Magnetic Piston Research Articles

A novel revolving piston minipump

In this study, a novel prototype high-efficiency miniature pump that uses magnetic properties of a ferrofluid in both pumping and valving mechanisms is presented. The minichannel consisting of a cylindrical pumping chamber, a check valve, an inlet and an outlet, comprises six bonded layers of PMMA. A cylindrical permanent magnet that is placed inside the chamber and is externally actuated by a motorized off-center permanent magnet, functions as a revolving piston which sweeps the perimeter of the cylinder. Ferrofluid is used to cover the gaps between the magnetic piston and the channel walls, also serves as a separating plug between the inlet and the outlet of the chamber preventing recirculation of the pumped fluid inside the chamber. This novel revolving piston design eliminates the need for an inlet valve. Pressure head is maintained using one ball check valve at the outlet of the pump. Water has been successfully pumped at flow rates of up to 934μL/min, backpressures of up to 994Pa, and maximum achieved volumetric efficiency of 79 percent while working at 80, 52, and 9rpm rates, respectively.

Dynamic Analysis of Gate Operated Magnetic Piston (GOPI) Engine Using ANSYS Software

The increasing depletion of fossil fuels lays imperative emphasis on alternate sources of energy for automobile application. In focus with the current trend of new sources of energy, this research paper presents the mathematical modeling, simulation and dynamic analysis of the Gate Operated Magnetic Piston Engine further referred as GOPI. In the GOPI engine, the motion of the piston is controlled by a high permeable magnetic shield gate. The dynamic analysis of the GOPI engine was done using the ANSYS software. The simulation was run for different operating conditions of the engine and the engine efficiency was found to be dependent on the material selected for gate modeling, thickness of the gate material, type of the shield material chosen for gate modeling, distance of the gate from fixed magnet to the magnetic piston, the pole strength of magnets and the mechanism used to operate the gate. The GOPI engine can be used to produce both electrical and mechanical power as outputs. This can further lead to a new era of engines running on magnetic potential thereby reducing the carbon footprints. The mechanical power generation using the GOPI engine has been discussed in detail in this paper.

Observation of collisionless shocks in a large current‐free laboratory plasma

AbstractWe report the first measurements of the formation and structure of a magnetized collisionless shock by a laser‐driven magnetic piston in a current‐free laboratory plasma. This new class of experiments combines a high‐energy laser system and a large magnetized plasma to transfer energy from a laser plasma plume to the ambient ions through collisionless coupling, until a self‐sustained MA∼ 2 magnetosonic shock separates from the piston. The ambient plasma is highly magnetized, current free, and large enough (17 m × 0.6 m) to support Alfvén waves. Magnetic field measurements of the structure and evolution of the shock are consistent with two‐dimensional hybrid simulations, which show Larmor coupling between the debris and ambient ions and the presence of reflected ions, which provide the dissipation. The measured shock formation time confirms predictions from computational work.

Two Stroke High Efficient Gate Operated Magnetic Engine: Basis for Modeling Approach

AbstractThe present report focuses on the fundamentals of modeling of a permanent magnet based gate operated repulsive magnetic piston engine further referred to as GOPI engine, applicable to electrical and mechanical power generation in large-scale system. In GOPI engine, the motion of the piston is controlled with help of a gate made up of magnetic shield material. The working of the engine depends upon magnetic and mechanical material properties of the gate like thickness of the gate, type of the shield material, distance of the gate from magnets, the pole strength of magnets and mechanism used to operate the gate. In GOPI engine the removal of complete mechanism of fuel burning process of the traditional engine gives a number of advantages like low frictional losses, reduced manufacturing cost, maintenance cost and compactness.

