Harry Han
PSFC
Tuesday, March 6, 2018
5:00pm
Gas-Puff Imaging (GPI) measures the spatially-resolved fluctuations in the plasma edge and SOL by imaging emission from a local gas puff. We plan to design and install a GPI system on TCV in Switzerland by June 2018. Installing a GPI system on TCV will provide a way to measure the edge turbulence which can provide access to interesting physics, such as the neutral density shadowing effect in GPI, turbulence characteristics during L-H transitions, GAMs, density shoulder formation, and density limit. The key components are being made in PSFC and SPC. Given these components, in order to obtain a decent signal-to-noise ratio, we need to consider the following parameters: flow rate of gases, temperature of gases, nozzle type, and gas species. I have been studying this parameter space by using DEGAS 2 to optimize the diagnostic design. DEGAS 2 is a Monte-Carlo code which is capable of simulating neutral particle transport in plasmas. Running DEGAS 2 with different parameters gives the brightness and emission for each viewing chord. The results showed that the fiducial case with the given geometry gives a usable brightness at the LCFS. Moreover, using high temperature gas puff, D2 puff, and collimated puff will give more brightness inside the LCFS than the fiducial case.
Plasma Science and Fusion Center
Massachusetts Institute of Technology
77 Massachusetts Avenue, NW17
Cambridge, MA 02139
info@psfc.mit.edu
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