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Title: LIDAR Thomson scattering diagnostic on JET (invited)

Abstract

By combining the time-of-flight or LIDAR principle with a Thomson backscatter diagnostic, spatial profiles of the electron temperature and density are measured in a magnetically confined fusion plasma. This technique was realized for the first time on the JET tokamak. A ruby laser (3-J pulse energy, 300-ps pulse duration, 0.5-Hz repetition rate) together with a 700-MHz bandwidth detection and registration system yields a spatial resolution of about 12 cm. A spectrometer with six channels in the wavelength range 400--800 nm gives a dynamic range of the temperature measurements of 0.3--20 keV. The stray light problem in the backscatter geometry is overcome by spectral discrimination and gating of the photomultipliers. A ruby filter in the spectral channel containing the laser wavelength allows calibration of the vignetting along the line of sight by means of Raman scattering, enabling the measurement of density profiles. The low level of background signal due to the short integration time for a single spatial point yields low statistical errors (..delta..T/sub e/ /T/sub e/ approx. =6%, ..delta..n/sub e/ /n/sub e/ approx. =4% at T/sub e/ = 6 keV, n/sub e/ = 3 x 10/sup 19/ m/sup -3/ ). Goodness-of-fit tests indicate that the systematic errors are within themore » same limits. The system is described and examples of measurements are given.« less

Authors:
; ; ; ; ; ; ; ; ; ;
Publication Date:
Research Org.:
JET Joint Undertaking, Abingdon, Oxon OX14 3EA, United Kingdom
OSTI Identifier:
6838253
Resource Type:
Journal Article
Journal Name:
Rev. Sci. Instrum.; (United States)
Additional Journal Information:
Journal Volume: 59:8
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; JET TOKAMAK; PLASMA DIAGNOSTICS; OPTICAL SPECTROMETERS; THOMSON SCATTERING; ELECTRON DENSITY; ELECTRON TEMPERATURE; OPTICAL RADAR; RESOLUTION; RUBY LASERS; INELASTIC SCATTERING; LASERS; MEASURING INSTRUMENTS; RADAR; RANGE FINDERS; SCATTERING; SOLID STATE LASERS; SPECTROMETERS; THERMONUCLEAR REACTORS; TOKAMAK TYPE REACTORS; 700102* - Fusion Energy- Plasma Research- Diagnostics

Citation Formats

Salzmann, H, Bundgaard, J, Gadd, A, Gowers, C, Hansen, K B, Hirsch, K, Nielsen, P, Reed, K, Schroedter, C, Weisberg, K, and others, and. LIDAR Thomson scattering diagnostic on JET (invited). United States: N. p., 1988. Web. doi:10.1063/1.1139686.
Salzmann, H, Bundgaard, J, Gadd, A, Gowers, C, Hansen, K B, Hirsch, K, Nielsen, P, Reed, K, Schroedter, C, Weisberg, K, & others, and. LIDAR Thomson scattering diagnostic on JET (invited). United States. https://doi.org/10.1063/1.1139686
Salzmann, H, Bundgaard, J, Gadd, A, Gowers, C, Hansen, K B, Hirsch, K, Nielsen, P, Reed, K, Schroedter, C, Weisberg, K, and others, and. 1988. "LIDAR Thomson scattering diagnostic on JET (invited)". United States. https://doi.org/10.1063/1.1139686.
@article{osti_6838253,
title = {LIDAR Thomson scattering diagnostic on JET (invited)},
author = {Salzmann, H and Bundgaard, J and Gadd, A and Gowers, C and Hansen, K B and Hirsch, K and Nielsen, P and Reed, K and Schroedter, C and Weisberg, K and others, and},
abstractNote = {By combining the time-of-flight or LIDAR principle with a Thomson backscatter diagnostic, spatial profiles of the electron temperature and density are measured in a magnetically confined fusion plasma. This technique was realized for the first time on the JET tokamak. A ruby laser (3-J pulse energy, 300-ps pulse duration, 0.5-Hz repetition rate) together with a 700-MHz bandwidth detection and registration system yields a spatial resolution of about 12 cm. A spectrometer with six channels in the wavelength range 400--800 nm gives a dynamic range of the temperature measurements of 0.3--20 keV. The stray light problem in the backscatter geometry is overcome by spectral discrimination and gating of the photomultipliers. A ruby filter in the spectral channel containing the laser wavelength allows calibration of the vignetting along the line of sight by means of Raman scattering, enabling the measurement of density profiles. The low level of background signal due to the short integration time for a single spatial point yields low statistical errors (..delta..T/sub e/ /T/sub e/ approx. =6%, ..delta..n/sub e/ /n/sub e/ approx. =4% at T/sub e/ = 6 keV, n/sub e/ = 3 x 10/sup 19/ m/sup -3/ ). Goodness-of-fit tests indicate that the systematic errors are within the same limits. The system is described and examples of measurements are given.},
doi = {10.1063/1.1139686},
url = {https://www.osti.gov/biblio/6838253}, journal = {Rev. Sci. Instrum.; (United States)},
number = ,
volume = 59:8,
place = {United States},
year = {1988},
month = {8}
}