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284 results on '"Hu, L. Q."'

1. 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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2. Counting rational points on biquadratic hypersurfaces

Author

Browning, T. D. and Hu, L. Q.

Subjects
Mathematics - Number Theory, 11D45 (11G35, 11G50, 11P55, 14G25)
Abstract

An asymptotic formula is established for the number of rational points of bounded anticanonical height which lie on a certain Zariski open subset of an arbitrary smooth biquadratic hypersurface in sufficiently many variables. The proof uses the Hardy--Littlewood circle method.

Published
2018

3. 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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5. 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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6. Performance of newly developed ICRF antennas on EAST.

Author

Zhang, X. J., Qin, C. M., Yuan, S., Yang, H., Zhu, G. H., Zhang, W., Liu, L. N., Wang, Y. S., Mao, Y. Z., Wang, L., Zhao, Y. P., Gong, X. Z., Cheng, Y., Deng, X., Zhang, K., Ju, S. Q., Lin, A., Hu, L. Q., Wan, B. N., and Song, Y. T.

Subjects
ANTENNAS (Electronics), CONSTRAINTS (Physics), ELECTRIC lines, ANTENNA design, MAGNETIC fields
Abstract

One of the keys to successful ion cyclotron range of frequency (ICRF) heating in Experimental Advanced Superconducting Tokamak (EAST) is maximizing the coupled power through evanescent layer in both L-mode and H-mode discharges. Increasing coupling efficiency is critical. To reach high power operation, two newly developed antennas have been tested on EAST. Here, we describe the key design features of the antenna and assess its performance by comparison with old four-strap antenna. The key design features are lower k|| spectrum, two current strap configuration, and field aligned faraday screen. The design for the newly developed antenna is balance between geometrical constraints and physics requirements on EAST. The faraday screen rods are fully aligned with the total magnetic field. To reduce the maximum voltage further in the transmission line, an impedance transformer in the vacuum transmission line was used. With these modifications, the loading is increased by 3 times and the heating efficiency is increased by 2-3 times as compared with old four-strap antenna in both L-mode and H-mode discharges. 4.0MW of the maximum injected power with these two antennas have been achieved at the maximum voltage of 15 kV in the transmission lines. We will report latest experimental results from these two ICRF antennas in the recent campaign of EAST. [ABSTRACT FROM AUTHOR]

Published
2023
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7. Simulations of neutral beam injection and ion cyclotron resonance heating synergy in high power EAST scenarios

Author

Yang, D. K., primary, Liao, L. Y., additional, Li, Y. H., additional, Zhong, G. Q., additional, Zhang, X. J., additional, Zhang, W., additional, Hao, B. L., additional, Hu, L. Q., additional, Wan, B. N., additional, Hu, Z. M., additional, Zhang, Y. M., additional, Gorini, G., additional, Nocente, M., additional, Tardocchi, M., additional, Li, X. Q., additional, Xiao, C. J., additional, and Fan, T. S., additional

Published
2022
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11. Simulations of neutral beam injection and ion cyclotron resonance heating synergy in high power EAST scenarios

Author

Yang, D, Liao, L, Li, Y, Zhong, G, Zhang, X, Zhang, W, Hao, B, Hu, L, Wan, B, Hu, Z, Zhang, Y, Gorini, G, Nocente, M, Tardocchi, M, Li, X, Xiao, C, Fan, T, Yang, D K, Liao, L Y, Li, Y H, Zhong, G Q, Zhang, X J, Hao, B L, Hu, L Q, Wan, B N, Hu, Z M, Zhang, Y M, Li, X Q, Xiao, C J, Fan, T S, Yang, D, Liao, L, Li, Y, Zhong, G, Zhang, X, Zhang, W, Hao, B, Hu, L, Wan, B, Hu, Z, Zhang, Y, Gorini, G, Nocente, M, Tardocchi, M, Li, X, Xiao, C, Fan, T, Yang, D K, Liao, L Y, Li, Y H, Zhong, G Q, Zhang, X J, Hao, B L, Hu, L Q, Wan, B N, Hu, Z M, Zhang, Y M, Li, X Q, Xiao, C J, and Fan, T S

