Article
Instruments & Instrumentation
A. Tema Biwole, L. Porte, S. Coda, A. Fasoli, TCV Team
Summary: This paper presents a diagnostic method for measuring the electron cyclotron emission (ECE) from non-thermal electrons in magnetically confined fusion plasmas. The paper also introduces a novel technique to mitigate refraction, which has been a limitation in previous versions of the diagnostic.
REVIEW OF SCIENTIFIC INSTRUMENTS
(2023)
Article
Nuclear Science & Technology
A. Tema Biwole, L. Porte, A. Fasoli, A. Simonetto, O. D'Arcangelo
Summary: The high vacuum and high temperature compatible viewing dump designed for Vertical ECE experiments in TCV has shown stable performance after seven years of in-vessel exposure, indicating its continued suitability for use in the experiments.
FUSION ENGINEERING AND DESIGN
(2021)
Article
Instruments & Instrumentation
Y. Zhu, Y. Chen, J. -h. Yu, C. Domier, G. Yu, X. Liu, G. Kramer, Y. Ren, A. Diallo, N. C. Luhmann, X. Li
Summary: The article introduces the usage of system-on-chip millimeter wave integrated circuit technology for density fluctuation imaging on the DIII-D tokamak fusion plasma, with customized CMOS chips that provide higher performance.
REVIEW OF SCIENTIFIC INSTRUMENTS
(2022)
Article
Physics, Fluids & Plasmas
R. Bielajew, U. Plank, G. D. Conway, A. E. Hubbard, P. Rodriguez-Fernandez, B. Vanovac, C. Yoo, A. E. White, ASDEX Upgrade Team
Summary: This study investigates the differences in edge turbulence between favorable and unfavorable magnetic configurations in discharges with matched heating power. It is found that in the L-mode phase, the amplitude of edge Trad fluctuations is lower in the favorable configuration, which is accompanied by increased E x B shear compared to the unfavorable case. However, in the unfavorable configuration, the amplitude of Trad fluctuations is higher and develops into weakly coherent mode during the I-mode phase.
Article
Nuclear Science & Technology
S. K. Nielsen, M. P. Gryaznevich, A. S. Jacobsen, T. Jensen, M. Jessen, S. B. Korsholm, J. Rasmussen, M. Salewski, M. G. Senstius, V Naulin, R. D. Nem, M. L. H. Korsgaard, A. C. Nilsson, F. Dam, A. Goltermann, A. C. Pedersen, M. T. Sutherland, T. Aalto, A. Hokkanen, A. Salmi, T. Tala
Summary: The article discusses the experimental results and setup of the small-sized tokamak NORTH located in Denmark. Different heating methods were used during experiments, resulting in rich fluctuation spectra in plasma phases. Future research plans and further installations on NORTH are also discussed.
FUSION ENGINEERING AND DESIGN
(2021)
Article
Nuclear Science & Technology
Juhyeok Jang, Jayhyun Kim, Jaewook Kim, Jeongwon Yoo, M. Lehnen, L. R. Baylor, N. W. Eidietis, D. Shiraki, Soohwan Park
Summary: Shattered pellet injection (SPI) is a promising technique for disruption mitigation in magnetic fusion devices. In KSTAR experiments, an AXUV array diagnostic system is used to obtain radiation distribution during disruptions. A tomographic reconstruction code has been developed for visualizing radiation images on the poloidal plane. The concentration of neon (Ne) significantly affects the radiation energy and current quench duration.
FUSION ENGINEERING AND DESIGN
(2022)
Article
Nuclear Science & Technology
T. Nakano, D. Douai, S. Vartanian, M. Fukumoto, S. H. Son, J. H. Jang, W. Jeong, J. Kim, S-H Hong, H. H. Lee
Summary: This study investigates the dependence of EC injection power, EC injection width, and prefilled He pressure on the efficiency of D2 outgassing. The results show that an increase in EC injection power leads to a clear increase in D2 outgassing. Among the parameters studied, the dependence of D2 outgassing on EC power injection is the most pronounced. It is also found that there exists an optimum prefilled He pressure for achieving maximum D2 outgassing efficiency under constant EC injection power.
NUCLEAR MATERIALS AND ENERGY
(2022)
Article
Physics, Fluids & Plasmas
J. Sinha, P. C. de Vries, M. L. Walker, D. J. Battaglia, F. Turco, A. Hyatt, H. T. Kim, J. Stober, R. Yoneda, Y. Gribov, S. R. Haskey, I Bykov, E. Hollmann, J. L. Herfindal, F. Glass, J. Chen, A. McLean
Summary: New experiments conducted at DIII-D have shown that a high-quality pre-ionized plasma can have a significant impact on the subsequent initiation process. It was found that a minimum EC power of 0.5 MW was required to create ionization in DIII-D, which would scale to roughly 6.5 MW for ITER.
