{"title":"Classical Cross-Field Self-Diffusion Due to Finite Larmor Radius","authors":"Tomonori Takizuka, S. Togo, K. Ibano, Yuki Homma","doi":"10.1585/pfr.18.1203090","DOIUrl":"https://doi.org/10.1585/pfr.18.1203090","url":null,"abstract":"","PeriodicalId":20247,"journal":{"name":"Plasma and Fusion Research","volume":"64 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2023-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139011376","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
K. Iwasaki, A. Ejiri, N. Tsujii, Kouji Shinohara, O. Watanabe, Seowon Jang, Yi Peng, Yu-Ting Lin, F. Adachi, Yiming Tian
{"title":"Anomalous Ion Heating in Lower Hybrid Wave Sustained Plasmas on the TST-2 Spherical Tokamak Device","authors":"K. Iwasaki, A. Ejiri, N. Tsujii, Kouji Shinohara, O. Watanabe, Seowon Jang, Yi Peng, Yu-Ting Lin, F. Adachi, Yiming Tian","doi":"10.1585/pfr.18.1402089","DOIUrl":"https://doi.org/10.1585/pfr.18.1402089","url":null,"abstract":"","PeriodicalId":20247,"journal":{"name":"Plasma and Fusion Research","volume":"172 ","pages":""},"PeriodicalIF":0.8,"publicationDate":"2023-12-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139011409","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Observation of Intermittent Chaos Caused by Delayed Feedback in a Laboratory Plasma","authors":"Takao Fukuyama, Yutaro Sueyoshi","doi":"10.1585/pfr.18.1401088","DOIUrl":"https://doi.org/10.1585/pfr.18.1401088","url":null,"abstract":"","PeriodicalId":20247,"journal":{"name":"Plasma and Fusion Research","volume":"16 1","pages":""},"PeriodicalIF":0.8,"publicationDate":"2023-11-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"139233355","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Taichi SEKI, Daichi KOBAYASHI, Tomohiko ASAI, Tsutomu TAKAHASHI, Jordan MORELLI
{"title":"Increased Relative Velocity due to Enhanced Magnetic Pressure Gradient for the Collision Experiment of High-Beta Plasmoids","authors":"Taichi SEKI, Daichi KOBAYASHI, Tomohiko ASAI, Tsutomu TAKAHASHI, Jordan MORELLI","doi":"10.1585/pfr.18.2401087","DOIUrl":"https://doi.org/10.1585/pfr.18.2401087","url":null,"abstract":"","PeriodicalId":20247,"journal":{"name":"Plasma and Fusion Research","volume":"46 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135942994","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Recently, a new method that applies vector tomography to laser-induced fluorescence has been introduced, enabling the measurement of quasi-periodic two-dimensional velocity field in plasma [H. Arakawa et al., Plasma Fusion Res. 18, 1401032 (2023)]. In this study, we experimentally demonstrated this method in a linear magnetized plasma and presented the initial measurement results. The observed two-dimensional velocity field allowed the evaluation of Reynolds force and its energy transfer.
{"title":"Observation of Quasi-Periodic Two-Dimensional Velocity Fields in Plasma Using Tomographic Laser-Induced Fluorescence Spectroscopy","authors":"Hiroyuki ARAKAWA, Makoto SASAKI, Shigeru INAGAKI, Kenichiro TERASAKA, Yuichi KAWACHI, Fumiyoshi KIN, Takuma YAMADA, Yoshihiko NAGASHIMA, Akihide FUJISAWA","doi":"10.1585/pfr.18.1201086","DOIUrl":"https://doi.org/10.1585/pfr.18.1201086","url":null,"abstract":"Recently, a new method that applies vector tomography to laser-induced fluorescence has been introduced, enabling the measurement of quasi-periodic two-dimensional velocity field in plasma [H. Arakawa et al., Plasma Fusion Res. 18, 1401032 (2023)]. In this study, we experimentally demonstrated this method in a linear magnetized plasma and presented the initial measurement results. The observed two-dimensional velocity field allowed the evaluation of Reynolds force and its energy transfer.","PeriodicalId":20247,"journal":{"name":"Plasma and Fusion Research","volume":"42 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136057999","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Ryosuke HIRAKA, Jabir AL SALAMI, Takumi TSUGIKI, Kazuaki HANADA, Changhong HU
Liquid metal divertors are expected to have higher thermal load tolerance compared with solid divertors. Precise prediction of liquid metal behavior using magnetohydrodynamic (MHD) simulation enables the practical designing of a liquid metal divertor. The aim of this study is to confirm the accuracy of an MHD simulation that is developed for liquid metal flow prediction. As a benchmark test of the MHD simulation, a comparison of the Galinstan flowing through a vertical magnetic field and the simulated results was performed, and qualitative reproduction using the MHD simulation was confirmed. In addition, the source of wave creation and the causes of failure of the quantitative reproduction were investigated, which is may caused by the variations of the Galinstan surface tension.
