Localized measurement of short wavelength plasma fluctuations with the DIII-D phase contrast imaging diagnostic
Author(s)Dorris, James R.; Rost, Jon C.; Porkolab, Miklos
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A novel rotating mask system has been designed and implemented on the DIII-D phase contrast imaging (PCI) diagnostic to produce the first spatially localized PCI measurements of a tokamak plasma. The localization technique makes use of the variation in the magnetic field component perpendicular to the viewing chord as a function of chord height. This new capability provides measurements in the range of 2<k<30 cm[superscript −1], 10 kHz<f<10 MHz, and 0.7<r/a<1. This technique provides a spatial resolution of 10 cm at k=15 cm[superscript −1] and can realistically provide measurements at a rate of 10 profiles/s. Calibration measurements show accurate characterization of the system transfer function making feasible a time dependent analysis that results in improved localization. Initial measurements show turbulence to peak near the plasma edge. This upgrade is part of a broader program to operate the DIII-D PCI at wave numbers up to 40 cm[superscript −1] to probe electron scale turbulence in the plasma core.
DepartmentMassachusetts Institute of Technology. Plasma Science and Fusion Center
Review of Scientific Instruments
American Institute of Physics
Dorris, J. R., J. C. Rost, and M. Porkolab. “Localized measurement of short wavelength plasma fluctuations with the DIII-D phase contrast imaging diagnostic.” Review of Scientific Instruments 80.2 (2009): 023503-10. ©2009 American Institute of Physics.
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