Electromagnetic Pressure Research Articles

Measuring flow and pressure of lithium coolant under developmental testing of a high-temperature cooling system of a space nuclear power plant

Sub-megawatt space NPP use lithium as a coolant and niobium alloy as a structural material. In order to refine the lithium-niobium technology of the material and design engineering, lithium-niobium loops were worked out in RSC Energia, and they were tested at a working temperature of lithium equal to 1070–1300 K. In order to measure the lithium flow and pressure, special gauges were developed, which made possible the calibration and checkout of the loops without their dismantling. The paper describes the architecture of the electromagnetic flowmeter and the electromagnetic vibrating-wire pressure transducer (gauge) for lithium coolant in the nuclear power plant cooling systems. The operating principles of these meters are presented. Flowmeters have been developed for channel diameters ranging from 10 to 100 mm, which are capable of measuring lithium flows in the range of 0.1 to 30 L/s with the error of 3% for design calibration and 1% for volume graduation. The temperature error of the pressure transducers does not exceed 0.4% per 100 K; the nonlinearity and hysteresis of the calibration curve do not exceed 0.3 and 0.4%, respectively. The transducer applications are illustrated by the examples of results obtained from tests on the NPP module mockup and heat pipes of a radiation cooler.

Unified position-dependent photon-number quantization in layered structures

We have recently developed a position-dependent quantization scheme for describing the ladder and effective photon-number operators associated with the electric field to analyze quantum optical energy transfer in lossy and dispersive dielectrics [Phys. Rev. A, 89, 033831 (2014)]. While having a simple connection to the thermal balance of the system, these operators only described the electric field and its coupling to lossy dielectric bodies. Here we extend this field quantization scheme to include the magnetic field and thus to enable description of the total electromagnetic field and discuss conceptual measurement schemes to verify the predictions. In addition to conveniently describing the formation of thermal balance, the generalized approach allows modeling of the electromagnetic pressure and Casimir forces. We apply the formalism to study the local steady state field temperature distributions and electromagnetic force density in cavities with cavity walls at different temperatures. The calculated local electric and magnetic field temperatures exhibit oscillations that depend on the position as well as the photon energy. However, the effective photon number and field temperature associated with the total electromagnetic field is always position-independent in lossless media. Furthermore, we show that the direction of the electromagnetic force varies as a function of frequency, position, and material thickness.

Experimental study on forming behavior of high-strength steel sheets under electromagnetic pressure

To experimentally investigate the forming behavior of automotive high-strength steel sheets under electromagnetic pressure, three high-strength steel sheets (DP780, DP980, and CP1180) were freely formed into hemi-elliptical protrusions. The experiments were performed using a spiral flat coil and open-cavity die. Aluminum driver plates were utilized for improving the forming efficiency. The forming behavior was investigated by evaluating characteristics such as peak height, limit height, and springback angle for various charge voltages. The effect of the aluminum driver plate on the forming behavior of the high-strength steel sheet was also observed.

Maxwell's stress tensor and the forces in magnetic liquids

Maxwell's stress tensor is well known from electromagnetic theory. But correct application of it to practical problems is by no means general knowledge even among experts. In this article we present a survey of the electromagnetic stress tensor and of the electromagnetic forces in strongly polarizable materials. We relate the observed ponderomotoric phenomena to the stress tensor and we present a number of applications in modern devices and processes using ferromagnetic colloids, so-called ferrofluids. We emphazise the correct applications of the stress tensor to these examples in contrast to common popular usage of a so-called “electromagnetic pressure”. We predict some new effects, e.g. density variations and pressure measurements in ferrofluids. Our work is based on two preceding articles by the present authors [4, 33] wherein the electromagnetic stress tensor is deduced from conservation laws together with Maxwell's equations and with thermodynamic relations.

Deep subwavelength Fabry-Perot resonances

Confinement of light by subwavelength objects facilitates the realization of compact photonic devices and the enhancement of light-matter interactions. The Fabry-Perot (FP) cavity provides an efficient tool for confining light. However, the conventional FP cavity length is usually comparable to or larger than the light wavelength, making them inconvenient for many applications. By manipulating the reflection phase at the cavity boundaries, the FP cavity length could be made much smaller than the wavelength. In this review, we consider the subwavelength FP resonance in a plasmonic system composed of a slit grating backed with a ground plane, covering the spectral range from microwave to THz and infrared regime. For very narrow slit width and spacer thickness, a typical zero-order and deep subwavelength FP resonance in the metallic slits can be strongly induced. Moreover, due to the subwavelength FP resonance, greatly enhanced electromagnetic pressure can also be induced in the system. The sign and magnitude of the electromagnetic pressure are dominated by the field penetration effect in the metal as well as the field enhancement in the FP cavities. The effect promises a variety of potential applications, such as detecting tiny motions and driving the mechanical oscillations.

