Design and Development of Mirnov Coil Sensor for Eddy Currents Experiment on Toroidal Vessel

Tokamak is a magnetic confinement device that confines hot plasma in the shape of torus during the process of thermonuclear fusion power generation. In tokamak, eddy currents are produced due to change in plasma positions during plasma instabilities that induce electromagnetic forces on interaction with the induced currents. Mirnov coils are widely used in tokamaks to study plasma positions during plasma instabilities. Principle objective of this paper is the design and development of Mirnov coil sensor to find eddy currents on a toroidal vessel. This paper presents an elaborative and practical construction technique of a Mirnov coil. The calibration method of a Mirnov coil is also discussed. Mirnov coils as an eddy current diagnostics are tested and experiments to measure magnetic fields due to induced current on torroidal vessel are performed using the coils.

Download Full-text

Outcome of TMS-based motor mapping depends on TMS current direction

10.1101/371997 ◽

2018 ◽

Author(s):

Jord JT Vink ◽

Petar I Petrov ◽

Stefano Mandija ◽

Rick M Dijkhuizen ◽

Sebastiaan FW Neggers

Keyword(s):

Primary Motor Cortex ◽

Motor Evoked Potentials ◽

Brain Regions ◽

Motor Area ◽

Current Direction ◽

Induced Current ◽

Motor Mapping ◽

Neurosurgical Planning ◽

Motor Maps ◽

Induced Currents

ABSTRACTNavigated transcranial magnetic stimulation (TMS) in combination with electromyography (EMG) recordings can be used to map the brain regions in which TMS evokes motor-evoked potentials (MEPs) in certain muscles. Navigated TMS (nTMS) is used increasingly to identify the functional motor area of different muscles for clinical applications, including neurosurgical planning. However, the accuracy of TMS-based mapping of functional motor areas may depend on the TMS-induced current direction due to anisotropic cortical morphology, complicating association of the functional motor maps with neuroanatomical structures. Furthermore, it is not clear how well nTMS can distinguish nearby muscle representations on the cortical surface. We therefore investigated the functional motor maps obtained with posterior-to-anterior (PA) and lateral-to-medial (LM) TMS-induced currents within a spatially defined area by stimulating targets in a grid of locations over the left primary motor cortex in 8 healthy participants. Results were compared to functional MRI (fMRI) activation maps obtained using a voluntary opposing thumb movement task. We found that TMS applied with PA-induced currents identifies a motor area that is located significantly more anterior (8.7 – 10.4 mm depending on the muscle) with respect to an MEP motor area identified using LM-induced currents for the same muscle. Motor maps obtained with LM-induced currents show more overlap with the motor map identified using fMRI compared to PA-induced currents. In conclusion, the spatial representation of the MEP motor map identified by TMS is dependent on the direction of the induced current. These findings suggest that the application of nTMS using an LM-induced current direction corresponds best with the hand motor area as measured with fMRI.

Download Full-text

ELECTROMAGNETIC PROCESSES IN A FLAT RECTANGULAR SYSTEM WITH AN INDUCTOR BETWEEN THIN BIFILAR COILS

Tekhnichna Elektrodynamika ◽

10.15407/techned2021.01.003 ◽

2021 ◽

Vol 2021 (1) ◽

pp. 3-9

Author(s):

Yu.V. Batygin ◽

◽

S.O. Shinderuk ◽

O.F. Yeryomina ◽

E.A. Chaplygin ◽

...

Keyword(s):

Magnetic Pulse ◽

Induced Current ◽

Analysis And Evaluation ◽

Electromagnetic Processes ◽

Time Shape ◽

Wide Range ◽

Induced Currents ◽

Metal Processing ◽

Induced Signal ◽

Practical Recommendations

The aim of the research is the analysis and evaluation of the electromagnetic processes characteristics in the proposed flat rectangular system consisting of a thin solenoid-inductor located between the branches of the bifilar, thin-walled multi-turn coils. The analysis of electromagnetic processes and the obtained estimates of the excited currents are carried out. It is shown that with a minimum gap between the windings of the solenoid-inductor and the bifilar, the time functions of the exciting current and the current induced in the bifilar windings are the same, and the amplitude of the latter is maximum and equal to half the current amplitude in the inductor. It was found that the proposed system has a practical invariance of the time shape and amplitude of the induced current in a wide range of variable geometric parameters. The minimal effect of the fields of induced currents on the processes in the solenoid-inductor and the minimum losses when removing the induced signal from the bifilar windings are noted. Physically, the first is due to the asymmetry of the excited magnetic field relative to the plane of the solenoid-inductor, the second is due to a significant decrease in spurious inter-turn capacitance due to the thinness of the bifilar windings. The obtained results allow us to give practical recommendations when choosing design solutions for elements of new circuits of equipment for magnetic pulse metal processing. References 14, figures 2.

