Magnetic Piston Research Articles

An implicit particle code with exact energy and charge conservation for electromagnetic studies of dense plasmas

A collisional particle code based on implicit energy- and charge-conserving methods is presented. A modified version of the particle-suppressed Jacobian-Free Newton-Krylov method that can enhance the solver efficiency is introduced. Mathematically, it is shown that this new approach can be viewed as a fixed-point iteration method for the particle positions. The model can exactly conserve global energy and local charge and can efficiently use time steps larger than the plasma period. The algorithm's ability to simulate dense plasmas accurately and efficiently is quantified by simulating the dynamic compression of a plasma slab via a magnetic piston in 1D planar geometry.

Research on a Variable Pressure Driving Method for Soft Robots Based on the Electromagnetic Effect.

This study proposes a novel variable air pressure supply structure based on the electromagnetic effect. This structure can be implemented in various soft robots driven by air pressure, including pneumatic artificial muscles, pneumatic soft grippers, and other soft robots. The structure's main body comprises a hollow circular tube, a magnetic piston arranged in the tube, and an electromagnetic solenoid nested outside the tube. The electromagnetic solenoid is designed with special winding and power supply access modes, generating either an attractive force or a repulsive force on the magnetic piston. This solenoid conforms with the magnetic piston expectation in the tube by changing the polarity direction. The interior of the whole structure is a closed space. The gas is conveyed to the soft robot by the gas guide hoses at the two ends of the structure, and the expansion energy of the compressed gas is fully utilized. Then, the gas supply pressure is controlled to drive the robot. The mathematical model of the structure is established based on the analysis of the electromagnetic force and gas pressure on the piston. The simulation results show that the structure's inherent vibration characteristics under various parameters align with expectations. The real-time automatic optimization of the controller parameters is realized by optimizing the incremental proportional-integral-derivative (PID) controller based on a neural network. The simulation results show that the structure can meet the application requirements. The experimental results show that the proposed gas supply structure can provide a continuous pressure supply curve with any frequency in a specific amplitude range and has an excellent tracking effect on the sinusoidal-like pressure curve.

The proof of concept of uninterrupted push‐pull electromagnetic propulsion and energy conversion systems for drones and planet landers

AbstractAlthough numerous models of aerial‐robots/drones and planet landers have been demonstrated to fly autonomously in natural and manmade environments for far‐reaching scientific and technological change to help humankind, no drone flowed yet with a push‐pull dual‐head electromagnetic propulsion (EMP) system ensuring unrestricted flight endurance. The precept of EMP is eminent as it hastens an object using a flowing electrical current, either to charge a field or opposing a magnetic field for locomotive use. Here we present a proof of concept to demonstrate the capability of a newly invented variable speed propulsion and energy conversion system for uninterruptedly generating the reciprocating motion of a magnetic piston by a solar battery‐driven polarity changer timing circuit together with a laser‐based timing circuit for redundancy. The reciprocating crusade of the magnetic piston could be successfully converted into rotary motion to generate continuous power for various multidisciplinary applications on Earth and the other planets effectively in lieu of long‐lasting rechargeable batteries. The proposed concept can also be used for devising various systems and subsystems from underwater to outer space by using light weight supermalloy, which ensures high magnetic fluxes with relatively low current. Lucrative applications include nanomaterial‐enabled locomotive applications. Aerial robots regulated with the EMP system could be used for fostering pharmaceutical florae in the international space station for drug design to negate the recently discovered phenomenon of Sanal flow choking in cardiovascular system at gravity and/or microgravity conditions. This concept is originated from mind and aimed for lucrative product developments of yocto to yotta scale energy systems and beyond by discovering new magnetic materials through the fourth industrial revolution. Herein, a proof of the concept of an unrestricted solar‐battery driven push‐pull electromagnetic propulsion and energy conversion device by use of light weight high power magnetic materials is presented.

