Abstract
In this paper we have demonstrated that stochastization of field lines, resulting from the interaction of the fundamental m/n=1/1 helical mode with other periodicities, plays an important role in sawtooth oscillations. The time scale for the stochastic temperature diffusion has been determined. It was shown to be sufficiently fast to account for the fast sawtooth crash, and is generally shorter than the time scales for the redistribution of current. The enhancement of the electron and ion viscosity, arising from the stochastic field lines, has been calculated. The enhanced electron viscosity always leads to an initial increase in the growth rate of the mode; the enhanced ion viscosity can ultimately lead to mode stabilization before a complete temperature redistribution or flux reconnection has occurred. A dynamical model has been introduced to calculate the path of the sawtooth oscillation through a parameter space of shear and amplitude of the helical perturbation. The stochastic trigger to the enhanced growth rate and the stabilization by the ion viscosity are also included in the mode. A reasonable prescription for the flux reconnection at the end of the growth phase allows us to determine the initial q-value for the successive sawtooth ramps. (J.P.N.).
Lichtenberg, A J;
[1]
Itoh, Kimitaka;
Itoh, Sanae;
Fukuyama, Atsushi
- California Univ., Berkeley, CA (United States). Dept. of Electrical Engineering and Computer Sciences
Citation Formats
Lichtenberg, A J, Itoh, Kimitaka, Itoh, Sanae, and Fukuyama, Atsushi.
The role of stochasticity in sawtooth oscillation.
Japan: N. p.,
1991.
Web.
Lichtenberg, A J, Itoh, Kimitaka, Itoh, Sanae, & Fukuyama, Atsushi.
The role of stochasticity in sawtooth oscillation.
Japan.
Lichtenberg, A J, Itoh, Kimitaka, Itoh, Sanae, and Fukuyama, Atsushi.
1991.
"The role of stochasticity in sawtooth oscillation."
Japan.
@misc{etde_10126153,
title = {The role of stochasticity in sawtooth oscillation}
author = {Lichtenberg, A J, Itoh, Kimitaka, Itoh, Sanae, and Fukuyama, Atsushi}
abstractNote = {In this paper we have demonstrated that stochastization of field lines, resulting from the interaction of the fundamental m/n=1/1 helical mode with other periodicities, plays an important role in sawtooth oscillations. The time scale for the stochastic temperature diffusion has been determined. It was shown to be sufficiently fast to account for the fast sawtooth crash, and is generally shorter than the time scales for the redistribution of current. The enhancement of the electron and ion viscosity, arising from the stochastic field lines, has been calculated. The enhanced electron viscosity always leads to an initial increase in the growth rate of the mode; the enhanced ion viscosity can ultimately lead to mode stabilization before a complete temperature redistribution or flux reconnection has occurred. A dynamical model has been introduced to calculate the path of the sawtooth oscillation through a parameter space of shear and amplitude of the helical perturbation. The stochastic trigger to the enhanced growth rate and the stabilization by the ion viscosity are also included in the mode. A reasonable prescription for the flux reconnection at the end of the growth phase allows us to determine the initial q-value for the successive sawtooth ramps. (J.P.N.).}
place = {Japan}
year = {1991}
month = {Aug}
}
title = {The role of stochasticity in sawtooth oscillation}
author = {Lichtenberg, A J, Itoh, Kimitaka, Itoh, Sanae, and Fukuyama, Atsushi}
abstractNote = {In this paper we have demonstrated that stochastization of field lines, resulting from the interaction of the fundamental m/n=1/1 helical mode with other periodicities, plays an important role in sawtooth oscillations. The time scale for the stochastic temperature diffusion has been determined. It was shown to be sufficiently fast to account for the fast sawtooth crash, and is generally shorter than the time scales for the redistribution of current. The enhancement of the electron and ion viscosity, arising from the stochastic field lines, has been calculated. The enhanced electron viscosity always leads to an initial increase in the growth rate of the mode; the enhanced ion viscosity can ultimately lead to mode stabilization before a complete temperature redistribution or flux reconnection has occurred. A dynamical model has been introduced to calculate the path of the sawtooth oscillation through a parameter space of shear and amplitude of the helical perturbation. The stochastic trigger to the enhanced growth rate and the stabilization by the ion viscosity are also included in the mode. A reasonable prescription for the flux reconnection at the end of the growth phase allows us to determine the initial q-value for the successive sawtooth ramps. (J.P.N.).}
place = {Japan}
year = {1991}
month = {Aug}
}