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1. 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

2. 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

4. 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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6. 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

7. 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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8. Observation of pedestal quasi-coherent mode in Type-I ELMy H-mode of HL-2A tokamak

Author

Wen, J., primary, Shi, Z. B., additional, Zhong, W. L., additional, Zou, X. L., additional, Jiang, M., additional, Chen, W., additional, Xu, J. Q., additional, Yang, Z. C., additional, Liang, A. S., additional, Ke, R., additional, Wu, N., additional, He, X. X., additional, Shi, P. W., additional, Xiao, G. L., additional, Tong, R. H., additional, Yu, X., additional, Zhu, Y. R., additional, Zhang, Y. P., additional, Gao, J. M., additional, Han, M. K., additional, Dong, J. Q., additional, Shen, Y., additional, and Ji, X. Q., additional

Published
2023
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9. Overview of the Recent Study on ELM Mitigation Physics with Different External Actuators on HL-2A Tokamak

Author

Xiao, G. L., Zhong, W. L., Zhang, Y. P., Zou, X. L., Liang, A. S., Feng, B. B., Bai, X. Y., Zhang, K., Mazon, D., Chen, C. Y., Chen, W., Cheng, J., Delpech, L., Ding, X. T., Dong, C. F., Dong, J. Q., Cui, Z. Y., Ekedahl, A., Gao, J. M., Giruzzi, G., Goniche, M., Han, M. K., He, X. X., Hoang, T., Huang, Z. H., Isobe, M., Ji, X. Q., Li, Y. G., Liu, A. D., Liu, C. H., Liu, L., Lu, B., Peysson, Y., Shi, P. W., Song, X. M., Sun, P., Wang, T. B., Wang, Z. H., Wang, Z. X., Wen, J., Xiao, W. W., Yan, L. W., Yang, Z. C., Yu, D. L., Yuan, G. L., Zhang, P. F., Zhou, Y., Shi, Z. B., Liu, Y., Yang, Q. W., Xu, M., and Duan, X. R.

Published
2020
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11. Progress of Divertor Heat and Particle Flux Control in EAST for Advanced Steady-State Operation in the Last 10 Years

Author

Wang, L., Xu, G. S., Hu, J. S., Li, K. D., Yuan, Q. P., Liu, J. B., Ding, F., Yu, Y. W., Luo, Z. P., Xu, J. C., Meng, L. Y., Wu, K., Zhang, B., Chen, M. W., Deng, G. Z., Liu, X. J., Yang, Z. S., Liu, X., Liu, S. C., Ding, R., Zuo, G. Z., Sun, Z., Wu, J. H., Cao, B., Zhang, Y., Duan, Y. M., Zhang, L., Qian, X. Y., Li, A., Chen, L., Jia, M. N., Si, H., Xia, T. Y., Sun, Y. W., Chen, Y. P., Li, Q., Luo, G. N., Yao, D. M., Xiao, B. J., Gong, X. Z., Zhang, X. D., Wan, B. N., Wang, H. Q., Guo, H. Y., Eldon, D., Garofalo, A. M., Liang, Y., Xu, S., Sang, C. F., Wang, D. Z., Dai, S. Y., Sun, J. Z., Ding, H. B., Maingi, R., Gan, K. F., Zou, X. L., and Du, H. L.

Published
2021
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14. Effect of Platinum Addition on Microstructure and Oxidation Behavior of Ni3Al-Base Alloys.

Author

Cao, Y. R., Shi, J. J., Zhou, G. Y., Zhang, Z. X., Zou, X. L., Lu, X. G., and Cao, G. H.