{"title":"Deformation Induced by Magnetic Field on GaInSn Flow Surface","authors":"Ryosuke HIRAKA, Jabir AL SALAMI, Takumi TSUGIKI, Kazuaki HANADA, Changhong HU","doi":"10.1585/pfr.18.2405083","DOIUrl":"https://doi.org/10.1585/pfr.18.2405083","url":null,"abstract":"Liquid metal divertors are expected to have higher thermal load tolerance compared with solid divertors. Precise prediction of liquid metal behavior using magnetohydrodynamic (MHD) simulation enables the practical designing of a liquid metal divertor. The aim of this study is to confirm the accuracy of an MHD simulation that is developed for liquid metal flow prediction. As a benchmark test of the MHD simulation, a comparison of the Galinstan flowing through a vertical magnetic field and the simulated results was performed, and qualitative reproduction using the MHD simulation was confirmed. In addition, the source of wave creation and the causes of failure of the quantitative reproduction were investigated, which is may caused by the variations of the Galinstan surface tension.","PeriodicalId":20247,"journal":{"name":"Plasma and Fusion Research","volume":"46 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136058000","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
One of the greatest challenges of simulating the high heat flux on the divertor in linear plasma devices is the achievement of ion temperatures of > 100 eV under high densities (≥1019 m−3). The slow wave in the ion cyclotron range of frequency has been employed for ion heating in GAMMA 10/PDX and demonstrated its high efficiency at middle densities of 1018 m−3. However, at high densities (≥1019 m−3), exciting the slow wave in the center of the plasma by external antennas becomes challenging. Alternatively, we have demonstrated the excitation of the difference-frequency (DF) slow wave using two high-density-applicable fast waves. In this study, we first applied the charge-exchange neutral particle analyzer (CX-NPA) to a DF wave heating experiment. Even when the bulk temperature did not increase significantly, the high-energy ions in the > 0.5 keV range were measured during the experiment. Such high-energy ions were only measured in the central line of sight of CX-NPA, indicating that the power deposition from the DF wave was largely centered and differed greatly from the normal heating scheme using external antennas. This result will motivate further pursue of exploiting nonlinearity of plasma media to produce different heating accessibilities.
{"title":"High-Energy Ion Generation During Difference-Frequency ICRF Wave Heating in GAMMA 10/PDX","authors":"Yudai SUGIMOTO, Mafumi HIRATA, Yousuke NAKASHIMA, Makoto ICHIMURA, Doyeon KIM, Takaaki KOZAWA, Shunya ENDO, Ryo KOBAYASHI, Ryuya IKEZOE, Naomichi EZUMI, Satoshi TOGO, Masayuki YOSHIKAWA, Junko KOHAGURA, Mizuki SAKAMOTO","doi":"10.1585/pfr.18.2402084","DOIUrl":"https://doi.org/10.1585/pfr.18.2402084","url":null,"abstract":"One of the greatest challenges of simulating the high heat flux on the divertor in linear plasma devices is the achievement of ion temperatures of > 100 eV under high densities (≥1019 m−3). The slow wave in the ion cyclotron range of frequency has been employed for ion heating in GAMMA 10/PDX and demonstrated its high efficiency at middle densities of 1018 m−3. However, at high densities (≥1019 m−3), exciting the slow wave in the center of the plasma by external antennas becomes challenging. Alternatively, we have demonstrated the excitation of the difference-frequency (DF) slow wave using two high-density-applicable fast waves. In this study, we first applied the charge-exchange neutral particle analyzer (CX-NPA) to a DF wave heating experiment. Even when the bulk temperature did not increase significantly, the high-energy ions in the > 0.5 keV range were measured during the experiment. Such high-energy ions were only measured in the central line of sight of CX-NPA, indicating that the power deposition from the DF wave was largely centered and differed greatly from the normal heating scheme using external antennas. This result will motivate further pursue of exploiting nonlinearity of plasma media to produce different heating accessibilities.","PeriodicalId":20247,"journal":{"name":"Plasma and Fusion Research","volume":"49 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136058142","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
A plasma recombination experiment was carried out using the linear electron cyclotron resonance (ECR) plasma device NUMBER as a preliminary step for forming a detached plasma. The electron density measured by an electrostatic probe in a divertor-simulated region was successfully increased up to approximately 6×1017 m−3. This increase was realized by installing an additional gas feed system to the region and using a circular polarizer to control the microwave polarization. Passive spectroscopic measurements performed on the high-density plasma yielded line spectra of He I 23P−n3D for the principal quantum number n ≤13, which are characterstic of helium recombining plasma. The line spectra were used to calculate an electron temperature of approximately 0.055 eV and an electron density of approximately 1.33 × 1018 m−3 by the Boltzmann plot method and Saha–Boltzmann equation, respectively.