Abstract

The EAST plasmas heated with deuterium neutral beam injection and ion cyclotron resonance heating (ICRH) have been simulated by the TRANSP code. The analysis has been conducted using the full wave solver TORIC5, the radio frequency (RF)-kick operator, and NUBEAM to model the RF heating effects on fast ion velocity distribution. In this work, we present several simulated results compared with experiments for high power EAST scenarios, indicating that the interactions between ICRH and fast ions can significantly accelerate fast ions, which are confirmed by the increased neutron yield and broadened neutron emission spectrum measurements.

Published
2022

14. Experimental investigation of electromagnetic GAMs under the influence of 3D magnetic topological structure in EAST

Author

Qu, H, primary, Kong, D F, additional, Xu, M, additional, Liu, A D, additional, Liang, Y F, additional, Zhang, S B, additional, Cai, H S, additional, Qiu, Z Y, additional, Chen, W, additional, Shi, T H, additional, Gu, S, additional, Duan, Y M, additional, Wang, H H, additional, Chu, N, additional, Zhao, H L, additional, Xiang, H M, additional, Wang, Y M, additional, Han, X, additional, Zhang, T, additional, Gao, X, additional, Feng, X, additional, Zhou, C, additional, Zhuang, G, additional, Hu, L Q, additional, Xu, G S, additional, and Gong, X Z, additional

Published
2022
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17. Neutron emission and fast ion simulation for high performance long pulses at EAST

Author

Yang, D, Zhang, Y, Xiao, M, Hu, Z, Liao, L, Sun, J, Zhong, G, Hu, L, Wan, B, Gorini, G, Nocente, M, Tardocchi, M, Xiao, C, Fan, T, Yang D. K., Zhang Y. M., Xiao M., Hu Z. M., Liao L. Y., Sun J. Q., Zhong G. Q., Hu L. Q., Wan B. N., Gorini G., Nocente M., Tardocchi M., Xiao C. J., Fan T. S., Yang, D, Zhang, Y, Xiao, M, Hu, Z, Liao, L, Sun, J, Zhong, G, Hu, L, Wan, B, Gorini, G, Nocente, M, Tardocchi, M, Xiao, C, Fan, T, Yang D. K., Zhang Y. M., Xiao M., Hu Z. M., Liao L. Y., Sun J. Q., Zhong G. Q., Hu L. Q., Wan B. N., Gorini G., Nocente M., Tardocchi M., Xiao C. J., and Fan T. S.

Abstract

Neutron emission spectroscopy and neutron yield measurements are important for high neutral beam injection (NBI) power heating at the Experimental Advanced Superconducting Tokamak (EAST). The neutron yields mainly depend on the deposition from NBI to the deuterium plasmas in the EAST. We have recently used TRANSP with time dependent diagnostic results to simulate the transport process of 30 s long pulse deuterium plasma discharges in the EAST, obtaining the time dependent fast ion distribution, neutron emission spectrum, and total neutron emission rate. Combined with the time trace of the result measured by a standard 235U fission chamber, the effects of different configurations of NBI heating in EAST fusion plasmas have been evaluated.

Published
2021

19. The cross-polarization scattering system for the magnetic fluctuation measurement in the Experimental Advanced Superconducting Tokamak

Author

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

Published
2021
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24. Development of gamma ray spectrometer with high energy and time resolutions on EAST tokamak

Author

Zhou, R, Zhong, G, Hu, L, Tardocchi, M, Rigamonti, D, Giacomelli, L, Nocente, M, Gorini, G, Fan, T, Zhang, Y, Hu, Z, Xiao, M, Li, K, Hong, B, Lin, S, Zhang, J, Zhou R. J., Zhong G. Q., Hu L. Q., Tardocchi M., Rigamonti D., Giacomelli L., Nocente M., Gorini G., Fan T. S., Zhang Y. M., Hu Z. M., Xiao M., Li K., Zhang Y. K., Hong B., Zhang Y., Lin S. Y., Zhang J. Z., Zhou, R, Zhong, G, Hu, L, Tardocchi, M, Rigamonti, D, Giacomelli, L, Nocente, M, Gorini, G, Fan, T, Zhang, Y, Hu, Z, Xiao, M, Li, K, Hong, B, Lin, S, Zhang, J, Zhou R. J., Zhong G. Q., Hu L. Q., Tardocchi M., Rigamonti D., Giacomelli L., Nocente M., Gorini G., Fan T. S., Zhang Y. M., Hu Z. M., Xiao M., Li K., Zhang Y. K., Hong B., Zhang Y., Lin S. Y., and Zhang J. Z.

