Design and Installation of a New Electron Cyclotron Emission Diagnostic Antenna in LHD

Plasma and Fusion Research

Takemura

Nagayama

et al. 2012

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This study reports characteristics of the interchange mode-like magnetohydrodynamic (MHD) mode through comparisons between fluctuations measured by electron cyclotron emission (ECE) and Soft X-ray (SX) in the Large Helical Device (LHD). The MHD mode, whose frequency is 0.74 to 2.7 kHz, is enhanced near ρ = 0.8, ι = 1. T e fluctuation data measured by ECE can identify the mode width by using the displacement amplitude profile whereas SX data cannot show the structure clearly. Furthermore the dependence of the width and amplitude on the pressure gradient is shown using T e fluctuations.

“…The MHD fluctuations were measured mainly by MP [6], SX detector arrays [7] and radiometer of ECE [5]. The frequency resolution of ECE is 1 GHz.…”

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Identification of MHD Mode Structure using ECE and SX Measurements

Plasma and Fusion Research

Takemura

Nagayama

et al. 2012

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“…After passing the high/low pass filter, the RF:ECE is downconverted to the lower side band (LSB)/upper side band (USB) intermediate frequency (IF) of up to 20 GHz by mixing with a proper coherent local oscillator (LO). In a conventional filter bank radiometer system, the generated IF is selected by the bandpass filter [3]. In the case of the filter bank system in LHD, the band width is 1 GHz, which corresponds to 2 cm spatial resolution in the radial direction.…”

Section: Analysis Procedures Of Dcecementioning

confidence: 99%

Validation of the Digital Correlation ECE Measurement Technique using Low-Frequency Fluctuation in LHD

Plasma and Fusion Research

Inagaki

Tokuzawa

et al. 2016

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We have proposed and developed a digital correlation ECE (DCECE) measurement method using a highspeed sampling digitizer. This is the first report of the validation of the DCECE using actual data of plasma. The experiment was conducted in the 18th cycle experiments in the large helical device (2014 fiscal year) and a several kHz electron temperature fluctuation was detected in the high ion temperature plasma. The results were compared to the conventional radiometer type ECE measurement. Moreover, it was found that the correlation profile depends on the analytical parameters of the IF conversion.

“…The gauss beam is matched to the corrugated wave guide behind M1 in the air. The detail is described in the reference [2].…”

Section: Ece Measurement Of Lhdmentioning

confidence: 99%

Initial Data of Digital Correlation ECE with a Giga Hertz Sampling Digitizer

Inagaki

Tokuzawa

et al. 2015

EPJ Web of Conferences

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Abstract. The proposed Digital Correlation ECE (DCECE) technique is applied in Large Helical Device. DCECE is realized by the use of the Giga Hertz Sampling Digitizer. The waveform of intermediate frequency band of ECE, whose frequency is several giga hertz, can be discretized and saved directly. The discretized IF data can be used for the analysis of correlation ECE with arbitrary parameter of spatial resolution and temporal resolution. In this paper, the characteristic of DCECE and initial Data in LHD is introduced.