"Multi-field/-scale Interactions of Turbulence with Neoclassical Tearing Modes and Impact on Plasma Confinement in the DIII-D Tokamak," by Laszlo Bardoczi (UCLA)

Date: 
Friday, May 13, 2016 - 1:00pm to 2:00pm
Series: 
Plasma Seminars

Plasma Seminar

Physics & Astronomy Building (PAB) Room 4-330
Friday, May 13, 2016
1-2PM

Guest Speaker: Laszlo Bardoczi (UCLA)

Talk Title: "Multi-field/-scale Interactions of Turbulence with Neoclassical Tearing Modes and Impact on Plasma Confinement in the DIII-D Tokamak"

Abstract:

I will present the first localized measurements of turbulent density and temperature fluctuations being modified by m=2, n=1 magnetic islands [1]. These islands are formed by the Neoclassical Tearing Mode (NTM) in tokamaks and are important as they degrade confinement and can lead to disruption. Gyrokinetic simulations predict that interaction with turbulence affects NTM stability [2]. Our measurements capture a mean reduction of turbulence inside (and enhancement just outside) the island region during island evolution. Additionally, in the island saturated state the fluctuations at the O-point are reduced compared to the X-point [3]. A novel, non-perturbative measurement technique finds reduced cross-field electron thermal diffusivity (by 1-2 orders of magnitude) at the O-point, consistent with the local turbulence reduction. Initial comparisons to GENE non-linear gyrokinetic simulations are promising with GENE qualitatively replicating the observations. These results are significant as they allow the validation of gyrokinetic simulations modeling the interaction of these multi-scale phenomena. Improved understanding of NTM physics and interaction with turbulence can lead to improved control of NTMs and plasma performance, therefore has potential implications for future fusion devices such as ITER.

[1] Bardoczi et al, accepted in Physical Review Letters
[2] Hornsby et alPlasma Physics and Controlled Fusion57, 05418 (2015)
[3] Bardoczi et al, accepted in Physics of Plasmas

Event Attachments: 
Location: 
PAB 4-330