In recent decades, tokamak discharges with zero total toroidal current have been reported in tokamak experiments, and this is one of the key problems in alternating current(AC) operations.An efficient free-boundary eq...In recent decades, tokamak discharges with zero total toroidal current have been reported in tokamak experiments, and this is one of the key problems in alternating current(AC) operations.An efficient free-boundary equilibrium code is developed to investigate such advanced tokamak discharges with current reversal equilibrium configuration. The calculation results show that the reversal current equilibrium can maintain finite pressure and also has considerable effects on the position of the X-point and the magnetic separatrix shape, and hence also on the position of the strike point on the divertor plates, which is extremely useful for magnetic design, MHD stability analysis, and experimental data analysis etc. for the AC plasma current operation on tokamaks.展开更多
The parametric decay instabilities （PDIs） of ion Bernstein wave with different input power levels are investigated via particle-in-cell simulation. It is found that the number of decay channels increases with the in...The parametric decay instabilities （PDIs） of ion Bernstein wave with different input power levels are investigated via particle-in-cell simulation. It is found that the number of decay channels increases with the input power. Resonant mode-mode couplings dominate for a low input power. With increasing the input power, the nonresonant PDIs appear to dissipate the energy of the injected wave and give rise to edge ion heating. The generated child waves couple with each other as well as the injected wave and /or act as a pump wave to excite new decay channels. As a result, the frequency spectrum is broadened with the increase of the input power.展开更多
Argon ion laser induced fluorescence measurements were carried out in a multipolar filament discharge with a broadband diode laser centered on 668 nm, which stimulated a transition from the metastable state in Ar（Ⅲ...Argon ion laser induced fluorescence measurements were carried out in a multipolar filament discharge with a broadband diode laser centered on 668 nm, which stimulated a transition from the metastable state in Ar（Ⅲ） 3d4F7/2 to 4p4D0 5/2. The intensity of the induced fluorescence at 442 nm was maximized by the optimization of the discharge parameters and the laser power. From the recovery of the background fluorescence after the laser was turned off, the ion diffusion coefficient was deduced and compared with the result inferred from the experiments of ion acoustic wave （IAW） damping.展开更多
In both quantum and classical field systems,conservation laws such as the conservation of energy and momentum are widely regarded as fundamental properties.A broadly accepted approach to deriving conservation laws is ...In both quantum and classical field systems,conservation laws such as the conservation of energy and momentum are widely regarded as fundamental properties.A broadly accepted approach to deriving conservation laws is built using Noether's method.However,this procedure is still unclear for relativistic particle-field systems where particles are regarded as classical world lines.In the present study,we establish a general manifestly covariant or geometric field theory for classical relativistic particle-field systems.In contrast to quantum systems,where particles are viewed as quantum fields,classical relativistic particle-field systems present specific challenges.These challenges arise from two sides.The first comes from the mass-shell constraint.To deal with the mass-shell constraint,the Euler–Lagrange–Barut(ELB)equation is used to determine the particle's world lines in the four-dimensional(4D)Minkowski space.Besides,the infinitesimal criterion,which is a differential equation in formal field theory,is reconstructed by an integro-differential form.The other difficulty is that fields and particles depend on heterogeneous manifolds.To overcome this challenge,we propose using a weak version of the ELB equation that allows us to connect local conservation laws and continuous symmetries in classical relativistic particle-field systems.By applying a weak ELB equation to classical relativistic particle-field systems,we can systematically derive local conservation laws by examining the underlying symmetries of the system.Our proposed approach provides a new perspective on understanding conservation laws in classical relativistic particle-field systems.展开更多
Detailed analysis of the low frequency instability is performed in a linear magnetized steady state plasma device. Identification and modification of the instability are presented.
