A high-frequency magnetic probe is designed and developed on the XuanL ong-50(EXL-50)spherical torus to measure high-frequency magnetic field fluctuation.The magnetic loop,radio filters,radio-frequency limiter,and dat...A high-frequency magnetic probe is designed and developed on the XuanL ong-50(EXL-50)spherical torus to measure high-frequency magnetic field fluctuation.The magnetic loop,radio filters,radio-frequency limiter,and data acquisition system of the probe are comprehensively examined.The fluctuation data from the EXL-50 plasma are analyzed in the time–frequency domain using fast Fourier transforms.Moreover,distinct high-frequency instabilities are detected using this diagnostic system.In particular,significant frequency chirping is observed,which is consistent with the bumpon-tail drive instability predicted using the Berk–Breizman model.展开更多
Two pairs of high-frequency magnetic probes were installed in the Large Helical Device （LHD）. During the injection of a perpendicular neutral beam, ion cyclotron emissions （ICEs） with the fundamental frequency cor...Two pairs of high-frequency magnetic probes were installed in the Large Helical Device （LHD）. During the injection of a perpendicular neutral beam, ion cyclotron emissions （ICEs） with the fundamental frequency corresponding to the ion cyclotron frequency at the plasma edge were detected, which are the same type of ICE as measured with the former spare ion cyclotron range of frequencies （ICRF） heating antennas. This type of ICE was further investigated with regard to the phase and intensity of signals. Another type of ICE was found in the LHD, and these ICEs were synchronized with bursts of toroidicity induced Alfv^n eigenmodes （TAE） and the rise of intensity of lost ion flux. Therefore the source of these ICEs was thought to be the particles transferred from the core to the outer region of plasma by the TAE bursts. The frequency of ICEs induced by the TAE bursts increases linearly with the magnetic field strength, since the ion cyclotron frequency increases with the magnetic field strength.展开更多
Endoscopic ultrasound(EUS) devices were first designed and manufactured more than 30 years ago,and since then investigators have reported EUS is effective for determining both the staging and the depth of invasion of ...Endoscopic ultrasound(EUS) devices were first designed and manufactured more than 30 years ago,and since then investigators have reported EUS is effective for determining both the staging and the depth of invasion of esophageal and gastric cancers.We review the present status,the methods,and the findings of EUS when used to diagnose and stage early esophageal and gastric cancer.EUS using high-frequency ultrasound probes is more accurate than conventional EUS for the evaluation of the depth of invasion of superficial esophageal carcinoma.The rates of accurate evaluation of the depth of invasion by EUS using high-frequency ultrasound probes were 70%-88% for intramucosal cancer,and 83%-94% for submucosal invasive cancer.But the sensitivity of EUS using high-frequency ultrasound probes for the diagnosis of submucosal invasive cancer was relatively low,making it difficult to confirm minute submucosal invasion.The accuracy of EUS using highfrequency ultrasound probes for early gastric tumor classification can be up to 80% compared with 63% for conventional EUS,although the accuracy of EUS using high-frequency ultrasound probes relatively decreases for those patients with depressed-type lesions,undifferentiated cancer,concomitant ulceration,expanded indications,type 0-Ⅰ lesions,and lesions located in the upper-third of the stomach.A 92% overall accuracy rate was achieved when both the endoscopic appearance and the findings from EUS using high-frequency ultrasound probes were considered together for tumor classification.Although EUS using high-frequency ultrasound probes has limitations,it has a high depth of invasion accuracy and is a useful procedure to distinguish lesions in the esophagus and stomach that are indicated for endoscopic resection.展开更多
基金supported by National Natural Science Foundation of China(No.11706151)。
文摘A high-frequency magnetic probe is designed and developed on the XuanL ong-50(EXL-50)spherical torus to measure high-frequency magnetic field fluctuation.The magnetic loop,radio filters,radio-frequency limiter,and data acquisition system of the probe are comprehensively examined.The fluctuation data from the EXL-50 plasma are analyzed in the time–frequency domain using fast Fourier transforms.Moreover,distinct high-frequency instabilities are detected using this diagnostic system.In particular,significant frequency chirping is observed,which is consistent with the bumpon-tail drive instability predicted using the Berk–Breizman model.
基金supported by NIFS budgets NIFS10ULRR003,NIFS11ULRR703,and NIFS11PLRR302
文摘Two pairs of high-frequency magnetic probes were installed in the Large Helical Device （LHD）. During the injection of a perpendicular neutral beam, ion cyclotron emissions （ICEs） with the fundamental frequency corresponding to the ion cyclotron frequency at the plasma edge were detected, which are the same type of ICE as measured with the former spare ion cyclotron range of frequencies （ICRF） heating antennas. This type of ICE was further investigated with regard to the phase and intensity of signals. Another type of ICE was found in the LHD, and these ICEs were synchronized with bursts of toroidicity induced Alfv^n eigenmodes （TAE） and the rise of intensity of lost ion flux. Therefore the source of these ICEs was thought to be the particles transferred from the core to the outer region of plasma by the TAE bursts. The frequency of ICEs induced by the TAE bursts increases linearly with the magnetic field strength, since the ion cyclotron frequency increases with the magnetic field strength.
文摘Endoscopic ultrasound(EUS) devices were first designed and manufactured more than 30 years ago,and since then investigators have reported EUS is effective for determining both the staging and the depth of invasion of esophageal and gastric cancers.We review the present status,the methods,and the findings of EUS when used to diagnose and stage early esophageal and gastric cancer.EUS using high-frequency ultrasound probes is more accurate than conventional EUS for the evaluation of the depth of invasion of superficial esophageal carcinoma.The rates of accurate evaluation of the depth of invasion by EUS using high-frequency ultrasound probes were 70%-88% for intramucosal cancer,and 83%-94% for submucosal invasive cancer.But the sensitivity of EUS using high-frequency ultrasound probes for the diagnosis of submucosal invasive cancer was relatively low,making it difficult to confirm minute submucosal invasion.The accuracy of EUS using highfrequency ultrasound probes for early gastric tumor classification can be up to 80% compared with 63% for conventional EUS,although the accuracy of EUS using high-frequency ultrasound probes relatively decreases for those patients with depressed-type lesions,undifferentiated cancer,concomitant ulceration,expanded indications,type 0-Ⅰ lesions,and lesions located in the upper-third of the stomach.A 92% overall accuracy rate was achieved when both the endoscopic appearance and the findings from EUS using high-frequency ultrasound probes were considered together for tumor classification.Although EUS using high-frequency ultrasound probes has limitations,it has a high depth of invasion accuracy and is a useful procedure to distinguish lesions in the esophagus and stomach that are indicated for endoscopic resection.