Study of the fine structure of the plasma current sheath and magnetic fields in the axial region of the PF-1000 facility

Results of measurements of magnetic fields in the plasma pinching region during the compression of the deuterium plasma current sheath (PCS) at the PF-1000 plasma focus facility are presented. The fine structure of the PCS (shock wave-magnetic piston) and its variations in the course of plasma compression toward the facility axis are studied using magnetic probes and laser interferometry. The radial distributions of the plasma density and current in the PCS are compared. It is shown that, in the shock wave region, the electron density of the compressed plasma is on the order of ∼1018 cm−3, whereas the PCS current is almost entirely concentrated in the magnetic piston region—a plasma layer with an electron density of less than 1015 cm−3. Efficient transportation of the current by the PCS into the axial region of the facility in discharges with a high neutron yield (Yn > 1011 neutrons/shot) is detected. It is shown that the total neutron yield is well described by the dependence Yn ≈ (1.5–3) × 1010Ip4, where Ip is the pinch current (in MA) flowing within the region r ≤ 13 mm.

Laser-driven, magnetized quasi-perpendicular collisionless shocks on the Large Plasma Device

The interaction of a laser-driven super-Alfvénic magnetic piston with a large, preformed magnetized ambient plasma has been studied by utilizing a unique experimental platform that couples the Raptor kJ-class laser system [Niemann et al., J. Instrum. 7, P03010 (2012)] to the Large Plasma Device [Gekelman et al., Rev. Sci. Instrum. 62, 2875 (1991)] at the University of California, Los Angeles. This platform provides experimental conditions of relevance to space and astrophysical magnetic collisionless shocks and, in particular, allows a detailed study of the microphysics of shock formation, including piston-ambient ion collisionless coupling. An overview of the platform and its capabilities is given, and recent experimental results on the coupling of energy between piston and ambient ions and the formation of collisionless shocks are presented and compared to theoretical and computational work. In particular, a magnetosonic pulse consistent with a low-Mach number collisionless shock is observed in a quasi-perpendicular geometry in both experiments and simulations.

Magnetic force micropiston: An integrated force/microfluidic device for the application of compressive forces in a confined environment

Cellular biology takes place inside confining spaces. For example, bacteria grow in crevices, red blood cells squeeze through capillaries, and chromosomes replicate inside the nucleus. Frequently, the extent of this confinement varies. Bacteria grow longer and divide, red blood cells move through smaller and smaller passages as they travel to capillary beds, and replication doubles the amount of DNA inside the nucleus. This increase in confinement, either due to a decrease in the available space or an increase in the amount of material contained in a constant volume, has the potential to squeeze and stress objects in ways that may lead to changes in morphology, dynamics, and ultimately biological function. Here, we describe a device developed to probe the interplay between confinement and the mechanical properties of cells and cellular structures, and forces that arise due to changes in a structure's state. In this system, the manipulation of a magnetic bead exerts a compressive force upon a target contained in the confining space of a microfluidic channel. This magnetic force microfluidic piston is constructed in such a way that we can measure (a) target compliance and changes in compliance as induced by changes in buffer, extract, or biochemical composition, (b) target expansion force generated by changes in the same parameters, and (c) the effects of compression stress on a target's structure and function. Beyond these issues, our system has general applicability to a variety of questions requiring the combination of mechanical forces, confinement, and optical imaging.

Magnetic piston model for higher ion charge and different electron and ion plasma temperatures

A new formula for the magnetic piston model, which explicitly describes how the momentum imparted to the ions by the magnetic pressure depends not only on the ion mass but also on the ion charge, as well as, on the plasma electron and ion temperatures, is derived following Rosenbluth's classical particle-field self-consistent plane approximation analytic calculation. The formula presented in this paper has implications in explaining the experimentally observed separation of the ions of different species and charges by the magnetic field penetrating the plasma and specularly reflecting them.

Dynamics of exploding plasmas in a large magnetized plasma

The dynamics of an exploding laser-produced plasma in a large ambient magneto-plasma was investigated with magnetic flux probes and Langmuir probes. Debris-ions expanding at super-Alfvénic velocity (up to MA=1.5) expel the ambient magnetic field, creating a large (>20 cm) diamagnetic cavity. We observe a field compression of up to B/B0=1.5 as well as localized electron heating at the edge of the bubble. Two-dimensional hybrid simulations reproduce these measurements well and show that the majority of the ambient ions are energized by the magnetic piston and swept outside the bubble volume. Nonlinear shear-Alfvén waves (δB/B0>25%) are radiated from the cavity with a coupling efficiency of 70% from magnetic energy in the bubble to the wave.