A flux difference splitting numerical scheme based on the finite volume method is applied to study ideal/resistive magnetohydrodynamics. The ideal/resistive MHD equations are cast as a set of hyperbolic conservation l...A flux difference splitting numerical scheme based on the finite volume method is applied to study ideal/resistive magnetohydrodynamics. The ideal/resistive MHD equations are cast as a set of hyperbolic conservation laws, and we develop a numerical capability to solve the weak solutions of these hyperbolic conservation laws by combining a multi-state Harten-Lax-Van Leer approximate Riemann solver with the hyperbolic divergence cleaning technique, high order shock-capturing reconstruction schemes, and a third order total variance diminishing Runge-Kutta time evolving scheme. The developed simulation code is applied to study the long time nonlinear evolution of the coalescence instability. It is verified that small structures in the instability oscillate with time and then merge into medium structures in a coherent manner. The medium structures then evolve and merge into large structures, and The physics of this interesting nonlinear dynamics this trend continues through all scale-lengths is numerically analyzed.展开更多
The systematic Langmuir probe measurements for a weakly magnetized plasma have been carried out in the Linear Magnetized Plasma Device for different magnetic fields. By comparing the ion current density of probes with...The systematic Langmuir probe measurements for a weakly magnetized plasma have been carried out in the Linear Magnetized Plasma Device for different magnetic fields. By comparing the ion current density of probes with different sizes, the sheath thickness can be evaluated. It is found that while the ratio of cylindrical probe's dimension to ion Larmor radius is not more than 2, the model of probe for non-magnetized plasma is still applicable.展开更多
An electron Penning-Malmberg trap, which can confine an electron column and provide a good platform to investigate the cross-field transportation of a strongly magnetized electron plasma, has been set up. With the dev...An electron Penning-Malmberg trap, which can confine an electron column and provide a good platform to investigate the cross-field transportation of a strongly magnetized electron plasma, has been set up. With the device, an electron plasma with a density of 107 cm-3 can be confined for a relatively long time. The structure of the trap, electron source, as well as the way how to measure electron plasma density profile and velocity distribution are introduced in detail.展开更多
基金supported by National Natural Science Foundation of China (No. 12075276)partly by the Comprehensive Research Facility for Fusion Technology Program of China (No. 2018000052-73-01-001228)。
文摘In recent decades, tokamak discharges with zero total toroidal current have been reported in tokamak experiments, and this is one of the key problems in alternating current(AC) operations.An efficient free-boundary equilibrium code is developed to investigate such advanced tokamak discharges with current reversal equilibrium configuration. The calculation results show that the reversal current equilibrium can maintain finite pressure and also has considerable effects on the position of the X-point and the magnetic separatrix shape, and hence also on the position of the strike point on the divertor plates, which is extremely useful for magnetic design, MHD stability analysis, and experimental data analysis etc. for the AC plasma current operation on tokamaks.
基金Supported by National Key R&D Program of China(No.2017YFB1104700)National Natural Science Foundation(No.61705227,No.61774155,No.11774340)+2 种基金Jilin Provincial Science&Technology Development Project(No.20180414019GH)Scientific Research Project of the Chinese Academy of Sciences(No.QYZDB-SSWSYS038)The Key Program of the International Partnership Program of CAS(No.181722KYSB20160015)~~
基金Supported by the JSPS-NRF-NSFC A3 Foresight Program in the Field of Plasma Physics(NSFC No 11261140328 and NRF No 2012K2A2A6000443)the National Magnetic Confinement Fusion Science Program of China under Grant No 2013GB111002+1 种基金the National Natural Science Foundation of China under Grant Nos 11175212 and 11475220the Program of Fusion Reactor Physics and Digital Tokamak with the Chinese Academy of Sciences 'One-Three-Five' Strategic Planning
文摘The parametric decay instabilities （PDIs） of ion Bernstein wave with different input power levels are investigated via particle-in-cell simulation. It is found that the number of decay channels increases with the input power. Resonant mode-mode couplings dominate for a low input power. With increasing the input power, the nonresonant PDIs appear to dissipate the energy of the injected wave and give rise to edge ion heating. The generated child waves couple with each other as well as the injected wave and /or act as a pump wave to excite new decay channels. As a result, the frequency spectrum is broadened with the increase of the input power.
文摘Argon ion laser induced fluorescence measurements were carried out in a multipolar filament discharge with a broadband diode laser centered on 668 nm, which stimulated a transition from the metastable state in Ar（Ⅲ） 3d4F7/2 to 4p4D0 5/2. The intensity of the induced fluorescence at 442 nm was maximized by the optimization of the discharge parameters and the laser power. From the recovery of the background fluorescence after the laser was turned off, the ion diffusion coefficient was deduced and compared with the result inferred from the experiments of ion acoustic wave （IAW） damping.
