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

Kubota, S.; Majeski, R.; Boyle, D. P.; Kaita, R.; Kozub, T.; Lantsov, R.; Merino, E.; Nguyen, X. V.; Peebles, W. A.; Rhodes, T. L.

doi:10.1063/1.5039418

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:

Kubota, S. ^[1]; Majeski, R. ^[2];

^[2];

^[2]; Kozub, T. ^[2]; Lantsov, R. ^[1]; Merino, E. ^[2]; Nguyen, X. V. ^[1]; Peebles, W. A. ^[1]; Rhodes, T. L. ^[1]

Univ. of California, Los Angeles, CA (United States)
Princeton Plasma Physics Lab. (PPPL), Princeton, NJ (United States)

Publication Date:: 2018-09-14

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.

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                    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.  https://doi.org/10.1063/1.5039418

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                    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.  https://doi.org/10.1063/1.5039418.  https://www.osti.gov/servlets/purl/1484244.

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@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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Similar Records

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

Abstract

Citation Formats

Performance projections for the lithium tokamak experiment (LTX) journal, April 2009

Density fluctuation measurements by far-forward collective scattering in the MST reversed-field pinch journal, October 2012

Compatibility of lithium plasma-facing surfaces with high edge temperatures in the Lithium Tokamak Experiment journal, May 2017

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Exploration of spherical torus physics in the NSTX device journal, March 2000

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Observation of Flat Electron Temperature Profiles in the Lithium Tokamak Experiment journal, July 2017

A frequency-modulated continuous-wave reflectometer for the Lithium Tokamak Experiment journal, May 2017

Fourier optics approach to far forward scattering and related refractive index phenomena in laboratory plasmas journal, July 1982

Characterization of a Dual-Mode Horn for Submillimeter Wavelengths (Short Papers) journal, August 1984

Diffraction of a Gaussian beam at an aperture journal, January 1990

Far-forward collective scattering measurements by FIR polarimeter-interferometer on J-TEXT tokamak journal, August 2016

Applications of the Fraunhofer-diffraction method for plasma-wave measurements journal, October 1983

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journal, October 2012

Compatibility of lithium plasma-facing surfaces with high edge temperatures in the Lithium Tokamak Experiment
journal, May 2017

Study of density fluctuations in plasmas by small-angle CO2 laser scattering
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Beam tracing in inhomogeneous anisotropic plasmas
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