TY - JOUR
T1 - Development of a high CMRR magnetic probe for the biased plasma in TU-Heliac
AU - Koike, Satoshi
AU - Kitajima, Sumio
AU - Okamoto, Atsushi
AU - Ishii, Keiichi
AU - Sato, Yu
AU - Tachibana, Jo
AU - Oku, Toshihiro
AU - Shimizu, Kosuke
AU - Inagaki, Shigeru
AU - Suzuki, Yasuhiro
AU - Takahashi, Hiromi
AU - Takayama, Masakazu
N1 - Publisher Copyright:
© 2014 The Japan Society of Plasma Science and Nuclear Fusion Research.
PY - 2014
Y1 - 2014
N2 - The plasma in Tohoku University Heliac (TU-Heliac) is biased by a hot cathode that drives the J × B poloidal rotation. In the biased plasma, a density collapse accompanied by high-frequency bursting density and potential fluctuations was observed. To eliminate the effect of potential fluctuations and to measure the magnetic fluctuation, a high common mode rejection ratio (CMRR) magnetic probe with a preamplifier at the probe head in a vacuum vessel was designed and installed. Owing to the absolute calibration, the magnetic probe has a high magnetic sensitivity of 104 V/T (@100 kHz), high CMRR of -75 dB (@500 kHz), and frequency bandwidth DC -1MHz. In the biased plasma, the power spectrum of the normal mode signal was 104 times larger than that of the common mode signal in all frequency ranges, which indicates that the probe can successfully minimize the capacitive pickup noise relative to the actual magnetic fluctuation signal. In addition, we successfully observed the broad spectrum (100 kHz < f < 300 kHz) of the magnetic fluctuation and MHD instability in the biased plasma in TU-Heliac.
AB - The plasma in Tohoku University Heliac (TU-Heliac) is biased by a hot cathode that drives the J × B poloidal rotation. In the biased plasma, a density collapse accompanied by high-frequency bursting density and potential fluctuations was observed. To eliminate the effect of potential fluctuations and to measure the magnetic fluctuation, a high common mode rejection ratio (CMRR) magnetic probe with a preamplifier at the probe head in a vacuum vessel was designed and installed. Owing to the absolute calibration, the magnetic probe has a high magnetic sensitivity of 104 V/T (@100 kHz), high CMRR of -75 dB (@500 kHz), and frequency bandwidth DC -1MHz. In the biased plasma, the power spectrum of the normal mode signal was 104 times larger than that of the common mode signal in all frequency ranges, which indicates that the probe can successfully minimize the capacitive pickup noise relative to the actual magnetic fluctuation signal. In addition, we successfully observed the broad spectrum (100 kHz < f < 300 kHz) of the magnetic fluctuation and MHD instability in the biased plasma in TU-Heliac.
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U2 - 10.1585/pfr.9.1202053
DO - 10.1585/pfr.9.1202053
M3 - Article
AN - SCOPUS:84988422551
VL - 9
JO - Plasma and Fusion Research
JF - Plasma and Fusion Research
SN - 1880-6821
M1 - 1202053
ER -