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Uses of Intense Microwaves in Tokamaks
Published in R A Cairns, A D R Phelps, P Osborne, Generation and Application of High Power Microwaves, 2020
First, for simplicity in explaining the effect, consider a slab geometry. In the presence of a magnetic field in the z-direction, with α-particles exchanging energy with waves travelling in the y-direction, one can show that the ratio of displacement of the guiding center in the x-direction, Δx, to (perpendicular) energy absorbed, ΔE, is Δx=−kyΔE/mΩω. This quantity is determined by wave and particle parameters only; ω is the wave frequency, ky is the wavenumber in the y-direction, m is the α-particle mass and Ω = 2eB/m is the α-particle gyrofrequency. In the slab case, upon repeated interactions with the wave, a particle will trace a line in x-E space (see Figure 2).
CRÈME96 and Related Error Rate Prediction Methods
Published in John D. Cressler, H. Alan Mantooth, Extreme Environment Electronics, 2017
Charged particles trapped in the radiation belt gyrate around a guiding-center magnetic field line in the Earth’s dipole magnetic field. As a particle approaches one of the magnetic poles, the magnetic field lines converge causing the pitch angle of the particle to rotate to 90° and then beyond causing the particle to spiral back toward the other magnetic pole. This is called mirroring. Particles are thus trapped between their mirror points. The altitude of a particle’s mirror points is determined by its pitch angle at the geomagnetic equator. Particles with the smallest equatorial pitch angle will have the lowest mirror point altitudes (particles with lower mirror points are removed by the atmosphere). A result of this is that satellites orbiting at low altitudes experience a higher flux of protons coming from the west because such protons are gyrating about a guiding-center field line above the satellite’s altitude and experience less atmospheric loss than protons striking the satellite from the east (because they are gyrating around a field line that is below the satellite).
Relation Between the Low Frequency GAM and the Neoclassical Flow
Published in Fusion Science and Technology, 2022
where =kinetic energy =electric charge of each species =zeroth order Maxwellian distribution function =perturbed distribution function =velocity of the guiding-center drift parallel to the magnetic field =velocity of the guiding-center drift across the magnetic field.
Breakup of transport barriers in plasmas with flow described by symplectic maps
Published in Radiation Effects and Defects in Solids, 2022
Carolina A. Tafoya, Julio J. Martinell
For a test particle moving in the magnetic field of a toroidal plasma (assumed in the z direction) subjected to an n electrostatic potential , the guiding center motion can be written as a Hamiltonian system which can be averaged over gyro-radius to take into account the finite Larmor radius effects, using It has to be pointed out that in this slab model the coordinates correspond to radial and poloidal coordinates respectively in the torus. For an infinite, discrete wave spectrum of the form the equations can be exactly converted into a discrete map, which after gyro-averaging takes the form (7) where and is the Bessel function of zero order.
The Development and Testing of a Digital ITER-Type Mock-Up Based on Virtual Reality Technology
Published in Fusion Science and Technology, 2021
Jin-Yang Li, Long Gu, Hu-Shan Xu, You-Peng Zhang, Cun-Feng Yao, Da-Jun Fan, Guan Wang, Xin-Kang Su
In order to evaluate the effect and performance of scientific data visualization, the particle trajectory and the corresponding plasma density in the digital ITER-type mock-up have been presented with real-time light rendering as shown in Fig. 8. The particle movement is driven by electromagnetic forces, and each guiding center of corresponding particles has a strong constraint relation to a single magnetic field line without wandering motion as shown in Fig. 8a. In addition, volumetric rendering of the time-dependent plasma density has been provided as an additional choice to users as shown in Fig. 8b without giving the isosurface in only the traditional way, where the volumetric rendering result is a water vapor–like cloud structure with the transparent property. In this way, users can get an intuitive feeling of the particle trajectory and corresponding volumetric rendering, which can help researchers and students fulfill the required design and training tasks in the way of WYSIWYG (“what you see is what you get”), which cannot be achieved in the real experimental facility.