skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Sawteeth and m=1 mode evolution during ECRH/ECCD on FTU tokamak

Abstract

Localized ECRH/ECCD has been performed on FTU with the specific aim of shaping the temperature/current density profile for controlling MHD activity. In particular, m=1 mode dynamics and stability are studied during the heating phase, when the steady-state, sawtoothing conditions of the ohmic plasma are modified by a strong off-axis electron heating. Depending on the position of the absorbing layer and on the density of the ohmic target plasma, sawteeth are temporarily suppressed, still in the presence of a slowly growing m=1 oscillation, or a complete quenching of any m=1 activity can be achieved. When direct current, driven by EC waves launched at {+-}10 deg. from the perpendicular in the up-shifted scheme, is added to the pure heating effect, different shapes and periods of relaxation phenomena in the plasma core are observed. Although low values of I{sub ECCD}/I{sub p} are expected because of rather high values of Z{sub eff} during heating, (I{sub ECCD}/I{sub p}=0.04 for p{sub BC}=800 KW, Z{sub eff}=5 and I{sub p}=360 kA), different local changes in the magnetic shear are thought to be responsible of these differences. Time-dependent calculations of current profiles, including transport and diffusion effects, and an analysis of the onset and stabilization of sawtooth oscillations basedmore » on the time evolution of s{sub 1} (the magnetic shear value at q=1) compared with that of a suitable critical value are performed.« less

Authors:
; ; ; ; ; ; ; ;  [1]; ; ; ; ;  [2];  [3];
  1. IFP, Ass.EURATOM-ENEA-CNR, Via R. Cozzi 53, Milano (Italy)
  2. CRE Frascati, Ass.EURATOM-ENEA-CNR (Italy)
  3. CRE Bologna, Via Don Fiammelli 2, Bologna (Italy)
Publication Date:
OSTI Identifier:
21210463
Resource Type:
Journal Article
Journal Name:
AIP Conference Proceedings
Additional Journal Information:
Journal Volume: 485; Journal Issue: 1; Conference: 13. topical conference on radio frequency power in plasmas, Annapolis, MD (United States), 12-14 Apr 1999; Other Information: DOI: 10.1063/1.59746; (c) 1999 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0094-243X
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; CURRENT DENSITY; CYCLOTRON RESONANCE; DIRECT CURRENT; ECR CURRENT DRIVE; ECR HEATING; ELECTRONS; FT TOKAMAK; MAGNETOHYDRODYNAMICS; PLASMA; PLASMA DIAGNOSTICS; PLASMA INSTABILITY; RF SYSTEMS; SAWTOOTH OSCILLATIONS; SHEAR; STEADY-STATE CONDITIONS; TEMPERATURE MEASUREMENT; TIME DEPENDENCE

Citation Formats

Ramponi, G., Airoldi, A., Bruschi, A., Cirant, S., Granucci, G., Lazzaro, E., Nowak, S., Simonetto, A., Sozzi, C., Buratti, P., Kroegler, H., Panaccione, L., Tudisco, O., Zerbini, M., Cenacchi, G., and Gandini, F. Sawteeth and m=1 mode evolution during ECRH/ECCD on FTU tokamak. United States: N. p., 1999. Web. doi:10.1063/1.59746.
Ramponi, G., Airoldi, A., Bruschi, A., Cirant, S., Granucci, G., Lazzaro, E., Nowak, S., Simonetto, A., Sozzi, C., Buratti, P., Kroegler, H., Panaccione, L., Tudisco, O., Zerbini, M., Cenacchi, G., & Gandini, F. Sawteeth and m=1 mode evolution during ECRH/ECCD on FTU tokamak. United States. doi:10.1063/1.59746.
Ramponi, G., Airoldi, A., Bruschi, A., Cirant, S., Granucci, G., Lazzaro, E., Nowak, S., Simonetto, A., Sozzi, C., Buratti, P., Kroegler, H., Panaccione, L., Tudisco, O., Zerbini, M., Cenacchi, G., and Gandini, F. Mon . "Sawteeth and m=1 mode evolution during ECRH/ECCD on FTU tokamak". United States. doi:10.1063/1.59746.
@article{osti_21210463,
title = {Sawteeth and m=1 mode evolution during ECRH/ECCD on FTU tokamak},
author = {Ramponi, G. and Airoldi, A. and Bruschi, A. and Cirant, S. and Granucci, G. and Lazzaro, E. and Nowak, S. and Simonetto, A. and Sozzi, C. and Buratti, P. and Kroegler, H. and Panaccione, L. and Tudisco, O. and Zerbini, M. and Cenacchi, G. and Gandini, F},
abstractNote = {Localized ECRH/ECCD has been performed on FTU with the specific aim of shaping the temperature/current density profile for controlling MHD activity. In particular, m=1 mode dynamics and stability are studied during the heating phase, when the steady-state, sawtoothing conditions of the ohmic plasma are modified by a strong off-axis electron heating. Depending on the position of the absorbing layer and on the density of the ohmic target plasma, sawteeth are temporarily suppressed, still in the presence of a slowly growing m=1 oscillation, or a complete quenching of any m=1 activity can be achieved. When direct current, driven by EC waves launched at {+-}10 deg. from the perpendicular in the up-shifted scheme, is added to the pure heating effect, different shapes and periods of relaxation phenomena in the plasma core are observed. Although low values of I{sub ECCD}/I{sub p} are expected because of rather high values of Z{sub eff} during heating, (I{sub ECCD}/I{sub p}=0.04 for p{sub BC}=800 KW, Z{sub eff}=5 and I{sub p}=360 kA), different local changes in the magnetic shear are thought to be responsible of these differences. Time-dependent calculations of current profiles, including transport and diffusion effects, and an analysis of the onset and stabilization of sawtooth oscillations based on the time evolution of s{sub 1} (the magnetic shear value at q=1) compared with that of a suitable critical value are performed.},
doi = {10.1063/1.59746},
journal = {AIP Conference Proceedings},
issn = {0094-243X},
number = 1,
volume = 485,
place = {United States},
year = {1999},
month = {9}
}