Generation of magnetized collisionless shocks by a novel, laser-driven magnetic piston

We present experiments on the Trident laser facility at Los Alamos National Laboratory which demonstrate key elements in the production of laser-driven, magnetized, laboratory-scaled astrophysical collisionless shocks. These include the creation of a novel magnetic piston to couple laser energy to a background plasma and the generation of a collisionless shock precursor. We also observe evidence of decoupling between a laser-driven fast ion population and a background plasma, in contrast to the coupling of laser-ablated slow ions with background ions through the magnetic piston. 2D hybrid simulations further support these developments and show the coupling of the slow to ambient ions, the formation of a magnetic and density compression pulses consistent with a collisionless shock, and the decoupling of the fast ions.

Stagnation of a gas puff Z pinch

Simulations of a gas puff Z pinch were performed, using an appropriately modified version of the M3D code [Park et al., Phys. Plasmas 6, 1796 (1999)]. The simulations investigated the stagnation process, including the effects of the shock driven by the magnetic piston and the influence of the Rayleigh Taylor instability. The results compare favorably with recent experimental measurements. The stagnated plasma reaches a quasi equilibrium with approximate balance of plasma pressure and magnetic pressure, measured by β≤1. The dependence of the stagnation radius on β and radiative energy loss are calculated, using a simple radiation model.

High-energy Nd:glass laser facility for collisionless laboratory astrophysics

A kilojoule-class laser (Raptor) has recently been activated at the Phoenix-laser-facility at the University of California Los Angeles (UCLA) for an experimental program on laboratory astrophysics in conjunction with the Large Plasma Device (LAPD). The unique combination of a high-energy laser system and the 18 meter long, highly-magnetized but current-free plasmawill support a new class of plasma physics experiments, including the first laboratory simulations of quasi-parallel collisionless shocks, experiments on magnetic reconnection, or advanced laser-based diagnostics of basic plasmas. Here we present the parameter space accessible with this new instrument, results from a laser-driven magnetic piston experiment at reduced power, and a detailed description of the laser system and its performance.

Experimental study of the structure of the plasma-current sheath on the PF-1000 facility

The results of studies of the plasma-current sheath structure on the PF-1000 facility in the stage close to the instant of pinch formation are presented. The measurements were performed using various modifications of the calibrated magnetic probes. Studies of the influence of the probe shape and dimensions on the measurements accuracy were done. The current flowing in the converging sheath at a distance of 40 mm from the axis of the facility electrodes was measured. In the optimal operating modes, this current is equal to the total discharge current, which indicates the high efficiency of current transportation toward the axis. In such shots a compact high-quality sheath forms with shock wave in front of the magnetic piston. It is shown that the neutron yield depends on the current compressed onto the axis. This dependence agrees well with the known scaling, Yn ∼ I4. The use of the total discharge current in constructing the current scaling, especially for facilities with a large stored energy, is unjustified.

Magnetohydrodynamic Augmentation of Pulse Detonation Rocket Engines

acts to accelerate the bypass air and potentially impart an overall net positive thrust to the system. An additional magnetic piston applying energy in the pulse detonation engine chamber can also act in concert with the pulse detonation rocket-induced magnetohydrodynamic ejector for separate or additional thrust augmentation. Results show potential performance gains under many flight and operating conditions (as high as a 6% increase in total impulse per cycle) but with some challenges associated with achieving these gains, suggesting further analysis and optimization are required.

Study of Reflected Shock Wave Perturbations at the Central Axis of Dense Plasma Column in a Plasma Focus

When the shock front (SF) hits the central axis of plasma focus device, a reflected shock moves radially outwards. The magnetic piston (MP) continues to compress inwards until it hits the out-going reflected shock front. In the Lee model, to avoid of complexity and explanation of nonzero radius for the plasma pinched column, the pressure assumed uniform from the SF to the MP. In this paper shock wave propagation by MHD equations and pressure propagations between two electrodes had been investigated. The results showed that influence of shock wave propagation on the inward motion current sheath by Lorentz force had considerable effects on plasma pinch behavior and it may have an important responsibility for dense plasma column disruption before occurrence of m = 0 instability.

