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1. Extragalactic fast X-ray transient from a weak relativistic jet associated with a Type Ic-BL supernova

Author

Sun, H., Li, W. -X., Liu, L. -D., Gao, H., Wang, X. -F., Yuan, W., Zhang, B., Filippenko, A. V., Xu, D., An, T., Ai, S., Brink, T. G., Liu, Y., Liu, Y. -Q., Wang, C. -Y., Wu, Q. -Y., Wu, X. -F., Yang, Y., Zhang, B. -B., Zheng, W. -K., Ahumada, T., Dai, Z. -G., Delaunay, J., Elias-Rosa, N., Benetti, S., Fu, S. -Y., Howell, D. A., Huang, Y. -F., Kasliwal, M. M., Karambelkar, V., Stein, R., Lei, W. -H., Lian, T. -Y., Peng, Z. -K., Ridnaia, A. V., Svinkin, D. S., Wang, X. -Y., Wang, A. -L., Wei, D. -M., An, J., Andrews, M., Bai, J. -M, Dai, C. -Y., Ehgamberdiev, S. A., Fan, Z., Farah, J., Feng, H. -C., Fynbo, J. P. U., Guo, W. -J., Guo, Z., Hu, M. -K., Hu, J. -W., Jiang, S. -Q., Jin, J. -J., Li, A., Li, J. -D., Li, R. -Z., Liang, Y. -F., Ling, Z. -X., Liu, X., Mao, J. -R., McCully, C., Mirzaqulov, D., Newsome, M., Gonzalez, E. Padilla, Pan, X., Terreran, G., Tinyanont, S., Wang, B. -T., Wang, L. -Z., Wen, X. -D., Xiang, D. -F., Xue, S. -J., Yang, J., Zhu, Z. -P., Cai, Z. -M., Castro-Tirado, A. J., Chen, F. -S., Chen, H. -L., Chen, T. -X., Chen, W., Chen, Y. -H., Chen, Y. -F., Chen, Y., Cheng, H. -Q., Cordier, B., Cui, C. -Z., Cui, W. -W., Dai, Y. -F., Fan, D. -W., Feng, H., Guan, J., Han, D. -W., Hou, D. -J., Hu, H. -B., Huang, M. -H., Huo, J., Jia, S. -M., Jia, Z. -Q., Jiang, B. -W., Jin, C. -C., Jin, G., Kuulkers, E., Li, C. -K., Li, D. -Y., Li, J. -F., Li, L. -H., Li, M. -S., Li, W., Li, Z. -D., Liu, C. -Z, Liu, H. -Y., Liu, H. -Q., Liu, M. -J., Lu, F. -J., Luo, L. -D., Ma, J., Mao, X., Nandra, K., O'Brien, P., Pan, H. -W., Rau, A., Rea, N., Sanders, J., Song, L. -M., Sun, S. -L., Sun, X. -J., Tan, Y. -Y., Tang, Q. -J., Tao, Y. -H., Wang, H., Wang, J., Wang, L., Wang, W. -X., Wang, Y. -L., Wang, Y. -S., Xiong, D. -R., Xu, H. -T., Xu, J. -J., Xu, X. -P., Xu, Y. -F., Xu, Z., Xue, C. -B., Xue, Y. -L., Yan, A. -L., Yang, H. -N., Yang, X. -T., Yang, Y. -J., Zhang, C., Zhang, J., Zhang, M., Zhang, S. -N., Zhang, W. -D., Zhang, W. -J., Zhang, Y. -H., Zhang, Z., Zhang, Z. -L., Zhao, D. -H., Zhao, H. -S., Zhao, X. -F., Zhao, Z. -J., Zhou, Y. -L., Zhu, Y. -X., and Zhu, Z. -C.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

Massive stars end their life as core-collapse supernovae, amongst which some extremes are Type Ic broad-lined supernovae associated with long-duration gamma-ray bursts (LGRBs) having powerful relativistic jets. Their less-extreme brethren make unsuccessful jets that are choked inside the stars, appearing as X-ray flashes or low-luminosity GRBs. On the other hand, there exists a population of extragalactic fast X-ray transients (EFXTs) with timescales ranging from seconds to thousands of seconds, whose origins remain obscure. Known sources that contribute to the observed EFXT population include the softer analogs of LGRBs, shock breakouts of supernovae, or unsuccessful jets. Here, we report the discovery of the bright X-ray transient EP240414a detected by the Einstein Probe (EP), which is associated with the Type Ic supernova SN 2024gsa at a redshift of 0.401. The X-ray emission evolution is characterised by a very soft energy spectrum peaking at < 1.3 keV, which makes it distinct from known LGRBs, X-ray flashes, or low-luminosity GRBs. Follow-up observations at optical and radio bands revealed the existence of a weak relativistic jet that interacts with an extended shell surrounding the progenitor star. Located on the outskirts of a massive galaxy, this event reveals a new population of explosions of Wolf-Rayet stars characterised by a less powerful engine that drives a successful but weak jet, possibly owing to a progenitor star with a smaller core angular momentum than in traditional LGRB progenitors., Comment: 43 pages, 9 figures, 4 tables, submitted. Comments are welcome