基金supported by National Natural Science Foundation of China(No.12005141)supported by National Natural Science Foundation of China(No.11805273)+2 种基金supported by the Collaborative Innovation Program of Hefei Science Center,CAS(No.2021HSCCIP019)National MC Energy R&D Program(No.2018YFE0304100)National Natural Science Foundation of China(No.11905220)。
文摘In both quantum and classical field systems,conservation laws such as the conservation of energy and momentum are widely regarded as fundamental properties.A broadly accepted approach to deriving conservation laws is built using Noether's method.However,this procedure is still unclear for relativistic particle-field systems where particles are regarded as classical world lines.In the present study,we establish a general manifestly covariant or geometric field theory for classical relativistic particle-field systems.In contrast to quantum systems,where particles are viewed as quantum fields,classical relativistic particle-field systems present specific challenges.These challenges arise from two sides.The first comes from the mass-shell constraint.To deal with the mass-shell constraint,the Euler–Lagrange–Barut(ELB)equation is used to determine the particle's world lines in the four-dimensional(4D)Minkowski space.Besides,the infinitesimal criterion,which is a differential equation in formal field theory,is reconstructed by an integro-differential form.The other difficulty is that fields and particles depend on heterogeneous manifolds.To overcome this challenge,we propose using a weak version of the ELB equation that allows us to connect local conservation laws and continuous symmetries in classical relativistic particle-field systems.By applying a weak ELB equation to classical relativistic particle-field systems,we can systematically derive local conservation laws by examining the underlying symmetries of the system.Our proposed approach provides a new perspective on understanding conservation laws in classical relativistic particle-field systems.
基金supported by the National Natural Science Foundation of China(No.10275065)in part by the JSPS-CAS Core University Program in the field of Plasma and Nuclear Fusion
文摘Detailed analysis of the low frequency instability is performed in a linear magnetized steady state plasma device. Identification and modification of the instability are presented.
基金supported by the National Magnetic Confinement Fusion Science Program of China(Nos.2013GB111002,2013GB105003,2013GB111000,2014GB124005,2015GB111003)National Natural Science Foundation of China(Nos.11305171,11405208)+2 种基金JSPSNRF-NSFC A3 Foresight Program in the field of Plasma Physics(NSFC-11261140328)the Science Foundation of the Institute of Plasma Physics,Chinese Academy of Sciences(DSJJ-15-JC02)the CAS Program for the Interdisciplinary Collaboration Team
文摘A flux difference splitting numerical scheme based on the finite volume method is applied to study ideal/resistive magnetohydrodynamics. The ideal/resistive MHD equations are cast as a set of hyperbolic conservation laws, and we develop a numerical capability to solve the weak solutions of these hyperbolic conservation laws by combining a multi-state Harten-Lax-Van Leer approximate Riemann solver with the hyperbolic divergence cleaning technique, high order shock-capturing reconstruction schemes, and a third order total variance diminishing Runge-Kutta time evolving scheme. The developed simulation code is applied to study the long time nonlinear evolution of the coalescence instability. It is verified that small structures in the instability oscillate with time and then merge into medium structures in a coherent manner. The medium structures then evolve and merge into large structures, and The physics of this interesting nonlinear dynamics this trend continues through all scale-lengths is numerically analyzed.
基金The project supported by the National Nature Science Foundation of China (No.19975047, No.10075046)
文摘The systematic Langmuir probe measurements for a weakly magnetized plasma have been carried out in the Linear Magnetized Plasma Device for different magnetic fields. By comparing the ion current density of probes with different sizes, the sheath thickness can be evaluated. It is found that while the ratio of cylindrical probe's dimension to ion Larmor radius is not more than 2, the model of probe for non-magnetized plasma is still applicable.
基金This work was supported by National Natural Science Foundation of China No. 19975047, 10075046 .
文摘An electron Penning-Malmberg trap, which can confine an electron column and provide a good platform to investigate the cross-field transportation of a strongly magnetized electron plasma, has been set up. With the device, an electron plasma with a density of 107 cm-3 can be confined for a relatively long time. The structure of the trap, electron source, as well as the way how to measure electron plasma density profile and velocity distribution are introduced in detail.
