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Title: Millimeter-wave interferometry and far-forward scattering for density fluctuation measurements on LTX-β

Abstract

The λ ≈ 1 mm (f = 288 GHz) interferometer for the Lithium Tokamak Experiment-β (LTX-β) will use a chirped-frequency source and a centerstack-mounted retro-reflector mirror to provide electron line density measurements along a single radial chord at the midplane. The interferometer is unique in the use of a single source (narrow-band chirped-frequency interferometry) and a single beam splitter for separating and recombining the probe and reference beams. The current work provides a documentation of the interferometry hardware and evaluates the capabilities of the system as a far-forward collective scattering diagnostic. As such, the current optical setup is estimated to have a detection range of 0.4 ≲ k ≲ 1.7 cm–1, while an improved layout will extend the upper k limit to ~3 cm–1. Measurements with the diagnostic on LTX are presented, showing interferometry results and scattered signal data. Furthermore, these diagnostics are expected to provide routine measurements on LTX-β for high frequency coherent density oscillations (e.g., Alfvénic modes during neutral beam injection) as well as for broadband turbulence.

Authors:
 [1];  [2]; ORCiD logo [2]; ORCiD logo [2];  [2];  [1];  [2];  [1];  [1];  [1]
  1. Univ. of California, Los Angeles, CA (United States)
  2. Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Publication Date:
Research Org.:
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1484244
Alternate Identifier(s):
OSTI ID: 1470793
Grant/Contract Number:  
AC02-09CH11466; FG02-99ER54527
Resource Type:
Accepted Manuscript
Journal Name:
Review of Scientific Instruments
Additional Journal Information:
Journal Volume: 89; Journal Issue: 10; Journal ID: ISSN 0034-6748
Publisher:
American Institute of Physics (AIP)
Country of Publication:
United States
Language:
English
Subject:
47 OTHER INSTRUMENTATION

Citation Formats

Kubota, S., Majeski, R., Boyle, D. P., Kaita, R., Kozub, T., Lantsov, R., Merino, E., Nguyen, X. V., Peebles, W. A., and Rhodes, T. L. Millimeter-wave interferometry and far-forward scattering for density fluctuation measurements on LTX-β. United States: N. p., 2018. Web. doi:10.1063/1.5039418.
Kubota, S., Majeski, R., Boyle, D. P., Kaita, R., Kozub, T., Lantsov, R., Merino, E., Nguyen, X. V., Peebles, W. A., & Rhodes, T. L. Millimeter-wave interferometry and far-forward scattering for density fluctuation measurements on LTX-β. United States. doi:https://doi.org/10.1063/1.5039418
Kubota, S., Majeski, R., Boyle, D. P., Kaita, R., Kozub, T., Lantsov, R., Merino, E., Nguyen, X. V., Peebles, W. A., and Rhodes, T. L. Fri . "Millimeter-wave interferometry and far-forward scattering for density fluctuation measurements on LTX-β". United States. doi:https://doi.org/10.1063/1.5039418. https://www.osti.gov/servlets/purl/1484244.
@article{osti_1484244,
title = {Millimeter-wave interferometry and far-forward scattering for density fluctuation measurements on LTX-β},
author = {Kubota, S. and Majeski, R. and Boyle, D. P. and Kaita, R. and Kozub, T. and Lantsov, R. and Merino, E. and Nguyen, X. V. and Peebles, W. A. and Rhodes, T. L.},
abstractNote = {The λ ≈ 1 mm (f = 288 GHz) interferometer for the Lithium Tokamak Experiment-β (LTX-β) will use a chirped-frequency source and a centerstack-mounted retro-reflector mirror to provide electron line density measurements along a single radial chord at the midplane. The interferometer is unique in the use of a single source (narrow-band chirped-frequency interferometry) and a single beam splitter for separating and recombining the probe and reference beams. The current work provides a documentation of the interferometry hardware and evaluates the capabilities of the system as a far-forward collective scattering diagnostic. As such, the current optical setup is estimated to have a detection range of 0.4 ≲ k⊥ ≲ 1.7 cm–1, while an improved layout will extend the upper k⊥ limit to ~3 cm–1. Measurements with the diagnostic on LTX are presented, showing interferometry results and scattered signal data. Furthermore, these diagnostics are expected to provide routine measurements on LTX-β for high frequency coherent density oscillations (e.g., Alfvénic modes during neutral beam injection) as well as for broadband turbulence.},
doi = {10.1063/1.5039418},
journal = {Review of Scientific Instruments},
number = 10,
volume = 89,
place = {United States},
year = {2018},
month = {9}
}

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