Experimental study and rheology of magneto-rheological fluid for a suspension system

The formulation and synthesis of magneto-rheological (MR) fluids formed by submerging iron particles in carrier fluids are the key points of this work. To reduce the corrosion, agglomeration, and sedimentation constraints of the MR fluid (MRF), iron particles are coated with natural gums like guar and xanthan. Various MR fluid samples were prepared using combinations of carrier fluids (paraffin oil and synthetic oil), magnetic particles (carbonyl iron and atomized iron dust), and additives. The magnetic particles were characterized using scanning electron microscopy (SEM). Carbonyl iron has a fiber-like structure, whereas atomized iron dust has a granular structure. The MR fluid containing xanthan gum-coated iron particles showed improved sedimentation properties. Furthermore, the magnetic field of the magnetic piston was tested by supplying power, and it was observed that the magnetic flux density increased with an increase in the current in amperes. By conducting a visual inspection, the sedimentation analysis of the prepared MR fluids demonstrated that MRF 2 and MRF 1 improved the sedimentation rate more significantly than the others. The rheological properties of the MR fluids were determined by measuring their yield stress with respect to the applied magnetic flux density. Paraffin oil-based MR fluid mixed with xanthan gum-coated carbonyl iron (MRF 2) showed higher yield stress than other fluids. The higher value of yield strength will boost the damping force of the MR damper to effectively suppress vibrations in the system.

Modify the Injection Machine Mechanism to Enhance the Recycling of Plastic Waste Mixed with MHD Nanoparticles

Recycling plastic waste (RPW) benefits the ecological footprint. Therefore, the authors test its mixing by magnetic hydrodynamic MHD nanofluid materials such as alumina in two sizes (βcore, βskin) prepared into a new device called the incubator installed in the desktop injection machine to enhance its solubility by taking advantage of the mixture’s heat via defining the oblique stagnation-point slip flow (OSPSF) of a nanofluid in two dimensions. The paper has been innovative in mathematically identifying the operating parameters’ values for the injection flow mechanism (IFM) via controlling in Riga magnetic field and piston orifice pressure using a meta-heuristic algorithm called WSA. The proposed (IFM) is used to experimentally enhance the mixture properties via parameters’ control to meet the output quality and predict the control equation for the Riga plate. IFM controls the amount of pushed nanoparticles in the mixture with a ratio of plastic to aluminum approximate by 96.1%: 3.9%. The defects were reduced by approximately 23.21%, with an increasing system performance of 70.98%.

Electromagnetic Engine Controlled using IR Sensor

The base idea of this paper is to control the electromagnetic engine to enhance a smooth rotation by measuring distance of the piston using an IR sensor. This electromagnetic engine consists of an electromagnet, permanent magnet, Infrared Sensor, powerful microcontroller and power supply. The permanent magnet acts as a piston in this electromagnetic engine, it has magnetic field energy for a proper function. The position of permanent magnet has to be noted for electromagnets energisation in order to reduce power consumption by electromagnet. The infrared sensor mounted with electromagnet set and pointed towards permanent magnet, whenever the permanent magnet moves towards electromagnet, sensor reads the change in magnetic piston position. The electromagnet is energized on the reach of permanent magnet near electromagnet. Control of electromagnets power supply is depends on the signal provided by IR sensor, this sensor is mainly makes timing control of power drive circuit through the microcontroller. This makes engine to run continuously and reducing its power consumption by providing a pulse to electromagnet.