Behavior of Non-metallic Inclusions in a Continuous Casting Tundish with Channel Type Induction Heating

A generalized three dimensional mathematical model, which adopted the Euler-Lagrange approach, has been developed for the motion of inclusions in a continuous casting tundish with channel type induction heating. The inclusion trajectories were obtained by numerical solution of the motion equation including gravity, buoyancy, drag, lift, added mass, Brownian, electromagnetic pressure and thermophoretic forces. Besides, the collision and coalescence of inclusions and adhesion to the lining solid surfaces were also taken into account. The Brownian, Stokes and turbulent collision were clarified, separately. Then the effect of induction heating power on the inclusion behavior was demonstrated. A reasonable agreement between the experimental observation and numerical results was obtained. The results indicate that the electromagnetic pressure force significantly promotes the removal of inclusions, especially for the bigger inclusion. Although the thermophoretic force goes against the removal of inclusions, its influence is negligibly small. The removal ratio of inclusions in the tundish with induction heating increases from 67.45% to 96.43%, while the power varies from 800 kW to 1200 kW. The collision and coalescence should be included when model the inclusion motion, because it can promote the removal of inclusion. The turbulent and Brownian collision becomes more active with the increasing power, while the Stokes collision is just opposite.

Resonance experiment on a microwave resonator system

A microwave resonator system is made, which has a tapered resonant cavity, a microwave source, and a transmission device. Because of the electromagnetic pressure gradient on the tapered resonant cavity, a net electromagnetic force along the axis of the cavity may be observed, which is needed to verify experimentally the use of the independent microwave resonator system. It is also needed to keep the independent microwave resonator system in resonating state, which is the important procedure to demonstrate the possibility of net electromagnetic force. Thus, a low-signal resonating experiment on the tapered resonant cavity combined with resonating parts is completed to accurately find out the resonant frequency of 2.45 GHz and to analyze the influence of temperature on the resonant state. Experimental result shows that the resonant frequency and quality factor of the independent microwave resonator system are 2.44895 GHz and 117495.08 respectively. When the temperature of the tapered resonant cavity wall rises, the resonant frequency will be decreased and the quality factor changed separately.

Deformation behavior and microstructure evolution of pure Cu subjected to electromagnetic bulging

In this paper, pure Cu sheet with thickness of 1mm was electromagnetically budged to form a conical shape workpiece. The deformation behavior and the microstructural evolution of the Cu sheet under electromagnetic bulging were systematically studied using strain analysis, optical microscopy (OM), electron backscattered diffraction (EBSD) and transmission electron microscopy (TEM). It is found that the strain distribution in the workpiece is quite un-uniform from the bottom to the top due to the inhomogeneous electromagnetic pressure generated by the spiral coil. The characterization of microstructure reveals that the bulge deformation of the Cu sheet is governed by dislocation multiple slip and cross slip, which cause finally the formation of cell structures. However, the size and the boundary width of cells are closely related to the plastic strain, i.e., the cell size and boundary width decrease with increasing strain. In addition, low misorientation angle of cells inside the grains increases with increasing strain. This structural evolution is discussed on the basis of the low energy dislocation structures (LEDS) theory.

Nonlinear optical rectification in vertically coupled InAs/GaAs quantum dots under electromagnetic fields, pressure and temperature effects

In this paper we explore the effects of the structural dimensions, applied electromagnetic fields, hydrostatic pressure and temperature on the nonlinear optical rectification (NOR) in Vertically Coupled InAs/GaAs Quantum Dots (VCQDs). The analytical expression of the NOR is analyzed by using the density matrix formalism, the effective mass and the Finite Difference Method (FDM). Obtained results show that the NOR obtained with this coupled system is not a monotonic function of the barrier width, electromagnetic fields, pressure and temperature. Also, calculated results reveal that the resonant peaks of the NOR can be blue-shifted or red-shifted energies depending on the energy of the lowest confined states in the VCQDs structure. In addition, this condition can be controlled by changes in the structural dimensions and the external proofs mentioned above.

Optimization of Supply and Exhaust Stroke of the Electro-Pneumatic Changeover Valve

To optimize the supply and exhaust stroke of electro-pneumatic changeover valve (EP valve), a basic structure of proportional solenoid which used in the EP valve is designed, and a computational model of proportional solenoid and EP valve simulation model are established based on the AMESim. Then the electric magnetic characteristic curves of proportional electromagnetic valve and EP valve output side air pressure curves of different supply and exhaust stroke are obtained by simulations. Through the analysis of the simulation results to optimize the supply and exhaust stroke of the EP valve.