Article
Physics, Fluids & Plasmas
Linzi Liu, Ruihai Tong, Xiaolan Zou, Haotian Chen, Yang Chen, Guanqi Dong, Guangzhou Hao, Xiaoxue He, Yuxiao Han, Xiaoquan Ji, Anshu Liang, Bo Li, Jiquan Li, Yonggao Li, Liang Liu, Zhongbin Shi, Huiling Wei, Fan Xia, Guoliang Xiao, Jiao Yin, Deliang Yu, Boda Yuan, Yiren Zhu, Wulyu Zhong, Min Xu
Summary: Instabilities at multiples of the ion cyclotron frequency have been discovered and termed as core ion cyclotron emission (ICE) in recent HL-2A neutral beam injection heated experiments. This study presents the characteristics of core ICE, including frequency dependence and harmonics features. The observed frequencies are found to be consistent with multiples of the deuterium cyclotron frequency near the magnetic axis. In addition, the core ICE exhibits a predominantly compressional property. The study also demonstrates that the core ICE harmonics represent independent multiple modes, with distinct spectrum features and individual excitation of each harmonic. Notably, the 4th harmonic ICE can be individually excited by varying the plasma current, suggesting a variation in the drive mechanism of core ICE across different frequency ranges.
Article
Chemistry, Physical
Mengqi Liu, Shuang Xia, Wenjian Wan, Jun Qin, Hua Li, Changying Zhao, Lei Bi, Cheng-Wei Qiu
Summary: Using doped InAs multilayers under moderate external magnetic fields with gradient epsilon-near-zero frequencies, broadband non-reciprocal absorption that can be tailored within the mid-infrared spectral region has been demonstrated. The study of magneto-optical absorption has stimulated diverse energy-technology-related explorations, showing potential in breaking the current theoretical efficiency limits of energy devices compared with reciprocal counterparts. However, experimentally realizing strong infrared non-reciprocal absorption remains an open challenge, and existing proposals of non-reciprocal absorbers are restricted to a narrow working waveband.
Article
Instruments & Instrumentation
X. Yu, Z. B. Shi, M. Jiang, G. Y. Yu, Y. L. Zhu, Z. C. Yang, W. Chen, Y. R. Zhu, K. R. Fang, R. H. Tong, J. H. Han, X. R. Zhang
Summary: In this study, a synthetic electron cyclotron emission (ECE) diagnostic is used to interpret ECE signals from preset plasma equilibrium profiles. The results show that the electron temperature (Te) profile in the overlap region can be obtained by receiving ECE signals at the high field side (HFS) of the plasma. The impact of relativistic frequency down-shift has been evaluated and corrected. The measurable range of HFS ECE has been calculated, and higher plasma parameters allow for a wider range of electron temperature measurements.
REVIEW OF SCIENTIFIC INSTRUMENTS
(2022)
Article
Nuclear Science & Technology
Min Jiang, Yilun Zhu, Xin Yu, Zhongbing Shi, N. C. Luhmann, Zhoujun Yang, Weichu Deng, Zengchen Yang, Yu Zhou, Ruihai Tong
Summary: The optical system for the HL-2M ECEI diagnostic, including the LO coupling and RF receiving optics, has been designed and analyzed. The LO optics efficiently illuminates the antenna array and drives the mixer diode, with higher beam intensity for channels probing the plasma edge. The RF optics guides the plasma emission signal to the antenna array and provides three types of field of view for plasma imaging.
FUSION ENGINEERING AND DESIGN
(2023)
Article
Nuclear Science & Technology
Takumi Onchi, Hiroshi Idei, Nagato Yanagi, Yifan Zhang, Kazuo Nakamura, Kengoh Kuroda, Makoto Hasegawa, Ryuya Ikezoe, Kazuaki Hanada, Takeshi Ido, Masahiro Kobayashi, Yuichi Ogawa, Minoru Yoshitani, Takemi Kawamura
Summary: Various scenarios of electron cyclotron heating can be explored in a high toroidal field spherical tokamak. In the QUEST spherical tokamak, doubling the toroidal field results in the emergence of the fundamental resonance layer for 28 GHz electron cyclotron waves. The second-harmonic resonance layer shifts toward the plasma central area. To increase the coil current from 50 to 100 kA, a current source is designed with 125 modules in parallel. The module power supply comprises a bank of lithium-ion capacitors and a DC-DC buck converter. In the bench test of a single module, the current was found to increase linearly and maintained the fiat-top as programmed.
FUSION ENGINEERING AND DESIGN
(2023)
Article
Physics, Fluids & Plasmas
S. G. Lee, J. Seol, H. H. Lee
Summary: This study investigates the toroidal rotation dynamics of KSTAR ohmic plasmas without any external torque sources. It is found that the toroidal rotation velocity increases as the plasma density rises, while the measured radial electric field is generally negative and its magnitude increases with the density. The study introduces a theoretical picture to explain the relation between the radial electric field and the toroidal rotation.
Article
Nuclear Science & Technology
Jiheon Song, Semin Joung, Young-Chul Ghim, Sang-hee Hahn, Juhyeok Jang, Jungpyo Lee
Summary: In this study, a neural network model inspired by a one-dimensional convolution U-net is developed for automatic and accurate acceleration of edge localized mode (ELM) detection from big diagnostic data of fusion devices, overcoming the problems of existing detection algorithms. The model achieves a positive and true prediction rate of approximately 90%, comparable to other algorithms with optimized hyperparameters. The ELM-burst detection methodology used in our model can be beneficial for determining plasma properties and is applicable to feature detection in time-series data of other engineering fields.
NUCLEAR ENGINEERING AND TECHNOLOGY
(2023)