Subjects
PLATINUM, SCANNING transmission electron microscopy, ALLOYS, THERMAL barrier coatings, MICROSTRUCTURE, OXIDATION
Abstract

In order to study the effect of Pt on bond coat in thermal barrier coating, the corresponding Pt modified Ni3Al-base alloys were fabricated using arc melting. The microstructure and the oxidation behavior of the Ni–25Al–xPt (x = 0, 10, 20 and 30 at %) alloys at 1100°C were characterized using X-ray diffraction, scanning and transmission electron microscopy. The experimental results showed that the Ni–25Al–xPt alloys kept a single γ′-Ni3Al phase structure when Pt content up to 20 at %, while Ni–25Al–30Pt alloy consisted of two-phase structures of γ-Ni and γ′-Ni3Al, which may be caused by the phase deviation resulting from the volatilization loss of Al. Isothermal oxidation test indicated that the addition of Pt in Ni3Al-base alloys promoted Al2O3 scale formation, affected the oxidation surface morphology, reduced oxidation weight gain and the thickness of the oxide layer. [ABSTRACT FROM AUTHOR]

Published
2023
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15. Modeling lower hybrid current drive in presence of an extreme spectral gap.

Author

Peysson, Y., Mazon, D., Artaud, J.-F., Ekedahl, A., Delpech, L., Hillairet, J., Maget, P., Zou, X. L., Bai, X. Y., Zhang, Y. P., Król, K., Bielecki, J., Jardin, A., Scholz, M., Dworak, D., and Decker, J.

Subjects
BREMSSTRAHLUNG, ELECTRON kinetic energy, TOROIDAL plasma, WKB approximation, THERMAL electrons, PLASMA currents, PLASMA beam injection heating
Abstract

In very large aspect ratio tokamaks, the radio-frequency wave at the Lower Hybrid (LH) frequency propagation domain may be strongly bounded, thus preventing in principle the build-up of a fast electron tail to drive all the toroidal plasma current, the usual toroidal upshift being much too weak in this case to bridge the well-known "spectral gap". Nevertheless, even if these conditions are fulfilled, a full current drive regime may be achieved experimentally, and non-thermal electrons with kinetic energies well above the thermal level are observed by measuring bremsstrahlung in the hard x-ray range. This contradiction raises the question of the physical mechanisms to pull out a tail of fast electrons from the thermal bulk, highlighting the fact that toroidal refraction may not be the single one at play. This was suggested by the improved agreement between modeling and observations when using the heuristic tail spectral model [J. Decker et al., Phys. Plasmas 21 (2014) 092504] on many machines, considering that the LH power spectrum is already broad as the wave crosses the separatrix from the antenna. In this context, the possibility to eliminate the contribution of the toroidal refraction allows to clearly identify the ability of this model to reproduce alone experimental results. This has been carried out for TRIAM-1M [H. Zushi, et al., Nucl. Fusion 43 (2003) 1600] and WEST [C. Bourdelle, et al., Nucl. Fusion 55 (2015) 063017] tokamaks, both characterized by a very large aspect ratio R/a>5.5, using the ALOHA/C3PO/LUKE/R5-X2 chain of codes based on a first principles approach. In extreme spectral gap conditions, simulations show that it must be already filled at the separatrix to reproduce observations quantitatively and some important parametric dependencies. In the context of the edge spectral broadening here addressed, the LH wave absorption is strongly enhanced for the main lobes of the power spectrum at low parallel refractive indexes even when the plasma is cold. They can be therefore absorbed in an almost single pass regime, an important feature which restores the validity of the underlying WKB approximation in ray-tracing calculations, thus justifying its use. A comparison with a discharge corresponding to a marginal unbridgeable spectral for WEST is also shown. [ABSTRACT FROM AUTHOR]

Published
2023
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17. Formation of the hot tail seeds for runaway electron generation during disruptions with lower hybrid waves in the HL-2A tokamak.

Author

Zhang, Y. P., Zou, X. L., Dong, Y. B., Bai, X. Y., Zhang, J., Ogawa, K., Gao, J. M., Cheng, S. K., Zhu, Y. X., Li, B., ji, X. Q., Liu, Y., Shi, Z. B., Zhong, W. L., and Xu, M.

