Tokamak-independent software analysis suite for multi-spectral line-polarization MSE diagnostics

Journal Article · Wed Jul 20 04:00:00 UTC 2016 · Review of Scientific Instruments

DOI: https://doi.org/10.1063/1.4958914 · OSTI ID:1304757

Scott, S. D. ^[1]; Mumgaard, R. T. ^[2]

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1. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
2. Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States)

A tokamak-independent analysis suite has been developed to process data from Motional Stark Effect (mse) diagnostics. The software supports multi-spectral line-polarization mse diagnostics which simultaneously measure emission at the mse σ and π lines as well as at two "background" wavelengths that are displaced from the mse spectrum by a few nanometers. This analysis accurately estimates the amplitude of partially polarized background light at the σ and π wavelengths even in situations where the background light changes rapidly in time and space, a distinct improvement over traditional "time-interpolation" background estimation. The signal amplitude at many frequencies is computed using a numerical-beat algorithm which allows the retardance of the mse photo-elastic modulators (pem's) to be monitored during routine operation. It also allows the use of summed intensities at multiple frequencies in the calculation of polarization direction, which increases the effective signal strength and reduces sensitivity to pem retardance drift. The software allows the polarization angles to be corrected for calibration drift using a system that illuminates the mse diagnostic with polarized light at four known polarization angles within ten seconds of a plasma discharge. As a result, the software suite is modular, parallelized, and portable to other facilities.

• Research Organization: Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)
• Sponsoring Organization: USDOE
• Grant/Contract Number: AC02-09CH11466
• OSTI ID: 1304757
• Report Number(s): PPPL--5240
• Journal Information: Review of Scientific Instruments, Journal Name: Review of Scientific Instruments Journal Issue: 11 Vol. 87; ISSN 0034-6748; ISSN RSINAK
• Publisher: American Institute of Physics (AIP)Copyright Statement
• Country of Publication: United States
• Language: English