Non-thermal effect on densification kinetics during microwave sintering of α-alumina

The microstructural evolution and densification kinetics of a-alumina were investigated and compared between conventional sintering and microwave sintering at 2.45 GHz in the intermediate stage, where the microwave seems to be the most efficient. Based on classical kinetics models, the calculated kinetics parameter demonstrated that the densification is greatly influenced by the presence of an electromagnetic field during sintering. It was assumed that the grain boundary diffusion is enhanced by an electromagnetic pressure induced by the microwave. (C) 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

Prediction and experimental measurement of the electromagnetic thrust generated by a microwave thruster system

A microwave thruster system that can convert microwave power directly to thrust without a gas propellant is developed. In the system, a cylindrical tapered resonance cavity and a magnetron microwave source are used respectively as the thruster cavity and the energy source to generate the electromagnetic wave. The wave is radiated into and then reflected from the cavity to form a pure standing wave with non-uniform electromagnetic pressure distribution. Consequently, a net electromagnetic thrust exerted on the axis of the thruster cavity appears, which is demonstrated through theoretical calculation based on the electromagnetic theory. The net electromagnetic thrust is also experimentally measured in the range from 70 mN to 720 mN when the microwave output power is from 80 W to 2500 W.

Development of Hybrid-Type Pressure Cell for High-Pressure and High-Field ESR Measurement

A hybrid-type piston-cylinder pressure cell for the electron spin resonance (ESR) measurement has been developed. The cylinder of this pressure cell consists of a NiCrAl inner cylinder and a CuBe outer sleeve, and all inner parts are made of zirconium oxide which has good transmittance to the millimeter and submillimeter waves. We confirmed that the pressure reaches 2.1 GPa. We have also developed a transmission-type high-field ESR system having two different modulation methods for this pressure cell. A test measurement without pressure cell for the two-dimensional orthogonal-dimer spin system of SrCu2(BO3)2 has been done successfully in the wide frequency region. The combination of this electromagnetic wave transmission-type pressure cell and this high-field ESR system is a promising tool for the study of the pressure-induced phase transition of SrCu2(BO3)2.

Induced electromagnetic pressure during microwave sintering of ZnO in magnetic field

Abstract This paper presents a unique technological approach for producing a tailored and controlled microstructure in pure zinc oxide using two different sintering methods. A microstructural comparative study between conventional and 2.45 GHz microwave sintered pure ZnO ceramics has been established. Data on the sintering behavior and grain growth as a function of the nature of the heating cycle are collected. The use of two step sintering cycles showed that high density can be achieved with almost complete suppression of grain growth. Compared to conventional sintering, microwave heated samples revealed a denser structure, as two step heated samples presented highest final densities for shorter sintering times. As a semiconductor, the material showed greater heating behavior in H -field which is traduced by higher energy absorption (higher ramp) at the beginning of the heating cycle. H -field sintered pellets showed higher densities and grain size uniformity than the ones sintered in E -field for identical heating cycles. This is likely due to an electromagnetic pressure induced by the combined effect of current loops submitted to a MW– H field.

Foreword for the special issue on Multimodal and Sensorimotor Bionics

Animals are quite efficient at discerning “objects” that appear in their surroundings, exceeding by far what technical systems have been able to replicate. Evolution has equipped animals with several modalities such as vision, hearing, and haptics to exploit different physical means of information representation: electromagnetic spectrum (vision), pressure waves (hearing), forces (haptics, tactile sensing), gravity (vestibular system), hydrodynamic velocity and pressure field (lateral-line system), etc. It is precisely the combination of these different sensing modalities that allows biological systems to attain their high level of accuracy and dependability in sensing their surroundings. A few words on the notions of multimodal and multisensory are in order (Stein et al 2010). A lateral line, for instance, consists of many sensors (neuromasts) all over the body. The conglomeration of all neuromasts allows a fish, say, a pike, to localize or even determine the shape of a roach in its neighborhood. Only through the total input of all neuromasts can the pike accomplish the localization task with the lateral line as a truly “multisensory” modality. In clear water the pike can then both “see” the roach and perceive it through its lateral-line system, a multimodal experience. How do all these modalities, with their specific, physically different transmission techniques, function? How does the brain generate “objects” as neuronal representations

Enhanced electromagnetic pressure in a sandwiched reflection grating

We suggest that strongly enhanced electromagnetic pressure can be induced at the boundary of a sandwiched reflection grating due to a special kind of deep subwavelength Fabry-Perot (FP)-like resonance. A theoretical formula will be derived and employed to study this effect at both the infrared and microwave regimes. The magnitude or sign of the electromagnetic force can be tuned by adjusting the system parameters, which in turn adjust the balance between the electric and magnetic energies stored in the system. In the infrared regime, a strong attractive pressure was found, which is controllable by the FP cavity length. In the microwave band, a repulsive pressure can be realized in most situations. What is rather amazing is that a strong attractive electromagnetic pressure, which has not been found previously, can also be demonstrated in some geometries in the microwave regime.

