In the presence of energetic particles(EPs)from auxiliary heating and burning plasmas,fishbone instability and Alfvén modes can be excited and their transition can take place in certain overlapping regimes.Using ...In the presence of energetic particles(EPs)from auxiliary heating and burning plasmas,fishbone instability and Alfvén modes can be excited and their transition can take place in certain overlapping regimes.Using the hybrid kinetic-magnetohydrodynamic model in the NIMROD code,we have identified such a transition between the fishbone instability and theβ-induced Alfvén eigenmode(BAE)for the NBI heated plasmas on HL-2 A.When the safety factor at magnetic axis is well below one,typical kink-fishbone transition occurs as the EP fraction increases.When q0 is raised to approaching one,the fishbone mode is replaced with BAE for sufficient amount of EPs.When q0 is slightly above one,the toroidicity-induced Alfvén eigenmode dominates at lower EP pressure,whereas BAE dominates at higher EP pressure.展开更多
The mechanical properties,thermodynamic properties and electronic structure of Mo1-xTax(Mo-Ta)alloys(x=0,0.0625,0.125,0.25,0.3125,0.5 and 1)were calculated by using firstprinciples.The electronic structure of Mo-Ta al...The mechanical properties,thermodynamic properties and electronic structure of Mo1-xTax(Mo-Ta)alloys(x=0,0.0625,0.125,0.25,0.3125,0.5 and 1)were calculated by using firstprinciples.The electronic structure of Mo-Ta alloys was analysed by the projected density of states(PDOS).The low temperature heat capacity was estimated by Fermi energy and Debye temperature.It is shown that the formation enthalpy will decrease with the increase of Ta content,and the cohesive energy will increase with the increase of the Ta content.On the other hand,the addition of Ta atoms will reduce the strength and improve the ductility of Mo-Ta alloys,the Debye temperature will decrease and the low temperature heat capacity will be improved with the increase of the Ta content.All these results will be useful for the research of new plasma grid(PG)materials,which is mainly used in neutral beam injection(NBI)systems to produce negative hydrogen ions.展开更多
In the presence of energetic particles(EPs),the long-lived mode(LLM) frequency multiplication with n=1,2,3,or higher is often observed on HL-2A,where n is the toroidal mode number.Hybrid kinetic-MHD model simulations ...In the presence of energetic particles(EPs),the long-lived mode(LLM) frequency multiplication with n=1,2,3,or higher is often observed on HL-2A,where n is the toroidal mode number.Hybrid kinetic-MHD model simulations of the energetic particle(EP) driven kink/fishbone modes on a static HL-2A-like tokamak using NIMROD code find that when the background plasma pressure is relatively high,and the EP pressure and the beam energy are relatively low,the mode frequency increases almost linearly with EP pressure,and the frequency is proportional to n(’frequency multiplication’),even in the absence of any equilibrium plasma rotation.In addition,the frequency multiplication persists as the safety factor at the magnetic axis q_(0)varies.In the absence of EPs,the growth rate of the 1/1 mode is the largest;however,as the EP pressure increases,the growth rate of 2/2 modes or 3/3 modes becomes dominant,suggesting that higher-n modes are more vulnerable to EPs.These results may shed light on the understanding of the toroidal mode number dependence of kink/fishbone modes in the advanced scenarios of tokamaks with weak or reversed central magnetic shear.展开更多
Numerical calculations of resistive internal kink mode with effects of energetic particles(EPs) on HL-2A have been performed using the hybrid kinetic-MHD model inplemented in the NIMROD code.The m/n=1/1 resistive inte...Numerical calculations of resistive internal kink mode with effects of energetic particles(EPs) on HL-2A have been performed using the hybrid kinetic-MHD model inplemented in the NIMROD code.The m/n=1/1 resistive internal kink mode is unstable in MHD limit.However, with kinetic effects of energetic ions, a fishbone mode is excited with mode frequency around 10 kHz.We calculate the impact of resistivity on the growth rate and frequency of ion fishbone mode,and the results are in good agreement with the analytic solutions, which are obtained by solving the fishbone dispertion relation including resistivity effect.The effects of βfracand cut off velocity of EP on fishbone mode are calculated in detail, where βfracis the ratio of EP pressure to background plasma pressure.This work presents a clear explanation of the stabilizing effect of ECRH on ion fishbone, which is first observed on HL-2A.展开更多
基金supported by the National Magnetic Confinement Fusion Science Program of China(No.2019YFE03050004)National Natural Science Foundation of China(Nos.11875253,11775221,51821005)+3 种基金the Fundamental Research Funds for the Central Universities at University of Science and Technology of China(No.WK3420000004)Huazhong University of Science and Technology(No.2019kfy XJJS193)the Collaborative Innovation Program of Hefei Science Center,CAS(No.2019HSC-CIP015)the U.S.Department of Energy(Nos.DE-FG02-86ER53218 and DE-SC0018001)。
文摘In the presence of energetic particles(EPs)from auxiliary heating and burning plasmas,fishbone instability and Alfvén modes can be excited and their transition can take place in certain overlapping regimes.Using the hybrid kinetic-magnetohydrodynamic model in the NIMROD code,we have identified such a transition between the fishbone instability and theβ-induced Alfvén eigenmode(BAE)for the NBI heated plasmas on HL-2 A.When the safety factor at magnetic axis is well below one,typical kink-fishbone transition occurs as the EP fraction increases.When q0 is raised to approaching one,the fishbone mode is replaced with BAE for sufficient amount of EPs.When q0 is slightly above one,the toroidicity-induced Alfvén eigenmode dominates at lower EP pressure,whereas BAE dominates at higher EP pressure.
