Ultrafast broadband frequency-modulation reflectometer for density profile measurements in GAMMA 10

Journal Article · Wed Jan 01 04:00:00 EST 1997 · Review of Scientific Instruments

DOI:https://doi.org/10.1063/1.1147601· OSTI ID:451774

Tokuzawa, T; Mase, A; Oyama, N; Itakura, A; Tamano, T ^[1]

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1. Plasma Research Center, University of Tsukuba, Ibaraki 305 (Japan)

A broadband microwave reflectometer was applied to the GAMMA 10 tandem mirror using a fast-sweep hyperabrupt varactor-tuned oscillator (HTO) that can be swept over the full band (12{endash}18 GHz) in less than 5 {mu}s. Clear fringes are observed during a plasma shot when the resultant frequencies from the reflectometer output are much larger than the ion cyclotron range of frequency (3{endash}10 MHz). The density profile measurement is performed for various sweep times of HTO from 1 ms to 5 {mu}s in which two reconstruction methods are utilized, zero-cross counting of the fringes and frequency analysis using the maximum entropy method. The reliability of the profile measurement seems to be improved when the sweep time is faster than 10{endash}30 {mu}s. The integrated value of many reconstructed density profiles agrees well with the profile obtained from a scanning interferometer. The fast-sweep reflectometer is also applied to the measurement of density fluctuations such as plasma movement as well as density profiles. {copyright} {ital 1997 American Institute of Physics.}

• OSTI ID: 451774
• Report Number(s): CONF-960543--
• Journal Information: Review of Scientific Instruments, Journal Name: Review of Scientific Instruments Journal Issue: 1 Vol. 68; ISSN 0034-6748; ISSN RSINAK
• Country of Publication: United States
• Language: English

Related Subjects

44 INSTRUMENTATION
INCLUDING NUCLEAR AND PARTICLE DETECTORS
70 PLASMA PHYSICS AND FUSION TECHNOLOGY
DATA PROCESSING
FREQUENCY MIXING
GAMMA 10 DEVICES
MAGNETIC MIRRORS
MICROWAVE EQUIPMENT
PERFORMANCE
PLASMA DENSITY
PLASMA DIAGNOSTICS
PLASMA RADIAL PROFILES
RADIATION DETECTORS
REFLECTIVITY
TIME RESOLUTION
microwave reflectometry
reflectometers