Published
2024

2. Soft X-ray prompt emission from a high-redshift gamma-ray burst EP240315a

Author

Liu, Y., Sun, H., Xu, D., Svinkin, D. S., Delaunay, J., Tanvir, N. R., Gao, H., Zhang, C., Chen, Y., Wu, X. -F., Zhang, B., Yuan, W., An, J., Bruni, G., Frederiks, D. D., Ghirlanda, G., Hu, J. -W., Li, A., Li, C. -K., Li, J. -D., Malesani, D. B., Piro, L., Raman, G., Ricci, R., Troja, E., Vergani, S. D., Wu, Q. -Y., Yang, J., Zhang, B. -B., Zhu, Z. -P., Postigo, A. de Ugarte, Demin, A. G., Dobie, D., Fan, Z., Fu, S. -Y., Fynbo, J. P. U., Geng, J. -J., Gianfagna, G., Hu, Y. -D., Huang, Y. -F., Jiang, S. -Q., Jonker, P. G., Julakanti, Y., Kennea, J. A., Kokomov, A. A., Kuulkers, E., Lei, W. -H., Leung, J. K., Levan, A. J., Li, D. -Y., Li, Y., Littlefair, S. P., Liu, X., Lysenko, A. L., Ma, Y. -N., Martin-Carrillo, A., O'Brien, P., Parsotan, T., Quirola-Vasquez, J., Ridnaia, A. V., Ronchini, S., Rossi, A., Mata-Sanchez, D., Schneider, B., Shen, R. -F., Thakur, A. L., Tohuvavohu, A., Torres, M. A. P., Tsvetkova, A. E., Ulanov, M. V., Wei, J. -J., Xiao, D., Yin, Y. -H. I., Bai, M., Burwitz, V., Cai, Z. -M., Chen, F. -S., Chen, H. -L., Chen, T. -X., Chen, W., Chen, Y. -F., Chen, Y. -H., Cheng, H. -Q., Cui, C. -Z., Cui, W. -W., Dai, Y. -F., Dai, Z. -G., Eder, J., Fan, D. -W., Feldman, C., Feng, H., Feng, Z., Friedrich, P., Gao, X., Guan, J., Han, D. -W, Han, J., Hou, D. -J., Hu, H. -B., Hu, T., Huang, M. -H., Huo, J., Hutchinson, I., Ji, Z., Jia, S. -M., Jia, Z. -Q., Jiang, B. -W., Jin, C. -C., Jin, G., Jin, J. -J., Keereman, A., Lerman, H., Li, J. -F., Li, L. -H., Li, M. -S., Li, W., Li, Z. -D., Lian, T. -Y., Liang, E. -W., Ling, Z. -X., Liu, C. -Z., Liu, H. -Y., Liu, H. -Q., Liu, M. -J., Liu, Y. -R., Lu, F. -J., LU, H. -J., Luo, L. -D., Ma, F. L., Ma, J., Mao, J. -R., Mao, X., McHugh, M., Meidinger, N., Nandra, K., Osborne, J. P., Pan, H. -W., Pan, X., Ravasio, M. E., Rau, A., Rea, N., Rehman, U., Sanders, J., Santovincenzo, A., Song, L. -M., Su, J., Sun, L. -J., Sun, S. -L., Sun, X. -J., Tan, Y. -Y., Tang, Q. -J., Tao, Y. -H., Tong, J. -Z., Wang, H., Wang, J., Wang, L., Wang, W. -X., Wang, X. -F., Wang, X. -Y., Wang, Y. -L., Wang, Y. -S., Wei, D. -M., Willingale, R., Xiong, S. -L., Xu, H. -T., Xu, J. -J., Xu, X. -P., Xu, Y. -F., Xu, Z., Xue, C. -B., Xue, Y. -L., Yan, A. -L., Yang, F., Yang, H. -N., Yang, X. -T., Yang, Y. -J, Yu, Y. -W., Zhang, J., Zhang, M., Zhang, S. -N., Zhang, W. -D., Zhang, W. -J., Zhang, Y. -H., Zhang, Z., Zhang, Z. -L., Zhao, D. -H., Zhao, H. -S., Zhao, X. -F., Zhao, Z. -J., Zhou, L. -X., Zhou, Y. -L., Zhu, Y. -X., Zhu, Z. -C., and Zuo, X. -X.

Subjects
Astrophysics - High Energy Astrophysical Phenomena
Abstract

Long gamma-ray bursts (GRBs) are believed to originate from core collapse of massive stars. High-redshift GRBs can probe the star formation and reionization history of the early universe, but their detection remains rare. Here we report the detection of a GRB triggered in the 0.5--4 keV band by the Wide-field X-ray Telescope (WXT) on board the Einstein Probe (EP) mission, designated as EP240315a, whose bright peak was also detected by the Swift Burst Alert Telescope and Konus-Wind through off-line analyses. At a redshift of $z=4.859$, EP240315a showed a much longer and more complicated light curve in the soft X-ray band than in gamma-rays. Benefiting from a large field-of-view ($\sim$3600 deg$^2$) and a high sensitivity, EP-WXT captured the earlier engine activation and extended late engine activity through a continuous detection. With a peak X-ray flux at the faint end of previously known high-$z$ GRBs, the detection of EP240315a demonstrates the great potential for EP to study the early universe via GRBs., Comment: 41 pages, 8 figures, 7 tables

Published
2024

3. I-mode Plasma Confinement Improvement by Real-time Lithium Injection and its Classification on EAST Tokamak

Author

Zhong, X. M., Zou, X. L., Liu, A. D., Song, Y. T., Zhuang, G., Liu, H. Q., Xu, L. Q., Li, E. Z., Zhang, B., Zuo, G. Z., Wang, Z., Zhou, C., Zhang, J., Shi, W. X., Gao, L. T., Wang, S. F., Gao, W., Jia, T. Q., Zang, Q., Zhao, H. L., Wang, M., Xu, H. D., Wang, X. J., Gao, X., Lin, X. D., Li, J. G., Group, EAST I-mode Working, and Team, EAST

Subjects
Physics - Plasma Physics
Abstract

I-mode is a promising regime for future fusion reactors due to the high energy confinement and the moderate particle confinement. However, the effect of lithium, which has been widely applied for particle recycling and impurity control, on I-mode plasma is still unclear. Recently, experiments of real-time lithium powder injection on I-mode plasma have been carried out in EAST Tokamak. It was found that the confinement performance of the I-mode can be improved by the lithium powder injection, which can strongly reduce electron turbulence (ET) and then trigger ion turbulence (IT). Four different regimes of I-mode have been identified in EAST. The Type I I-mode plasma is characterized by the weakly coherent mode (WCM) and the geodesic-acoustic mode (GAM). The Type II I-mode is featured as the WCM and the edge temperature ring oscillation (ETRO). The Type III I-mode corresponds to the plasma with the co-existence of ETRO, GAM, and WCM. The Type IV I-mode denotes the plasma with only WCM but without ETRO and GAM. It has been observed that WCM and ETRO are increased with lithium powder injection due to the reduction of ion and electron turbulence, and the enhancement of the pedestal electron temperature gradient. EAST experiments demonstrate that lithium powder injection is an effective tool for real-time control and confinement improvement of I-mode plasma.

Published
2024

5. Characteristics of the edge temperature ring oscillation during stationary improved confnement mode in EAST

Author

Liu, A. D., Zou, X. L., Zhong, X. M., Song, Y. T., Han, M. K., Duan, Y. M., Liu, H. Q., Wang, T. B., Li, E. Z., Zhang, L., Feng, X., Zhuang, G., and group, EAST I-mode working

Subjects
Physics - Plasma Physics
Abstract

I-mode is a natural ELMy-free regime with H-mode like improved energy confnement and L-mode like particle confnement, making it an attractive scenario for future tokamak based fusion reactors. A kind of low frequency oscillation was widely found and appeared to be unique in I-mode, with the frequency between stationary zonal flow and geodesic-acoustic mode (GAM) zonal flow. In EAST, 90 percent I-mode shots have such mode, called edge temperature ring oscillation (ETRO). The mode probably plays an important role during I-mode development and sustainment, while investigations are needed to clarify the differences between ETRO and the similar mode named as low frequency edge oscillation (LFEO) in AUG and C-Mod, especially whether it is still GAM. In the paper, the ETRO characteristics in EAST were investigated in detail and most do not agree with GAM, including that 1) during L-I transition with edge Te and Ti both increasing, ETRO has a smaller frequency than GAM; 2) ETRO has distinct harmonics in various diagnostics; 3) The magnetic component of ETRO is dominated by m = 1 structure; 4) ETRO is accompanied by turbulence transition between electron-scale and ion-scale; 5) As I-mode approaching to H-mode, ETRO frequency would decrease rapidly with Te increasing. These features imply that ETRO is probably caused by the stationary zonal flow with fnite frequency. Moreover, other damping mechanisms need to be involved besides collision in the Imode edge region. It was found that modest fueling could decrease the ETRO intensity with the I-mode confnement sustaining, suggesting that supersonic molecular beam injection (SMBI) could be used as an effective tool to control ETRO., Comment: 23 pages, 16 figures

