Comparative study of charged particle dynamics in time-stationary and time-varying spatially chaotic magnetic fields with sinusoidal spatiotemporal dependence

2021 ◽  
Vol 31 (8) ◽  
pp. 083113
Author(s):  
Subha Samanta
Keyword(s):  
Charged Particle ◽  
Magnetic Fields ◽  
Comparative Study ◽  
Particle Dynamics ◽  
Time Varying

Gestural Articulations of Embodied Spatiality

2015 ◽  
pp. 233-256
Author(s):  
Lai Har Judy Lee ◽  
Yam San Chee
Keyword(s):  
Charged Particle ◽  
Magnetic Fields ◽  
Charged Particles ◽  
Particle Dynamics ◽  
Frame Of Reference ◽  
Game Based Learning ◽  
Design Based Research ◽  
3D Game ◽  
Electric And Magnetic Fields ◽  
Game Environment

The work described in this paper is part of a design-based research involving the use of a game-based learning curriculum to foster students' understanding of physics concepts and principles governing the motion of charged particles in electric and magnetic fields. Students engaged in game-play and discussed the dynamics of the charged particles within the 3D game environment. The discussion sessions were video-recorded and an analysis was carried out on the gestures used by a group of students attempting to generalize their observations of the phenomena. The students' gestures were analyzed to gain insights on their embodied sense-making of charged particle dynamics. The analysis showed that the students used gestures to (1) establish a shared frame of reference, (2) enact embodied game experience, and (3) enable the development of new understanding that surpasses their own existing vocabulary. Implications are discussed with regard to how teachers may take students' gestures into account when facilitating the development of concepts with a strong visuo-spatial core.

scholarly journals Charged particle dynamics near an X-point of a non-symmetric magnetic field with closed field lines

2020 ◽  
Vol 86 (2) ◽  
Author(s):  
Elena Elbarmi ◽  
Wrick Sengupta ◽  
Harold Weitzner
Keyword(s):  
Magnetic Field ◽  
Charged Particle ◽  
Magnetic Fields ◽  
Particle Dynamics ◽  
Closed Field ◽  
Symmetric Vacuum ◽  
Field Lines ◽  
Particle Confinement ◽  
Special Case ◽  
The Magnetic Field

Understanding particle drifts in a non-symmetric magnetic field is of primary interest in designing optimized stellarators in order to minimize the neoclassical radial loss of particles. Quasisymmetry and omnigeneity, two distinct properties proposed to ensure radial localization of collisionless trapped particles in stellarators, have been explored almost exclusively for magnetic fields with nested flux surfaces. In this work, we examine radial particle confinement when all field lines are closed. We then study charged particle dynamics in the special case of a non-symmetric vacuum magnetic field with closed field lines obtained recently by Weitzner & Sengupta (Phys. Plasmas, vol. 27, 2020, 022509). These magnetic fields can be used to construct magnetohydrodynamic equilibria for low pressure. Expanding in the amplitude of the non-symmetric fields, we explicitly evaluate the omnigeneity and quasisymmetry constraints. We show that the magnetic field is omnigeneous in the sense that the drift surfaces coincide with the pressure surfaces. However, it is not quasisymmetric according to the standard definitions.

ESCAPE TRAJECTORIES VERSUS MAGNETIC ENTRAPMENT: CHARGED PARTICLE DYNAMICS IN POLOIDAL MAGNETIC FIELDS AROUND SCHWARZSCHILD BLACK HOLES

2009 ◽  
Vol 18 (04) ◽  
pp. 529-548 ◽  
Author(s):  
GIOVANNI PRETI
Keyword(s):  
Charged Particle ◽  
Magnetic Fields ◽  
Flat Space ◽  
Particle Dynamics ◽  
Space Time ◽  
Escape Trajectories ◽  
Magnetic Bottle ◽  
Particle Confinement ◽  
The Given ◽  
Poloidal Magnetic Fields

We examine the nonequatorial orbits of charged particles under the combined influence of Schwarzschild curvature and external purely poloidal magnetic fields — the uniform and dipole ones — corresponding to analytical solutions to the Maxwell equations in the given space–time. Particle confinement in bound cross-equatorial orbits can occur, due to a magnetic bottle effect, but also natural escape trajectories can be obtained, without the need for additional devices — like electric or toroidal magnetic fields — previously invoked to this end. The conditions leading to either of these outcomes, entrapment or escape, are examined, and a comparison with the flat space–time case is made, evaluating the role played by gravity in the overall charged particle dynamics.

scholarly journals Millimeter (MM) wave and microwave frequency radiation produce deeply penetrating effects: the biology and the physics

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Martin L. Pall
Keyword(s):  
Magnetic Fields ◽  
Electric Fields ◽  
Cardiac Activity ◽  
Maximum Level ◽  
Voltage Sensor ◽  
The Body ◽  
Time Varying ◽  
The Brain ◽  
Mm Waves

Abstract Millimeter wave (MM-wave) electromagnetic fields (EMFs) are predicted to not produce penetrating effects in the body. The electric but not magnetic part of MM-EMFs are almost completely absorbed within the outer 1 mm of the body. Rodents are reported to have penetrating MM-wave impacts on the brain, the myocardium, liver, kidney and bone marrow. MM-waves produce electromagnetic sensitivity-like changes in rodent, frog and skate tissues. In humans, MM-waves have penetrating effects including impacts on the brain, producing EEG changes and other neurological/neuropsychiatric changes, increases in apparent electromagnetic hypersensitivity and produce changes on ulcers and cardiac activity. This review focuses on several issues required to understand penetrating effects of MM-waves and microwaves: 1. Electronically generated EMFs are coherent, producing much higher electrical and magnetic forces then do natural incoherent EMFs. 2. The fixed relationship between electrical and magnetic fields found in EMFs in a vacuum or highly permeable medium such as air, predicted by Maxwell’s equations, breaks down in other materials. Specifically, MM-wave electrical fields are almost completely absorbed in the outer 1 mm of the body due to the high dielectric constant of biological aqueous phases. However, the magnetic fields are very highly penetrating. 3. Time-varying magnetic fields have central roles in producing highly penetrating effects. The primary mechanism of EMF action is voltage-gated calcium channel (VGCC) activation with the EMFs acting via their forces on the voltage sensor, rather than by depolarization of the plasma membrane. Two distinct mechanisms, an indirect and a direct mechanism, are consistent with and predicted by the physics, to explain penetrating MM-wave VGCC activation via the voltage sensor. Time-varying coherent magnetic fields, as predicted by the Maxwell–Faraday version of Faraday’s law of induction, can put forces on ions dissolved in aqueous phases deep within the body, regenerating coherent electric fields which activate the VGCC voltage sensor. In addition, time-varying magnetic fields can directly put forces on the 20 charges in the VGCC voltage sensor. There are three very important findings here which are rarely recognized in the EMF scientific literature: coherence of electronically generated EMFs; the key role of time-varying magnetic fields in generating highly penetrating effects; the key role of both modulating and pure EMF pulses in greatly increasing very short term high level time-variation of magnetic and electric fields. It is probable that genuine safety guidelines must keep nanosecond timescale-variation of coherent electric and magnetic fields below some maximum level in order to produce genuine safety. These findings have important implications with regard to 5G radiation.

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