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A heterodyne dispersion interferometer for wide bandwidth density measurements on DIII-D

Journal Article · · Review of Scientific Instruments
DOI:https://doi.org/10.1063/1.5037997· OSTI ID:1609191
 [1];  [2];  [2];  [2];  [2];  [2];  [2];  [2];  [2];  [2];  [3];  [3];  [4];  [4];  [4];  [5]
  1. National Inst. for Fusion Science, Gifu (Japan); DOE/OSTI
  2. General Atomics, San Diego, CA (United States)
  3. Palomar College, San Marcos, CA (United States)
  4. Univ. of California, Los Angeles, CA (United States)
  5. California State Univ., San Marcos, CA (United States)
+ Show Author Affiliations
In order to improve both the density and particularly the temporal resolution beyond previous dispersion interferometers (DIs), a heterodyne technique based on an acousto-optic (AO) cell has been added to the DI. A 40 MHz drive frequency for the AO cell allows density fluctuation measurements into the MHz range. A CO2 laser-based heterodyne DI (HDI) installed on DIII-D has demonstrated that the HDI is capable of tracking the density evolution throughout DIII-D discharges, including disruption events and other rapid transient phenomena. The data also show good agreement with independent density measurements obtained with the existing DIII-D two-color interferometer. The HDI line-integrated density resolution sampled over a 1 s interval is ~9 × 1017 m-2. Density fluctuations induced by MHD instabilities are also successfully measured by the HDI.
Research Organization:
General Atomics, San Diego, CA (United States); Princeton Univ., NJ (United States); Tech-X Corporation, Boulder, CO (United States)
Sponsoring Organization:
USDOE Office of Science (SC)
Grant/Contract Number:
AC02-09CH11466; FC02-04ER54698; FC02-06ER54875; FC02-08ER54972
OSTI ID:
1609191
Alternate ID(s):
OSTI ID: 1461569
Journal Information:
Review of Scientific Instruments, Journal Name: Review of Scientific Instruments Journal Issue: 10 Vol. 89; ISSN 0034-6748
Publisher:
American Institute of Physics (AIP)Copyright Statement
Country of Publication:
United States
Language:
English

References (8)

Dispersion interferometer for controlled fusion devices journal April 1993
Dispersion interferometer based on a CO2 laser for TEXTOR and burning plasma experiments journal May 2006
Dispersion interferometer using modulation amplitudes on LHD (invited) journal November 2014
Design of a dispersion interferometer combined with a polarimeter to increase the electron density measurement reliability on ITER journal September 2016
Bench testing of a heterodyne CO 2 laser dispersion interferometer for high temporal resolution plasma density measurements journal December 2016
Two-dimensional straightness measurement based on optical knife-edge sensing journal September 2017
Tests of a full-scale ITER toroidal interferometer and polarimeter (TIP) prototype on the DIII-D tokamak (invited) journal October 2018
Tests of a two-color interferometer and polarimeter for ITER density measurements journal October 2017

Cited By (1)

Innovations in Technology and Science R&D for ITER journal January 2019

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Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
instruments & instrumentation
physics