Abstract

A new gamma ray spectrometer with high energy and time resolutions has been developed and installed on the EAST tokamak to study fast ion and runaway electron behaviors. The spectrometer is based on a LaBr3(Ce) scintillator detector and a fully digital data acquisition system that is based on a digitizer with digital pulse processing algorithms. The energy resolution of the spectrometer is about 3.9% at 662 keV, and the spectrometer can operate stably at a counting rate as high as 1 MHz, monitored by using a light emitting diode monitoring system. The measured gamma ray spectrum is simulated based on Geant4 and unfolded with the high-resolution boosted Gold deconvolution algorithm, aiming at reconstructing the energy distribution functions of fast ions and runaway electrons.

Published
2019

26. An active Bonner sphere spectrometer capable of intense neutron field measurement

Author

Hu, Z. M., primary, Ge, L. J., additional, Sun, J. Q., additional, Zhang, Y. M., additional, Du, T. F., additional, Peng, X. Y., additional, Chen, J., additional, Zhang, H., additional, Nocente, M., additional, Rebai, M., additional, Croci, G., additional, Tardocchi, M., additional, Gorini, G., additional, Hu, L. Q., additional, Zhong, G. Q., additional, Zhou, R. J., additional, Chen, J. X., additional, Li, X. Q., additional, and Fan, T. S., additional

Published
2019
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27. Five-channel tunable W-band Doppler backscattering system in the experimental advanced superconducting tokamak

Author

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

Published
2019
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29. Experimental study of quasi-coherent mode using EAST tangential CO2 laser collective scattering diagnostic in far-forward mode

Author

Sun, P. J., primary, Li, Y. D., additional, Ren, Y., additional, Zhang, X. D., additional, Wu, G. J., additional, Wang, Y. M., additional, Shi, T. H., additional, Lyu, B., additional, Duan, Y. M., additional, Zhang, J. Z., additional, Wang, F. D., additional, Liu, H. Q., additional, Mao, S. T., additional, Xu, L. Q., additional, Li, Q., additional, Li, P., additional, Bi, J., additional, Hu, L. Q., additional, and Li, J. G., additional

Published
2019
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31. Neutron emission spectroscopy measurements with a compact liquid scintillation detector for NBI-heated plasma at EAST

Author

Ge, L, Hu, Z, Zhang, Y, Sun, J, Yuan, X, Peng, X, Chen, Z, Du, T, Gorini, G, Nocente, M, Tardocchi, M, Hu, L, Zhong, G, Lin, S, Wan, B, Li, X, Zhang, G, Chen, J, Fan, T, Ge, L J, Hu, Z M, Zhang, Y M, Sun, J Q, Peng, X Y, Chen, Z J, Du, T F, Hu, L Q, Zhong, G Q, Lin, S Y, Wan, B N, Li, X Q, Zhang, G H, Chen, J X, Fan, T S, Ge, L, Hu, Z, Zhang, Y, Sun, J, Yuan, X, Peng, X, Chen, Z, Du, T, Gorini, G, Nocente, M, Tardocchi, M, Hu, L, Zhong, G, Lin, S, Wan, B, Li, X, Zhang, G, Chen, J, Fan, T, Ge, L J, Hu, Z M, Zhang, Y M, Sun, J Q, Peng, X Y, Chen, Z J, Du, T F, Hu, L Q, Zhong, G Q, Lin, S Y, Wan, B N, Li, X Q, Zhang, G H, Chen, J X, and Fan, T S