Download Full-text

A Comparative Study on the Induced Current Density in Humans Exposed to ELF Electric Fields

Journal of Communications Software and Systems ◽

10.24138/jcomss.v3i1.265 ◽

2007 ◽

Vol 3 (1) ◽

pp. 17

Author(s):

Vitantonio Amoruso ◽

Giovanna Calò ◽

Francesco Lattarulo ◽

Dragan Poljak ◽

Andres Peratta ◽

...

Keyword(s):

Boundary Element Method ◽

Comparative Study ◽

Electric Fields ◽

Current Density ◽

Human Body ◽

Homogeneous Model ◽

Induced Current ◽

Sphere Model ◽

Theoretical Methods ◽

Induced Currents

A comparison between two theoretical methods, recently adopted for evaluating induced currents in a human body, is here presented. In both cases, a vertical ELF electric field is assumed for the coupling to a standard human subject.Specifically, the diakoptic method (DM), applied to a homogeneous multi-sphere model of man with low partitioning degree, and the Boundary Element Method (BEM), applied to a non-homogeneous model with high partitioning degree, have been selected. The analytical and numerical formulations, respectively distinctive of the above methods, are carefully described and a number of data are reported and commentedupon.

Download Full-text

Kinetic analysis of acetylcholine-induced current in isolated frog sympathetic ganglion cells

Journal of Neurophysiology ◽

10.1152/jn.1989.61.2.283 ◽

1989 ◽

Vol 61 (2) ◽

pp. 283-290 ◽

Cited By ~ 9

Author(s):

N. Akaike ◽

N. Tokutomi ◽

H. Kijima

Keyword(s):

Dose Response ◽

Sympathetic Ganglion ◽

Ganglion Cells ◽

Rapid Change ◽

Receptor Activation ◽

Hill Coefficient ◽

Kinetic Properties ◽

Activation Process ◽

Induced Current ◽

Induced Currents

1. Kinetic properties of activation and inactivation phases of the ACh-gated nicotinic current were investigated in isolated frog sympathetic ganglion cells using "concentration-clamp" technique under voltage-clamp conditions. This technique combines internal perfusion with a rapid change of the external solution within a few milliseconds. 2. The dose-response curve for the peak current induced by ACh showed a sigmoidal increase, in which the apparent dissociation constant Kd and Hill coefficient were 2.6 x 10(-5) M and 2.0, respectively. 3. The current-voltage relationship of ACh-induced currents were linear at potentials more negative than the reversal potential (EACh) of -5.5 +/- 1.3 mV (mean +/- SE) but showed a slight inward rectification at positive potentials over +20 mV. Since this current could be generated predominantly by an increase of Na+ and K+ conductances, the value of EACh was close to the theoretical potential, -1.3 mV, for the total amount of both Na+ and K+ or Cs+ in the extracellular and intracellular solutions. 4. There was no difference between the dose-response curves of ACh- and nicotine-induced currents. The ACh-induced current was suppressed in a competitive manner by the nicotinic antagonists, d-tubocurarine and hexamethonium, but muscarine did not induce any response, indicating that the ACh-gated current might be mediated by the nicotinic ACh receptor-ionophore complex. 5. There was a latent period of the order of milliseconds in the ACh receptor activation phase before attaining exponential increase of activation process.(ABSTRACT TRUNCATED AT 250 WORDS)

Download Full-text

Deploying vertical wires with drones to study wind turbine electrification under fair weather

10.5194/egusphere-egu21-4556 ◽

2021 ◽

Author(s):

Pol Fontanes Molina ◽

Marcelo Arcanjo ◽

Joan Montanyà Puig ◽

Carmen Guerra-Garcia

Keyword(s):

