are placed on either side of the floating magnet. Theoretical modeling is discussed involving the superposition of the magnetic fields and magnetic forces, which include semi-analytical equations, from the various magnets in the system to determine the characteristics of the bi-stable potential well. Stability equations for achieving static bi-stability and for maintaining stable levitation during intra-well and inter-well motion were discussed. An experimental prototype is presented whose frequency response characteristics were validated for varying input sinusoidal excitations. Once the dynamics of the bi-stable system were validated, copper coils are incorporated into the diamagnetic plates to enable the vibration energy harvesting capability of the levitation mechanism. The floating magnet underwent chaotic and interwell motions for a range of input sinusoidal excitation frequencies, 5.8 Hz – 8 Hz, at input accelerations of 1.99 m/s2 to 3.79 m/s2, and peak system efficiencies of close to 2.5% were achieved.

Design and Analysis of a Bistable Vibration Energy Harvester Using Diamagnetic Levitation Mechanism

In this paper, a novel bistable vibration energy harvester using the diamagnetic levitation mechanism is conceptualized, designed, fabricated, and experimented comprehensively. The bistable energy harvester consists of a floating magnet, lifting magnets, diamagnetic plates, and coils. The lifting magnets placed symmetrically on the both sides of the base are designed to balance the weight of the floating magnet and produce a bistable potential well. The floating magnet is stabilized in the horizontal direction by diamagnetic plates which are made of pyrolytic graphite. Ring-shaped coils are designed for transduction and flanked by the side of diamagnetic plates. Theoretical modeling and analyses are carried out to compare with experimental data. Throughout the theoretical and experimental results, a peak power of $333.7~\mu \text{w}$ is generated from a vibration level of 0.6 m/ $\text{s}^{2}$ over a range of 0.5–4.5 Hz. It is indicated that the bistable energy harvester can efficiently operate at extremely low frequencies (<5 Hz).

An enhanced performance of a horizontal diamagnetic levitation mechanism–based vibration energy harvester for low frequency applications

This article identifies and studies key parameters that characterize a horizontal diamagnetic levitation mechanism–based low frequency vibration energy harvester with the aim of enhancing performance metrics such as efficiency and volume figure of merit. The horizontal diamagnetic levitation mechanism comprises three permanent magnets and two diamagnetic plates. Two of the magnets, lifting magnets, are placed co-axially at a distance such that each attracts a centrally located magnet, floating magnet, to balance its weight. This floating magnet is flanked closely by two diamagnetic plates which stabilize the levitation in the axial direction. The influence of the geometry of the floating magnet, the lifting magnet, and the diamagnetic plate is parametrically studied to quantify their effects on the size, stability of the levitation mechanism, and the resonant frequency of the floating magnet. For vibration energy harvesting using the horizontal diamagnetic levitation mechanism, a coil geometry and eddy current damping are critically discussed. Based on the analysis, an efficient experimental system is setup which showed a softening frequency response with an average system efficiency of 25.8% and a volume figure of merit of 0.23% when excited at a root mean square acceleration of 0.0546 m/s2 and at a frequency of 1.9 Hz.

磁気浮上系による振動発電の基礎研究

In this paper, theoretical modeling and analysis of a diamagnetic levitation-based vibration energy harvester having low resonance frequency (< 2 Hz) is presented. The system fundamentally consists of four objects, i.e., a floating magnet, lifting magnet and two diamagnetic plates. We adopt the magnetic dipole model for modeling the attractive force between the floating and lifting magnets, and the thin coil model and the discrete volume method for modeling the diamagnetic repulsive forces come from two diamagnetic plates. In addition, an equilibrium position of the floating magnet on horizontal and vertical directions are discussed. In the presented model, the influence of the tilting motion of the floating magnet and the electromagnetic effect of the induction coil are neglected. Finally, a time history response analysis of the floating magnet is performed by solving the equations of motion. The results show that the presented harvester has the resonance frequency of approximately 2 Hz.

A Horizontal Diamagnetic Levitation Based Low Frequency Vibration Energy Harvester

This paper investigates a horizontal diamagnetic levitation (HDL) system for vibration energy harvesting in contrast to the vertical diamagnetic levitation (VDL) system recently proposed by Wang et al. (2013, “A Magnetically Levitated Vibration Energy Harvester,” Smart Mater. Struct., 22(5), p. 055016). In this configuration, two large magnets, alias lifting magnets (LMs), are arranged co-axially at a distance such that in between them a magnet, alias floating magnet (FM), is passively levitated at a laterally offset equilibrium position. The levitation is stabilized in the horizontal direction by two diamagnetic plates (DPs) made of pyrolytic graphite placed on each side of the FM. This HDL configuration mitigates the limitation on the amplitude of the FM imposed in the VDL configuration and exploits the ability to tailor the geometry to meet specific applications due to its frequency tuning capability. A simple circular coil geometry is designed to replace a portion of the pyrolytic graphite plate without sacrificing the stability of the levitation for transduction. An experimental setup exhibits a weak softening frequency response and validates the theoretical findings; at an input root mean square (RMS) acceleration of 0.0434 m/s2 and at a resonant frequency of 1.2 Hz, the prototype generated a RMS power of 3.6 μW with an average system efficiency of 1.93%.