Computation of Mass Sweeping Efficiency Factor and Current Efficiency Factor in Z-pinch Devices

In this paper, mass sweeping efficiency factor (fm) and current efficiency factor (fi) have been computed for Z-pinch devices. We used slug model for analysis of Z-pinch dynamics. Magnetic piston reaps electrons and ions in duration of motion. But only a fraction of plasma mass sweeps with magnetic piston, therefore we should add mass sweeping efficiency factor (fm) in equations. Such like alone the fraction of electrical current flows of magnetic piston and remainder of it flows of internal and external radial of magnetic piston, so we should add fi in equations. In this paper, equations are solved with characteristics of CERN Z-pinch device (its length and radius, resistivity, circuit inductance and capacitanc and plasma inductance) and with values of Boggasch experiments (discharge voltage: 15 kV, initial pressure: 400 pa). Recorded code runs with different values of fm and fi and in each section, pinch time and pinch current are compared with Boggasch experimental values. Optimum values for fm and fi obtain with Comparing between numerical values and experimental values. These values are fi = 0.8 and fm = 0.08.

English

The Stirling cycle cooler is a free piston linear motor driven device. The cooling technology using reversed Stirling cycle offers an outstanding opportunity to provide a compact, environment friendly system with comparable energy consumption. Analysis of Stirling cryocoolers has been an important research area for the past many years. This cooler operates as a closed regenerative cycle: closed because there are no valves, a fixed mass of working fluid (usually helium) being repeatedly circulated through the same thermodynamic processes; and it’s called as a regenerative cycle as the key component is the thermal regenerator. The linear motor can be considered as the heart of the entire cooler. It drives the compressor piston (or power piston), which compresses the working fluid alternately. In the present work, moving magnet concept has been employed in contrast to the conventional moving coil type motor. This innovative idea avoids the requirements of oscillating electrical connections and reduces the risk of contamination of the working fluid. The permanent magnet material and magnetization, coil gage size and the materials for the inner and outer yoke are important from the point of view of motor performance and cost. The influence of different geometric and electromagnetic parameters on the performance of the motor is analyzed in this paper. For the analysis of each configuration, the relation between the magnet height under the influence of magnetic field and piston amplitude is established mathematically. The periodic variation of active magnet height in the magnetic field has been analyzed electromagnetically and the relations among the parameters are determined.

Operation of microsecond plasma opening switches

Closing and breaking of current in microsecond megaampere plasma opening switches are considered. Conductivity current scaling in the switch due to plasma acceleration by a magnetic piston is discussed and compared with experimental data. Two ways of determining the width of a current channel are taken up. This channel results from the diffusion of the magnetic field in the plane of the piston followed by the convective ejection of the field “frozen” in the accelerated plasma flow behind the shock wave into the bridge. Based on experimental data, a scaling law for the voltage on the switch according to the switch parameters is derived. The problem of reverse closing, which limits the efficiency of storage energy extraction into the load, is considered.

Plasma Dynamics in Opening Switches

The energy balance of a plasma opening switch in the conduction stage is calculated, in which the dominant process is magnetic field penetration into the plasma volume due to the magnetic piston effect. This mechanism is typical for a microsecond plasma opening switch of the mega-ampere range. It is also shown that the process of magnetic field penetration into the switch plasma is determined by the field diffusion near the magnetic piston, followed by the convective transport of magnetic field in the plasma. This transport is due to the field being frozen-in into the plasma flow behind the shock wavefront, which is formed in the plasma accelerated by the magnetic field pressure. The shock wave propagation leads to the formation of directed plasma flow with falling density, velocity, and pressure in the region between the magnetic piston and the shock wavefront. The following analysis of gas dynamics and related electromagnetic problems reveals the most important processes determining plasma and magnetic field dynamics.

Dynamics of the magnetic field transport in a plasma opening switch

It is shown that the process of magnetic field penetration into the plasma bridge in a plasma opening switch is determined by the field diffusion near the magnetic piston, followed by the convective transport of magnetic field in the bridge. This transport is due to the field being “frozen in” to the flow of plasma behind the front of a shock wave, which is formed in the plasma accelerated by the magnetic field pressure.