Improved performance of the Thomson scattering system in RFX

R. Pasqualotto, A. Sardella, A. Intravaia, L. Marrelli

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Abstract

A Thomson scattering diagnostic is used in the RFX reversed field pinch experiment to measure single pulse, multipoint electron temperature (Te) profiles. Recent significant improvements have provided reliable and routine operation of the diagnostic. Custom developed CAMAC charge analog-to-digital converters have been introduced, which sample the plasma light 170 ns after the laser light and have greater sensitivity. The spectrometer configuration and the calibration procedure have been optimized. These upgrades have finally led to better fitted scattering spectra and more regular estimates of Teprofiles, allowing the measurement of temperatures as low as 20 eV. The introduction of a second spectrometer has recently added a further ten positions to the original ten point profile, resolving the often steep Teedge gradient. On axis values are in good agreement with other Temeasurements from SXR diagnostics (either SiLi and double filter method). Teprofiles are typically rather flat, but some dependence on the plasma parameters, like density and pinch parameter, has been drawn. Significant Teprofile modifications have been observed during transient events like pulsed poloidal current drive and pellet injection. The diagnostic will be completed soon, allowing production of 27 point profiles, with the introduction of the third spectrometer. Double pulse operation of the laser is in progress. © 7999 American Institute of Physics.
Original languageEnglish
Pages (from-to)1416 - 1420
Number of pages5
JournalReview of Scientific Instruments
Volume70
Issue number2
DOIs
Publication statusPublished - 1999
Externally publishedYes

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All Science Journal Classification (ASJC) codes

  • Instrumentation

Cite this

Pasqualotto, R., Sardella, A., Intravaia, A., & Marrelli, L. (1999). Improved performance of the Thomson scattering system in RFX. Review of Scientific Instruments, 70(2), 1416 - 1420. https://doi.org/10.1063/1.1149629