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Title: Predicting high harmonic ion cyclotron heating efficiency in Tokamak plasmas

Abstract

Observations of improved radio frequency (RF) heating efficiency in high-confinement (H-) mode plasmas on the National Spherical Tokamak Experiment (NSTX) are investigated by whole-device linear simulation. We present the first full-wave simulation to couple kinetic physics of the well confined core plasma to the poorly confined scrape-off plasma. The new simulation is used to scan the launched fast-wave spectrum and examine the steady-state electric wave field structure for experimental scenarios corresponding to both reduced, and improved RF heating efficiency. We find that launching toroidal wave-numbers that required for fast-wave propagation excites large amplitude (kVm 1 ) coaxial standing modes in the wave electric field between the confined plasma density pedestal and conducting vessel wall. Qualitative comparison with measurements of the stored plasma energy suggest these modes are a probable cause of degraded heating efficiency. Also, the H-mode density pedestal and fast-wave cutoff within the confined plasma allow for the excitation of whispering gallery type eigenmodes localised to the plasma edge.

Authors:
 [1];  [2];  [1];  [1];  [1];  [1]
  1. ORNL
  2. XCEL
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States). Oak Ridge Leadership Computing Facility (OLCF)
Sponsoring Org.:
USDOE Office of Science (SC)
OSTI Identifier:
1037019
DOE Contract Number:  
DE-AC05-00OR22725
Resource Type:
Journal Article
Journal Name:
Physical Review Letters
Additional Journal Information:
Journal Volume: 107; Journal Issue: 14; Journal ID: ISSN 0031-9007
Country of Publication:
United States
Language:
English
Subject:
43 PARTICLE ACCELERATORS; AMPLITUDES; CYCLOTRONS; EFFICIENCY; ELECTRIC FIELDS; EXCITATION; HARMONICS; HEATING; KINETICS; LAUNCHING; PHYSICS; PLASMA; PLASMA DENSITY; SIMULATION

Citation Formats

Green, David L, Jaeger, E. F., Berry, Lee A, Chen, Guangye, Ryan, Philip Michael, and Canik, John. Predicting high harmonic ion cyclotron heating efficiency in Tokamak plasmas. United States: N. p., 2011. Web. doi:10.1103/PhysRevLett.107.145001.
Green, David L, Jaeger, E. F., Berry, Lee A, Chen, Guangye, Ryan, Philip Michael, & Canik, John. Predicting high harmonic ion cyclotron heating efficiency in Tokamak plasmas. United States. https://doi.org/10.1103/PhysRevLett.107.145001
Green, David L, Jaeger, E. F., Berry, Lee A, Chen, Guangye, Ryan, Philip Michael, and Canik, John. 2011. "Predicting high harmonic ion cyclotron heating efficiency in Tokamak plasmas". United States. https://doi.org/10.1103/PhysRevLett.107.145001.
@article{osti_1037019,
title = {Predicting high harmonic ion cyclotron heating efficiency in Tokamak plasmas},
author = {Green, David L and Jaeger, E. F. and Berry, Lee A and Chen, Guangye and Ryan, Philip Michael and Canik, John},
abstractNote = {Observations of improved radio frequency (RF) heating efficiency in high-confinement (H-) mode plasmas on the National Spherical Tokamak Experiment (NSTX) are investigated by whole-device linear simulation. We present the first full-wave simulation to couple kinetic physics of the well confined core plasma to the poorly confined scrape-off plasma. The new simulation is used to scan the launched fast-wave spectrum and examine the steady-state electric wave field structure for experimental scenarios corresponding to both reduced, and improved RF heating efficiency. We find that launching toroidal wave-numbers that required for fast-wave propagation excites large amplitude (kVm 1 ) coaxial standing modes in the wave electric field between the confined plasma density pedestal and conducting vessel wall. Qualitative comparison with measurements of the stored plasma energy suggest these modes are a probable cause of degraded heating efficiency. Also, the H-mode density pedestal and fast-wave cutoff within the confined plasma allow for the excitation of whispering gallery type eigenmodes localised to the plasma edge.},
doi = {10.1103/PhysRevLett.107.145001},
url = {https://www.osti.gov/biblio/1037019}, journal = {Physical Review Letters},
issn = {0031-9007},
number = 14,
volume = 107,
place = {United States},
year = {Sat Jan 01 00:00:00 EST 2011},
month = {Sat Jan 01 00:00:00 EST 2011}
}

Works referenced in this record:

An overview of the ITER project
journal, October 2007


Kinetic Alfvén waves and plasma transport at the magnetopause
journal, June 1997


Sheared Poloidal Flow Driven by Mode Conversion in Tokamak Plasmas
journal, May 2003


Global-wave solutions with self-consistent velocity distributions in ion cyclotron heated plasmas
journal, June 2006


Exploration of finite ion orbit effects in the ion cyclotron range of frequencies
journal, July 2009


Exploration of spherical torus physics in the NSTX device
journal, March 2000


High harmonic fast waves in high beta plasmas
journal, November 1995


Advances in high-harmonic fast wave physics in the National Spherical Torus Experiment
journal, May 2010


Spectral effects on fast wave core heating and current drive
journal, June 2009


Equilibrium properties of spherical torus plasmas in NSTX
journal, November 2001


A radio-frequency sheath boundary condition and its effect on slow wave propagation
journal, October 2006


Simulations of alpha parameters in a TFTR DT supershot with high fusion power
journal, December 1995