Subjects
*TOKAMAKS, *ELECTRONS, *ELECTRON temperature, *SEEDS, *ELECTRIC fields
Abstract

The hot tail generation is expected to be the dominant mechanism for the runaway electron (RE) seed formation during disruptions, especially in large devices with high electron temperature such as international thermonuclear experimental reactor. This issue has been studied in the HL-2A tokamak by using the superthermal electrons produced by lower hybrid waves (LHWs), which can adjust the hot tail distribution. It was observed that RE generation was significantly enhanced during disruptions with LHWs. The measurements show that the multitudinous superthermal electrons with energy of 40–60 keV created by LHWs greatly transform the landscape of hot tail distribution. The tail electrons can be directly converted into REs under the acceleration of the high toroidal electric field during disruptions. Runaway current plateaus are more likely to be formed than in normal disruptions without LHWs. However, some abnormal phenomena have also been observed, that is, RE generation was not enhanced and no runaway current plateau was formed during some disruptions with LHWs. It is found that this is attributed to the complete loss of RE seeds caused by strong magnetic fluctuations, which prevents the generation of REs during disruptions. This may provide a way to avoid the generation of REs during disruptions by actively exciting magnetic fluctuations. [ABSTRACT FROM AUTHOR]

Published
2023
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18. A review of supersonic molecular beam injection for plasma fueling and physical studies in magnetic fusion devices

Author

Xiao, G. L., primary, Zhong, W. L., additional, Duan, X. R., additional, Feng, B. B., additional, Chen, C. Y., additional, Bucalossi, J., additional, Zou, X. L., additional, Hu, J. S., additional, Kwak, Jong-Gu, additional, Xiao, W. W., additional, Takenaga, H., additional, Chen, Z. Y., additional, Sun, H. J., additional, Zhang, Y. P., additional, Yin, J., additional, Zhu, Y. R., additional, Tong, R. H., additional, Yu, D. L., additional, Shi, Z. B., additional, and Xu, M., additional

Published
2022
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23. Coherent modes and turbulences observations with multi-channel Doppler reflectometer on experimental advanced superconducting tokamak

Author

Feng, X., primary, Liu, A. D., additional, Zhou, C., additional, Zou, X. L., additional, Zhuang, G., additional, Wang, T. B., additional, Liu, Y., additional, Wang, S. X., additional, Li, Y. Y., additional, Shi, T. H., additional, Wang, M. Y., additional, Liu, H. Q., additional, Zhou, T. F., additional, Zhao, H. L., additional, Wang, Y. M., additional, Zhang, S. B., additional, Zhang, J., additional, Liu, Z. Y., additional, Ji, J. X., additional, Fan, H. R., additional, Zhong, X. M., additional, Xie, J. L., additional, Li, H., additional, Lan, T., additional, Liu, Z. X., additional, Mao, W. Z., additional, Ding, W. X., additional, and Liu, W. D., additional

Published
2020
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24. Recent LHCD experiments on HL-2A and LHCD system development on HL-2M

Author

Lu, B., primary, Bai, X. Y., additional, Peysson, Y., additional, Zhang, Y. P., additional, Mazon, D., additional, Xiao, G. L., additional, Zou, X. L., additional, Zeng, H., additional, Liang, J., additional, Wang, C., additional, Chen, Y. L., additional, Ekedahl, A., additional, Delpech, L., additional, Wang, J. Q., additional, Feng, K., additional, Wang, H., additional, Rao, J., additional, Li, B, additional, Wang, S, additional, Song, X. M., additional, Cheng, J., additional, Zhou, Y., additional, Shi, Z. B., additional, Hillairet, J., additional, Bertrand, E., additional, Giruzzi, G., additional, and Hoang., T., additional

Published
2020
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25. Measurements of the fast electron bremsstrahlung during lower hybrid current drive in the HL-2A tokamak

Author

Zhang, Y. P., primary, Mazon, D., additional, Peysson, Y., additional, Malard, P., additional, Zhang, P. F., additional, Zhang, J., additional, Zou, X. L., additional, Zhou, J., additional, Xu, H. B., additional, Bai, X. Y., additional, Yang, J. W., additional, Yuan, G. L., additional, Song, X. Y., additional, Li, X., additional, Zhong, W. L., additional, Ding, X. T., additional, Chen, W., additional, Li, Y. G., additional, Hoang, T., additional, Delpech, L., additional, Ekedahl, A., additional, Isobe, M., additional, Song, X. M., additional, Lu, B., additional, Liu, Yi, additional, Shi, Z. B., additional, Yang, Q. W., additional, Xu, M., additional, Duan, X. R., additional, and Liu, Y., additional

Published
2019
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27. Lower Hybrid Current Drive in High Aspect Ratio Tokamaks.

