DIII-D RESEARCH OPPORTUNITIES FORUM FOR THE 2008 EXPERIMENTAL CAMPAIGN
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| Title | 304: Turbulence spreading experiment in plasma core | ||
| Name: | Keith Burrell ( |
Affiliation: | General Atomics |
| Research Area: | Transport Model Validation | Presentation time: | Not requested | Co-Author(s): | -- |
| Description: | The goal of this experiment is to determine whether we can
experimentally detect the spatial spreading of turbulence which is predicted by various analytic calculations and gyrokinetic code runs. | ||
| Experimental Approach/Plan: | Use the same plasma and ECH configuration that J. DeBoo used to do the
ECH swing experiment--modulated ECH at two different radial locations in an L-mode, sawtooth-free plasma. Modulate ECH out of phase at the two locations so that grad Te is modified in the region between the two radial positions. From rho_2 outward, the plasma sees constant power input and, hence, should have constant gradients. Look for modulation in the turbulence and transport in the outer region correlated with the ECH modulation. We need to worry that there might be a transient modulation due to the fact that the heat from the inner gyrotron has to travel further to get out. Accordingly, right after the switch, there may be a transient alteration in the radial flux. Hence, we need to use long enough ECH modulation that this can die out. For this experiment to work, we need to match the powers from the gyrotrons very exactly. We know that we can make the basic plasma and perform the modulation; however, we didn't acquire the proper turbulence measurements in the last experiment. | ||
| Background: | Recent theoretical work indicates that there is a nonlocal character
to turbulence in magnetized plasmas. Turbulence can be driven from free energy sources in one location and manifest itself both at that location and in more distant areas. The issue is that, in most cases, the plasma is also unstable to microturbulence in that more distant location. Accordingly, to do a meaningful experiment, we need to find ways to separate the local and nonlocal effects. | ||
| Resource Requirements: | 4-5 gyrotrons | ||
| Diagnostic Requirements: | -- | ||
| Analysis Requirements: | -- | ||
| Other Requirements: | -- | ||
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