利用线性电子回旋共振(ECR)等离子体装置NUMBER进行了等离子体复合实验，作为分离等离子体形成的初步步骤。静电探针测量的电子密度成功地增加到大约6×1017 m−3。这种增加是通过在该区域安装额外的气体供给系统和使用圆形偏振器来控制微波偏振来实现的。对高密度等离子体进行了被动光谱测量，得到了主量子数n≤13的He I 23P−n3D谱线，这是氦复合等离子体的特征。利用谱线计算得到的电子温度约为0.055 eV，电子密度约为1.33 × 1018 m−3，分别采用玻尔兹曼图法和saha -玻尔兹曼方程。
{"title":"Volumetric Recombination in the Linear ECR Plasma Device NUMBER","authors":"Konan YAGASAKI, Atsushi OKAMOTO, Takaaki FUJITA, Minami SUGIMOTO, Shunya HIGUCHI, Muneo KOIKE, Koki SATO, Yuto YAMADA","doi":"10.1585/pfr.18.2401082","DOIUrl":"https://doi.org/10.1585/pfr.18.2401082","url":null,"abstract":"A plasma recombination experiment was carried out using the linear electron cyclotron resonance (ECR) plasma device NUMBER as a preliminary step for forming a detached plasma. The electron density measured by an electrostatic probe in a divertor-simulated region was successfully increased up to approximately 6×1017 m−3. This increase was realized by installing an additional gas feed system to the region and using a circular polarizer to control the microwave polarization. Passive spectroscopic measurements performed on the high-density plasma yielded line spectra of He I 23P−n3D for the principal quantum number n ≤13, which are characterstic of helium recombining plasma. The line spectra were used to calculate an electron temperature of approximately 0.055 eV and an electron density of approximately 1.33 × 1018 m−3 by the Boltzmann plot method and Saha–Boltzmann equation, respectively.","PeriodicalId":20247,"journal":{"name":"Plasma and Fusion Research","volume":"133 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135923141","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Systematic experiments were carried out in the 23rd Large Helical Device experiment campaign to explore the interaction between fast ions and ion-scale turbulence focusing on the impact of varying the power of the neutral beam (NB) injection. During the NB heating, two distinct phases of turbulence reduction were observed. The first phase was a transient reduction of about 10 msec immediately following the initiation of the NB injection. This reduction in turbulence was noticeable even while the electron density and temperature profiles remained nearly unchanged. The second phase involved a continuous reduction that maintained a lower turbulence level throughout the duration of the NB injection. The physics mechanisms underlying these phenomena are not fully understood yet. However, it is likely that two distinct processes of turbulence stabilization, each corresponding to the transient and continuous reduction phases, are at work due to the influence of the fast ions.
{"title":"Observation of Interaction between Fast Ions and Turbulence in Large Helical Device","authors":"Hikona SAKAI, Kenji TANAKA, Toshiki KINOSHITA, Kunihiro OGAWA","doi":"10.1585/pfr.18.2402069","DOIUrl":"https://doi.org/10.1585/pfr.18.2402069","url":null,"abstract":"Systematic experiments were carried out in the 23rd Large Helical Device experiment campaign to explore the interaction between fast ions and ion-scale turbulence focusing on the impact of varying the power of the neutral beam (NB) injection. During the NB heating, two distinct phases of turbulence reduction were observed. The first phase was a transient reduction of about 10 msec immediately following the initiation of the NB injection. This reduction in turbulence was noticeable even while the electron density and temperature profiles remained nearly unchanged. The second phase involved a continuous reduction that maintained a lower turbulence level throughout the duration of the NB injection. The physics mechanisms underlying these phenomena are not fully understood yet. However, it is likely that two distinct processes of turbulence stabilization, each corresponding to the transient and continuous reduction phases, are at work due to the influence of the fast ions.","PeriodicalId":20247,"journal":{"name":"Plasma and Fusion Research","volume":"31 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2023-09-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135865351","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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