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Title: The transport characteristics of passing fast ions produced by nonlocal overlapping of drift island surfaces and magnetic island surfaces

Abstract

The structure of the drift-island surface of passing fast ions (PFIs) is investigated in the presence of the resonant interaction with a magnetic island. Two overlapping regions of the drift-island surface and the magnetic island surface are found, one corresponding to local overlapping region and the other to non-local one. Here, the word “nonlocal” denotes that the resonances in the core plasma can have effects on the PFIs near the plasma boundary, while the “local” represents that the PFIs just near the resonant location are influenced. The nonlocal overlapping constructs a transport path along which the PFIs can become losses. There are three kinds of drift-island surfaces to join in forming the transport paths. A pitch angle region, which is called pitch angle gap, is found near the plasma boundary, where the drift-island surface cannot be formed and few PFIs are lost. The pitch-angle selective features of PFI losses are obtained by analyzing the three kinds of drift-island surfaces. The coupling between the crowd drift island surfaces and the collision can induce the prompt losses of PFIs and rapidly slowing down of PFI energy. The time of the prompt losses and the slowing down rate are calculated. Qualitatively, the theoreticalmore » results are in well agreement with the experimental observations in ASDEX Upgrade [M. García-Muñoz et al., Nucl. Fusion 47, L10 (2007)].« less

Authors:
; ; ;  [1];  [2]
  1. School of Nuclear Science and Technology, University of South China, Hengyang 421001 (China)
  2. School of Mathematics and Physics, University of South China, Hengyang 421001 (China)
Publication Date:
OSTI Identifier:
22599974
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 23; Journal Issue: 8; Other Information: (c) 2016 Author(s); Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; 71 CLASSICAL AND QUANTUM MECHANICS, GENERAL PHYSICS; ASDEX TOKAMAK; INCLINATION; IONS; MAGNETIC ISLANDS; PITCHES; PLASMA; RESONANCE; SLOWING-DOWN; SURFACES; TRANSPORT THEORY

