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Title: A frequency-modulated continuous-wave reflectometer for the Lithium Tokamak Experiment

Authors:
 [1];  [2];  [1];  [2]; ORCiD logo [2]; ORCiD logo [2];  [2];  [2];  [2];  [1];  [1]; ORCiD logo [2]
  1. Department of Physics and Astronomy, University of California, Los Angeles, California 90095, USA
  2. Princeton Plasma Physics Laboratory, Princeton, New Jersey 08543, USA
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
1361837
Grant/Contract Number:
AC02-09CH11466; FG02-99ER54527
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
Review of Scientific Instruments
Additional Journal Information:
Journal Volume: 88; Journal Issue: 5; Related Information: CHORUS Timestamp: 2018-02-14 20:18:04; Journal ID: ISSN 0034-6748
Publisher:
American Institute of Physics
Country of Publication:
United States
Language:
English

Citation Formats

Kubota, S., Majeski, R., Peebles, W. A., Bell, R. E., Boyle, D. P., Kaita, R., Kozub, T., Lucia, M., Merino, E., Nguyen, X. V., Rhodes, T. L., and Schmitt, J. C.. A frequency-modulated continuous-wave reflectometer for the Lithium Tokamak Experiment. United States: N. p., 2017. Web. doi:10.1063/1.4981811.
Kubota, S., Majeski, R., Peebles, W. A., Bell, R. E., Boyle, D. P., Kaita, R., Kozub, T., Lucia, M., Merino, E., Nguyen, X. V., Rhodes, T. L., & Schmitt, J. C.. A frequency-modulated continuous-wave reflectometer for the Lithium Tokamak Experiment. United States. doi:10.1063/1.4981811.
Kubota, S., Majeski, R., Peebles, W. A., Bell, R. E., Boyle, D. P., Kaita, R., Kozub, T., Lucia, M., Merino, E., Nguyen, X. V., Rhodes, T. L., and Schmitt, J. C.. Mon . "A frequency-modulated continuous-wave reflectometer for the Lithium Tokamak Experiment". United States. doi:10.1063/1.4981811.
@article{osti_1361837,
title = {A frequency-modulated continuous-wave reflectometer for the Lithium Tokamak Experiment},
author = {Kubota, S. and Majeski, R. and Peebles, W. A. and Bell, R. E. and Boyle, D. P. and Kaita, R. and Kozub, T. and Lucia, M. and Merino, E. and Nguyen, X. V. and Rhodes, T. L. and Schmitt, J. C.},
abstractNote = {},
doi = {10.1063/1.4981811},
journal = {Review of Scientific Instruments},
number = 5,
volume = 88,
place = {United States},
year = {Mon May 01 00:00:00 EDT 2017},
month = {Mon May 01 00:00:00 EDT 2017}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1063/1.4981811

Citation Metrics:
Cited by: 1work
Citation information provided by
Web of Science

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  • The frequency modulated continuous wave reflectometer was developed for the first time on the HL-2A tokamak. The system utilizes a voltage controlled oscillator and an active multiplier for broadband coverage and detects as heterodyne mode. Three reflectometers have been installed and operated in extraordinary mode polarization on HL-2A to measure density profiles at low field side, covering the Q-band (33–50 GHz), V-band (50–75 GHz), and W-band (75–110 GHz). For density profile reconstruction from the phase shift of the probing wave, a corrected phase unwrapping method is introduced in this article. The effectiveness of the method is demonstrated. The density profilemore » behavior of a fast plasma event is presented and it demonstrates the capability of the reflectometer. These diagnostics will be contributed to the routine density profile measurements and the plasma physics study on HL-2A.« less
  • A new reflectometer system designed to monitor density fluctuations associated with rf waves has been successfully demonstrated on the DIII-D tokamak. It is a direct, internal, and nonperturbing diagnostic with access into the plasma core. This new diagnostic is motivated by a desire to improve understanding of rf wave physics issues, such as wave trajectory, heating mechanisms, rf wave deposition profile, and wave number, and is highly relevant to planned tokamaks such as ITER and TPX. This work is the first application of reflectometry to rf wave studies in a tokamak. Feedforward tracking receiver techniques are employed to remove frequencymore » instabilities due to inherent drifts in the microwave sources and frequency pulling. In order to minimize spurious pickup of the rf pulse ([similar to]60 MHz), heterodyne detection techniques are utilized, and all components are installed inside an rf shielding box. The system operates in the extraordinary mode ([ital X]-mode) at 70 GHz. In this paper, a detailed description of the system, and data illustrating its successful operation will be presented.« less
  • The millimeter-wave frequency-modulated continuous-wave (FM-CW) reflectometer on NSTX is a multichannel system providing electron density profile measurements with a frequency coverage of 13-53 GHz [corresponding O-mode density range of (0.21-3.5)x10{sup 13} cm{sup -3}]. Recently, this system has been modified to allow ultrafast full-band sweeps for repetition intervals down to 10 {mu}s. For this system to function as a fluctuation diagnostic it is crucial to eliminate artifacts in the phase derivative caused by nonlinearities in the frequency sweep; we introduce a simple hardware technique for reducing these artifacts to {approx_equal}0.3%. For NSTX, the additional bandwidth ({<=}100 kHz) greatly enhances the capabilitymore » of the FM-CW reflectometer as a diagnostic for low frequency magnetohydrodynamics instabilities (e.g., internal kinks, resistive wall modes, neoclassical tearing modes, as well as fast-particle driven fishbones and low frequency toroidal Alfven eigenmodes)« less
  • Frequency modulation reflectometer has been developed to measure the plasma density profile of the Korea Superconducting Tokamak Advanced Research tokamak. Three reflectometers are operating in extraordinary polarization mode in the frequency range of Q band (33.6–54 GHz), V band (48–72 GHz), and W band (72–108 GHz) to measure the density up to 7 × 10{sup 19} m{sup −3} when the toroidal magnetic field is 2 T on axis. The antenna is installed inside of the vacuum vessel. A new vacuum window is developed by using 50 μm thick mica film and 0.1 mm thick gold gasket. The filter bank ofmore » low pass filter, notch filter, and Faraday isolator is used to reject the electron cyclotron heating high power at attenuation of 60 dB. The full frequency band is swept in 20 μs. The mixer output is directly digitized with sampling rate of 100 MSamples/s. The phase is obtained by using wavelet transform. The whole hardware and software system is described in detail and the measured density profile is presented as a result.« less