Scrape-off layer reflectometer for Alcator C-Mod

G. R. Hanson, J. B. Wilgen, C. Lau, Y. Lin, G. M. Wallace, S. J. Wukitch

Research output: Contribution to journalArticlepeer-review

14 Scopus citations

Abstract

A two-frequency x -mode reflectometer operating from 100 to 146 GHz is deployed on Alcator C-Mod to measure the density profile and fluctuations in the scrape-off layer (SOL) immediately in front of the new J-port ICRF antenna and the new C-port lower hybrid launcher. The reflectometer covers densities from 1016 to 1020 m-3 at 5-5.4 T. To provide the greatest flexibility and capability to deal with density fluctuations approaching 100% peak-to-peak in the SOL, both full-phase and differential-phase measurement capabilities with sweep speeds of ∼10 μs to >1 ms are implemented. The differential-phase measurement uses a difference frequency of 500 MHz, corresponding to cutoff layer separations ranging from about 0.1 to 1 mm. The reflectometer has six sets of launchers: three on the ICRF antenna and three on the lower hybrid launcher. Both the ICRF antenna and the lower hybrid launcher incorporate reflectometer antennas at their top, bottom, and midplane locations.

Original languageEnglish
Article number10F114
JournalReview of Scientific Instruments
Volume79
Issue number10
DOIs
StatePublished - 2008
Externally publishedYes

Funding

This work was supported by Oak Ridge National Laboratory, managed by UT-Battelle, LLC, for the U.S. Department of Energy under Contract No. DE-AC05-00OR22725, and by the MIT Plasma Science & Fusion Center under Contract No. DE-FC02-99ER54512.

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