Published
2023

6. The Lobster Eye Imager for Astronomy Onboard the SATech-01 Satellite

Author

Ling, Z. X., Sun, X. J., Zhang, C., Sun, S. L., Jin, G., Zhang, S. N., Zhang, X. F., Chang, J. B., Chen, F. S., Chen, Y. F., Cheng, Z. W., Fu, W., Han, Y. X., Li, H., Li, J. F., Li, Y., Li, Z. D., Liu, P. R., Lv, Y. H., Ma, X. H., Tang, Y. J., Wang, C. B., Xie, R. J., Xue, Y. L., Yan, A. L., Zhang, Q., Bao, C. Y., Cai, H. B., Cheng, H. Q., Cui, C. Z., Dai, Y. F., Fan, D. W., Hu, H. B., Hu, J. W., Huang, M. H., Jia, Z. Q., Jin, C. C., Li, D. Y., Li, J. Q., Liu, H. Y., Liu, M. J., Liu, Y., Pan, H. W., Qiu, Y. L., Sugizaki, M., Sun, H., Wang, W. X., Wang, Y. L., Wu, Q. Y., Xu, X. P., Xu, Y. F., Yang, H. N., Yang, X., Zhang, B., Zhang, M., Zhang, W. D., Zhang, Z., Zhao, D. H., Cong, X. Q., Jiang, B. W., Li, L. H., Qiu, X. B., Sun, J. N., Su, D. T., Wang, J., Wu, C., Xu, Z., Yang, X. M., Zhang, S. K., Zhang, N., Zhu, Y. F., Ban, H. Y., Bi, X. Z., Cai, Z. M., Chen, W., Chen, X., Chen, Y. H., Cui, Y., Duan, X. L., Feng, Z. G, Gao, Y., He, J. W., He, T., Huang, J. J., Li, F., Li, J. S., Li, T. J., Li, T. T., Liu, H. Q., Liu, L., Liu, R., Liu, S., Meng, N., Shi, Q., Sun, A. T., Wang, Y. M., Wang, Y. B., Wu, H. C., Xu, D. X, Yang, Y. Q, Yang, Y., Yu, X. S., Zhang, K. X., Zhang, Y. L., Zhang, Y. H., Zhang, Y. T., Zhou, H., Zhu, X. C., Cheng, J. S., Qin, L., Wang, L., Wang, Q. L., Bai, M., Gao, R. L., Ji, Z., Liu, Y. R., Ma, F. L., Shi, Y. J., Su, J., Tan, Y. Y., Tong, J. Z., Xu, H. T., Xue, C. B., Xue, G. F., and Yuan, W.

Subjects
Astrophysics - Instrumentation and Methods for Astrophysics, High Energy Physics - Experiment, Physics - Instrumentation and Detectors
Abstract

The Lobster Eye Imager for Astronomy (LEIA), a pathfinder of the Wide-field X-ray Telescope of the Einstein Probe (EP) mission, was successfully launched onboard the SATech-01 satellite of the Chinese Academy of Sciences on 27 July 2022. In this paper, we introduce the design and on-ground test results of the LEIA instrument. Using state-of-the-art Micro-Pore Optics (MPO), a wide field-of-view (FoV) of 346 square degrees (18.6 degrees * 18.6 degrees) of the X-ray imager is realized. An optical assembly composed of 36 MPO chips is used to focus incident X-ray photons, and four large-format complementary metal-oxide semiconductor (CMOS) sensors, each of 6 cm * 6 cm, are used as the focal plane detectors. The instrument has an angular resolution of 4 - 8 arcmin (in FWHM) for the central focal spot of the point spread function, and an effective area of 2 - 3 cm2 at 1 keV in essentially all the directions within the field of view. The detection passband is 0.5 - 4 keV in the soft X-rays and the sensitivity is 2 - 3 * 10-11 erg s-1 cm-2 (about 1 mini-Crab) at 1,000 second observation. The total weight of LEIA is 56 kg and the power is 85 W. The satellite, with a design lifetime of 2 years, operates in a Sun-synchronous orbit of 500 km with an orbital period of 95 minutes. LEIA is paving the way for future missions by verifying in flight the technologies of both novel focusing imaging optics and CMOS sensors for X-ray observation, and by optimizing the working setups of the instrumental parameters. In addition, LEIA is able to carry out scientific observations to find new transients and to monitor known sources in the soft X-ray band, albeit limited useful observing time available., Comment: Accepted by RAA

Published
2023
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7. First wide field-of-view X-ray observations by a lobster eye focusing telescope in orbit

Author

Zhang, C., Ling, Z. X., Sun, X. J., Sun, S. L., Liu, Y., Li, Z. D., Xue, Y. L., Chen, Y. F., Dai, Y. F., Jia, Z. Q., Liu, H. Y., Zhang, X. F., Zhang, Y. H., Zhang, S. N., Chen, F. S., Cheng, Z. W., Fu, W., Han, Y. X., Li, H., Li, J. F., Li, Y., Liu, P. R., Ma, X. H., Tang, Y. J., Wang, C. B., Xie, R. J., Yan, A. L., Zhang, Q., Jiang, B. W., Jin, G., Li, L. H., Qiu, X. B., Su, D. T., Sun, J. N., Xu, Z., Zhang, S. K., Zhang, Z., Zhang, N., Bi, X. Z., Cai, Z. M., He, J. W., Liu, H. Q., Zhu, X. C., Cheng, H. Q., Cui, C. Z., Fan, D. W., Hu, H. B., Huang, M. H., Jin, C. C., Li, D. Y., Pan, H. W., Wang, W. X., Xu, Y. F., Yang, X., Zhang, B., Zhang, M., Zhang, W. D., Zhao, D. H., Bai, M., Ji, Z., Liu, Y. R., Ma, F. L., Su, J., Tong, J. Z., Wang, Y. S., Zhao, Z. J., Feldman, C., O'Brien, P., Osborne, J. P., Willingale, R., Burwitz, V., Hartner, G., Langmeier, A., Müller, T., Rukdee, S., Schmidt, T., Kuulkers, E., and Yuan, W.

