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Title: Simulations of peeling-ballooning modes with electron cyclotron resonance heating

Abstract

The effects of the deposited power and deposited position of Electron Cyclotron Resonance Heating (ECRH) on Peeling-Ballooning (P-B) modes are simulated using BOUT++ code in this paper. The simulation results show that as the deposited position moves from the top to the bottom of the pedestal, the edge localized mode (ELM) size decreases first and then increases, finally decreases again. For ECRH with different deposited power, the effects on P-B modes are similar if they have the same peak value of the power deposition profile. These results show that the effects of ECRH on P-B modes are primarily determined by the change in pressure profile caused by ECRH. As long as ECRH can lead to large enough change in pressure profile, ECRH can efficiently affect the dynamics of P-B modes.

Authors:
;  [1];  [2];  [1];  [2];  [2]
  1. College of Physical Science and Technology, Sichuan University, Chengdu 610065 (China)
  2. (China)
Publication Date:
OSTI Identifier:
22600087
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physics of Plasmas; Journal Volume: 23; Journal Issue: 5; 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; B CODES; BALLOONING INSTABILITY; COMPUTERIZED SIMULATION; DEPOSITION; DEPOSITS; ECR HEATING; EDGE LOCALIZED MODES; ELECTRON CYCLOTRON-RESONANCE