基金supported by National Natural Science Foundation of China(No.11820101004)the National Key R&D Program of China(2017YFE0300100,2017YFE0301100)。
文摘The mechanical properties,thermodynamic properties and electronic structure of Mo1-xTax(Mo-Ta)alloys(x=0,0.0625,0.125,0.25,0.3125,0.5 and 1)were calculated by using firstprinciples.The electronic structure of Mo-Ta alloys was analysed by the projected density of states(PDOS).The low temperature heat capacity was estimated by Fermi energy and Debye temperature.It is shown that the formation enthalpy will decrease with the increase of Ta content,and the cohesive energy will increase with the increase of the Ta content.On the other hand,the addition of Ta atoms will reduce the strength and improve the ductility of Mo-Ta alloys,the Debye temperature will decrease and the low temperature heat capacity will be improved with the increase of the Ta content.All these results will be useful for the research of new plasma grid(PG)materials,which is mainly used in neutral beam injection(NBI)systems to produce negative hydrogen ions.
基金supported by the National Magnetic Confinement Fusion Program of China (No. 2019YFE03050004)National Natural Science Foundation of China (Nos.11875253,11775221,51821005 and 11875018)+2 种基金the Fundamental Research Funds for the Central Universities (Nos.WK3420000004 and 2019kfyXJJS193)the Collaborative Innovation Program of Hefei Science Center,CAS (No. 2019HSC-CIP015)the U S Department of Energy (Nos.DEFG02-86ER53218 and DE-SC0018001)
文摘In the presence of energetic particles(EPs),the long-lived mode(LLM) frequency multiplication with n=1,2,3,or higher is often observed on HL-2A,where n is the toroidal mode number.Hybrid kinetic-MHD model simulations of the energetic particle(EP) driven kink/fishbone modes on a static HL-2A-like tokamak using NIMROD code find that when the background plasma pressure is relatively high,and the EP pressure and the beam energy are relatively low,the mode frequency increases almost linearly with EP pressure,and the frequency is proportional to n(’frequency multiplication’),even in the absence of any equilibrium plasma rotation.In addition,the frequency multiplication persists as the safety factor at the magnetic axis q_(0)varies.In the absence of EPs,the growth rate of the 1/1 mode is the largest;however,as the EP pressure increases,the growth rate of 2/2 modes or 3/3 modes becomes dominant,suggesting that higher-n modes are more vulnerable to EPs.These results may shed light on the understanding of the toroidal mode number dependence of kink/fishbone modes in the advanced scenarios of tokamaks with weak or reversed central magnetic shear.
基金supported by the National Magnetic Confinement Fusion Program (Nos.2014GB110000, 2014GB124002 and 2015GB101004)National Natural Science Foundation of China (Nos.11475058, 11875253 and 11775221)+1 种基金the Fundamental Research Funds for the Central Universities (No.WK3420000004)the supports from US Department of Energy (Nos.DE-FG0286ER53218 and DE-FC02-08ER54975)
文摘Numerical calculations of resistive internal kink mode with effects of energetic particles(EPs) on HL-2A have been performed using the hybrid kinetic-MHD model inplemented in the NIMROD code.The m/n=1/1 resistive internal kink mode is unstable in MHD limit.However, with kinetic effects of energetic ions, a fishbone mode is excited with mode frequency around 10 kHz.We calculate the impact of resistivity on the growth rate and frequency of ion fishbone mode,and the results are in good agreement with the analytic solutions, which are obtained by solving the fishbone dispertion relation including resistivity effect.The effects of βfracand cut off velocity of EP on fishbone mode are calculated in detail, where βfracis the ratio of EP pressure to background plasma pressure.This work presents a clear explanation of the stabilizing effect of ECRH on ion fishbone, which is first observed on HL-2A.