1. Stereoscopic Pellet Imaging
Shot
Motivation
Using the stereoscopic imaging system developed for C-Mod, with a high speed PSI CCD camera, 28 frames at 2ms per frame, we imaged pellets injected into several L-mode shots near the end of the 2006 campaign. The three dimensional data confirmed the the striations are primarily moving in the poloidal direction.
Furthermore, the direction in which the striations move changes over a spatial scale of 10’s of ion Gyro radii, and a temporal scale ~50ms. This is consistent with the expected frequency and spatial scale of Zonal Flows.
fGAM ~ 16 kHz, krri ~ .2
Z (cm)
Trajectory of striation emitted in frame 12
Trajectory of striation emitted in frame 23
Major Radius (cm)
Trajectory of striation emitted in frame 19
Trajectory of striation emitted in frame 16
Trajectory of pellet
Major Radius (cm)

2. Stereoscopic Pellet Imaging
H-Mode Velocities
L-Mode Velocities
Shot
Motivation
Furthermore, these striated structures have qualitatively different behavior during L-Mode and H-Mode operation. L-Mode shots have striations that move in both the positive and negative ion diamagnetic velocity. Striations in H-Mode move purely in the negative ion diamagnetic drift direction. This would indicate that the striations behavior is to some extent dependent upon the back ground plasma conditions, such as flow.

3. Stereoscopic Pellet Imaging
Idea
Observe scaling of poloidal flows.
Theory and Gyro-kinetic simulations indicate that the frequency of poloidal flows gnerated by GAMs should go like.
Furthermore the velocity of the zero frequency Zonal Flows scales as the ion thermal velocity.
Experiment
A dedicated run day to investigate how the behavior of the striations differs in L-mode and H-mode plasmas.
Ohmically vary plasma temperature.
Attempt to observe if there is a scaling in the time between when the striations are emitted in different directions, and compare this with the square root dependence of the GAM frequency
Attempt to observe a change in the distribution in in the magnitude of velocities of the striations.