Subjects
Astrophysics - High Energy Astrophysical Phenomena, Astrophysics - Instrumentation and Methods for Astrophysics
Abstract

As a novel X-ray focusing technology, lobster eye micro-pore optics (MPO) feature both a wide observing field of view and true imaging capability, promising sky monitoring with significantly improved sensitivity and spatial resolution in soft X-rays. Since first proposed by Angel (1979), the optics have been extensively studied, developed and trialed over the past decades. In this Letter, we report on the first-light results from a flight experiment of the Lobster Eye Imager for Astronomy ($LEIA$), a pathfinder of the wide-field X-ray telescope of the Einstein Probe mission. The piggyback imager, launched in July 2022, has a mostly un-vignetted field of view of $18.6^\circ \times 18.6^\circ $. Its spatial resolution is in the range of 4$-$7 arcmin in FWHM and the focal spot effective area is 2$-$3 cm$^2$, both showing only mild fluctuations across the field of view. We present images of the Galactic center region, Sco X-1 and the diffuse Cygnus Loop nebular taken in snapshot observations over 0.5$-$4 keV. These are truly wide-field X-ray images of celestial bodies observed, for the first time, by a focusing imaging telescope. Initial analyses of the in-flight data show excellent agreement between the observed images and the on-ground calibration and simulations. The instrument and its characterization are briefly described, as well as the flight experiment. The results provide a solid basis for the development of the present and proposed wide-field X-ray missions using lobster eye MPO., Comment: 11 pages, 4 figures. Accepted for publication in Astrophysical Journal Letter

Published
2022
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8. Characterization of Pedestal Burst Instabilities during I-mode to H-mode Transition in the EAST Tokamak

Author

Zhong, X. M., Zou, X. L., Liu, A. D., Song, Y. T., Zhuang, G., Li, E. Z., Zhang, B., Zhang, J., Zhou, C., Feng, X., Duan, Y. M., Ding, R., Liu, H. Q., Lv, B., Wang, L., Xu, L. Q., Zhang, L., Zhao, Hailin, Zhang, Tao, Zang, Qing, Ding, B. J., Li, M. H., Qin, C. M., Wang, X. J., Zhang, X. J., and Team, EAST

Subjects
Physics - Plasma Physics
Abstract

Quasi-periodic Pedestal Burst Instabilities (PBIs), featuring alternative turbulence suppression and bursts, have been clearly identified by various edge diagnostics during I-mode to H-mode transition in the EAST Tokamak. The radial distribution of the phase perturbation caused by PBI shows that PBI is localized in the pedestal. Prior to each PBI, a significant increase of density gradient close to the pedestal top can be clearly distinguished, then the turbulence burst is generated, accompanied by the relaxation of the density profile, and then induces an outward particle flux. The relative density perturbation caused by PBIs is about $6 \sim 8\%$. Statistic analyses show that the pedestal normalized density gradient triggering the first PBI has a threshold value, mostly in the range of $22 \sim 24$, suggesting that a PBI triggering instability could be driven by the density gradient. And the pedestal normalized density gradient triggering the last PBI is about $30 \sim 40$ and seems to increase with the loss power and the chord-averaged density. In addition, the frequency of PBI is likely to be inversely proportional to the chord-averaged density and the loss power. These results suggest that PBIs and the density gradient prompt increase prior to PBIs can be considered as the precursor for controlling I-H transition.

Published
2021
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9. Influence of Micro-turbulence on Neoclassical Tearing Mode Onset

Author

Shi, Tonghui, Wei, L., Wang, H. H., Li, E., Shen, B., Qian, J. P., Wang, Y. M., Zhang, T., Zhao, H. L., Zeng, L., Zhang, Y., Liu, H. Q., Ma, Q., Chen, D. L., Luo, Z. P., Li, Y. Y., Shen, Z. C., Xu, L. Q., Zhang, B., Li, M. H., Wang, Z. X., Ling, B. L., Gong, X. Z., Sun, Y., and Wan, B.

Subjects
Physics - Plasma Physics
Abstract

Direct evidence of micro-turbulence effect on the onset of neoclassical tearing mode (NTM) is reported for the first time in this letter. A puzzling positive correlation between critical width of seed island of NTM and normalized plasma pressure beta_p is first observed employing a novel method for clearly separating the processes of seed island and the onset of NTM in the EAST tokamak. Different from the methods developed before, the width of the seed island is well controlled by slowly ramping up the current in resonant magnetic perturbation coils. It is revealed that the positive correlation is mainly attributed to the enhancement of perpendicular transport by micro-turbulence, which overcomes the destabilizing effect of beta_p on the onset of NTM. Reduced magnetohydrodynamics (MHD) modeling well reproduced the two states of nonlinear bifurcations observed in this experiment by including the finite transport effect. This result provides a new route for understanding multi-scale interaction in plasma physics.

Published
2021

10. Edge Temperature Ring Oscillation Modulated by Turbulence Transition for Sustaining Stationary Improved Energy Confinement Plasmas

Author

Liu, A. D., Zou, X. L., Han, M. K., Wang, T. B., Zhou, C., Wang, M. Y., Duan, Y. M., Verdoolaege, G., Dong, J. Q., Wang, Z. X., Feng, X., Xie, J. L., Zhuang, G., Ding, W. X., Zhang, S. B., Liu, Y., Liu, H. Q., Wang, L., Li, Y. Y., Wang, Y. M., Lv, B., Hu, G. H., Zhang, Q., Wang, S. X., Zhao, H. L., Qu, C. M., Liu, Z. X., Liu, Z. Y., Zhang, J., Ji, J. X., Zhong, X. M., Lan, T., Li, H., Mao, W. Z., Liu, W. D., and Team, EAST

Subjects
Physics - Plasma Physics
Abstract

A reproducible stationary improved confinement mode (I-mode) has been achieved recently in the Experimental Advanced Superconducting Tokamak, featuring good confinement without particle transport barrier, which could be beneficial to solving the heat flux problem caused by edge localized modes (ELM) and the helium ash problem for future fusion reactors. The microscopic mechanism of sustaining stationary I-mode, based on the coupling between turbulence transition and the edge temperature oscillation, has been discovered for the first time. A radially localized edge temperature ring oscillation (ETRO) with azimuthally symmetric structure ($n=0$,$m=0$) has been identified and it is caused by alternative turbulence transitions between ion temperature gradient modes (ITG) and trapped electron modes (TEM). The ITG-TEM transition is controlled by local electron temperature gradient and consistent with the gyrokinetic simulations. The self-organizing system consisting with ETRO, turbulence and transport transitions plays the key role in sustaining the I-mode confinement. These results provide a novel physics basis for accessing, maintaining and controlling stationary I-mode in the future., Comment: 11 pages, 6 figures

Published
2020

11. I-mode investigation on the Experimental Advanced Superconducting Tokamak

Author

Feng, X., Liu, A. D., Zhou, C., Liu, Z. X., Wang, M. Y., Zhuang, G., Zou, X. L., Wang, T. B., Zhang, Y. Z., Xie, J. L., Liu, H. Q., Zhang, T., Liu, Y., Duan, Y. M., Hu, L. Q., Hu, G. H., Kong, D. F., Wang, S. X., Zhao, H. L., Li, Y. Y., Shao, L. M., Xia, T. Y., Ding, W. X., Lan, T., Li, H., Mao, W. Z., Liu, W. D., Gao, X., Li, J. G., Zhang, S. B., Zhang, X. H., Liu, Z. Y., Qu, C. M., Zhang, S., Zhang, J., Ji, J. X., Fan, H. R., and Zhong, X. M.

