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UC
Davis PDG:Temperature
Snakes on TEXT-U
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During high power ECRH, the sawteeth amplitudes increase significantly and a high amplitude coherent plasma perturbation occurs inside the sawtooth inversion radius. As shown in the time trace of channel #1515 (red) in (b), this perturbation grows in amplitude, leading to the sawtooth crash.
Owing to the high spatial resolution of the ECE Imaging system, this coherent perturbation is found to originate from the rotation of the multiple peaks in electron temperature profiles, as shown in the above figure. This is similar to the reported "density snake" phenomenon [A. Weller, et al., Phys. Rev. Lett., Vol. 59(20), 2303, 1987]. The mode numbers m=1, n=1 are determined from correlation analysis.
For further technical details, and ECE Imaging measurements and results from TEXT-U, please examine the following links:
2-D
temperature profiles
2-D
temperature images
Temperature
profile evolution during sawteeth activity
Temperature
profile evolution during tearing mode activity
Cross-correlation
measurements of electron temperature fluctuations
The unique features of the ECE Imaging diagnostics derive from the use of wideband, low cost monolithic and hybrid Schottky diode mixer arrays. Follow the links below to learn more about both the technology and the techniques employed in ECE Imaging.
Imaging
array design and fabrication
Correlation
Measurements
UC Davis has fabricated and installed multichannel ECE Imaging systems on other fusion plasma tokamaks across the world. Follow the links below for a description of the systems involved, and to sample data collected with these systems.
ECE
Imaging on the RTP tokamak in the U.S.A.
ECE
Imaging on the TEXTOR tokamak in Germany
Comments to: Bihe Deng