Citation Formats

Cao, Jinjia, Gong, Xueyu, E-mail: gongxueyu-usc@163.com, Xiang, Dong, Huang, Qianhong, and Yu, Jun. The transport characteristics of passing fast ions produced by nonlocal overlapping of drift island surfaces and magnetic island surfaces. United States: N. p., 2016. Web. doi:10.1063/1.4959868.
Cao, Jinjia, Gong, Xueyu, E-mail: gongxueyu-usc@163.com, Xiang, Dong, Huang, Qianhong, & Yu, Jun. The transport characteristics of passing fast ions produced by nonlocal overlapping of drift island surfaces and magnetic island surfaces. United States. doi:10.1063/1.4959868.
Cao, Jinjia, Gong, Xueyu, E-mail: gongxueyu-usc@163.com, Xiang, Dong, Huang, Qianhong, and Yu, Jun. 2016. "The transport characteristics of passing fast ions produced by nonlocal overlapping of drift island surfaces and magnetic island surfaces". United States. doi:10.1063/1.4959868.
@article{osti_22599974,
title = {The transport characteristics of passing fast ions produced by nonlocal overlapping of drift island surfaces and magnetic island surfaces},
author = {Cao, Jinjia and Gong, Xueyu, E-mail: gongxueyu-usc@163.com and Xiang, Dong and Huang, Qianhong and Yu, Jun},
abstractNote = {The structure of the drift-island surface of passing fast ions (PFIs) is investigated in the presence of the resonant interaction with a magnetic island. Two overlapping regions of the drift-island surface and the magnetic island surface are found, one corresponding to local overlapping region and the other to non-local one. Here, the word “nonlocal” denotes that the resonances in the core plasma can have effects on the PFIs near the plasma boundary, while the “local” represents that the PFIs just near the resonant location are influenced. The nonlocal overlapping constructs a transport path along which the PFIs can become losses. There are three kinds of drift-island surfaces to join in forming the transport paths. A pitch angle region, which is called pitch angle gap, is found near the plasma boundary, where the drift-island surface cannot be formed and few PFIs are lost. The pitch-angle selective features of PFI losses are obtained by analyzing the three kinds of drift-island surfaces. The coupling between the crowd drift island surfaces and the collision can induce the prompt losses of PFIs and rapidly slowing down of PFI energy. The time of the prompt losses and the slowing down rate are calculated. Qualitatively, the theoretical results are in well agreement with the experimental observations in ASDEX Upgrade [M. García-Muñoz et al., Nucl. Fusion 47, L10 (2007)].},
doi = {10.1063/1.4959868},
journal = {Physics of Plasmas},
number = 8,
volume = 23,
place = {United States},
year = 2016,
month = 8
}
  • The enhanced transport of passing energetic ions (PEIs) in presence of the resonant interactions with a rotating magnetic island is investigated within the drift kinetic framework. When the island rotation plays a role in the resonant interaction, we find that the velocities of PEIs satisfy a constraint relation of resonant flux surface in phase space. The resonant flux surfaces overlap with the magnetic flux surfaces in real space. A new transport channel responsible for the PEIs moving across the magnetic flux surfaces, i.e., continuously overlapping, is found. Two kinds of radial motions can be induced by the surface overlapping: onemore » arises from the coupling between the resonance and the collision with the background plasma and the other from not completely overlapping of the two surfaces. The two radial motions and the symmetry-breaking induced radial motion constitute the total radial motion. When the pitch-angle scattering rate is very weak, the surface-shear induced transport is dominant. Only a small increase in the collision rate can significantly influence the total transport.« less
  • The effect of poloidally mode coupled, ballooning type electrostatic drift waves on a magnetic island has been studied both analytically and numerically. It has been shown quantitatively that particle orbits become stochastic and their behavior can be a possible candidate for the radial plasma transport across a magnetic island of a tokamak. The transport is significant in that it takes place even when the flux surface is not destroyed. The mechanism of the stochasticity generation is understood as an overlapping of secondary islands caused by resonance between periodic particle motions in the magnetic island and Fourier modes of {bold E{times}B}more » drift due to the electrostatic drift waves. The diffusion process perpendicular to magnetic surface has been analyzed by approximating the distribution to the Gaussian type. In addition, local diffusion process in the vicinity of Kolmogorov, Arnold, and Moser surfaces has been discussed. {copyright} {ital 1997 American Institute of Physics.}« less
  • We present a direct measurement of the quenching of nonlocal heat transport in a laser produced plasma by high external magnetic fields. Temporally resolved measurements of the electron temperature profile transverse to a high power laser beam were obtained using imaging Thomson scattering. The results are simulated with the 2D hydrodynamic code LASNEX with a recently included magnetic field model that self-consistently evolves the fields in the plasma.
  • We present a direct measurement of the quenching of nonlocal heat transport in a laser-produced plasma by applying large external magnetic fields (>10 T). The temporally resolved Thomson-scattering measurements of the electron temperature profile show that the heat front propagation transverse to a high-power laser beam is slowed resulting in extremely strong local heating. We find agreement with hydrodynamic modeling when including a magnetic field model that self-consistently evolves the fields in the plasma.
  • In evaluating neoclassical transport by radially local simulations, the magnetic drift tangential to a flux surface is usually ignored in order to keep the phase-space volume conservation. In this paper, effect of the tangential magnetic drift on the local neoclassical transport is investigated. To retain the effect of the tangential magnetic drift in the local treatment of neoclassical transport, a new local formulation for the drift kinetic simulation is developed. The compressibility of the phase-space volume caused by the tangential magnetic drift is regarded as a source term for the drift kinetic equation, which is solved by using a two-weightmore » δf Monte Carlo method for non-Hamiltonian system [G. Hu and J. A. Krommes, Phys. Plasmas 1, 863 (1994)]. It is demonstrated that the effect of the drift is negligible for the neoclassical transport in tokamaks. In non-axisymmetric systems, however, the tangential magnetic drift substantially changes the dependence of the neoclassical transport on the radial electric field E{sub r}. The peaked behavior of the neoclassical radial fluxes around E{sub r }={sub  }0 observed in conventional local neoclassical transport simulations is removed by taking the tangential magnetic drift into account.« less