An optimal design of a mono-stable vertical diamagnetic levitation based electromagnetic vibration energy harvester

A detailed analysis of a mono-stable vertical diamagnetic levitation (VDL) system for optimal vibration energy harvesting is presented. Initial studies showed that simple analytical techniques such as the dipole model and the image method provide useful guideline for understanding the potential of a diamagnetic levitation system, however, it is discussed here that the more accurate semi-analytical techniques such as the thin coil model and the discrete volume method are needed for quantitative optimization and design of the VDL system. With the semi-analytical techniques, the influence of the cylindrical geometry of the floating magnet, the lifting magnet and the diamagnetic plate are parametrically studied to assess their effects on the levitation gap, size of the system and the natural frequency.For efficient vibration energy harvesting using the VDL system, ways to mitigate eddy current damping and a coil geometry for transduction are critically discussed. With the optimized parameters, an experimental system is realized which showed a hardening type nonlinearity. The results show an overall efficiency of 1.54 percent, a root mean square (rms) power output of 1.72µW when excited at a peak acceleration of 0.081m/s2 and at a frequency of 2.1Hz.

A magnetically levitated vibration energy harvester

In this paper a novel electromagnetic vibration type energy harvester that uses a diamagnetic levitation system is conceptualized, designed, fabricated, and tested. The harvester uses two diamagnetic plates made of pyrolytic graphite between which a cylindrical magnet levitates passively. Two thick cylindrical coils, placed in grooves which are engraved in the pyrolytic graphite plates, are used to convert the mechanical energy into electrical energy efficiently. The geometric configurations of the coils are selected based on the field distribution of the magnet to enhance the efficiency of the harvester. A thorough theoretical analysis is carried out to compare with experimental results. At an input power of 103.45 μW and at a frequency of 2.7 Hz, the harvester generated a power of 0.74 μW with a system efficiency of 0.72%. Both theoretical and experimental results show that this new energy harvesting system can capture low frequency broadband spectra.

Thickness dependence of the Casimir force between a magnetodielectric plate and a diamagnetic plate

This paper examines the repulsive Casimir force between a magnetodielectric plate, with static permeability greater than static permittivity, and a diamagnetic plate. As the thickness of the magnetodielectric plate is decreased, the attractive component of the Casimir force decreases more than the repulsive one. This effect makes the net Casimir force repulsive, and a larger repulsive Casimir force is generated compared to the Casimir force between the plates with infinite thickness.

Diamagnetic effect on the Casimir force

The Casimir force between a diamagnetic plate and a magnetodielectric plate at finite temperature is considered. Under the condition that the permittivity of the magnetodielectric plate is sufficiently small, we show that the diamagnetic property dominantly determines the asymptotic behavior of the repulsive Casimir force for large separations. On the basis of this simple property, we present numerical results showing that if an effective permeability of a superconductor is much less than one, its diamagnetic response can be indirectly detected by measuring the Casimir force.

726 反磁性グラファイト板に作用する反磁性磁気力の準静的計測(特性解析,OS-23 磁気浮上・磁気軸受,総合テーマ「伝統を,未来へ!」)

726 反磁性グラファイト板に作用する反磁性磁気力の準静的計測(特性解析,OS-23 磁気浮上・磁気軸受,総合テーマ「伝統を,未来へ!」)

Stable diamagnetic self-levitation of a micro-magnet by improvement of its magnetic gradients

A disc-shaped SmCo magnet with a diameter of 0.85 mm is levitated above a graphite diamagnetic plate at a height of about 14 μm. The magnet is magnetised into a double dipole. The levitation of multipolar magnets above a diamagnetic material was suggested in 1956 by Boerdijk and patented in 1995 by Pelrine, but without any known published experimental results. In this letter, both theoretical and experimental results are presented.

Diamagnetic Levitating Rotor

This paper analyzes some basic design aspects for a three phase diamagnetic levitating rotor. A proposed design uses a triangular configuration of magnets for a levitating rotor. A formula for finding a the approximate levitation point of the rotor is given. The proposed system uses three phase alternating current and a nine coil configuration to drive the levitating rotor. For this configuration, moment plots for different radial positions and tilt angles of the coils are given for a specific coil geometry. In addition, a way to find the effectiveness of finitely thick diamagnetic plates by using the method of images is also presented with normalized plots for some common, cylindrical NdFeB magnet geometries.