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The multichannel motional Stark effect diagnostic on TFTR

Technical Report ·
DOI:https://doi.org/10.2172/7046934· OSTI ID:7046934
Although the q profile plays a key role in theories of instabilities and plasma equilibrium, it has been quite difficult to measure until the recent development of the motional Stark effect (MSE) diagnostic. A multichannel motional Stark effect polarimeter system has recently been installed on the Tokamak Fusion Test Reactor (TFTR). The diagnostic can measure the magnetic field pitch angle ({gamma}{sub p} = tan{sup {minus}1} (B{sub T})/(B{sup p})) at ten radial locations. The doppler shifted D{sub alpha} radiation from a TFTR heating beam is viewed near tangential to the toroidal magnetic field via a re-entrant front surface reflecting mirror. The field of view covers from inboard of the magnetic axis to near the outboard edge of the plasma with a radial spatial resolution of 3--5 cm. A high throughput f/2 optics system results in an uncertainty for {gamma}{sub p} of {approximately}0.1{degrees}--0.2{degrees} with a time resolution of {approximately}5--10 ms. Initial pinch angle profiles from TFTR have been obtained. The MSE data is consistent with the estimated magnetic axis position from external magnetic measurements and the q=1 radius is in good agreement with the inversion radius from the electron cyclotron emission temperature measurements.
Research Organization:
Princeton Univ., NJ (United States). Plasma Physics Lab.
Sponsoring Organization:
DOE; USDOE, Washington, DC (United States)
DOE Contract Number:
AC02-76CH03073
OSTI ID:
7046934
Report Number(s):
PPPL-2853; ON: DE92018435
Country of Publication:
United States
Language:
English