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Shaping Effects of the E-Fishbone in tokamaks

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Plasma Science and Technology 2013年第1期15卷 12-16页

作者：王中天王龙龙永兴董家齐何志雄刘宇唐昌建 Southwestern Institute of Physics Institute of Physics Chinese Academy of Sciences Physics Department of Sichuan University

Shaping effects of the E-fishbone in tokamaks are investigated. Coordinates related to the Solov＇ev configuration are used to calculate the precession frequency and kinetic contribu- tion. It is shown that elongation does not change the precession frequency and the kinetic energy. Growth rates of the E-fishbone vary with elongation which essentially has destabilizing effects. For elongated tokamaks, triangularity has a stabilizing effect on the modes which play a compensative role. The results may apply to Sunist.

关键词： shaping effects E-fishbone tokamaks Solov＇ev configuration

Effect of Equilibrium Current Profiles on External Kink Modes in tokamaks

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Plasma Science and Technology 2014年第8期16卷 726-731页

作者：刘超刘悦马照帅 Key Laboratory of Materials Modification by Laser Ion and Electron Beams (Dalian University of Technology Ministry of Education

Based on a linearized MHD model, the effect of equilibrium current profiles on external kink modes in tokamaks is studied by MARS code. Three types of equilibrium current profiles are adopted in this work. Firstly, a set of parabolic equilibrium current profiles are chosen. In these profiles the maximum current values in the center of the plasma are fixed, and the currents have different gradient and jump at the plasma boundary. The effects of the current gradient and jump on the growth rate of external kink mode are investigated. It is found that the current jump which causes the q profiles to change plays an important role in the externM kink modes in tokamaks. Secondly, a set of step equilibrium current profiles with different jump positions are chosen. The effect of jump position on external kink modes is discussed. Thirdly, a set of parabolic equilibrium current profiles with current bumps are chosen for the case of off-axis heating. The effects of height~ width and position of the current bumps on external kink modes are analyzed. The fiat equilibrium current profiles are disadvantageous for the MHD stabilities of tokamaks, because of the large current jump at the plasma edge. The peaked equilibrium current profiles and a large and localized current bump near the plasma edge benefit the MHD stabilities of tokamaks.

关键词： external kink mode equilibrium current profile tokamaks

Dust Charging and Dynamics in tokamaks

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Plasma Science and Technology 2011年第1期13卷 11-14页

作者：富田幸博河村学思黄治辉潘宇东严龙文 National Institute for Fusion Science Southwestern Institute of Physics

Fundamental characteristics of charging of a dust particle and its dynamics in SOL/divertor plasma in tokamaks are studied. According to the OML （orbit motion limited） theory, the charging process is extremely faster, with a charging time of nanoseconds, than the dynamics process of the dust particle in SOL/divertor plasma, with a characteristic time of mil- liseconds, which means that the local charge state can be taken as the equilibrium charge state. It was clarified that the equilibrium charge Zd, eq can be determined in the form of Zd, eq/RdTe, which is a function of both the normalized relative speed of plasma ion flow with respect to the velocity of the dust particle and the plasma temperature ratio. After the investigation of domi- nant forces acting on dust particles, the friction forces due to the plasma ion absorption and ion Coulomb scattering are found of the same order for the case of low relative speed. The critical radius of a dust particle, for which the gravity is larger than the friction forces due to plasma ions, is obtained.

关键词： dust particle dust charging OML model tokamaks

Recent progress on deep learning-based disruption prediction algorithm in HL-2A tokamak

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Chinese Physics B 2023年第7期32卷 1-11页

作者：杨宗谕刘宇航朱晓博陈正威夏凡钟武律高喆张轶泼刘仪 Southwestern Institute of Physics Chengdu 610043China Tsinghua University Beijing 100084China

Disruption prediction and mitigation is a crucial topic,especially for future large-scale tokamaks,due to disruption’sconcomitant harmful effects on the devices.On this topic,disruption prediction algorithm takes the responsibility to giveaccurate trigger signal in advance of disruptions,therefore the disruption mitigation system can effectively alleviate theharmful effects.In the past 5 years,a deep learning-based algorithm is developed in HL-2A tokamak.It reaches a truepositive rate of 92.2%,a false positive rate of 2.5%and a total accuracy of 96.1%.Further research is implementedon the basis of this algorithm to solve three key problems,i.e.,the algorithm’s interpretability,real-time capability andtransferability.For the interpretability,HL-2A’s algorithm gives saliency maps indicating the correlation between thealgorithm’s input and output by perturbation analysis.The distribution of correlations shows good coherence with thedisruption causes.For the transferability,a preliminary disruption predictor is successfully developed in HL-2M,a newlybuilt tokamak in China.Although only 44 shots are used as the training set of this algorithm,it gives reasonable outputswith the help of data from HL-2A and J-TEXT.For the real-time capacity,the algorithm is accelerated to deal with an inputslice within 0.3 ms with the help of some adjustments on it and TFLite framework.It is also implemented into the plasmacontrol system and gets an accuracy of 89.0%during online test.This paper gives a global perspective on these results anddiscusses the possible pathways to make HL-2A’s algorithm a more comprehensive solution for future tokamaks.