Abstract

Neutron emission spectroscopy (NES) measurement aimed at providing the information on fast ions induced by auxiliary heating systems at Experimental Advanced Superconducting Tokamak (EAST), with a liquid scintillation detector is described. It is the first time that the NES diagnostics are employed to probe fast ions induced by neutral beam injection (NBI) at EAST. The time trace of the fusion neutrons, obtained by the liquid scintillation detector, was consistent with the result measured by a standard 235U fission chamber under NBI heating scenario, which verifies the performance of the detector. NUBEAM code is used to determine the fast deuteron velocity distribution using the parametrized plasma profiles as input. The pulse height spectrum of the fusion neutrons was successfully reproduced by combining the simulation of the neutron energy spectrum and the calculation of the detector response functions. The experimental data are also interpreted from a view of weight functions, which illustrate the velocity-space sensitivity of the liquid scintillation detector with a radial line of sight. The results demonstrate the capability of the liquid scintillation detector to contribute to studies on fast-ion physics at EAST.

Published
2018

32. Velocity-space sensitivity of time-of-flight neutron spectrometer at EAST in deuterium plasma

Author

Ge, L, Hu, Z, Zhang, Y, Sun, J, Yuan, X, Peng, X, Chen, Z, Du, T, Nocente, M, Gorini, G, Tardocchi, M, Hu, L, Zhong, G, Wan, B, Li, X, Fan, T, Ge, L. J., Hu, Z. M., Zhang, Y. M., Sun, J. Q., Yuan, X., Peng, X. Y., Chen, Z. J., Du, T. F., Nocente, M., Gorini, G., Tardocchi, M., Hu, L. Q., Zhong, G. Q., Wan, B. N., Li, X. Q., Fan, T. S., Ge, L, Hu, Z, Zhang, Y, Sun, J, Yuan, X, Peng, X, Chen, Z, Du, T, Nocente, M, Gorini, G, Tardocchi, M, Hu, L, Zhong, G, Wan, B, Li, X, Fan, T, Ge, L. J., Hu, Z. M., Zhang, Y. M., Sun, J. Q., Yuan, X., Peng, X. Y., Chen, Z. J., Du, T. F., Nocente, M., Gorini, G., Tardocchi, M., Hu, L. Q., Zhong, G. Q., Wan, B. N., Li, X. Q., and Fan, T. S.

Abstract

The Time-Of-Flight Enhanced Diagnostics (TOFED) neutron spectrometer with a double-ring structure has been installed at the Experimental Advanced Superconducting Tokamak (EAST) to perform advanced neutron emission spectroscopy diagnosis for deuterium plasma. In order to reduce the random coincidence from the background neutrons and gamma-rays, TOFED was moved outside the experimental hall and placed in the newly-built nuclear diagnostics laboratory in 2017. In this paper, the instrument-specific weight functions of TOFED are derived by taking the instrument response matrix and the radial line of sight in this new layout into consideration. The results show that the instrument is predominantly sensitive to counter-passing particles in the region where time-of-flights < 69.4 ns, while events at higher time-of-flights (corresponding lower neutron energies) are mostly representative of co-passing ions. The instrument-specific weight functions express the relationship between data in a given channel of the spectrum and the velocity space region that contributes to that. The results can be applied for energetic particle physics studies at EAST, in particular to compare data from different diagnostic techniques.

Published
2018

33. Development of gamma ray spectrometer with high energy and time resolutions on EAST tokamak.

Author

Zhou, R. J., Zhong, G. Q., Hu, L. Q., Tardocchi, M., Rigamonti, D., Giacomelli, L., Nocente, M., Gorini, G., Fan, T. S., Zhang, Y. M., Hu, Z. M., Xiao, M., Li, K., Zhang, Y. K., Hong, B., Zhang, Y., Lin, S. Y., and Zhang, J. Z.