Electric Field ◽

Wind Turbine ◽

Corona Discharge ◽

Turbine Blades ◽

Induced Current ◽

Fair Weather ◽

Wind Turbine Blades ◽

Vertical Speed ◽

Induced Currents ◽

The Wire

The response of tall structures such as towers to the electrical atmosphere is well known, but much has to be learned about how the rotation of wind turbine blades affects the electrical response of wind turbines. To better understand current induction and the appearance of point/corona discharge from wind turbine blades, a series of experiments lifting vertical wires with drones under fair weather conditions have been conducted. During the experiments, the length of the wire (vertical) and its vertical velocity were recorded using the drone&#8217;s telemetry. Additionally, the wire was grounded through a pico-ammeter to measure current induction and a corona discharge detector, based on a wideband current measurement coil, was placed close to the tip of the lifting wire to detect possible point/corona discharge appearance at the wire tip.Preliminary tests included testing the sensor in the laboratory by measuring artificially generated corona pulses, to verify that pulses from this sensor registered on the field could be attributed to point/corona discharge phenomena. Measured amplitude for this induced current was on the order of hundreds of nano-amps.For these experiments, an insulated copper wire with&#160; 0.14&#937;/m resistance and with the top tip exposed to the environment was deployed using two different tips, a rounded tip of 1mm radius and a sharp needle tip of 0.1mm radius. The electric field at the ground level was measured using an electric field mill. All flights were performed during the morning and the ground electric field amplitude ranged from 50V/m to 200V/m.When using rounded tips, corona discharge was not detected by the coil, but an induced current proportional to the vertical speed of the wire was measured. This component of the current is interpreted as a change of potential in time, and the amplitude of these induced currents is on the order of tens of nano-amps.Results when using the sharp tip showed two clear sources of induced currents on the wire, vertical speed (as in the rounded case) and corona discharge. When using the sharp tip, corona discharge was detected when the wire reached around 50 m and induced current amplitude increased with altitude. A pulsating current was measured by the coil sensor indicating the existence of corona discharge on the wire.The rate of decrease of the measured currents after reaching steady positions of the wires might be attributed to the screening effect of the released charge.These experiments proved that key factors for the current induction on wind turbine blades include the change in height at a certain speed, along with the occurrence of point/corona discharges with the radius of curvature of the blade tips. Under the effects of electrified thunderclouds, the magnitudes of the currents could reach several orders of magnitude.&#160;

Download Full-text

Induction heating of a shape memory alloy beam

The European Physical Journal Applied Physics ◽

10.1051/epjap/2018170394 ◽

2018 ◽

Vol 83 (3) ◽

pp. 30905 ◽

Cited By ~ 1

Author(s):

S. Dufour ◽

G. Vinsard

Keyword(s):

Temperature Field ◽

Shape Memory Alloy ◽

Shape Memory ◽

Induction Heating ◽

Mechanical Model ◽

Eddy Currents ◽

Shape Change ◽

Nickel Titanium ◽

Thin Shells ◽

Induced Currents

The shape memory alloy heating by eddy currents is a quick solution for the shape change. Then, the analysis of the temperature field as a function of the shape is important to build a mechanical model in large deformation. Even if the temperature can be obtained by experiment, a computational model is useful. The computation of the induced currents in a nickel–titanium shape memory alloy beam is here considered with a T − Ω model adapted to thin shells with the help of a change of coordinates. It allows us to take into account the shape change, without the need of remeshing, as a function of the temperature. Experiments are carried out to validate the model.

Download Full-text

Substance P-induced calcium entry in endothelial cells is secondary to depletion of intracellular stores

AJP Heart and Circulatory Physiology ◽

10.1152/ajpheart.1995.268.3.h962 ◽

1995 ◽

Vol 268 (3) ◽

pp. H962-H973 ◽

Cited By ~ 8

Author(s):

N. R. Sharma ◽

M. J. Davis

Keyword(s):

Endothelial Cells ◽

Substance P ◽

Reversal Potential ◽

Induced Current ◽

Inward Current ◽

Porcine Coronary Artery ◽

Store Depletion ◽

Patch Pipette ◽

Induced Currents ◽

Patch Technique

Substance P (SP) induces an elevation in cytosolic Ca2+ concentration ([Ca2+]i) in porcine coronary artery endothelial cells by way of Ca2+ influx and release from intracellular stores. We tested the hypothesis that SP-induced Ca2+ influx occurs due to activation of a Ca(2+)-permeable influx pathway coupled to depletion of intracellular stores. With the use of the perforated patch technique and fura 2 microfluorimetry, a fivefold greater increase in [Ca2+]i per unit decrease in membrane potential was obtained in the presence of SP (10 nM) compared with resting state, implying that SP increased Ca2+ conductance. When K+ channels were blocked, SP activated a net inward current with a reversal potential (2.5 +/- 1 mV) not significantly different from that (2 +/- 1 mV) for inward current recorded in response to store depletion by (2,5-di-tert-butylhydroquinone) (BHQ, 10 microM). Increasing bath [Ca2+] induced a similar shift in reversal potential for SP- and BHQ-induced currents. Inositol 1,4,5-trisphosphate (20 microM), applied through the patch pipette, activated an inward current with Ca2+ selectivity similar to SP- and BHQ-activated currents. Dialysis of cells with heparin (5 mg/ml) completely blocked SP-induced inward current but not BHQ-induced current. These results suggest that the SP-induced increase in Ca2+ conductance can be completely explained by activation of a Ca(2+)-permeable influx pathway coupled to depletion of intracellular stores.

