Renewable energy stations(RES) must satisfy voltage security and power factor requirements for safe and efficient operation. However, these requirements often conflict, posing challenges in practical applications. Thi...
详细信息
In order to advance the research on suppressing tearing modes and driving plasma rotation, a DC power supply (PS) system has been developed for dynamic resonant magnetic perturbation (DRMP) coils and applied in th...
详细信息
In order to advance the research on suppressing tearing modes and driving plasma rotation, a DC power supply (PS) system has been developed for dynamic resonant magnetic perturbation (DRMP) coils and applied in the J-TEXT experiment. To enrich experimental phe- nomena in the J-TEXT tokamak, applying the circulating current four-quadrant operation mode in the DRMP DC PS system is proposed. By using the circulating current four-quadrant oper- ation, DRMP coils can be smoothly controlled without the dead-time when the current polarity reverses. Essential circuit analysis, control optimization and simulation of desired scenarios have been performed for normal current. Relevant simulation and test results are also presented.
The equilibrium fitting code (EFIT) and its application in the J-TEXT tokamak are integrated by the Matlab language. The function of analysis and visualization to the results is added. In addition, the experiment da...
详细信息
The equilibrium fitting code (EFIT) and its application in the J-TEXT tokamak are integrated by the Matlab language. The function of analysis and visualization to the results is added. In addition, the experiment data measured by soft X-ray (SXR) are used to calculate plasma equilibrium as a constraint condition. The improved EFIT code is used for J-TEXT discharge and the profiles of plasma parameters such as flux function, safety factor q, pressure and current density are obtained from the reconstructed configurations.
Recently, hydrogen fueling experiments with supersonic molecular beam injection (SMBI) system have been performed in the J-TEXT tokamak. To evaluate the effects of the in- jection amount of SMBI on plasma behaviors,...
详细信息
Recently, hydrogen fueling experiments with supersonic molecular beam injection (SMBI) system have been performed in the J-TEXT tokamak. To evaluate the effects of the in- jection amount of SMBI on plasma behaviors, moderate and intensive SMBs have been separately injected and compared with each other in Ohmic discharges. With moderate SMBs, electron den- sity increases about twice as before, the size of magnetic island slightly decreases, and the edge toroidal rotation speed in a counter-current direction, measured by a high resolution spectrometer (Carbon V ion, 227.09 nm, r/a-= 0.7-0.8), is accelerated from 8 km/s to 12 km/s. The state of higher electron density with moderate SMBI can be maintained for a long period, which indicates that plasma confinement is improved. However, with intensive SMBs, the accompanied magne- tohydrodynamic (MHD) activities are triggered, and the electron density increases moderately. The edge toroidal velocity is decreased, in certain cases even reversed in the co-current direction. The statistical result of experimental data for moderate and intensive SMBs suggests a preferred fueling amount (less than 3.2 ~ 1019) to improve the SMBI fueling efficiency in experiments.
Antiferromagnetic materials with van der Waals (vdW) layered structures hold great promises for developing the next generation of electronic and optoelectronic devices, providing unique combinations of terahertz spin ...
详细信息
Antiferromagnetic materials with van der Waals (vdW) layered structures hold great promises for developing the next generation of electronic and optoelectronic devices, providing unique combinations of terahertz spin dynamics, ultrastability against magnetic fields disturbance, and low power consumption. Here, we demonstrate unconventional nonvolatile bistable planar Hall effect (PHE) in few-layer GdTe3, a natural vdW heterostructure consisting of metallic Te layers and antiferromagnetic (AFM) GdTe bilayers. By fully unfolding the magnetic phase diagram of few-layer GdTe3 utilizing temperature- and angle-dependent magnetotransport measurements, we identify that the nonvolatile switching of bistable PHE states is rooted in the fourfold Néel vector flipping between two perpendicular in-plane magnetocrystalline anisotropy axes, each flipping reverses the signs of the PHE state. The efficient magnetic field (H) write-in and zero-field read out of the PHE memory pave the way for 2D AFM-based spintronics such as nonvolatile information storage and logic operations.