Subjects
GAMMA ray spectrometer, SCINTILLATORS, DATA acquisition systems, GAMMA rays, FAST ions, LIGHT emitting diodes, DISTRIBUTION (Probability theory), STELLARATORS
Abstract

A new gamma ray spectrometer with high energy and time resolutions has been developed and installed on the EAST tokamak to study fast ion and runaway electron behaviors. The spectrometer is based on a LaBr3(Ce) scintillator detector and a fully digital data acquisition system that is based on a digitizer with digital pulse processing algorithms. The energy resolution of the spectrometer is about 3.9% at 662 keV, and the spectrometer can operate stably at a counting rate as high as 1 MHz, monitored by using a light emitting diode monitoring system. The measured gamma ray spectrum is simulated based on Geant4 and unfolded with the high-resolution boosted Gold deconvolution algorithm, aiming at reconstructing the energy distribution functions of fast ions and runaway electrons. [ABSTRACT FROM AUTHOR]

Published
2019
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35. Velocity-space sensitivity of time-of-flight neutron spectrometer at EAST in deuterium plasma

Author

Ge, L. J., primary, Hu, Z. M., additional, Zhang, Y. M., additional, Sun, J. Q., additional, Yuan, X., additional, Peng, X. Y., additional, Chen, Z. J., additional, Du, T. F., additional, Nocente, M., additional, Gorini, G., additional, Tardocchi, M., additional, Hu, L. Q., additional, Zhong, G. Q., additional, Wan, B. N., additional, Li, X. Q., additional, and Fan, T. S., additional

Published
2018
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38. Neutron emission spectroscopy measurements with a compact liquid scintillation detector for NBI-heated plasma at EAST

Author

Ge, L J, primary, Hu, Z M, additional, Zhang, Y M, additional, Sun, J Q, additional, Yuan, X, additional, Peng, X Y, additional, Chen, Z J, additional, Du, T F, additional, Gorini, G, additional, Nocente, M, additional, Tardocchi, M, additional, Hu, L Q, additional, Zhong, G Q, additional, Lin, S Y, additional, Wan, B N, additional, Li, X Q, additional, Zhang, G H, additional, Chen, J X, additional, and Fan, T S, additional

Published
2018
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40. Recent progress of RF-dominated experiments on EAST.

Author

Liu, F. K., Zhao, Y. P., Shan, J. F., Zhang, X. J., Ding, B. J., Wang, X. J., Wang, M., Xu, H. D., Qin, C. M., Li, M. H., Gong, X. Z., Hu, L. Q., Wan, B. N., Song, Y. T., and Li, J. G.

Subjects
RADIO frequency, LOWER hybrid heating, CYCLOTRON resonance, TOKAMAKS, PINCH effect (Physics), PLASMA confinement devices
Abstract

The research of EAST program is mostly focused on the development of high performance steady state scenario with ITER-like poloidal configuration and RF-dominated heating schemes. With the enhanced ITER-relevant auxiliary heating and current drive systems, the plasma profile control by coupling/integration of various combinations has been investigated, including lower hybrid current drive (LHCD), electron cyclotron resonance heating (ECRH) and ion cyclotron resonance heating (ICRH). The 12 MW ICRH system has been installed on EAST. Heating and confinement studies using the Hydrogen Minority Heating scheme have been investigated. One of the importance challenges for EAST is coupling higher power into the core plasma, experiments including changing plasma position, electron density, local gas puffing and antenna phasing scanning were performed to improve ICRF coupling efficiency on EAST. Results show that local gas injection and reducing the k∥ can improve the coupling efficiency directly. By means of the 4.6 GHz and 2.45 GHz LHCD systems, H-mode can be obtained and sustained at relatively high density, even up to ne ~ 4.5 × 1019 m-3, where a current drive effect is still observed. Meanwhile, effect of source frequency (2.45GHz and 4.6GHz) on LHCD characteristic has been studied on EAST, showing that higher frequency improves penetration of the coupled LH (lower hybrid) power into the plasma core and leads to a better effect on plasma characteristics. Studies demonstrate the role of parasitic effects of edge plasma in LHCD and the mitigation by increasing source frequency. Experiments of effect of LH spectrum and plasma density on plasma characteristics are performed, suggesting the possibility of plasma control for high performance. The development of a 4MW ECRH system is in progress for the purpose of plasma heating and MHD control. The built ECRH system with 1MW source power has been successfully put into use on EAST in 2015. H-mode discharges with L-H transition triggered by ECRH injection were obtained and its effects on the electron temperature, particle confinement and the core MHD stabilities were observed. By further exploring and optimizing the RF combination for the sole RF heating and current drive regime, fully non-inductive H-mode discharges with Vloop~0V has progressed steadily in the 2016 campaign. The overview of the significant progress of RF dominated experiments is presented in this paper. [ABSTRACT FROM AUTHOR]