Subjects
Physics - Plasma Physics
Abstract

By analyzing large quantities of discharges in the unfavorable ion $ \vec B\times \nabla B $ drift direction, the I-mode operation has been confirmed in EAST tokamak. During the L-mode to I-mode transition, the energy confinement has a prominent improvement by the formation of a high-temperature edge pedestal, while the particle confinement remains almost identical to that in the L-mode. Similar with the I-mode observation on other devices, the $ E_r $ profiles obtained by the eight-channel Doppler backscattering system (DBS8)\cite{J.Q.Hu} show a deeper edge $ E_r $ well in the I-mode than that in the L-mode. And a weak coherent mode (WCM) with the frequency range of 40-150 kHz is observed at the edge plasma with the radial extend of about 2-3 cm. WCM could be observed in both density fluctuation and radial electric field fluctuation, and the bicoherence analyses showed significant couplings between WCM and high frequency turbulence, implying that the $ E_r $ fluctuation and the caused flow shear from WCM should play an important role during I-mode. In addition, a low-frequency oscillation with a frequency range of 5-10 kHz is always accompanied with WCM, where GAM intensity is decreased or disappeared. Many evidences show that the a low-frequency oscillation may be a novel kind of limited cycle oscillation but further investigations are needed to explain the new properties such as the harmonics and obvious magnetical perturbations., Comment: 14 pages, 7 figures

Published
2019
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12. High-k turbulence characteristics in density modulation experiments of EAST

Author

Chen, F., primary, Li, P., additional, Li, Y. D., additional, Wang, X. J., additional, Wu, G. J., additional, Geng, J. S., additional, Wang, Y. H., additional, Sun, N., additional, Sun, P. J., additional, Wang, M., additional, Ding, B. J., additional, Wu, C. B., additional, Li, E. Z., additional, Zhou, T. F., additional, Zhao, H. L., additional, Zang, Q., additional, Wang, S. X., additional, Liu, H. Q., additional, Jin, Y. F., additional, Lyu, B., additional, and Li, J. G., additional

Published
2024
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13. Design of geometric phase measurement in EAST Tokamak

Author

Lan, T., Liu, H. Q., Liu, J., Jie, Y. X., Wang, Y. L., Gao, X., and Qin, H.

Subjects
Physics - Plasma Physics
Abstract

The optimum scheme for geometric phase measurement in EAST Tokamak is proposed in this paper. The theoretical values of geometric phase for the probe beams of EAST Polarimeter-Interferometer (POINT) system are calculated by path integration in parameter space. Meanwhile, the influences of some controllable parameters on geometric phase are evaluated. The feasibility and challenge of distinguishing geometric effect in the POINT signal are also assessed in detail., Comment: 7 pages, 7 figures

Published
2016
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14. The first results of the hydrogen cyanide (HCN) interferometer measuring experimental research apparatus for electromagnetic science (ERAES) for hypersonic vehicle plasma in near space.

Author

Zhang, J. B., Liu, H. Q., Zhang, Y., Wei, X. C., Xie, J. X., Wang, S. X., Lian, H., Jie, Y. X., and Hu, L. Q.

Subjects
*PLASMA sheaths, *ELECTRON density, *PLASMA waves, *SPACE plasmas, *ELECTROMAGNETIC waves
Abstract

The formation of a plasma sheath on the surface of spacecraft or satellites during high-speed atmospheric entry is a significant factor that affects communication and radar detection. Experimental research apparatus for electromagnetic science can simulate this plasma sheath and study the interaction mechanisms between electromagnetic waves and plasma sheaths. Electron density is a crucial parameter for this research. Therefore, in this paper, a HCN heterodyne interferometer has been designed to measure the electron densities of the device, which range from 1 × 109 to 3 × 1013 cm−3 and the pressure ranges from 50 to 1500 Pa. The light source is a HCN laser with a wavelength of 337 µm, which exhibits higher spatial resolution compared to microwave interferometers. The interferometer is configured as a Mach–Zehnder interferometer, which generates an intermediate frequency through the Doppler shift achieved by a rotating grating. The spatial and temporal resolution of the HCN interferometry reach ∼14 mm and 100 µs, respectively. Antenna-coupled ALGaN/GaN-HEMT detectors have been utilized, as they possess higher sensitivity—with a typical reduction factor responsivity of around 900 V/W—than VDI planar-diode Integrated Conical Horn Fundamental Mixers in HCN interferometry. Recently, the initial results of the HCN interferometer designed for ERAES have been obtained during an experimental campaign, demonstrating a phase resolution of up to 0.04π. [ABSTRACT FROM AUTHOR]

Published
2024
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15. Internal measurements of electromagnetic geodesic acoustic mode (GAM) in EAST plasmas.

Author

Wang, Y. H., Ding, W. X., Zhou, C., Liu, A. D., Feng, X., Lian, H., Liu, H. Q., Chu, Y. Q., Brower, D. L., Mao, W. Z., Xie, J. L., Gao, L. T., Zhu, R. J., Zhong, X. M., Ren, H. J., Chen, Z., Shi, W. X., and Wang, S. F.

Subjects
ELECTROMAGNETIC measurements, VELOCITY measurements, GEODESICS, TOKAMAKS, POLARIMETRY, MICROWAVE reflectometry
Abstract

Velocity, density, and magnetic fluctuations of the geodesic acoustic mode (GAM) have been measured using the Doppler backscattering system, Faraday-effect polarimeter-interferometer, and external pick-up coils in the Experimental Advanced Superconducting Tokamak. Simultaneous measurements of density and velocity fluctuations at the midplane and top of plasmas demonstrate that m = 1 density fluctuations are quantitatively balanced by the compression of perpendicular flow fluctuations. Furthermore, internal magnetic fluctuations associated with GAM have now been directly measured by laser-based Faraday-effect polarimetry for the first time. Line-averaged magnetic fluctuations (up to 16 Gauss, B ̃ ¯ R , GAM B T ∼ 0.066 %) are significantly larger than those extrapolated from edge coils (a few Gauss) and that magnetic fluctuations increase with β. The observed discrepancy between finite β theory and experimental data indicates the need for further theoretical investigations. [ABSTRACT FROM AUTHOR]

Published
2024
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16. A terahertz solid-state source interferometer–polarimeter designed for long pulse discharges on EAST.

Author

Wang, S. X., Liu, H. Q., Zhang, J. B., Xu, C., Lian, H., and Zou, Z. Y.

