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Title: Design of multipulse Thomson scattering diagnostic for SST-1 tokamak

Abstract

A multipulse Nd:YAG (Yttrium aluminum garnet) Thomson scattering (TS) system is designed and developed for measuring electron temperature (T{sub e}) and density (n{sub e}) profiles of SST-1 tokamak. The system operates at vertical, divertor, and horizontal (midplane) regions of plasma and measures the electron temperature of 20 eV to 1.5 keV and density of 10{sup 18}-10{sup 19} m{sup -3}. Six Nd:YAG lasers synchronized with external control is used to get three different temporal resolutions (30 Hz, 180 Hz, and 1 kHz). The entire system is laboratory tested for the stability of alignment and performance over a distance of 30 m. Different imaging lens assemblies are designed to image the scattered photons from each of the scattering region to an array of optical fibers. A low cost and compact five-channel interference filter polychromator is designed, fabricated, and tested for its image quality and the filter transmission characteristics. Detection system with an avalanche photodiode and required signal conditioning electronics is developed for detecting the scattered photons. A data acquisition and control module operating on PXI bus is developed for the real time data acquisition and system control. A detailed description of design and testing of TS subsystems is presented in this article.

Authors:
; ; ; ; ; ; ; ;  [1]
  1. Institute For Plasma Research, Bhat, Gandhinagar 382 428 (India)
Publication Date:
OSTI Identifier:
20953420
Resource Type:
Journal Article
Resource Relation:
Journal Name: Review of Scientific Instruments; Journal Volume: 78; Journal Issue: 4; Other Information: DOI: 10.1063/1.2724775; (c) 2007 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
70 PLASMA PHYSICS AND FUSION TECHNOLOGY; ALUMINIUM; ALUMINIUM OXIDES; DATA ACQUISITION; DENSITY; DESIGN; ELECTRON TEMPERATURE; FERRITE GARNETS; FILTERS; INTERFERENCE; ION TEMPERATURE; OPTICAL FIBERS; PHOTODIODES; PHOTONS; PLASMA; THOMSON SCATTERING; TOKAMAK DEVICES; YTTRIUM; YTTRIUM COMPOUNDS

Citation Formats

Kumar, Ajai, Chavda, Chhaya, Saxena, Y. C., Singh, Ranjeet, Thakar, Aruna, Thomas, Jinto, Patel, Kiran, Pandya, Kaushal, and Bedakihale, Vijay. Design of multipulse Thomson scattering diagnostic for SST-1 tokamak. United States: N. p., 2007. Web. doi:10.1063/1.2724775.
Kumar, Ajai, Chavda, Chhaya, Saxena, Y. C., Singh, Ranjeet, Thakar, Aruna, Thomas, Jinto, Patel, Kiran, Pandya, Kaushal, & Bedakihale, Vijay. Design of multipulse Thomson scattering diagnostic for SST-1 tokamak. United States. doi:10.1063/1.2724775.
Kumar, Ajai, Chavda, Chhaya, Saxena, Y. C., Singh, Ranjeet, Thakar, Aruna, Thomas, Jinto, Patel, Kiran, Pandya, Kaushal, and Bedakihale, Vijay. Sun . "Design of multipulse Thomson scattering diagnostic for SST-1 tokamak". United States. doi:10.1063/1.2724775.
@article{osti_20953420,
title = {Design of multipulse Thomson scattering diagnostic for SST-1 tokamak},
author = {Kumar, Ajai and Chavda, Chhaya and Saxena, Y. C. and Singh, Ranjeet and Thakar, Aruna and Thomas, Jinto and Patel, Kiran and Pandya, Kaushal and Bedakihale, Vijay},
abstractNote = {A multipulse Nd:YAG (Yttrium aluminum garnet) Thomson scattering (TS) system is designed and developed for measuring electron temperature (T{sub e}) and density (n{sub e}) profiles of SST-1 tokamak. The system operates at vertical, divertor, and horizontal (midplane) regions of plasma and measures the electron temperature of 20 eV to 1.5 keV and density of 10{sup 18}-10{sup 19} m{sup -3}. Six Nd:YAG lasers synchronized with external control is used to get three different temporal resolutions (30 Hz, 180 Hz, and 1 kHz). The entire system is laboratory tested for the stability of alignment and performance over a distance of 30 m. Different imaging lens assemblies are designed to image the scattered photons from each of the scattering region to an array of optical fibers. A low cost and compact five-channel interference filter polychromator is designed, fabricated, and tested for its image quality and the filter transmission characteristics. Detection system with an avalanche photodiode and required signal conditioning electronics is developed for detecting the scattered photons. A data acquisition and control module operating on PXI bus is developed for the real time data acquisition and system control. A detailed description of design and testing of TS subsystems is presented in this article.},
doi = {10.1063/1.2724775},
journal = {Review of Scientific Instruments},
number = 4,
volume = 78,
place = {United States},
year = {Sun Apr 15 00:00:00 EDT 2007},
month = {Sun Apr 15 00:00:00 EDT 2007}
}
  • It is proposed to measure the electron distribution function (EDF) in the T-15 tokamak plasma and to investigate the EDF time-behavior by means of a Thomson scattering technique. 8 refs., 1 fig.
  • This paper describes the design and operation of a 40 spatial channel Thomson scattering system that uses multiple 20-Hz Nd:YAG lasers to measure the electron temperature and density profiles periodically throughout an entire plasma discharge. As many as eight lasers may be fired alternately for an average measurement frequency of 160 Hz, or they may be fired in rapid succession ({lt}10 kHz), producing a burst of pulses for measuring transient events. The high spatial resolution (1.3 cm) and wide dynamic range (10 eV--20 keV) enable this system to resolve large electron density and temperature gradients formed at the plasma edgemore » and in the scrape-off layer during H-mode operation. These features provide a formidable tool for studying {ital L}--{ital H} transitions, edge localized modes (ELMs), beta limits, transport, and disruptions in an efficient manner suitable for large tokamak operation where shot-to-shot scans are impractical. The scattered light is dispersed by interference filter polychromators and detected by silicon avalanche photodiodes. Laser control and data acquisition are performed in real time by a VME-based microcomputer. Data analysis is performed by a MicroVAX 3400. Additional features of this system include real-time analysis capability, full statistical treatment of error bars based on the measured background light, and laser beam quality and alignment monitoring during plasma operation. Results of component testing, calibration, plasma operation, and error analysis are presented.« less
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