Published
2017
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41. Experimental study of quasi-coherent mode using EAST tangential CO2 laser collective scattering diagnostic in far-forward mode.

Author

Sun, P. J., Li, Y. D., Ren, Y., Zhang, X. D., Wu, G. J., Wang, Y. M., Shi, T. H., Lyu, B., Duan, Y. M., Zhang, J. Z., Wang, F. D., Liu, H. Q., Mao, S. T., Xu, L. Q., Li, Q., Li, P., Bi, J., Hu, L. Q., and Li, J. G.

Subjects
ELECTRON density, SCATTERING (Physics), EDGE-localized modes (Plasma instabilities), CARBON dioxide, REFLECTOMETER
Abstract

A quasi-coherent mode (QCM) was measured by the tangential CO2 laser collective scattering diagnostic at high plasma electron density during both enhanced Dα/small edge-localized mode (ELM) and ELM-free H mode phases in Experimental Advanced Superconducting Tokamak (EAST). Experimental results from only local oscillator CO2 laser scattering prove that the QCM is measured by the scattering diagnostic in the far-forward mode. The driven QCM density fluctuation ( k ⊥ < 3 cm−1) and magnetic fluctuation suggest that the QCM is an electromagnetic mode. The typical frequency of the QCM is f ≈ 26.5 kHz. A combination analysis of scattering signals and Mirnov signals suggests that the QCM has toroidal mode number n ≈ 17 and rotates along with the electron diamagnetic drift velocity direction in the lab frame. The analysis of Mirnov and reflectometer signals supports that the QCM locates in the edge pedestal region. The QCM power has been found to be related to both the Dα signal and the pedestal density gradient. A comparison of the EAST QCM and C-Mod quasi-coherent mode has been given in detail. [ABSTRACT FROM AUTHOR]

Published
2019
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42. Initial measurements of plasma current and electron density profiles using a polarimeter/interferometer (POINT) for long pulse operation in EAST (invited)

Author

Liu, H. Q., primary, Qian, J. P., additional, Jie, Y. X., additional, Ding, W. X., additional, Brower, D. L., additional, Zou, Z. Y., additional, Li, W. M., additional, Lian, H., additional, Wang, S. X., additional, Yang, Y., additional, Zeng, L., additional, Lan, T., additional, Yao, Y., additional, Hu, L. Q., additional, Zhang, X. D., additional, and Wan, B. N., additional

Published
2016
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43. Measurement and simulation of the response function of time of flight enhanced diagnostics neutron spectrometer for beam ion studies at EAST tokamak

Author

Peng, X. Y., primary, Chen, Z. J., additional, Zhang, X., additional, Du, T. F., additional, Hu, Z. M., additional, Ge, L. J., additional, Zhang, Y. M., additional, Sun, J. Q., additional, Gorini, G., additional, Nocente, M., additional, Tardocchi, M., additional, Hu, L. Q., additional, Zhong, G. Q., additional, Pu, N., additional, Lin, S. Y., additional, Wan, B. N., additional, Li, X. Q., additional, Zhang, G. H., additional, Chen, J. X., additional, and Fan, T. S., additional

Published
2016
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45. Upgrade of Langmuir probe diagnostic in ITER-like tungsten mono-block divertor on experimental advanced superconducting tokamak

Author

Xu, J. C., primary, Wang, L., additional, Xu, G. S., additional, Luo, G. N., additional, Yao, D. M., additional, Li, Q., additional, Cao, L., additional, Chen, L., additional, Zhang, W., additional, Liu, S. C., additional, Wang, H. Q., additional, Jia, M. N., additional, Feng, W., additional, Deng, G. Z., additional, Hu, L. Q., additional, Wan, B. N., additional, Li, J., additional, Sun, Y. W., additional, and Guo, H. Y., additional

Published
2016
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47. Experimental observation of (intermediate, high)-k micro-turbulence in different type H mode plasmas in EAST.

