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  • IF =1.193

  • ISSN 1009-0630

  • e-ISSN 2058-6272

  • CN 34-1187/TL

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Achievement of 1000 s plasma generation of RF source for neutral beam injector
Chundong HU (胡纯栋), Yahong XIE (谢亚红), Yongjian XU (许永建), et al.
Plasma Sci. Technol.    2019, 21(2): 022001; doi: 10.1088/2058-6272/aaf1e0
Abstract41)      PDF (884KB)(250)      

A radio frequency (RF) ion source was developed for neutral beam injector in Institute of Plasma Physics, Chinese Academy of Sciences (ASIPP). A cylindrical driver based RF plasma source was tested and optimized for long pulse operation. Recently, the plasma source achieved 1000 s stable plasma discharge with RF power of 35 kW and source pressure of 0.7 Pa for the first time. The heat loading on each of driver components such as the Faraday shield (FS), RF coil and expansion chamber was measured by the water flow calorimeter system. The experiment results showed that FS is the component with highest heat loading and the heat loading on FS was about 65.8% of total heat loading on source. The details of the long pulse operation of RF plasma source are presented in this paper.

CO2 conversion by thermal plasma with carbon as reducing agent: high CO yield and energy efficiency
Peng LIU (刘朋)1, Xuesong LIU (刘雪松)1, Jun SHEN (沈俊)1, et al.
Plasma Sci. Technol.    2019, 21(1): 012001; doi: 10.1088/2058-6272/aadf30
Abstract32)      PDF (612KB)(306)      

A key problem in CO2 conversion by thermal plasma is suppressing the inverse reactions, CO+O→CO2 and CO+0.5O2 →CO2 , to simultaneously obtain high CO yield and energy efficiency. This can be done by quickly quenching the decomposed gas or rapidly taking away free oxygen from decomposed gas. In this paper, experiments of CO2 conversion by thermal plasma with carbon as a reducing agent are presented. Carbon quickly devoured free oxygen in thermal plasma decomposed gas, and not only is the inverse reaction completely suppressed, but the discharge energy to form oxygen atoms, oxygen molecular, and thermal energy is also reused. A CO2 conversion rate of 67%–94% and the corresponding electric energy efficiency of about 70% are achieved, both are much higher than that seen so far by other plasma implementations.

Geodesic acoustic mode in a reduced two-fluid model
Haijun REN (任海骏)
Plasma Sci. Technol.    2017, 19(12): 122001; doi: 10.1088/2058-6272/aa936f
Abstract152)      PDF (362KB)(387)      

A reduced two-fluid model is constructed to investigate the geodesic acoustic mode (GAM). The ion dynamics is sufficiently considered by including an anisotropic pressure tensor and inhibited heat flux vector, whose evolutions are determined by equations derived from the 16-momentum model. Electrons are supposed to obey the Boltzmann distribution responding to the electrostatic oscillation with near ion acoustic velocity. In the large safety factor limit, the GAM frequency is identical with the kinetic one to the order of 1/ q2 when zeroing the anisotropy. For general anisotropy, the reduced two-fluid model generates the frequency agreeing well with the kinetic result with arbitrary electron temperature. The present simplified fluid model will be of great use and interest for young researchers and students devoted to plasma physics.

Realization of minute-long steady-state H-mode discharges on EAST
Xianzu GONG (龚先祖) 1,Baonian WAN (万宝年) 1,Jiangang LI (李建刚) 1, et al.
Plasma Sci. Technol.    2017, 19(3): 032001; doi: 10.1088/2058-6272/19/3/032001
Abstract276)      PDF (1063KB)(782)      

In the 2016 EAST experimental campaign, a steady-state long-pulse H-mode discharge with an ITER-like tungsten divertor lasting longer than one minute has been obtained using only RF heating and current drive, through an integrated control of the wall conditioning, plasma configuration, divertor heat flux, particle exhaust, impurity management, and effective coupling of multiple RF heating and current drive sources at high injected power. The plasma current (Ip ∼0.45 MA) was fully-noninductively driven (V loop <0.0 V) by a combination of ∼2.5 MW LHW, ∼0.4 MW ECH and ∼0.8 MW ICRF. This result demonstrates the progress of physics and technology studies on EAST, and will benefit the physics basis for steady state operation of ITER and CFETR.