关键词： macroinstabilities tokamaks neural networks magnetic confinement and equilibrium

The CASTOR-K Code,Recent Developments and Applications

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Plasma Science and Technology 2015年第2期17卷 89-96页

作者： F.NABAIS D.BORBA R.COELHO A.FIGUEIREDO J.FERREIRA N.LOUREIRO P.RODRIGUES Associao EURATOM/IST Instituto de Plasmas e Fuso Nuclear-Instituto Superior TcnicoUniversidade de Lisboa

The CASTOR-K code is a hybrid magnetohydrodynamic （MHD）-drift kinetic code developed for the study of MHD modes in the presence of energetic ion populations. It allows a fast assessment of the linear stability of the modes, as well as an accurate calculation of damping due to thermal species （Landau damping）. These capabilities make the code an invaluable tool for parametric studies and data analysis. In recent years, CASTOR-K has been mostly used to analyze JET data, including the identification of mechanisms involved in the expulsion of energetic ions from the plasma. However, in order to prepare the code to be used for a wider range of tokamaks including ITER, the code is being subject to a series of important improvements. These improvements aim not only to introduce new physics in the code but also to make it capable of exchanging data with other codes through its integration in modelling infrastructures. In this paper a description of the CASTOR-K code is presented, as well as a summary of the most important results obtained with this code and a description of the new improvements being implemented.

关键词： controlled fusion tokamaks plasma instabilities magnetohydrodynamics（MHD） Alfven waves energetic particles

Long Pulse Operation of High Performance Plasmas in JT-60U

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Plasma Science and Technology 2006年第1期8卷 1-4页

作者： S.IDE the 3T-60 Team Naka Fusion Research Establishment Japan Atomic Energy Agency NakaIbaraki311-0193Japan

Recent experimental progress in JT-60U advanced tokamak research is presented： sustainment of the normalized beta （βN）- 3 in a normal magnetic shear plasma, the bootstrap current fraction （fBs） - 45% in a weak shear plasma and - 75% in a reversed magnetic shear plasma in a nearly fully non-inductive current drive condition for longer than the current relaxation time. Achievement of high-density, high-radiation fraction together with high-confinement in advanced plasmas is demonstrated. Achievements and findings in long pulse operations after system modification are presented as well. A 65 s discharge of Ip = 0.7 MA was successfully obtained. As a result, high-βN of 2.3 was successfully sustained for a very long period of 22.3 s. In addition, a 30 s standard ELMy H-mode plasma of Ip up to 1.4 MA was also obtained. Effectiveness of divertor pumping to control particle recycling and the electron density under the saturated wall retention was demonstrated. These achievements and issues in development are discussed.

关键词： transport properties magnetohydrodynamics tokamaks

Quantization Conditions, for a Wormhole Wave Function Revisited, as to How a Wormhole Throat Could Generate GW and Gravitons: Simple Version of Negative Energy Form Wormhole Obtained from First Principles, and Comparison with Tokamak GW/Gravitons Done

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Journal of High Energy Physics, Gravitation and Cosmology 2023年第1期9卷 124-133页

作者： Andrew Walcott Beckwith Department of Physics Chongqing University Chongqing China

We revisit how we utilized how Weber in 1961 initiated the process of quantization of early universe fields to the issue of what was for a wormhole mouth. While the wormhole models are well understood, there is not such a consensus as to how the mouth of a wormhole could generate signals. We try to develop a model for doing so and then revisit it, the Wormhole while considering a Tokamak model we used in a different publication as a way of generating GW, and Gravitons.

关键词： Minimum Scale Factor Cosmological Constant Space-Time Bubble Bouncing Cosmologies tokamaks

Magnetic field topology modeling under resonant magnetic perturbations on EAST

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Plasma Science and Technology 2019年第6期21卷 98-105页

作者：黄杰铃木康浩梁云峰贾曼妮孙有文楚南许吉禅吴木泉 EAST team Institute of Plasma Physics Chinese Academy of Sciences Hefei 230031 People's Republic of China University of Science and Technology of China Hefei 230026 People's Republic of China National Institutes of Fusion Sciences National Institutes of Natural Sciences Oroshi-cho 322-6 Toki 509-5292 Japan SOKENDAI The Graduate University for Advanced Studies Oroshi-cho 322-6 Toki 509-5292 Japan Institute for Energy and Climate Reserch-Plasma Physics Forschungszentrum Juelich Association EURATOM-FZJ Trilateral Euregio Cluster D-52425 Juelich Germany

In order to understand the mechanism by which the resonant magnetic perturbation (RMP)mitigates or suppresses the edge-localized mode (ELM),the topological study of the edge magnetic field in ELM mitigation or suppression phase is a critical issue.To model the three-dimensional magnetic field topology superposed RMP on Experimental Advanced Superconducting Tokamak,a numerical model using the field line tracing method for both vacuum and ideal plasma response approximations is proposed.Using the numerical model,the topological change and the penetration depth of the stochastic field lines in the edge magnetic field are studied in an RMP experiment.Comparing profiles of minimum9 on edge stochastic field lines and the particle flux pattem,the ideal plasma response changes the field line penetration depth while remaining similar profile relative to vacuum approximation.To mitigate and suppress ELM strongly,the deep penetration of RMP fields and topological changes of the edge magnetic field is a key from our modeling.

关键词： magnetic topology ideal plasma response tokamaks resonant magnetic perturbation

A general comparison between tokamak and stellarator plasmas

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Matter and Radiation at Extremes 2016年第4期1卷 192-200页

作者： Yuhong Xu Southwestern Institute of Physics PO Box 432Chengdu 610041People's Republic of China

This paper generally compares the essential features between tokamaks and stellarators,based on previous review work individually made by authors on several specific topics,such as theories,bulk plasma transport and edge divertor physics,along with some recent results.It aims at summarizing the main results and conclusions with regard to the advantages and disadvantages in these two types of magnetic fusion devices.The comparison includes basic magnetic configurations,magnetohydrodynamic(MHD)instabilities,operational limits and disruptions,neoclassical and turbulent transport,confinement scaling and isotopic effects,plasma rotation,and edge and divertor physics.Finally,a concept of quasi-symmetric stellarators is briefly referred along with a comparison of future application for fusion reactors.

关键词： tokamaks Stellarators Magnetohydrodynamic(MHD) Plasma transport and confinement Divertor