Das toroidale schwachionisierte Magnetoplasma I

1967 ◽  
Vol 22 (12) ◽  
pp. 1890-1903
Author(s):  
F. Karger
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Electric Field ◽  
Electric Field Strength ◽  
Electric Fields ◽  
Transverse Electric ◽  
Refined Theory ◽  
Toroidal Plasma ◽  
Dc Discharge ◽  
Transverse Electric Fields

In a previous paper31 discrepancies between theory and experiment were found on investigating the positive column in a curved magnetic field. The approximation derived in 31 for the torus drift in a weakly ionized magnetoplasma is therefore checked here (Part I) with a refined theory which also yields the transverse electric field strength. Experimentally, both the transverse electric fields and the density profiles in the DC discharge were determined in addition to the longitudinal electric field strength.The discrepancies occurring in 31 are ascribed to the fact that the plasma concentrates at the cathode end of the magnetic field coils, this effect having a considerable influence on the form of the transverse density profile and on the stability behaviour. Part II later will show how the influence of this concentration can be eliminated and what effect in the current-carrying toroidal plasma causes a marked reduction of the charge carrier losses.

Effect of external magnetic field on lane formation in driven pair-ion plasmas

2021 ◽  
Vol 87 (2) ◽  
Author(s):  
Swati Baruah ◽  
U. Sarma ◽  
R. Ganesh
Keyword(s):  
Magnetic Field ◽  
External Magnetic Field ◽  
Field Strength ◽  
Electric Field ◽  
Electric Field Strength ◽  
Coupling Parameter ◽  
Critical Parameters ◽  
Coulomb Coupling ◽  
Lane Formation ◽  
Parameter Values

Lane formation dynamics in externally driven pair-ion plasma (PIP) particles is studied in the presence of external magnetic field using Langevin dynamics (LD) simulation. The phase diagram obtained distinguishing the no-lane and lane states is systematically determined from a study of various Coulomb coupling parameter values. A peculiar lane formation-disintegration parameter space is identified; lane formation area extended to a wide range of Coulomb coupling parameter values is observed before disappearing to a mixed phase. The different phases are identified by calculating the order parameter. This and the critical parameters are calculated directly from LD simulation. The critical electric field strength value above which the lanes are formed distinctly is obtained, and it is observed that in the presence of the external magnetic field, the PIP system requires a higher value of the electric field strength to enter into the lane formation state than that in the absence of the magnetic field. We further find out the critical value of electric field frequency beyond which the system exhibits a transition back to the disordered state and this critical frequency is found as an increasing function of the electric field strength in the presence of an external magnetic field. The movement of the lanes is also observed in a direction perpendicular to that of the applied electric and magnetic field directions, which reveals the existence of the electric field drift in the system under study. We also use an oblique force field as the external driving force, both in the presence and absence of the external magnetic field. The application of this oblique force changes the orientation of the lane structures for different applied oblique angle values.

scholarly journals Photoluminescence of CdSe/ZnS quantum dots in nematic liquid crystals in electric fields

2018 ◽  
Vol 9 ◽  
pp. 1544-1549 ◽  
Author(s):  
Margarita A Kurochkina ◽  
Elena A Konshina ◽  
Daria Khmelevskaia
Keyword(s):  
Quantum Dots ◽  
Liquid Crystals ◽  
Field Strength ◽  
Electric Field ◽  
Electric Field Strength ◽  
Electric Fields ◽  
Dielectric Anisotropy ◽  
Vertical Position ◽  
Decay Times ◽  
Pl Intensity

We have experimentally investigated the effect of the reorientation of a nematic liquid crystal (LC) in an electric field on the photoluminescence (PL) of CdSe/ZnS semiconductor quantum dots (QDs). To the LC with positive dielectric anisotropy, 1 wt % QDs with a core diameter of 5 nm was added. We compared the change of PL intensity and decay times of QDs in LC cells with initially planar or vertically orientated molecules, i.e., in active or passive LC matrices. The PL intensity of the QDs increases four-fold in the active LC matrix and only 1.6-fold in the passive LC matrix without reorientation of the LC molecules. With increasing electric field strength, the quenching of QDs luminescence occurred in the active LC matrix, while the PL intensity did not change in the passive LC matrix. The change in the decay time with increasing electric field strength was similar to the behavior of the PL intensity. The observed buildup in the QDs luminescence can be associated with the transfer of energy from LC molecules to QDs. In a confocal microscope, we observed the increase of particle size and the redistribution of particles in the active LC matrix with the change of the electric field strength. At the same time, no significant changes occurred in the passive LC matrix. With the reorientation of LC molecules from the planar in vertical position in the LC active matrix, quenching of QD luminescence and an increase of the ion current took place simultaneously. The obtained results are interesting for controlling the PL intensity of semiconductor QDs in liquid crystals by the application of electric fields.

