"Experimental and Gyrokinetic Studies of Multi-Channel Transport in the Core of Alcator C-Mod Plasmas"
Event details
| Date | 25.01.2013 |
| Hour | 10:30 › 11:30 |
| Speaker | Dr. N.T. Howard, Plasma Science and Fusion Center, Alcator C-Mod Team, MIT, Cambridge, USA |
| Location |
PPB 019
|
| Category | Conferences - Seminars |
In the core of fusion plasmas, it is generally accepted that measured levels of heat and particle transport result from the presence of low frequency plasma turbulence driven by the plasma’s density and temperature gradients. Identifying what turbulent mode or modes, such as Ion Temperature Gradient (ITG) or Trapped Electron Mode (TEM), may be dominantly responsible for the observed transport across a wide range of operating parameters is of great interest for enhancing predictive capability for ITER and beyond. Utilizing a unique set of diagnostic tools on Alcator C-Mod, electron and ion heat and impurity particle transport are investigated in detail. Precise characterization of the spatial and temporal behavior of the full, time-evolving, radial profile of non-intrinsic, trace impurities is possible using a novel multi-pulse laser blow-off system coupled with measurements provided by a high resolution x-ray crystal spectrometer. These new measurements allow for determination of trace impurity transport inside of r/a=0.6. Additionally, a newly installed Correlation Electron Cyclotron Emission (CECE) system is used to characterize turbulent electron temperature fluctuations, providing the first local and quantitative fluctuation measurements in the core of C-Mod plasmas. To validate the leading model of plasma microturbulence, experimental results are rigorously compared with nonlinear gyrokinetic simulations performed using the GYRO code. The fidelity with which empirical trends in energy and particle confinement (i.e. scaling with plasma current and heating power) can be reproduced by GYRO will be discussed in detail, and gyrokinetic analysis of new experiments that probe changes in turbulence and transport across the ITG/TEM boundary will be presented.
Practical information
- Expert
- Free
Organizer
- Prof. P. Ricci, CRPP
Contact
- Prof. P. Ricci, CRPP