6.5.1 A collaborative process based on systems engineering and mechatronics methods

AbstractThe laws of physics bring into play geometric dimensions and directions. Consequently, systems engineering can in no way ignore the reciprocal effects of choices concerning the system's geometry and architecture on expected performance (electromagnetic phenomena, heat propagation and pressure loss, for example, are recurring issues in systems engineering projects).Such challenges elicit the need to define which processes and methods would permit to concurrently design a system's architecture, its geometry, and the three‐dimensional layout of its constituent parts.The purpose of this report is to present elements of an answer to this need. They were provided by a systems engineering methodology based on system architecture and three‐dimensional models as well as functional models. Based on modeling and simulation techniques, this methodology was developed and applied as part of the O2M research project sponsored by the competitiveness clusters System@tic and Moveo (two French agencies promoting applied research projects that bring together research laboratories, large industrial groups, and small and medium‐sized organizations).

Molecular reorientation of a nematic liquid crystal by thermal expansion

A unique feature of nematic liquid crystals is orientational order of molecules that can be controlled by electromagnetic fields, surface modifications and pressure gradients. Here we demonstrate a new effect in which the orientation of nematic liquid crystal molecules is altered by thermal expansion. Thermal expansion (or contraction) causes the nematic liquid crystal to flow; the flow imposes a realigning torque on the nematic liquid crystal molecules and the optic axis. The optical and mechanical responses activated by a simple temperature change can be used in sensing, photonics, microfluidic, optofluidic and lab-on-a-chip applications as they do not require externally imposed gradients of temperature, pressure, surface realignment, nor electromagnetic fields. The effect has important ramifications for the current search of the biaxial nematic phase as the optical features of thermally induced structural changes in the uniaxial nematic liquid crystal mimic the features expected of the biaxial nematic liquid crystal.

Evaluation of the Influence of Sensor Geometry and Physical Parameters on Impedance-Based Structural Health Monitoring

Structural Health Monitoring (SHM) is the process of damage identification in mechanical structures that encompasses four main phases: damage detection, damage localization, damage extent evaluation and prognosis of residual life. Among various existing SHM techniques, the one based on electromechanical impedance measurements has been considered as one of the most effective, especially in the identification of incipient damage. This method measures the variation of the electromechanical impedance of the structure as caused by the presence of damage by using piezoelectric transducers bonded on the surface of the structure (or embedded into it). The most commonly used smart material in the context of the present contribution is the lead zirconate titanate (PZT). Through these piezoceramic sensor-actuators, the electromechanical impedance, which is directly related to the mechanical impedance of the structure, is obtained as a frequency domain dynamic response. Based on the variation of the impedance signals, the presence of damage can be detected. A particular damage metric can be used to quantify the damage. For the success of the monitoring procedure, the measurement system should be robust enough with respect to environmental influences from different sources, in such a way that correct and reliable decisions can be made based on the measurements. The environmental influences become more critical under certain circumstances, especially in aerospace applications, in which extreme conditions are frequently encountered. In this paper, the influence of electromagnetic radiation, temperature and pressure variations, and ionic environment have been examined in laboratory. In this context, the major concern is to determine if the impedance responses are affected by these influences. In addition, the sensitivity of the method with respect to the shape of the PZT patches is evaluated. Conclusions are drawn regarding the monitoring efficiency, stability and precision.

Coupled modes in magnetized dense plasma with relativistic-degenerate electrons

Low frequency electrostatic and electromagnetic waves are investigated in ultra-dense quantum magnetoplasma with relativistic-degenerate electron and non-degenerate ion fluids. The dispersion relation is derived for mobile as well as immobile ions by employing hydrodynamic equations for such plasma under the influence of electromagnetic forces and pressure gradient of relativistic-degenerate Fermi gas of electrons. The result shows the coexistence of shear Alfven and ion modes with relativistically modified dispersive properties. The relevance of results to the dense degenerate plasmas of astrophysical origin (for instance, white dwarf stars) is pointed out with brief discussion on ultra-relativistic and non-relativistic limits.