Visualizing magnetically driven converging radiative shock generated in Z-pinch foil liner implosion

A study of the evolution and structure of magnetically driven converging radiative shock waves generated in Z-pinch foil liner implosion at an 8-MA pulsed-power facility is presented. End-on extreme ultraviolet images show an inward propagating shock that is circular to <±5% as a function of azimuthal angle, with a standard deviation in the emission intensity of <±30%, implying good cylindrical symmetry. The launch time and shock trajectory are determined by linear fitting of the measured data, giving a shock speed of Mach 6. One-dimensional radiation hydrodynamics MULTI-IFE-Z simulations agree with the experimental observations qualitatively and confirm the existence of a radiative precursor. It is demonstrated with experiment and simulation that the radiative shock wave is generated by magnetic piston compression of dense plasma shell. Analytic estimates of the post-shock plasma conditions suggest that these Z-pinch magnetically-driven high-Mach shocks are strongly radiatively cooled. It is applicable to the optically thick downstream, optically thin upstream radiative shock regime; thus, it can be described by three-layer model, which potentially could be applied to scale studies of astrophysical shocks in the laboratory.

Magnetic Field Penetration in Axially Symmetric High-Current Plasma Systems

This article analyzes the transport of a magnetic field in axisymmetric plasma systems using simple formulas derived for its velocity in collisionless and collisional plasmas. The analysis shows that the magnetic field velocity in both cases is determined by the magnetic field rise rate to plasma density ratio raised to the power of 1/2. As the plasma density increases, the field velocity starts to depend on the plasma aggregation by a magnetic piston. Because the electron flow velocity in any case is limited by the axial drift velocity in crossed magnetic and polarization electric fields, the current channel conductivity is suppressed with respect to the Spitzer value by a factor equal to the magnetization parameter raised to one or another power.

Design of an Artificial Muscle Pressure Supply Mode Based on the Connected Structure

This paper proposes an air pressure supply structure for artificial muscles. The main body of the structure comprises a hollow tube, an electromagnet in the outer layer, and a magnetic piston in the inner diameter of the tube. At both ends, a hose interface connects the air inlet of the artificial muscle. Under the action of controlling changes in current, the electromagnet nested in the outer wall causes the movement of the piston by changing the force between the electromagnet and the magnetic piston and by changing the law of air pressure in the tube. Because the inside of the tube is a closed space, the movement of the magnetic piston in the tube causes a change in the volume of the gas at both ends, thus forming pressure differences of different sizes and directions. Therefore, this air supply, with specific oscillatory characteristics, can be used to produce the desired movement of artificial muscles. Through system modeling, theoretical analysis, and simulation experiments of the connected pressure supply structure, we verified that the system has inherent characteristics similar to a spring damping structure. In view of the inherent characteristics of this kind of structure, this paper introduces the trend of input and output changes by considering the deviation value, details how to improve the traditional neural network PID control algorithm, and discusses the intelligent optimization of controller parameters. Simulation results show that the improved control method can effectively overcome the nonlinear and coupling characteristics of the system, and the gas supply structure can provide a continuous pressure supply curve of an arbitrary waveform and a frequency within a certain amplitude range. The designed air supply structure was applied to a quadruped robot, using its oscillating characteristics to generate rhythmic movement. Compared with the traditional pressure control method, the piston was driven to produce reciprocating motion by fully exploiting the energy stored in the compressed gas, so as to reduce the external energy input and reduce the comprehensive energy consumption of the system. In addition, the control algorithm improved in this paper can meet diverse pressure requirements for driving artificial muscles. Moreover, the independent control of leg support force and stiffness can be realized by combining it with the antagonistic joints. This structure can be widely used in the pressure supply of outdoor robot artificial muscle.

Mildly relativistic collisionless shock formed by magnetic piston

By using particle-in-cell simulations, we study the collision of two plasma flows with one of them carrying a magnetic field. Ion interpenetration results in the formation of a magnetic piston with the magnetic field compression proportional to the density ratio of the colliding plasmas. The counterpropagating ions in the nonmagnetized plasma upstream from the piston excite the ion Weibel instability, which turns into magnetic turbulence. The thickness of the piston increases with time, and it turns into a reverse magnetized shock after less than one ion gyro period. In front of the piston, the time needed to decrease the nonmagnetized ion anisotropy using the magnetic turbulence is much larger than the ion gyroperiod in the piston. Consequently, particles are reflected by the piston, which acts as a wall initiating a transient phase. After several ion periods, the formation of this electromagnetic forward shock is, then, accelerated by the piston, and at large timescale, the dissipation of energy is eventually mediated only by the Weibel turbulence. We report here a new configuration of shocks, where a reverse magnetized and a forward electromagnetic shock coexist separated by a tangential discontinuity. Particle acceleration and heating in the two shock structures and relevance of this scenario of collisionless shock formation to laboratory experiments and astrophysical conditions are discussed.

