Phase contrast imaging measurements of reversed shear Alfven eigenmodes during sawteeth in Alcator C-Mod

Observation of reversed shear Alfvén eigenmodes during sawteeth in Alcator C-Mod

Observation of reversed shear Alfvén eigenmodes between sawtooth crashes in the Alcator C-Mod tokamak.

Groups of frequency chirping modes observed between sawtooth crashes in the Alcator C-Mod tokamak are interpreted as reversed shear Alfvén eigenmodes near the q=1 surface. These modes indicate that a reversed shear q profile is generated during the relaxation phase of the sawtooth cycle. Two important parameters, q_{min} and its radial position, are deduced from comparisons of measured density ...

Experimental Studies and Analysis of Alfvén Eigenmodes in Alcator C-Mod

Alfvén cascades (ACs) or equivalently, reverse shear Alfvén eigenmodes (RSAE) have been observed in Alcator C-Mod during current ramp experiments in the presence of intense ICRF driven energetic minority tails. These experiments were carried out at ITER relevant densities and magnetic field. Phase contrast imaging (PCI) and magnetic pick-up coils have been used for detecting the Alfvén eigenmod...

Measurements of ion cyclotron range of frequencies mode converted wave intensity with phase contrast imaging in Alcator C-Mod and comparison with full-wave simulations

Citation Tsujii, N., M. Porkolab, P. T. Bonoli, Y. Lin, J. C. Wright, S. J. Wukitch, E. F. Jaeger, D. L. Green, and R. W. Harvey. “Measurements of ion cyclotron range of frequencies mode converted wave intensity with phase contrast imaging in Alcator C-Mod and comparison with full-wave simulations.” Physics of Plasmas 19, no. 8 (2012): 082508. As Published http://dx.doi.org/10.1063/1.4745613 Pu...

PSFC / JA - 99 - 15 Plasma Rotation During Ohmic H - modes in Alcator C - Mod Tokamak

Core plasma rotation is observed to change from the counter-to co-current direction during the transition from low (L) to high (H) confinement mode, in Alcator C-Mod plasmas that are heated purely ohmically. The changes of the toroidal velocities deduced from impurity Doppler measurements and magnetic perturbations associated with "sawteeth" are quantitatively similar. The magnitude of the chan...