Abstract

A 0.65 THz Solid-state Source Interferometer–Polarimeter (SSIP) with vertical viewing has been installed for line-integrated density and Faraday rotation measurements on Experimental Advanced Superconducting Tokamak (EAST). The SSIP utilizes three independent solid-state diode sources based on frequency multiplier (X48) to provide the probing beam at a fixed frequency of 0.65 THz with ∼2.5 mW output power, which provide an Intermediate Frequency (IF) with wide range, and the highest IF is up to ∼10 MHz. The mixers optimized for high sensitivity, ∼750 mV/mW, are used in the SSIP system, which permits multichannel interferometer–polarimeter on EAST with a low phase noise. The resolution of the integrated density is 3.3 × 1017 m−2, and the Faraday rotation is about 1.5°. The density measurement has been implemented with IF ∼0.85 MHz, in a plasma with plasma current ∼300 kA on EAST. The line-averaged density, 3.5 × 1019 m−3, measured by the SSIP shows good agreement with the results measured by the POlarimeter–INTerferometer (POINT) system and the CO2 dispersion interferometer system in the same discharge. [ABSTRACT FROM AUTHOR]

Published
2024
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17. Design of a real-time frequency stabilization system for dual laser-based interferometer on EAST.

Author

Wang, Y., Yao, Y., Liu, H. Q., Zhang, Y., Zhang, J. M., Jie, Y. X., and Zou, Z. Y.

Abstract

This study addresses the challenge of intermediate frequency (IF) instability in the far-infrared polarimeter/interferometer (POINT) of the Experimental Advanced Superconducting Tokamak (EAST) to ensure the accuracy and stability of electron density measurements. Sudden and extensive IF shifts of the lasers can cause instability and even measurement errors of the diagnostic system. This paper introduces a comprehensive solution for stabilizing IF fluctuations. First, analog IF is converted into digital form using an analog-to-digital converter, and the digitalized signal is processed by a digital signal system based on a ZYNQ processor. The exact value of the IF is obtained by acquiring the point of maximum amplitude through the fast Fourier transform method, while the ZYNQ processor loaded with a fuzzy control algorithm will precisely adjust the laser cavity length via piezoelectric ceramics, achieving frequency stabilization within a target range. Comparative analyses confirm the method's efficacy in managing sudden frequency shifts, maintaining stability within 850 ± 100 kHz (a central frequency of 850 kHz, fluctuating within a range of ±100 kHz), with a control speed of 0.5 s per action and robust against variations up to 270 kHz. This efficient and rapid control mechanism fulfills the critical need for IF stabilization, ensuring the stability and precision of the POINT system in the EAST discharge experiments. [ABSTRACT FROM AUTHOR]

Published
2024
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18. Coupling between the Alfvén eigenmode and edge-coherent mode on the experimental advanced superconducting tokamak

Author

Wang, M Y, primary, Liu, A D, additional, Zhou, C, additional, Zhuang, G, additional, Feng, X, additional, Zhang, J, additional, Zhong, X M, additional, Zhang, R B, additional, Wang, Y H, additional, Yang, J X, additional, Li, H, additional, Lan, T, additional, Xie, J L, additional, Liu, H Q, additional, Liu, Z X, additional, Mao, W Z, additional, Ding, W X, additional, and Liu, W D, additional

Published
2024
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21. Development and validation of a nomogram and risk stratification system to predict overall survival after surgical repair for pediatric patients with medulloblastoma based on easily accessible variables.

Author

FANG, C.-H., WEN, C., YANG, B., SONG, Y.-H., LIU, H.-Q., TIAN, L., CHEN, H., and BAO, N.

Abstract

OBJECTIVE: This study aimed to develop and validate a nomogram and risk stratification system for the overall survival of pediatric patients with medulloblastoma after surgical repair. PATIENTS AND METHODS: In this multicenter, retrospective study, consecutive patients who underwent surgery for medulloblastoma at Shanghai Children's Medical Center and the First Affiliated Hospital of Fujian Medical University from 2010 to 2022 formed the training and external validation datasets, respectively. Univariable and multivariable Cox regression analyses were performed to identify variables associated with mortality in the training dataset. A nomogram prediction model was developed based on independent variables in the multivariable Cox regression analysis to predict the 1-, 3-, and 5-year overall survival. The area under receiver operating characteristic curve (AUC) and calibration curve were used to evaluate the discrimination and calibration of the nomogram. A risk stratification system based on the median risk score was also established to divide patients into two risk groups. RESULTS: In the training dataset, Cox regression analyses identified tumor size, brainstem involvement and chemotherapy as independent predictors for overall survival. The AUC of the nomogram was 0.75 at 1 year, 0. 75 at 3 years, 0.77 at 5 years in the training dataset, 0.74 at 1 year, 0.70 at 3 years, and 0.70 at 5 years in the validation dataset. The calibration curve for the probability of 1-, 3-, and 5-year survival showed good agreement between the nomogram prediction and actual observation in the training and validation datasets. The risk stratification system could perfectly classify patients into two risk groups, and the overall survival in the two groups had a good division. CONCLUSIONS: This low-cost, convenient, and noninvasive nomogram can be translated into clinical practice as a tool for risk stratification and individualized prognosis prediction for children with medulloblastoma. [ABSTRACT FROM AUTHOR]

Published
2024

22. Fluctuation-induced dynamo effect in a magnetic confinement plasma

Author

Mao, W. Z., primary, Ding, W. X., additional, Liu, H. Q., additional, Ti, A., additional, Brower, D. L., additional, Lian, H., additional, Chu, Y. Q., additional, Zeng, L., additional, Zhao, H. L., additional, Zhang, L., additional, Qian, J. P., additional, Zang, Q., additional, Gong, X. Z., additional, Hu, L. Q., additional, Xu, L. Q., additional, Zhou, C., additional, Lan, T., additional, Liu, A. D., additional, Xie, J. L., additional, Zhuang, G., additional, Song, Y. T., additional, Wan, B. N., additional, and Li, J. G., additional

Published
2023
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27. An E-band multi-channel Doppler backscattering system on EAST.

Author

Liu, S., Zhou, C., Liu, A. D., Zhuang, G., Feng, X., Zhang, J., Zhong, X. M., Ji, J. X., Zhang, S. B., Liu, H. Q., Wang, S. X., Fan, H. R., Wang, S. F., Gao, L. T., Shi, W. X., Chen, X. Y., and Liu, W. D.

Subjects
BACKSCATTERING, RAY tracing, SIGNAL filtering, WAVENUMBER, TOKAMAKS
Abstract

An E-band (60–90 GHz) multi-channel Doppler backscattering (DBS) system with X-mode polarization has been installed on the Experimental Advanced Superconducting Tokamak (EAST), which can measure the turbulence at five different radial locations simultaneously. This system can launch 31 fixed microwave frequencies in the range of 60–90 GHz with a 1 GHz interval into the plasma, and five probing signals are selected by employing a reference signal and multiple filters. During experiments, the frequency of the reference signal is tunable in the E-band, and the selected probing signals can be changed as needed without any other adjustments, which can be performed in one shot or between shots. Furthermore, the incident angle can be adjusted from −10° to 20°, and the wavenumber range is 4–25 cm−1 with a wavenumber resolution of Δk/k ≤ 0.35. Ray tracing simulations are employed to calculate the scattering locations and the perpendicular wavenumber. In this article, the hardware design, ray tracing, and initial results obtained from the EAST plasma will be presented. [ABSTRACT FROM AUTHOR]

Published
2023
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28. Numerical investigation of the 2/1 double tearing mode in EAST with the CLT code.