Self-magnetic insulation in plasma opening switches

The paper analyses the penetration of a magnetic field into the plasma bridge of nanosecond and microsecond opening switches. For switches with a conduction time of ~100 ns, simple formulae are derived to estimate the magnetic field velocity in collisionless and collisional plasmas. It is shown that in both cases this velocity is determined by the magnetic field rise rate to plasma density ratio raised to the power of 1/2. As the conduction time is increased to ~1 ${\rm \mu}$ s, the field velocity starts to depend on the plasma aggregation by a magnetic piston. At the same time, irrespective of the conduction time, the electron flow velocity is limited by the radial drift velocity in crossed magnetic and polarization electric fields. Such a limitation suppresses the current channel conductivity with respect to the Spitzer value by a factor equal to the electron magnetization parameter raised to one or another power. On completion of the conduction phase, the rate of rise of the switch resistance is proportional to the electron drift velocity. The peak switch voltage obtained in calculations is compared with its values recorded in experiments on mega-ampere current switching. A procedure is also presented for calculating the switch parameters to obtain the maximum possible voltage in the phase of current cutoff.

High-Mach number, laser-driven magnetized collisionless shocks

Collisionless shocks are ubiquitous in space and astrophysical systems, and the class of supercritical shocks is of particular importance due to their role in accelerating particles to high energies. While these shocks have been traditionally studied by spacecraft and remote sensing observations, laboratory experiments can provide reproducible and multi-dimensional datasets that provide a complementary understanding of the underlying microphysics. We present experiments undertaken on the OMEGA and OMEGA EP laser facilities that show the formation and evolution of high-Mach number collisionless shocks created through the interaction of a laser-driven magnetic piston and a magnetized ambient plasma. Through time-resolved, 2-D imaging, we observe large density and magnetic compressions that propagate at super-Alfvénic speeds and that occur over ion kinetic length scales. The electron density and temperature of the initial ambient plasma are characterized using optical Thomson scattering. Measurements of the piston laser-plasma are modeled with 2-D radiation-hydrodynamic simulations, which are used to initialize 2-D particle-in-cell simulations of the interaction between the piston and ambient plasmas. The numerical results show the formation of collisionless shocks, including the separate dynamics of the carbon and hydrogen ions that constitute the ambient plasma and their effect on the shock structure. The simulations also show the shock separating from the piston, which we observe in the data at late experimental times.

Axial magnetic field and toroidally streaming fast ions in the dense plasma focus are natural consequences of conservation laws in the curved axisymmetric geometry of the current sheath. II. Towards a first principles theory