Since the beta function of the electron beam within the undulator has a great influence on the power gain of the free electron laser(FEL),optimization of the undulator lattice becomes *** this paper,the transfer mat...
详细信息
Since the beta function of the electron beam within the undulator has a great influence on the power gain of the free electron laser(FEL),optimization of the undulator lattice becomes *** this paper,the transfer matrix of the planar undulator is obtained from differential equations of the electron *** on this,the lattice function of the planar undulator in a terahertz FEL oscillator proposed by Huazhong University of Science and technology(HUST-FEL) is optimized and the expressions of the average beta function are *** accuracy of the optimization result was confirmed well by the numerical *** application range of this analytical method is given as *** last,the emittance growth in the horizontal direction due to the attenuation of the magnetic field is discussed.
Static synchronous compensators(STATCOM)can be used as a reactive power compensation for induction motor(IM)loads due to its effective control and good *** voltage control(TVC)in a STATCOM has a great influence on vol...
详细信息
Static synchronous compensators(STATCOM)can be used as a reactive power compensation for induction motor(IM)loads due to its effective control and good *** voltage control(TVC)in a STATCOM has a great influence on voltage dynamics which is a significant concern in a system with many IM *** paper investigates the interaction between IM loads and TVC in a STATCOM under weak grid conditions from the viewpoint of active and reactive power flow.A corresponding induction machine model is proposed,based on which the interaction mechanism between IM loads and TVC in a STATCOM can be intuitively *** is shown that the negative damping component provided by TVC in a STATCOM can lead to system oscillation *** strength and the inertia constant of the induction machine affect the extent of such ***-domain simulation results of IM loads connected to an infinite system through a long transmission line,with STATCOM compensation implemented in MATLAB/Simulink,validate the correctness of the analyses.
Prediction of disruptions caused by locked modes using the Back-Propagation (BP) neural network is completed on J-TEXT tokamak. The network, which is based on the BP neural network, uses Mirnov coils and locked mode...
详细信息
Prediction of disruptions caused by locked modes using the Back-Propagation (BP) neural network is completed on J-TEXT tokamak. The network, which is based on the BP neural network, uses Mirnov coils and locked mode coils signals as input data, and outputs a signal including information of prediction of locked mode. The rate of successful prediction of locked modes is more than 90%. For intrinsic locked mode disruptions, the network can give a prewarning signal about 1 ms ahead of the locking-time. For the disruption caused by resonant magnetic perturbation (RMPs) locked modes, the network can give a prewarning signal about 10 ms ahead of the locking-time.
In this work, we use the three-dimensional resistive MHD code NIMROD to investigate the impact of resistivity inhomogeneity on the sawtooth process of an reversed field pinch (RFP) plasma. The simulation employs a non...
详细信息
Molecular adsorption plays a key role in heterogeneous catalysis, with the d-band center theory being extensively utilized for qualitative analysis of adsorption behavior of molecules on transition-metal surfaces. How...
详细信息
Molecular adsorption plays a key role in heterogeneous catalysis, with the d-band center theory being extensively utilized for qualitative analysis of adsorption behavior of molecules on transition-metal surfaces. However, adsorption energies predicted by d-band center theory can have large errors, especially when a wide range of metals is considered. The physical mechanism responsible for the deviation has been unclear, posing significant challenges of the precise design of catalysts. Here, we have integrated density-functional theory calculations with artificial intelligence approaches to develop a unifying model that quantitatively evaluates the adsorption energy of water on various transition-metal surfaces. Data mining revealed that the large deviations between the d-band center theory predictions and first-principles calculations primarily stem from surface relaxation effects. Additionally, we discovered that the synergistic effects of electron donation and back donation, which are mediated by the d and p orbitals in metals, also play a role in these deviations, although their impact is less significant compared to that of the surface relaxation. These findings enhance our understanding of molecular adsorption behavior and are poised to influence research fields such as surface science and heterogeneous catalysis.
暂无评论