Inactivation of Microorganisms in Cloudy Ginkgo (Ginkgo biloba Linn.) Juice by Pulsed Electric Fields

2007 ◽  
Vol 13 (2) ◽  
pp. 83-90 ◽  
Author(s):  
H. Zhang ◽  
Z. Wang ◽  
R.-J. Yang ◽  
S.-Y. Xu
Keyword(s):  
Field Strength ◽  
Electric Field ◽  
Electric Field Strength ◽  
Electric Fields ◽  
Treatment Time ◽  
Synergistic Effects ◽  
Pulsed Electric Fields ◽  
Bath Temperature ◽  
Microbial Inactivation ◽  
Plate Counts

Pulsed electric fields (PEF) were applied to neutral ginkgo cloudy juice to study the influence of the electric field strength, the treatment time and temperature on microbial inactivation. The results showed that microbial inactivation increased with the electric field strength, the treatment time and temperature. PEF treatment caused 3.39 and 4.44-log cycles reduction of coliforms and total plate counts, respectively, when pulse duration was 3 μs, the electric field strength 30 kV/cm, the treatment time 520 μs and the water bath temperature 15°C. Under the same conditions, the microbial shelf life of ginkgo cloudy juice was extended to 24 days at 4°C and 18 days at room temperature. A 3.7-log cycles reduction of the total yeast and mould counts was obtained by applying 390 μs of 30 kV/cm at 15°C.Yeast and mould cells were less resistant to PEF process than bacteria cells. The effect of heat generated during the PEF treatment was limited on microbial inactivation. Temperature and the induced heat by PEF had synergistic effects to microbial inactivation in cloudy ginkgo juice.

Effect of Electric Field Strength on Texture Evolution of IF Steel Sheet during Annealing

2012 ◽  
Vol 706-709 ◽  
pp. 2617-2621
Author(s):  
Chang Shu He ◽  
Xiang Zhao ◽  
Wei Ping Tong ◽  
Liang Zuo
Keyword(s):  
Field Strength ◽  
Electric Field ◽  
Electric Field Strength ◽  
Electric Fields ◽  
Applied Electric Field ◽  
Steel Sheet ◽  
Texture Evolution ◽  
If Steel ◽  
X Ray Diffraction ◽  
If Steel Sheet

Specimens cut from a cold-rolled IF steel sheet of 1 mm thickness were respectively annealed at 750°C for 20min under a range of DC electric fields (1kV/cm~4kV/cm). The Effect of electric field strength on recrystallization texture of IF steel sheet was studied by mean of X-ray diffraction ODF analysis. It was found that γ-fiber textures were notably enhanced as electric field strength increased. The strength of γ-fiber textures got their peak values as the applied electric field reached to 4kV/cm. The possible reason for such phenomena was discussed in the viewpoint of interaction between the applied electric field and the orientation-dependent stored-energy in deformed metals which is known as the driving force for recrystallization during annealing.

Electrokinetic Instability Flow in Nanofilm-Coated Microfluidic Channels

2009 ◽  
Vol 60-61 ◽  
pp. 330-333
Author(s):  
Wei Chih Chen ◽  
Ting Fu Hong ◽  
Wen Bo Luo ◽  
Chang Hsien Tai ◽  
Chien Hsiung Tsai ◽  
...  
Keyword(s):  
Field Strength ◽  
Electric Field ◽  
Electric Field Strength ◽  
Electric Fields ◽  
Flow Instability ◽  
Microfluidic Channels ◽  
Conductivity Ratio ◽  
Electrokinetic Instability ◽  
Two Samples ◽  
Significant Difference

This paper presented a parametric experimental study of electrokinetic instability phenomena in a cross-shaped configuration microfluidic device with varying channel depths and conductivity ratios. The flow instability is observed when applied electric field strength exceeds a certain critical value. The critical electric field strength is examined as a function of the conductivity ratio of two samples liquid, microchannel depth, and the treatment of microchannel wetted surface. It is found that the critical electric field strengths for the onset of electrokinetic instability are strongly dependent on the conductivity ratio of two samples liquid, and decrease as the channel depths increasing of microfluidic devices. In the present study, the surface inside microchannels is treated utilizing hydrophilic and hydrophobic organic-based SOG (spin-on-glass) nanofilms for glass-based microchips. The experimental results indicate that no significant difference for the critical electric fields for the onset of electrokinetic instability phenomena in both hydrophilic and hydrophobic SOG coating in the surface of microchannels. The critical electric fields for the onset of electrokinetic instability phenomena are slightly lower in both SOG coated cases in compare with that of the non-coated microchannel.