This paper continues earlier discussion [S. K. H. Auluck, Phys. Plasmas 21, 102515 (2014)] concerning the formulation of conservation laws of mass, momentum, and energy in a local curvilinear coordinate system in the dense plasma focus. This formulation makes use of the revised Gratton-Vargas snowplow model [S. K. H. Auluck, Phys. Plasmas 20, 112501 (2013)], which provides an analytically defined imaginary surface in three dimensions which resembles the experimentally determined shape of the plasma. Unit vectors along the local tangent to this surface, along the azimuth, and along the local normal define a right-handed orthogonal local curvilinear coordinate system. The simplifying assumption that physical quantities have significant variation only along the normal enables writing laws of conservation of mass, momentum, and energy in the form of effectively one-dimensional hyperbolic conservation law equations using expressions for various differential operators derived for this coordinate system. This formulation demonstrates the highly non-trivial result that the axial magnetic field and toroidally streaming fast ions, experimentally observed by multiple prestigious laboratories, are natural consequences of conservation of mass, momentum, and energy in the curved geometry of the dense plasma focus current sheath. The present paper continues the discussion in the context of a 3-region shock structure similar to the one experimentally observed: an unperturbed region followed by a hydrodynamic shock containing some current followed by a magnetic piston. Rankine-Hugoniot conditions are derived, and expressions are obtained for the specific volumes and pressures using the mass-flux between the hydrodynamic shock and the magnetic piston and current fraction in the hydrodynamic shock as unknown parameters. For the special case of a magnetic piston that remains continuously in contact with the fluid being pushed, the theory gives closed form algebraic results for the fraction of current flowing in the hydrodynamic shock, specific volume, pressure, and fluid velocity of the hydrodynamic shock region, the tangential, normal, and azimuthal components of velocity in the magnetized plasma, the density of the magnetized plasma, the normal and tangential components of the magnetic field, and the tangential, normal, and azimuthal components of the electric field. This explains the occurrence of azimuthally streaming high energy deuterons experimentally observed by Frascati and Stuttgart. The expression derived for the azimuthal component of vector potential can serve as the basis for a proposed experimental test of the theory.

On the generation of magnetized collisionless shocks in the large plasma device

Collisionless shocks are common phenomena in space and astrophysical systems, and in many cases, the shocks can be modeled as the result of the expansion of a magnetic piston though a magnetized ambient plasma. Only recently, however, have laser facilities and diagnostic capabilities evolved sufficiently to allow the detailed study in the laboratory of the microphysics of piston-driven shocks. We review experiments on collisionless shocks driven by a laser-produced magnetic piston undertaken with the Phoenix laser laboratory and the Large Plasma Device at the University of California, Los Angeles. The experiments span a large parameter space in laser energy, background magnetic field, and ambient plasma properties that allow us to probe the physics of piston-ambient energy coupling, the launching of magnetosonic solitons, and the formation of subcritical shocks. The results indicate that piston-driven magnetized collisionless shocks in the laboratory can be characterized with a small set of dimensionless formation parameters that place the formation process in an organized and predictive framework.

Theoretical and experimental studies of a magnetically actuated valveless micropump

This paper presents the prototype design, fabrication, and characterization of a magnetically actuated micropump. The pump body consists of three nozzle/diffuser elements and two pumping chambers connected to the ends of a flat-wall pumping cylinder. A cylindrical permanent magnet placed inside the pumping cylinder acts as a piston which reciprocates by using an external magnetic actuator driven by a motor. The magnetic piston is covered by a ferrofluid to provide self-sealing capability. A prototype composed of three bonded layers of polymethyl-methacrylate (PMMA) has been fabricated. Water has been successfully pumped at pressures of up to 750 Pa and flow rates of up to 700 µl min−1 while working at the piston actuation frequency of 4 and 5 Hz, respectively. 3D numerical simulations are also carried out to study the performance of the pump. The best experimental and numerical volumetric efficiency of the pump are about 7 and 8%, respectively, at the piston speed of 0.03 m s−1. The contactless external actuation feature of the design enables integration of the pump with other PMMA-based microfluidic systems with low cost and disposability.