Author

Peysson, Y., Mazon, D., Artaud, J.-F., Ekedahl, A., Delpech, L., Hillairet, J., Hoang, T., Zou, X. L., Bai, X. Y., Zhang, Y. P., Krol, K., Bielecki, J., Jardin, A., Scholz, M., Dworak, D., and Decker, J.

Abstract

A multi-machine study has been carried out to investigate the impact of a strongly bounded wave propagation domain on the Lower Hybrid current drive, a condition which occurs principally in high aspect ratio tokamaks. In this regime, the condition of kinetic resonance can be far above the upper boundary of the propagation domain, and may not be achieved by the usual toroidal upshift. Therefore no tail of fast electrons can be pulled out from the thermal bulk. Nevertheless, while tokamak plasmas are in principle almost transparent to the wave in this regime so-called "unbridgeable spectral gap", full current drive is well achieved for the two tokamaks considered in this study, TRIAM-1M (Zushi et al. Nucl Fusion 43:1600, 2003) and WEST (Bourdelle et al. Nucl Fusion 55:063017, 2015), both characterized by a very large aspect ratio R / a > 5.5 . The case of the high aspect ratio tokamak HL-2A (Liu et al. Nucl Fusion 45:S239, 2005) for which the wave propagation domain has also an upper boundary, but close to the resonance condition, is considered by comparison. First principles modeling of the rf-driven current and the fast electron bremsstrahlung using the ALOHA/C3PO/LUKE/R5-X2 chain of codes shows unambiguously that the spectral gap must be already filled at the separatrix in order to reproduce quantitatively observations and some important parametric dependencies. This result is an important milestone in the physics understanding of the Lower Hybrid current drive, highlighting the existence of a powerful and likely universal alternative mechanism to bridge the spectral gap, that is not related to toroidal magnetic refraction. With an initially broad power spectrum, lobes with low parallel refractive indexes that carry most of the plasma current can be absorbed in almost single pass, restoring the full validity of the ray-tracing approximation for describing the propagation of the Lower Hybrid wave in cold plasmas. [ABSTRACT FROM AUTHOR]

Published
2020
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28. A Hard X-Ray Pinhole Camera System for Fast Electron Bremsstrahlung Measurements in the HL-2A Tokamak

Author

Zhang, Y. P., Mazon, D., Zhang, J., Zhang, P. F., Malard, P., Xu, H. B., Zhou, J., Peysson, Y., Zou, X. L., Yang, J. W., Yuan, G. L., Isobe, M., Song, X. Y., Li, X., Liu, Yi, Shi, Z. B., Xu, M., Duan, X. R., and Team, the HL-2A

Abstract

AbstractA hard X-ray pinhole camera system has been recently built at the HL-2A tokamak to measure the evolution of space-time distribution of fast electrons in the energy range of 20 to 200 keV. The camera is mainly composed of a fan-shaped detector array, an observation window, a pinhole mechanism, and a data processing system. The detector array consists of 21 CdTe detectors that are arranged in a poloidal section. The camera views the plasma perpendicularly through an observation window mounted in a horizontal port on the equatorial plane. The data processing is implemented by a fast spectrometry based on field-programmable gate array technology. The time and space resolution of the camera can reach 2 to 16 ms and 2 cm, respectively. During the HL-2A experiment campaign in 2018, measurements of fast electrons produced by lower hybrid waves using the camera were successfully performed. The performance of the camera and the first experimental results with some discussions are presented in this paper.