scholarly journals Electric and magnetic field of different transpositions of overhead power line

2017 ◽  
Vol 66 (3) ◽  
pp. 595-605 ◽  
Author(s):  
Ramūnas Deltuva ◽  
Robertas Lukočius
Keyword(s):  
Magnetic Field ◽  
Field Strength ◽  
Electric Field ◽  
Transmission Line ◽  
Electric Field Strength ◽  
Power Transmission ◽  
Power Transmission Line ◽  
Limit Values ◽  
Electric Power Supply ◽  
Overhead Power Transmission Line

AbstractIn Lithuanian and Polish electric power supply systems, the power transmission lines of 400 kV voltage represent one of the most potential sources of electric and magnetic fields generation. The 400 kV double-circuit overhead power transmission line and its surrounding environment were herby described and simulated through Finite Element Method usingCOMSOL Multiphysicsoftware package. This study includes magnetic and electric field calculations. The study shows that the values of magnetic field strength and electric field strength present in the vicinity of a 400 kV overhead power transmission line tend to exceed limit values established in the Normative. Measurements are suggested to be taken for the purpose of finding maximum values of magnetic and electric field strength. To reduce these values, it is recommended to increase the height of supports, and restrict human personal and economic activities.

scholarly journals Weak rTMS-induced electric fields produce neural entrainment in humans

2019 ◽  
Author(s):  
Elina Zmeykina ◽  
Matthias Mittner ◽  
Walter Paulus ◽  
Zsolt Turi
Keyword(s):  
Field Strength ◽  
Electric Field ◽  
Electric Field Strength ◽  
Electric Fields ◽  
Repetitive Transcranial Magnetic Stimulation ◽  
Current Standard ◽  
Conventional Dose ◽  
Novel Approach ◽  
Resting Motor Threshold ◽  
Field Strengths

Repetitive transcranial magnetic stimulation (rTMS) is a potent tool for modulating endogenous oscillations in humans. The current standard dosing method for rTMS defines the electric field strength only indirectly. A better characterization of the electric field strength induced by a given rTMS protocol is necessary in order to improve the understanding of the neural mechanisms of rTMS. In this study we used a novel approach, in which individualized prospective computational modeling of the induced electric field guided the choice of stimulation intensity. We consistently found that rhythmic rTMS protocols increased neural synchronization in the posterior alpha frequency band when measured simultaneously with scalp electroencephalography. We observed this effect already at electric field strengths of roughly half the lowest conventional dose, which is 80% of the resting motor threshold. We conclude that rTMS can induce immediate electrophysiological effects at much weaker electric field strengths than previously thought.

scholarly journals Comparative Modeling of Transcranial Magnetic and Electric Stimulation in Mouse, Monkey, and Human

2018 ◽  
Author(s):  
Ivan Alekseichuk ◽  
Kathleen Mantell ◽  
Sina Shirinpour ◽  
Alexander Opitz
Keyword(s):  
Finite Element ◽  
Field Strength ◽  
Electric Field ◽  
Electric Field Strength ◽  
Electric Fields ◽  
Mouse Brain ◽  
Electric Stimulation ◽  
Human Model ◽  
Brain Anatomy ◽  
List Type

ABSTRACTTranscranial magnetic stimulation (TMS) and transcranial electric stimulation (TES) are increasingly popular methods to noninvasively affect brain activity. However, their mechanism of action and dose-response characteristics remain under active investigation. Translational studies in animals play a pivotal role in these efforts due to a larger neuroscientific toolset enabled by invasive recordings. In order to translate knowledge gained in animal studies to humans, it is crucial to generate comparable stimulation conditions with respect to the induced electric field in the brain. Here, we conduct a finite element method (FEM) modeling study of TMS and TES electric fields in a mouse, capuchin monkey, and human model. We systematically evaluate the induced electric fields and analyze their relationship to head and brain anatomy. We find that with increasing head size, TMS-induced electric field strength first increases and then decreases according to a two-term exponential function. TES-induced electric field strength strongly decreases from smaller to larger specimen with up to 100x fold differences across species. Our results can serve as a basis to compare and match stimulation parameters across studies in animals and humans.HIGHLIGHTSTranslational research in brain stimulation should account for large differences in induced electric fields in different organismsWe simulate TMS and TES electric fields using anatomically realistic finite element models in three species: mouse, monkey, and humanTMS with a 70 mm figure-8 coil creates an approximately 2-times weaker electric field in a mouse brain than in monkey and human brains, where electric field strength is comparableTwo-electrode TES creates an approximately 100-times stronger electric field in a mouse brain and 3.5-times stronger electric field in a monkey brain than in a human brain

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