Simulations of Ar gas-puff Z-pinch radiation sources with double shells and central jets on the Z generator

Radiation-magnetohydrodynamic simulations using the non-local thermodynamic equilibrium Mach2-Tabular Collisional-Radiative Equilibrium code in (r, z) geometry are performed for two pairs of recent Ar gas-puff Z-pinch experiments on the refurbished Z generator with an 8 cm diameter nozzle. One pair of shots had an outer-to-inner shell mass ratio of 1:1.6 and a second pair had a ratio of 1:1. In each pair, one of the shots had a central jet. The experimental trends in the Ar K-shell yield and power are reproduced in the calculations. However, the K-shell yield and power are significantly lower than the other three shots for the case of a double-shell puff of 1:1 mass ratio and no central jet configuration. Further simulations of a hypothetical experiment with the same relative density profile of this configuration, but higher total mass, show that the coupled energy from the generator and the K-shell yield can be increased to levels achieved in the other three configurations, but not the K-shell power. Based on various measures of effective plasma radius, the compression in the 1:1 mass ratio and no central jet case is found to be less because the plasma inside the magnetic piston is hotter and of lower density. Because of the reduced density, and the reduced radiation cooling (which is proportional to the square of the density), the core plasma is hotter. Consequently, for the 1:1 outer-to-inner shell mass ratio, the load mass controls the yield and the center jet controls the power.

영구자석을 이용한 전단모드 MR 댐퍼 설계 및 해석

A novel Permanent Magnet based Magneto Rheological (PM-MR) damper is proposed in this paper. The principle of proposed MR damper is achieved by designing a linearly varying magnetization area with-respect to the movable permanent magnetic based piston setup. Nowadays, commercially available MR damper uses electromagnetic coils for generating the variable magnetic fields corresponding to the variable damping force. The amount of magnetic field produced by the electromagnetic coils are depends on the biasing current of voltage source. The key enabling concept of the proposed MR damper is to replace the electromagnetic coils and the voltage sources by utilizing the variable area based permanent magnetic piston setup. The proposed unique design structure of PM-MR damper has an increasing shear mode damping force with the piston movement in both jounce and rebound motion. In this research, analytical model of the proposed structure is derived and the structural design of proposed concept is verified using numerical CAD tool. As a result, the damping force is increase when piston movement in both jounce and rebound motion.

Component based design of a drug delivery capsule robot

Since the introduction of Wireless Capsule Endoscopy (WCE) researchers have started exploring the design space of Medical Capsule Robots (MCRs): embedded micro-systems that can operate autonomously within the human body and can diagnose, prevent, monitor, and cure diseases. Although the research in the area of MCRs is an active topic and has grown exponentially, current devices provide only limited functionalities because their design process is expensive and time consuming. To open this research field to a wider community and, at the same time, create better designs through advanced tool support, in our previous works we presented a design environment for the rapid development of MCRs. In this paper, this environment was adopted to design a Drug Delivery Capsule (DDC) based on a coil-magnet-piston mechanism. The force of the coil acting on the magnetic piston and the drug release profile were modeled and assessed on bench-top with a maximum relative error below 5%. Then, in vivo trials were performed to validate the DDC functionality with a scheduled drug release profile for a 5h and 24min procedure. The resulting design environment template is available open source for further development of drug delivery applications as well as to serve as guideline in prototyping novel MCRs addressing other clinical needs.

Magnetic Repulsion Piston Engine

Magnetic Repulsion Piston Engine

Comparison of measured and computed radial trajectories of plasma focus devices UMDPF1 and UMDPF0

In published literature, there has been scant data on radial trajectory of the plasma focus and no comparison of computed with measured radial trajectory. This paper provides the first such comparative study. We compute the trajectories of the inward-moving radial shock and magnetic piston of UMDPF1 plasma focus and compare these with measured data taken from a streak photograph. The comparison shows agreement with the measured radial trajectory in terms of average speeds and general shape of trajectory. This paper also presents the measured trajectory of the radially compressing piston in another machine, the UMDPF0 plasma focus, confirming that the computed radial trajectory also shows similar general agreement. Features of divergence between the computed and measured trajectories, towards the end of the radial compression, are discussed. From the measured radial trajectories, an inference is made that the neutron yield mechanism could not be thermonuclear. A second inference is made regarding the speeds of axial post-pinch shocks, which are recently considered as a useful tool for damage testing of fusion-related wall materials.