Published
2021
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29. Roles of turbulence– and pressure-gradient–induced flows in triggering H-mode at marginal heating power on HL-2A tokamak

Author

Cheng, J., primary, Dong, J. Q., additional, Yan, L. W., additional, He, Z. X., additional, Xie, H. S., additional, Xiao, Y., additional, Zhao, K. J., additional, Huang, Z. H., additional, Xu, J. Q., additional, Liu, L., additional, Shi, Z. B., additional, Zhong, W. L., additional, Yu, D. L., additional, Ji, X. Q., additional, Huang, Y., additional, Song, X. M., additional, Yang, Q. W., additional, Ding, X. T., additional, Zou, X. L., additional, and Duan, X. R., additional

Published
2016
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32. Effect of lower hybrid current drive on pedestal instabilities in the HL-2A tokamak.

Author

Xiao, G. L., Zhong, W. L., Zou, X. L., Duan, X. R., Liu, A. D., Bai, X. Y., Cheng, J., Cui, Z. Y., Delpech, L., Ding, X. T., Dong, J. Q., Ekedahl, A., Feng, B. B., Giruzzi, G., Gao, J. M., Goniche, M., Hoang, G. T., Ji, X. Q., Jiang, M., and Lu, B.

Subjects
TOKAMAKS, POLOIDAL magnetic fields, FUSION reactors, MAGNETIC fields, PLASMA density
Abstract

Edge localized mode (ELM) mitigation with lower hybrid current drive (LHCD) has been observed in the HL-2A tokamak. This mitigation effect is very sensitive to the parameters as the plasma density and the LHCD absorbed power, i.e., more easily to be observed for high density and large LHCD absorbed power. The divertor peak heat load released by ELM has been significantly reduced during the mitigation phase. The pedestal density gradient is slightly reduced during ELM mitigation, and the plasma rotation velocity and ion temperature are significantly reduced by LHCD. It has been found that the ELM mitigation is not synchronized with the LHCD, while it is synchronized with the increase of the pedestal turbulence, showing that the enhancement of the transport due to the pedestal turbulence can be the direct cause of the ELM mitigation. [ABSTRACT FROM AUTHOR]

Published
2017
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34. Heat and Particle Transport Experiments in Tore Supra and HL-2A with ECRH and SMBI

Author

Zou, X. L., Song, S., Giruzzi, G., Garbet, X., Honoré, Cyrille, Ségui, J.-L., Elbeze, D., Clairet, F., Sabot, R., Bucalossi, J., Hennequin, Pascale, Lenholm, M., Magne, R., Tore Supra, Team, Laboratoire de Physique des Plasmas (LPP), Université Paris-Saclay-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11)-École polytechnique (X)-Observatoire de Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)

Subjects
[PHYS.PHYS.PHYS-PLASM-PH]Physics [physics]/Physics [physics]/Plasma Physics [physics.plasm-ph], ComputingMilieux_MISCELLANEOUS
Abstract

International audience

Published
2009

35. Development of frequency modulated continuous wave reflectometer for electron density profile measurement on the HL-2A tokamak

Author

Zhong, W. L., primary, Shi, Z. B., additional, Huang, X. L., additional, Liu, Z. T., additional, Chen, W., additional, Jiang, M., additional, Li, J., additional, Cui, Z. Y., additional, Song, X. M., additional, Chen, L. Y., additional, Zou, X. L., additional, Ding, X. T., additional, Liu, Yi, additional, Yan, L. W., additional, Yang, Q. W., additional, and Duan, X. R., additional

Published
2014
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37. A long-pulse high-confinement plasma regime in the Experimental Advanced Superconducting Tokamak

Author

Li, J., primary, Guo, H. Y., additional, Wan, B. N., additional, Gong, X. Z., additional, Liang, Y. F., additional, Xu, G. S., additional, Gan, K. F., additional, Hu, J. S., additional, Wang, H. Q., additional, Wang, L., additional, Zeng, L., additional, Zhao, Y. P., additional, Denner, P., additional, Jackson, G. L., additional, Loarte, A., additional, Maingi, R., additional, Menard, J. E., additional, Rack, M., additional, and Zou, X. L., additional

