"Reduction of Core Turbulence in I-mode Plasmas in Alcator C-Mod"
Event details
| Date | 21.01.2013 |
| Hour | 10:30 › 11:30 |
| Speaker | Prof. A.E. White, Plasma Science and Fusion Center, Alcator C-Mod Team, MIT, Cambridge, USA |
| Location |
PPB 019
|
| Category | Conferences - Seminars |
In this talk, recent observations of reduced core fluctuations in the ELM-free high confinement regime, I-mode, at Alcator C-Mod [E.S. Marmar, et al. Nuclear Fusion, 49(10):104014, 2009] will be presented. Measurements of core and edge electron temperature fluctuations are possible using C-Mod’s ECE systems, including a newly installed Correlation ECE diagnostic. Both long wavelength (kθρs < 0.5) density and electron temperature fluctuation levels decrease from L-mode levels by up to 30%-50% in I-mode. The reduction in core turbulence is correlated with increases in confinement in I-mode compared to L-mode. Core density fluctuations (ρ < 0.8) are reduced prior to the onset of the edge-localized (0.95 < ρ < 1.0) weakly coherent mode (WCM) and prior to the reduction of low-frequency edge turbulence during I-mode. This result has significant implications for our understanding of the dynamics of confinement transitions such as I-mode and H-mode, where changes in edge turbulence are typically observed to occur prior to changes in core turbulence.
Practical information
- Informed public
- Free
Organizer
- Prof. P. Ricci, CRPP
Contact
- Prof. P. Ricci, CRPP