Citation Formats

Huang, J., Tang, C. J., Key Laboratory of High Energy Density Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064, Chen, S. Y., E-mail: sychen531@163.com, Key Laboratory of High Energy Density Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064, and Southwestern Institute of Physics, Chengdu 610041. Simulations of peeling-ballooning modes with electron cyclotron resonance heating. United States: N. p., 2016. Web. doi:10.1063/1.4948482.
Huang, J., Tang, C. J., Key Laboratory of High Energy Density Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064, Chen, S. Y., E-mail: sychen531@163.com, Key Laboratory of High Energy Density Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064, & Southwestern Institute of Physics, Chengdu 610041. Simulations of peeling-ballooning modes with electron cyclotron resonance heating. United States. doi:10.1063/1.4948482.
Huang, J., Tang, C. J., Key Laboratory of High Energy Density Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064, Chen, S. Y., E-mail: sychen531@163.com, Key Laboratory of High Energy Density Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064, and Southwestern Institute of Physics, Chengdu 610041. 2016. "Simulations of peeling-ballooning modes with electron cyclotron resonance heating". United States. doi:10.1063/1.4948482.
@article{osti_22600087,
title = {Simulations of peeling-ballooning modes with electron cyclotron resonance heating},
author = {Huang, J. and Tang, C. J. and Key Laboratory of High Energy Density Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064 and Chen, S. Y., E-mail: sychen531@163.com and Key Laboratory of High Energy Density Physics and Technology of Ministry of Education, Sichuan University, Chengdu 610064 and Southwestern Institute of Physics, Chengdu 610041},
abstractNote = {The effects of the deposited power and deposited position of Electron Cyclotron Resonance Heating (ECRH) on Peeling-Ballooning (P-B) modes are simulated using BOUT++ code in this paper. The simulation results show that as the deposited position moves from the top to the bottom of the pedestal, the edge localized mode (ELM) size decreases first and then increases, finally decreases again. For ECRH with different deposited power, the effects on P-B modes are similar if they have the same peak value of the power deposition profile. These results show that the effects of ECRH on P-B modes are primarily determined by the change in pressure profile caused by ECRH. As long as ECRH can lead to large enough change in pressure profile, ECRH can efficiently affect the dynamics of P-B modes.},
doi = {10.1063/1.4948482},
journal = {Physics of Plasmas},
number = 5,
volume = 23,
place = {United States},
year = 2016,
month = 5
}
  • A minimum set of equations based on the peeling-ballooning (P-B) model with nonideal physics effects (diamagnetic drift, E×B drift, resistivity, and anomalous electron viscosity) is found to simulate pedestal collapse when using the new BOUT++ simulation code, developed in part from the original fluid edge code BOUT. Nonlinear simulations of P-B modes demonstrate that the P-B modes trigger magnetic reconnection, which leads to the pedestal collapse. With the addition of a model of the anomalous electron viscosity under the assumption that the electron viscosity is comparable to the anomalous electron thermal diffusivity, it is found from simulations using a realisticmore » high-Lundquist number that the pedestal collapse is limited to the edge region and the edge localized mode (ELM) size is about 5–10% of the pedestal stored energy. Furthermore, this is consistent with many observations of large ELMs.« less
  • A minimum set of equations based on the peeling-ballooning (P-B) model with nonideal physics effects (diamagnetic drift, ExB drift, resistivity, and anomalous electron viscosity) is found to simulate pedestal collapse when using the new BOUT++ simulation code, developed in part from the original fluid edge code BOUT. Nonlinear simulations of P-B modes demonstrate that the P-B modes trigger magnetic reconnection, which leads to the pedestal collapse. With the addition of a model of the anomalous electron viscosity under the assumption that the electron viscosity is comparable to the anomalous electron thermal diffusivity, it is found from simulations using a realisticmore » high-Lundquist number that the pedestal collapse is limited to the edge region and the edge localized mode (ELM) size is about 5%-10% of the pedestal stored energy. This is consistent with many observations of large ELMs.« less
  • The time evolution of edge localized modes (ELMs) in the Joint European Torus tokamak [P. H. Rebut et al., Nucl. Fusion 25, 1011 (1985)] is investigated using the JETTO predictive modeling code [M. Erba et al., Plasma Phys. Controlled Fusion 39, 261 (1997)]. It is found that both pressure-driven ballooning and current-driven peeling modes can play a role in triggering the ELM crashes. In the simulations carried out, each large ELM consists of a sequence of quasicontinuous small ELM crashes. Each sequence of ELM crashes is separated from the next sequence by a relatively longer ELM-free period. The initial crashmore » in each ELM sequence can be triggered either by a pressure-driven ballooning mode or by a current-driven peeling mode, while the subsequent crashes within that sequence are triggered by current-driven peeling modes, which are made more unstable by the reduction in the pressure gradient resulting from the initial crash. The HELENA and MISHKA ideal magnetohydrodynamic stability codes [A. B. Mikhailovskii et al., Plasma Phys. Rep. 23, 713 (1997)] are used to validate the stability criteria used in the JETTO simulations. This stability analysis includes infinite-n ideal ballooning, finite-n ballooning, and low-n kink/peeling modes.« less
  • The simulations of edge localized modes (ELMs) with a 5-field peeling-ballooning (P-B) model using BOUT++ code are reported in this paper. In order to study the particle and energy transport in the pedestal region, the pressure equation is separated into ion density and ion and electron temperature equations. Through the simulations, the length scale L{sub n} of the gradient of equilibrium density n{sub i0} is found to destabilize the P-B modes in ideal MHD model. With ion diamagnetic effects, the growth rate is inversely proportional to n{sub i0} at medium toroidal mode number n. For the nonlinear simulations, the gradientmore » of n{sub i0} in the pedestal region can more than double the ELM size. This increasing effect can be suppressed by thermal diffusivities χ{sub ∥}, employing the flux limited expression. Thermal diffusivities are sufficient to suppress the perturbations at the top of pedestal region. These suppressing effects lead to smaller ELM size of P-B modes.« less
  • An electron cyclotron emission (ECE) receiver inside the electron cyclotron resonance heating (ECRH) transmission line has been brought into operation. The ECE is extracted by placing a quartz plate acting as a Fabry-Perot interferometer under an angle inside the electron cyclotron wave (ECW) beam. ECE measurements are obtained during high power ECRH operation. This demonstrates the successful operation of the diagnostic and, in particular, a sufficient suppression of the gyrotron component preventing it from interfering with ECE measurements. When integrated into a feedback system for the control of plasma instabilities this line-of-sight ECE diagnostic removes the need to localize themore » instabilities in absolute coordinates.« less