Published
2013
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38. Dynamics of Low-Intermediate–High-Confinement Transitions in Toroidal Plasmas

Author

Cheng, J., primary, Dong, J. Q., additional, Itoh, K., additional, Yan, L. W., additional, Xu, M., additional, Zhao, K. J., additional, Hong, W. Y., additional, Huang, Z. H., additional, Ji, X. Q., additional, Zhong, W. L., additional, Yu, D. L., additional, Itoh, S.-I., additional, Nie, L., additional, Kong, D. F., additional, Lan, T., additional, Liu, A. D., additional, Zou, X. L., additional, Yang, Q. W., additional, Ding, X. T., additional, Duan, X. R., additional, and Liu, Yong, additional

Published
2013
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40. Experimental observation of turbulence transition and a critical gradient threshold for trapped electron mode in tokamak plasmas.

Author

Zhong, W. L., Shi, Z. B., Yang, Z. J., Xiao, G. L., Yang, Z. C., Zhang, B. Y., Shi, P. W., Du, H. R., Pan, X. M., Zhou, R. B., Wan, L. H., Zou, X. L., Xu, M., Duan, X. R., Yong Liu, and Zhuang, G.

Subjects
TURBULENCE, ION traps, TOKAMAKS, MICROWAVE reflectometers, PLASMA gases
Abstract

In HL-2A and J-TEXT ohmic confinement regimes, an electrostatic turbulence with quasi-coherent characteristics in spectra of density fluctuations was observed by multi-channel microwave reflectometers. These quasi-coherent modes (QCMs) were detectable in a large plasma region (r/a ~ 0.3-0.8). The characteristic frequencies of QCMs were in the range of 30-140 kHz. The mode is rotated in the electron diamagnetic direction. In the plasmas with QCMs, trapped electron mode (TEM) was predicted to be unstable by gyrokinetic simulations. The combined experimental results show that the TEM is survived in the linear ohmic confinement regime of plasmas. The quasi-coherent TEM was replaced by broad-band fluctuations when the plasma transits from linear to saturated ohmic confinement regime. The observation was strongly related to the turbulence transition from TEM to ion temperature gradient mode. A critical gradient threshold for TEM excitation in electron temperature gradient was directly found. The effect of TEM on density profile peaking was presented. [ABSTRACT FROM AUTHOR]

Published
2016
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43. Observation of a Spontaneous Particle-Transport Barrier in the HL-2A Tokamak

Author

Xiao, W. W., primary, Zou, X. L., additional, Ding, X. T., additional, Yao, L. H., additional, Feng, B. B., additional, Song, X. M., additional, Song, S. D., additional, Zhou, Y., additional, Liu, Z. T., additional, Yuan, B. S., additional, Sun, H. J., additional, Ji, X. Q., additional, Gao, Y. D., additional, Li, Y. G., additional, Yan, L. W., additional, Yang, Q. W., additional, Liu, Yi, additional, Dong, J. Q., additional, Duan, X. R., additional, Liu, Yong, additional, and Pan, C. H., additional

Published
2010
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44. A method of particle transport study using supersonic molecular beam injection and microwave reflectometry on HL-2A tokamak

Author

Xiao, W. W., primary, Zou, X. L., additional, Ding, X. T., additional, Dong, J. Q., additional, Yao, L. H., additional, Song, S. D., additional, Liu, Z. T., additional, Gao, Y. D., additional, Feng, B. B., additional, Song, X. M., additional, Yang, Q. W., additional, Yan, L. W., additional, Liu, Yi, additional, Duan, X. R., additional, Pan, C. H., additional, and Liu, Yong, additional

Published
2010
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48. First ECRH Modulation Experiments in Tore Supra.

Author

Zou, X. L., Artaud, J. F., Bouquey, F., Clary, J., Darbos, C., Giruzzi, G., Lennholm, M., Magne, R., and Ségui, J. L.

Subjects
ELECTRON cyclotron resonance heating, TOKAMAKS, ELECTRONIC modulation, HEAT transfer, ELECTRIC inverters
Published
2003

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