Author

Li, J. Y., Liu, Z. X., Zhang, W., Ma, Z. W., Gao, X., Li, G. Q., Liu, H. Q., Wu, M. F., Liu, Y. J., Deng, C. C., Li, P. C., Yang, K. N., Yin, X. Y., Li, H., Xie, J. L., Lan, T., Mao, W. Z., Liu, A. D., Zhou, C., and Ding, W. X.

Subjects
PLASMA flow, STARK effect, ELECTRON emission, SAFETY factor in engineering, MAGNETIC fields, TOKAMAKS
Abstract

The pressure crashes observed in shot No. 71326 in the Experimental Advanced Superconducting Tokamak are numerically investigated with the three-dimensional, toroidal, and full resistive-magnetohydrodynamics code (CLT). Based on the experimental observations, the pressure crash is caused by the nonlinear evolution of the m/n = 2/1 double tearing mode (DTM), where n and m are the toroidal and poloidal mode numbers, respectively. However, we find that the m/n = 2/1 DTM is stable based on the safety factor (q) profile from the equilibrium code EFIT, which indicates that the original q profile is somewhat inconsistent with the actual profile due to q measurement uncertainty. Since there is no motional Stark effect diagnostic for this shot, the local information of the magnetic field is missing, which leads to the largest contribution to the discrepancy. If other information is perfectly known and the q profile is the only uncertainty, then we could provide some information for the EFIT reconstruction by comparing our simulation results with electron cyclotron emission signals to constrain the uncertainty of the q profile to a much smaller region. The influence of plasma rotation and the two-fluids effect is also discussed. [ABSTRACT FROM AUTHOR]

Published
2023
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31. First Wide Field-of-view X-Ray Observations by a Lobster-eye Focusing Telescope in Orbit

Author

Zhang, C., primary, Ling, Z. X., additional, Sun, X. J., additional, Sun, S. L., additional, Liu, Y., additional, Li, Z. D., additional, Xue, Y. L., additional, Chen, Y. F., additional, Dai, Y. F., additional, Jia, Z. Q., additional, Liu, H. Y., additional, Zhang, X. F., additional, Zhang, Y. H., additional, Zhang, S. N., additional, Chen, F. S., additional, Cheng, Z. W., additional, Fu, W., additional, Han, Y. X., additional, Li, H., additional, Li, J. F., additional, Li, Y., additional, Liu, P. R., additional, Ma, X. H., additional, Tang, Y. J., additional, Wang, C. B., additional, Xie, R. J., additional, Yan, A. L., additional, Zhang, Q., additional, Jiang, B. W., additional, Jin, G., additional, Li, L. H., additional, Qiu, X. B., additional, Su, D. T., additional, Sun, J. N., additional, Xu, Z., additional, Zhang, S. K., additional, Zhang, Z., additional, Zhang, N., additional, Bi, X. Z., additional, Cai, Z. M., additional, He, J. W., additional, Liu, H. Q., additional, Zhu, X. C., additional, Cheng, H. Q., additional, Cui, C. Z., additional, Fan, D. W., additional, Hu, H. B., additional, Huang, M. H., additional, Jin, C. C., additional, Li, D. Y., additional, Pan, H. W., additional, Wang, W. X., additional, Xu, Y. F., additional, Yang, X., additional, Zhang, B., additional, Zhang, M., additional, Zhang, W. D., additional, Zhao, D. H., additional, Bai, M., additional, Ji, Z., additional, Liu, Y. R., additional, Ma, F. L., additional, Su, J., additional, Tong, J. Z., additional, Wang, Y. S., additional, Zhao, Z. J., additional, Feldman, C., additional, O’Brien, P., additional, Osborne, J. P., additional, Willingale, R., additional, Burwitz, V., additional, Hartner, G., additional, Langmeier, A., additional, Müller, T., additional, Rukdee, S., additional, Schmidt, T., additional, Kuulkers, E., additional, and Yuan, W., additional

Published
2022
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34. Eastern sites

Author

Früh-Green, G.L., primary, Orcutt, B.N., additional, Green, S.L., additional, Cotterill, C., additional, Morgan, S., additional, Akizawa, N., additional, Bayrakci, G., additional, Behrmann, J.-H., additional, Boschi, C., additional, Brazleton, W.J., additional, Cannat, M., additional, Dunkel, K.G., additional, Escartin, J., additional, Harris, M., additional, Herrero-Bervera, E., additional, Hesse, K., additional, John, B.E., additional, Lang, S.Q., additional, Lilley, M.D., additional, Liu, H.-Q., additional, Mayhew, L.E., additional, McCaig, A.M., additional, Menez, B., additional, Morono, Y., additional, Quéméneur, M., additional, Rouméjon, S., additional, Sandaruwan Ratnayake, A., additional, Schrenk, M.O., additional, Schwarzenbach, E.M., additional, Twing, K.I., additional, Weis, D., additional, Whattham, S.A., additional, Williams, M., additional, and Zhao, R., additional

Published
2017
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35. Central sites

Author

Früh-Green, G.L., primary, Orcutt, B.N., additional, Green, S.L., additional, Cotterill, C., additional, Morgan, S., additional, Akizawa, N., additional, Bayrakci, G., additional, Behrmann, J.-H., additional, Boschi, C., additional, Brazleton, W.J., additional, Cannat, M., additional, Dunkel, K.G., additional, Escartin, J., additional, Harris, M., additional, Herrero-Bervera, E., additional, Hesse, K., additional, John, B.E., additional, Lang, S.Q., additional, Lilley, M.D., additional, Liu, H.-Q., additional, Mayhew, L.E., additional, McCaig, A.M., additional, Menez, B., additional, Morono, Y., additional, Quéméneur, M., additional, Rouméjon, S., additional, Sandaruwan Ratnayake, A., additional, Schrenk, M.O., additional, Schwarzenbach, E.M., additional, Twing, K.I., additional, Weis, D., additional, Whattham, S.A., additional, Williams, M., additional, and Zhao, R., additional

Published
2017
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36. Northern sites

Author

Früh-Green, G.L., primary, Orcutt, B.N., additional, Green, S.L., additional, Cotterill, C., additional, Morgan, S., additional, Akizawa, N., additional, Bayrakci, G., additional, Behrmann, J.-H., additional, Boschi, C., additional, Brazleton, W.J., additional, Cannat, M., additional, Dunkel, K.G., additional, Escartin, J., additional, Harris, M., additional, Herrero-Bervera, E., additional, Hesse, K., additional, John, B.E., additional, Lang, S.Q., additional, Lilley, M.D., additional, Liu, H.-Q., additional, Mayhew, L.E., additional, McCaig, A.M., additional, Menez, B., additional, Morono, Y., additional, Quéméneur, M., additional, Rouméjon, S., additional, Sandaruwan Ratnayake, A., additional, Schrenk, M.O., additional, Schwarzenbach, E.M., additional, Twing, K.I., additional, Weis, D., additional, Whattham, S.A., additional, Williams, M., additional, and Zhao, R., additional