Download Full-text

Iteration Coupling Simulation of Random Waves and Wave-Induced Currents

Journal of Applied Mathematics ◽

10.1155/2012/205376 ◽

2012 ◽

Vol 2012 ◽

pp. 1-13

Author(s):

Jinhai Zheng ◽

Tianwen Wang ◽

Gang Wang ◽

Chenming Zhang ◽

Chi Zhang

Keyword(s):

Wave Field ◽

Circulation Model ◽

Wave Transformation ◽

Induced Current ◽

Random Waves ◽

Three Dimensional Model ◽

Current Interaction ◽

Induced Currents ◽

Coupling Algorithm ◽

Wave Induced

A two-way coupling algorithm for wave-current interaction is developed and implemented into a nearshore circulation model to investigate the effects of fully wave-current interaction on irregular wave transformation over an elliptic shoal. The wave field is simulated by a spectral wave model WABED, and the wave-induced current is solved by a quasi-three-dimensional model WINCM. The surface roller effects are represented in the formulation of surface stress, and the roller characteristics are solved by a roller evolution model. The proposed two-way coupling algorithm can describe both the generation of wave-induced current and the current-induced wave transformation, which is more physically reasonable than the one-way approaches. The model test with a laboratory experiment shows that wave-induced currents have an important influence on the wave transformation, for example, the wave energy defocusing due to the strong jet-like current along the centerline of the shoal. It is revealed that the accuracy of simulated wave field can be significantly improved by taking into account the two-way wave-current interaction.

Download Full-text

Magnetically induced ring currents in naphthalene-fused heteroporphyrinoids

Physical Chemistry Chemical Physics ◽

10.1039/d1cp02381k ◽

2021 ◽

Author(s):

Markus Rauhalahti ◽

D Sundholm ◽

Mikael P. Johansson

Keyword(s):

Current Density ◽

Quantum Chemical ◽

Ring Current ◽

Induced Current ◽

Ring Currents ◽

Induced Currents

The magnetically induced current density of an intriguing naphthalene-fused heteroporphyrin have been studied, using the quantum-chemical, gauge-including magnetically induced currents (GIMIC) method. The ring-current strengths and current-density pathways for the...

Download Full-text

AC losses of no-insulation high temperature superconductor (RE)Ba2Cu3Ox coils induced by ripple magnetic fields in machines

10.36227/techrxiv.12611825.v1 ◽

2020 ◽

Author(s):

Yawei Wang

Keyword(s):

High Temperature ◽

Magnetic Fields ◽

High Temperature Superconductor ◽

Eddy Currents ◽

Ac Loss ◽

Ac Losses ◽

Induced Current ◽

Risk Optimization ◽

Current Flows ◽

The Stability

No-insulation high temperature superconductor (NI HTS) (RE)Ba2Cu3Ox coil technology is effective in enhancing the thermal stability of HTS coils. Applying the NI technique on the rotor windings of HTS machines can improve the stability and reliability of the machines. However, the NI HTS rotor windings experience ripple magnetic fields, which leads to induced eddy currents through the turn-to-turn contacts. The accompanying turn-to-turn losses will considerably affect the machine efficiency. In this study, we compared experimentally the losses of NI HTS coils subjected to external AC magnetic fields with those of insulated coils. Measurement system based on calibration-free method is developed for the AC loss measurement on HTS coils exposed to external AC magnetic fields. The results show that the AC loss of NI HTS coils can be 20 times higher than that of insulated HTS coils, and lowering turn-to-turn resistivity can significantly reduce this AC loss. Modeling analysis shows that most of induced current flows in the outer turns of the NI HTS coil because of skin effect, and lower turn-to-turn resistivity leads to higher induced current in superconducting layers and more significant accumulation of turn-to-turn loss. This will increase quench risk. Optimization of turn-to-turn resistivity is required when the NI HTS coil is applied in the machines environments.

Download Full-text