The MAST motional Stark effect diagnostic
2010 (English)In: REVIEW OF SCIENTIFIC INSTRUMENTS, Melville, NY: AMER INST PHYSICS , 2010, Vol. 81, no 10, 10D738- p.Conference paper (Refereed)
A motional Stark effect (MSE) diagnostic is now installed and operating routinely on the MAST spherical tokamak, with 35 radial channels, spatial resolution of similar to 2.5 cm, and time resolution of similar to 1 ms at angular noise levels of similar to 0.5 degrees. Conventional (albeit very narrow) interference filters isolate pi or sigma polarized emission. Avalanche photodiode detectors with digital phase-sensitive detection measure the harmonics of a pair of photoelastic modulators operating at 20 and 23 kHz, and thus the polarization state. The pi component is observed to be significantly stronger than sigma, in reasonably good agreement with atomic physics calculations, and as a result, almost all channels are now operated on pi. Trials with a wide filter that admits the entire Stark pattern (relying on the net polarization of the emission) have demonstrated performance almost as good as the conventional channels. MSE-constrained equilibrium reconstructions can readily be produced between pulses.
Place, publisher, year, edition, pages
Melville, NY: AMER INST PHYSICS , 2010. Vol. 81, no 10, 10D738- p.
, Review of scientific instruments, ISSN 0034-6748
IdentifiersURN: urn:nbn:se:kth:diva-27353DOI: 10.1063/1.3494254ISI: 000283754000117ScopusID: 2-s2.0-78149426771OAI: oai:DiVA.org:kth-27353DiVA: diva2:377653
18th Topical Conference on High-Temperature Plasma Diagnostics Wildwood, NJ, MAY 16-20, 2010
QC 201012142010-12-142010-12-132010-12-14Bibliographically approved