Author

Wu, G. J., Li, Y. D., Sun, P. J., Li, P., Bi, J., Wang, S. X., Liu, H. Q., Zhang, X. D., and Hu, L. Q.

Subjects
PLASMA turbulence, PLASMA flow, PLASMA confinement devices, TOKAMAKS, ELECTRON density, ELECTROMAGNETIC wave scattering
Abstract

Both k1 = 12 cm−1 (intermediate-k) and k2 = 22 cm−1 (high-k) micro-turbulence (k⊥ρs ∼ 1–4) in gradient region plasmas were measured simultaneously by the EAST poloidal CO2 laser collective scattering system. Their behaviors have been studied in detail in both ELM-free/type III ELMy and enhanced Da (EDA) H mode plasma discharges. Compared with that in the previous L mode phase, it can be seen obviously that the mean frequency of lower-k (k1) micro-turbulence increases and that of higher-k (k2) decreases during the ELM-free or type III ELMy H mode phase, while frequency-integrated spectral power (Stot) of both k1 and k2 micro-turbulence seems almost the same. On the other hand, both Stot and mean frequency of k1/k2 micro-turbulence show continuous increase during the EDA H mode phase. These results imply that the response of (intermediate, high)-k micro-turbulence on different type H mode is different. Further cross-correlation analysis between k1 and k2 micro-turbulence shows that their cross-correlation value is a little lower in H mode phase than the previous L mode phase. It can also be found that the cross-correlation value decreases gradually during the ELM-free and subsequent type-III ELMy phases, and it is almost zero in the EDA H mode phase. These new results could shed some light on the comprehensive understanding of mechanisms under H mode physics. [ABSTRACT FROM AUTHOR]

Published
2018
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48. Production of high-quality ZnO films by the two-step annealing method.

Author

Ye, J. D., Gu, S. L., Zhu, S. M., Qin, F., Liu, S. M., Liu, W., Zhou, X., Hu, L. Q., Zhang, R., Shi, Y., and Zheng, Y. D.

Subjects
ANNEALING of crystals, ZINC oxide thin films, THIN films, EPITAXY, CRYSTAL growth, CHEMISORPTION
Abstract

In this study, a two-step annealing method is advanced to produce high-quality ZnO films with excellent structural, electrical, and optical properties. The effects of oxygen and nitrogen annealing on the properties of undoped ZnO films are reversible to each other and are attributed to the creation and annihilation of extrinsic trap states of antisite oxygen OZn and oxygen vacancies VO, which result from the chemisorption and desorption of oxygen, respectively. Moreover, annealing in nitrogen causes slight nitrogen incorporation, subsequently increasing the resistivity and inducing compressive stress in the film. The key to this two-step method is to keep the chemisorption and desorption of oxygen in equilibrium. Due to the similarity of annealing ambient with the growth condition, this process can be transplanted and employed in the in situ preparation of high-quality ZnO epilayers. [ABSTRACT FROM AUTHOR]

Published
2004
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49. Edge Magnetic Topology Change Induced by LHCD and Its Profound Effects in EAST

Author

Liang, Yunfeng, Gong, X. Z., Hu, L. Q., Hu, J. S., Liu, F. K., Jie, Y. X., Pearson, J., Qian, J. P., Shan, J. F., Shen, B., Shi, T. H., Sun, Y., Gan, K. F., Wang, F. D., Wang, H. Q., Wang, M., Zhang, S. B., Zhang, T., Yan, N., Xu, G. S., Guo, H. Y., Wan, B. N., Li, J. G., Gauthier, E., team, the EAST, Wang, L., Rack, M., Wang, Y. M., Lv, B., Ding, B. J., and Chen, R.

Published
2012

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