Integrated Operating Scenario to Achieve 100-Second, High Electron Temperature Discharge on EAST
QIAN Jinping (钱金平), GONG Xianzu (龚先祖), WAN Baonian (万宝年), et al.
Plasma Sci. Technol.    2016, 18(5): 457-459; doi: 10.1088/1009-0630/18/5/01
Abstract317)      PDF (223KB)(663)      

Stationary long pulse plasma of high electron temperature was produced on EAST for the first time through an integrated control of plasma shape, divertor heat flux, particle exhaust, wall conditioning, impurity management, and the coupling of multiple heating and current drive power. A discharge with a lower single null divertor conguration was maintained for 103 s at a plasma current of 0.4 MA, q95 ≈7.0, a peak electron temperature of >4.5 keV, and a central density ne(0)~2.5×1019 m-3. The plasma current was nearly non-inductive (Vloop <0.05 V, poloidal beta ∼0.9) driven by a combination of 0.6 MW lower hybrid wave at 2.45 GHz, 1.4 MW lower hybrid wave at 4.6 GHz, 0.5 MW electron cyclotron heating at 140 GHz, and 0.4 MW modulated neutral deuterium beam injected at 60 kV. This progress demonstrated strong synergy of electron cyclotron and lower hybrid electron heating, current drive, and energy confinement of stationary plasma on EAST. It further introduced an example of integrated “hybrid” operating scenario of interest to ITER and CFETR.

A New Method for Measurements of the Poloidal Rotation Velocities and Wavelength Calibration of X-ray Imaging Crystal Spectrometer in Magnetic Fusion Devices
SHI Yuejiang (石跃江) 1,LYU Bo (吕波) 2,WANG Fudi (王福地) 2,M. BITTER 3,et al.
Plasma Sci. Technol.    2015, 17(4): 265-267; doi: 10.1088/1009-0630/17/4/01
Abstract317)      PDF (4251KB)(1228)      

A new simple method is presented for the wavelength calibration and measurement of poloidal rotation velocities with X-ray imaging crystal spectrometer (XICS) in magnetic fusion devices. In this method, the toroidal rotation of plasma is applied for high precise alignment and wavelength calibration of the poloidal XICS. The measurement threshold of poloidal rotation velocity can be lowered to 1-3 km/s with this method.

First Achievement of Plasma Heating for EAST Neutral Beam Injector
HU Chundong (胡纯栋) for the NBI team
Plasma Sci. Technol.    2015, 17(1): 1-3; doi: 10.1088/1009-0630/17/1/01
Abstract250)      PDF (5642KB)(1386)      

As one of the most effective methods for plasma heating, a neutral beam injector (NBI) achieved plasma heating and current driving for the first time in EAST 2014 experimental campaign. According to the research plan of the EAST physics experiment, the first NBI (EAST- NBI-1) has been built and become operational in 2014. In this article, the latest experiment results of EAST-NBI-1 are reported as follows: (1) EAST achieves H-mode plasma in the case of NBI heating alone, (2) EAST achieves 22 s long pulse stable H-mode plasma in the case of simultaneous NBI and lower hybrid wave (LHW) heating. The measurement data show that the loop voltage decreased and the plasma stored energy increased obviously. The results indicate that EAST-NBI-1 has achieved plasma heating and current driving, and thus lays a foundation for the construction of EAST-NBI-2, which will be built in a few months this year.

Achievement of 100 s Long Pulse Neutral Beam Extraction in EAST Neutral Beam Injector
HU Chundong (胡纯栋) for the NBI team
Plasma Sci. Technol.    2013, 15(3): 201-203; doi: 10.1088/1009-0630/15/3/01
Abstract209)      PDF (9204KB)(1106)      

Neutral beam injection (NBI) is recognized as one of the most e®ective means for plasma heating. A 100 s long pulse neutral beam with 30 keV beam energy, 10 A beam current and a 100 s long pulse modulating neutral beam with 50 keV beam energy, 16 A beam current were achieved in the EAST neutral beam injector on the test-stand. The preliminary results suggest that EAST-NBI system initially possess the ability of long pulse beam extraction.

Preliminary Results of Ion Beam Extraction Tests on EAST Neutral Beam Injector
HU Chundong (胡纯栋) for the NBI team
Plasma Sci. Technol.    2012, 14(10): 871-873; doi: 10.1088/1009-0630/14/10/03
Abstract349)      PDF (2955KB)(1325)      
The neutral beam injection (NBI) system is one of the most important auxiliary plasma heating and current driving methods for fusion device. A high power ion beam of 3 MW with 80 keV beam energy in 0.5 second beam duration and a long pulse ion beam of 4 seconds with 50 keV beam energy ion beam extraction were achieved on the EAST neutral beam injector on the test-stand. The preliminary results show that the EAST-NBI system was developed successfully on schedule.
Operation with 1 MA plasma current in EAST
QIAN Jinping, GONG Xianzu, LI Jiangang, WAN Baonian, LING Bili, SHEN Biao, TI Ang, Guoqiang
Plasma Sci. Technol.    2011, 13(1): 1-2;
Abstract895)           

Discharge with a plasma current of 1 MA at a line-averaged density of 1.8×1019m-3 was realized in EAST, a fully superconducting tokamak. The key issues to achieve the discharge with 1 MA plasma current include both early shaping and LHCD assistance during start-up phase to extend the voltage margin of PF coils for easier plasma control, an optimization of the control methodology for PF coils to avoid over-current fault and a very good wall condition. A better wall condition was achieved mainly by extensive Lithium coating. Both stationary H-mode and diverted plasma discharge of 100 s were also obtained.