Published
2017
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37. Expedition 357 summary

Author

Früh-Green, G.L., primary, Orcutt, B.N., additional, Green, S.L., additional, Cotterill, C., additional, Morgan, S., additional, Akizawa, N., additional, Bayrakci, G., additional, Behrmann, J.-H., additional, Boschi, C., additional, Brazleton, W.J., additional, Cannat, M., additional, Dunkel, K.G., additional, Escartin, J., additional, Harris, M., additional, Herrero-Bervera, E., additional, Hesse, K., additional, John, B.E., additional, Lang, S.Q., additional, Lilley, M.D., additional, Liu, H.-Q., additional, Mayhew, L.E., additional, McCaig, A.M., additional, Menez, B., additional, Morono, Y., additional, Quéméneur, M., additional, Rouméjon, S., additional, Sandaruwan Ratnayake, A., additional, Schrenk, M.O., additional, Schwarzenbach, E.M., additional, Twing, K.I., additional, Weis, D., additional, Whattham, S.A., additional, Williams, M., additional, and Zhao, R., additional

Published
2017
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38. Expedition 357 methods

Author

Früh-Green, G.L., primary, Orcutt, B.N., additional, Green, S.L., additional, Cotterill, C., additional, Morgan, S., additional, Akizawa, N., additional, Bayrakci, G., additional, Behrmann, J.-H., additional, Boschi, C., additional, Brazleton, W.J., additional, Cannat, M., additional, Dunkel, K.G., additional, Escartin, J., additional, Harris, M., additional, Herrero-Bervera, E., additional, Hesse, K., additional, John, B.E., additional, Lang, S.Q., additional, Lilley, M.D., additional, Liu, H.-Q., additional, Mayhew, L.E., additional, McCaig, A.M., additional, Menez, B., additional, Morono, Y., additional, Quéméneur, M., additional, Rouméjon, S., additional, Sandaruwan Ratnayake, A., additional, Schrenk, M.O., additional, Schwarzenbach, E.M., additional, Twing, K.I., additional, Weis, D., additional, Whattham, S.A., additional, Williams, M., additional, and Zhao, R., additional

Published
2017
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39. Western sites

Author

Früh-Green, G.L., primary, Orcutt, B.N., additional, Green, S.L., additional, Cotterill, C., additional, Morgan, S., additional, Akizawa, N., additional, Bayrakci, G., additional, Behrmann, J.-H., additional, Boschi, C., additional, Brazleton, W.J., additional, Cannat, M., additional, Dunkel, K.G., additional, Escartin, J., additional, Harris, M., additional, Herrero-Bervera, E., additional, Hesse, K., additional, John, B.E., additional, Lang, S.Q., additional, Lilley, M.D., additional, Liu, H.-Q., additional, Mayhew, L.E., additional, McCaig, A.M., additional, Menez, B., additional, Morono, Y., additional, Quéméneur, M., additional, Rouméjon, S., additional, Sandaruwan Ratnayake, A., additional, Schrenk, M.O., additional, Schwarzenbach, E.M., additional, Twing, K.I., additional, Weis, D., additional, Whattham, S.A., additional, Williams, M., additional, and Zhao, R., additional

Published
2017
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40. An innovative divertor concept, the fish tail divertor, for reducing the surface temperature on the divertor target plate in EAST tokamak experiments.

Author

Zhang, Y., Zhang, X. D., Qiu, Q. L., Zhang, J., Li, B., Chen, L., Luo, Z. P., Qian, J. P., Wang, L., Liu, H. Q., Meng, L. Y., Liu, X., Zhang, B., Shen, B., Yuan, Q. P., Xiao, B. J., Gong, X. Z., Xu, G. S., Hu, J. S., and Lu, K.

Subjects
SURFACE temperature, FUSION reactor divertors, TOKAMAKS, FUSION reactors, PLASMA currents, MAGNETIC fields
Abstract

An innovative divertor concept, the fish tail divertor, is proposed in this paper, aimed at reducing the surface temperature on the tokamak divertor plate as well as that due to the edge localized modes. This new concept has been implemented in experiments to demonstrate its capability of strike point sweeping on the plate at a frequency range from 10 to 100 Hz by using an oscillating magnetic field. A strike point movement of 5–6 cm is achieved by applying a coil current of several percent of plasma current, leading to a significant reduction of divertor surface temperature. The result indicates a possible application in a fusion reactor. [ABSTRACT FROM AUTHOR]

Published
2023
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42. Effects of ICRF waves to EAST LHCD discharges on intrinsic rotations

Author

Jin, Y F, primary, Lyu, B, additional, Bae, C, additional, Zhang, X J, additional, Rice, J E, additional, Wang, F D, additional, Fu, J, additional, Liu, H Q, additional, Zhang, H M, additional, Zeng, L, additional, Chu, Y Q, additional, Zang, Q, additional, Bin, B, additional, Li, Y C, additional, He, L, additional, Lu, D A, additional, and Liu, H J, additional

Published
2022
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43. Characterization of beam ion loss in high poloidal beta regime on EAST

Author

Fu, J, primary, Huang, J, additional, Wang, J F, additional, Yu, L M, additional, Van Zeeland, M A, additional, Chang, J F, additional, Hao, B L, additional, Chen, J L, additional, Wu, M Q, additional, Hu, W H, additional, Xu, Z, additional, Gao, W, additional, Su, J X, additional, Sun, Y X, additional, Liang, R R, additional, Zang, Q, additional, Liu, H Q, additional, Lyu, B, additional, Zhong, G Q, additional, Zhang, B, additional, and Gong, X Z, additional

Published
2022
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48. Study of the mechanism of ITB formation and sustainment with optimized q profiles in ELMy H mode discharges on the EAST

Author

Chu, Y Q, primary, Liu, H Q, additional, Zhang, S B, additional, Jie, Y X, additional, Lian, H, additional, Wu, M Q, additional, Zhu, X, additional, Wu, C B, additional, Xu, L Q, additional, Wang, Y F, additional, Wang, S X, additional, Zhang, T, additional, Yang, Y, additional, Hanada, K, additional, Lyu, B, additional, Li, Y Y, additional, and Zang, Q, additional

Published
2021
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50. Observation of synergy between lower hybrid waves at two frequencies in EAST

Author

Choi, W., primary, Poli, F. M., additional, Li, M. H., additional, Baek, S. G., additional, Gorenlenkova, M., additional, Ding, B. J., additional, Gong, X. Z., additional, Chan, A., additional, Duan, Y. M., additional, Hu, J. H., additional, Lian, H., additional, Lin, S. Y., additional, Liu, H. Q., additional, Qian, J. P., additional, Wallace, G., additional, Wang, Y. M., additional, Zang, Q., additional, and Zhao, H. L., additional

Published
2021
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