27P-C07
Density and temperature fluctuations measured by correlation radiometry andcorrelation reflectometry on Heliotron JG. M. Weir1, K. Nagasaki1, S. Inagaki2, H. Kishikawa3, S. Yamamoto1, K. Sakamoto1, N.
Kenmochi1, Y. Nakamura3, H. Okada1, T. Minami1, S. Kado1, S. Kobayashi1, S. Ohshima1, S.
Konoshima1, K. Hada3, Y. Ohtani3, N. Asavathavornvanit3, X. Lu3, K. Murakami3, N. Inklin3, and T.
Mizuuchi1
12Institute of Advanced Energy, Kyoto University, Uji, Kyoto 611-0011, Japan
Research Institute for Applied Mechanics, Kyushu University, Hakozaki, Fukuoka 812-8581, Japan
3Graduate School of Energy Science, Kyoto University, Uji, Kyoto 611-0011, Japan

Diagnostics that simultaneously resolve multiple
spatial and temporal scales are necessary to study
the interaction between turbulence and transport.
The development of high bandwidth oscilloscopes[1] (up to 100 GHz) enables the direct measurementof microwaves during plasma experiments, which
are used to measure electron temperature andplasma density fluctuations at multiple radial scales.
A Teledyne LeCroy oscilloscope with 36 GHz
bandwidth (80 GS/s) has been used as part of aheterodyne radiometer, and separately as part of areflectometer system, to make fluctuation
measurements on Heliotron J.
The oscilloscope was used to directly measure
the Intermediate Frequency (IF) spectrum from aradiometer with a 56 GHz local oscillator,
corresponding to 2nd harmonic Electron Cyclotron
Emission (ECE) between 58-74 GHz.
IF Spectrum (1.6µs time-window)-120

Oscilloscope
Mixer Harmonics

P IF [dB/Hz]-140-160
70 GHzNotch Filter-180

ECE Radiometer BW-200

01020f [GHz]30

Fig.1. ECE Intermediate Frequency (IF) spectrum
measured by a 36 GHz oscilloscope (shot 58666).

Figure (1) shows the IF spectrum measured during
shot 58666 in the standard magnetic configurationof Heliotron J. The signal at 14 GHz is reduced
due to a 70 GHz waveguide notch-filter that is used
to suppress signal at the electron cyclotron resonant
heating frequency.
Low frequency fluctuations (10-60 kHz) aremeasured in magnetic diagnostics, and coherent
electron temperature fluctuations are measured

across the plasma radius at the same frequencies.
Figure (2) shows the coherence between two
radially separated ECE channels.

Fig.2. Electron temperature fluctuations are measured
between radially separated ECE channels (shot 58666).

A conventional single-sightline correlation ECE(cECE) radiometer has been developed andimplemented on Heliotron J, and the first results
using the new cECE diagnostic will be presented.
Additionally, the oscilloscope was used tomeasure the launched and reflected waves between
24-28 GHz, corresponding to the steep plasma
density gradient region, during two-source
microwave reflectometry experiments. The radialcorrelation length of the edge plasma density
fluctuations was measured to be approximately 5mm in the high bumpiness magnetic configurationof Heliotron J.
Acknowledgments
The author acknowledges support as anInternational Research Fellow of the JapaneseSociety for the Promotion of Science.
References[1] Teledyne LeCroy, Teledyne Lecroy Introduces NewLabmaster And Wavemaster Oscilloscopes For
Testing Next-Generation High-Speed Electrical And
Optical Links. (Web) 8 May 2015.
[2] H. Tsuchiya: Plasma Fus. Res. 9 (2014) 3402021.