Electron temperature fluctuation measurements in the I-mode and L-mode edge at ASDEX Upgrade

Speaker 1: Rachel Bielajew


Tuesday, November 17, 2020



PSFC Student Seminars

I-mode is a naturally ELM-free improved confinement regime which is promising for future reactors because it exhibits high energy confinement without high particle confinement.  I-modes are often characterized by the presence of the Weakly Coherent Mode (WCM) in the pedestal.  The role of the WCM in heat and particle transport and whether the WCM is responsible for the separation of the transport channels are open questions.  Measurements of electron temperature fluctuations can be obtained using a Correlation Electron Cyclotron Emission (CECE) diagnostic, which measures long wavelength electron temperature fluctuation amplitudes, spectra, and correlation lengths. This research investigates edge and pedestal (rho_pol = 0.9-1.0) temperature fluctuation measurements in L-mode and I-mode at ASDEX Upgrade from a 24-channel CECE radial comb.  In this work, studies of two I-mode/L-mode discharges will be presented: one with a WCM only present in I-mode only, and one with a WCM in both I-mode and L-mode.  The role of collisionality in L-mode vs. I-mode edge turbulence is investigated. 

Zoom link:  https://mit.zoom.us/j/97594071409, pwd: Fusion

Zoom easy link:  https://mit.zoom.us/j/97594071409?pwd=RE9iKzNwMFNKN1ZQTEJCaVFYUmd2dz09