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张双喜博士报告
2017-04-13
聚变理论与模拟中心
Title about: Modelling the Lagrangian of magnetized plasmas with electrostatic perturbations and low- frequency magnetic perturbations by gyrokinetic model Speaker: 张双喜 博士 Time: Tuesday, April 18th , 3:00 pm Venue: Rm. 413, Bld. 11#, Yuquan CampusAbstract ：It’s well-known that due to the fact that the inverse-square structure of Coulomb force determines Poisson’s equation which associates the electrostatic potential with the charge density on particle’s coordinates, the fundamental Lagrangian 1-form, which determines the dynamics of all ions and electrons in the magnetized plasma with electrostatic perturbations, can be modeled by a Vlasov-Poisson model. By transforming this Lagrangian 1-form to the new one on gyrocenter coordinates up to the second order, the new potential includes the potential generated by Coulomb force on the new coordinates plus a finite Larmor radius term. It’s shown that the fundamental Lagrangian 1-form on the new coordinates can still be modeled by a gyrokinetic Vlasov-Poisson model with the polarization density recovered on the new coordinates. The numerical application of this new model could help reduce numerical error, numerical instabilities and numerical burden for the simulation of the electrostatic turbulence in magnetized plasma. The similar method can also be applied to low-frequency magnetic perturbations resulting a gyrokinetic Ampere-Poisson model. Eventually, a gyrokinetic Ampere-Poisson-Vlasov model can be derived by combining electrostatic perturbations and low-frequency magnetic perturbations together.
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Six Lectures on Gyrokinetic Theory by Prof. Alain Brizard
2017-04-03
聚变理论与模拟中心
Title: Six Lectures on Gyrokinetic TheorySpeaker: Prof. Alain J. Brizard, Saint Michael’s College (USA)Time: April 10, April 12, April 14, April 17, April 19, April 21, 2017, 9:00-11:00 AMVenue: Rm. 413-1, Bld. 11#, Yuquan CampusYou are warmly welcomed to take part in it.
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Physics of Alfvén waves and energetic particles in fusion plasmas--Linear physics and stability in tokamaks by Prof. Fulvio Zonca
2017-04-03
聚变理论与模拟中心
Title: Physics of Alfvén waves and energetic particles in fusion plasmas--Linear physics and stability in tokamaksSpeaker: Prof. Fulvio ZoncaTime and Location: Lectures (9am-11am) and Q&A Sessions (3pm-5pm) will be held at IFTS on April 27-29 and May 4-6-8-10Venue: Rm. 413-1, Bld. 11#, Yuquan CampusYou are warmly welcomed to take part in it.
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任洋研究员报告
2017-04-03
聚变理论与模拟中心
title about: Exploring the Regime of Validity of Global Gyrokinetic Simulation with Spherical Tokamak Plasmasspeaker: Dr. Yang RenTime: Thursday, April 6th, 02:00 pmVenue: Rm. 413, Bld. 11#, Yuquan Campus题目：Exploring the Regime of Validity of Global Gyrokinetic Simulation with Spherical Tokamak PlasmasAbstract Plasma turbulence is considered one of the main mechanisms for driving anomalous thermal transport in magnetic confinement fusion devices. Based on first-principle model, gradient-driven gyrokinetic simulations have often been used to explain turbulence-driven transport in present fusion devices, and in fact, many present predictive codes are based on the assumption that turbulence is gradient-driven. However, using the electrostatic global particle-in-cell Gyrokinetic Tokamak Simulation (GTS) code [1], we will show that while global gradient-driven gyrokinetic simulations provide decent agreement in ion thermal transport with a set of NBI-heated NSTX H-mode plasmas, they are not able to explain observed electron thermal transport variation in a set of RF-heated L-mode plasmas, where a factor of 2 decrease in electron heat flux is observed after the cessation of RF heating. Thus, identifying the regime of validity of the gradient-driven assumption is essential for first-principle gyrokinetic simulation. This understanding will help us more confidently predict the confinement performance of ITER and future magnetic confinement devices. The work is supported by DOE and computational resource is provided by NERSC.[1] W.X. Wang et al., Phys. Plasmas 17, 072511 (2010)
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李罗权院士报告
2017-04-03
聚变理论与模拟中心
Title about: Generation of helium and oxygen EMIC waves by the bunch distribution of oxygen ions associated with fast magnetosonic shocks in the magnetosphere Speaker: 李罗权院士,Institute of Earth Science, Academia Sinica, Nankang, Taiwan Time: Thursday, April 6th, 3:30pmVenue: Rm. 413, Bld. 11#, Yuquan CampusAbstract: Electromagnetic ion cyclotron (EMIC) waves are often observed in the magnetosphere with frequency usually in the proton and helium cyclotron bands and sometimes in the oxygen band. The temperature anisotropy, caused by injection of energetic ions or by compression of magnetosphere, can efficiently generate proton EMIC waves, but not as efficient for helium or oxygen EMIC waves. Here we propose a new generation mechanism for helium and oxygen EMIC waves associated with fast magnetosonic shocks, which are observed in the magnetosphere. These shocks can be associated with either dynamic pressure enhancement or shocks in the solar wind and can lead to the formation of a “bunch” distribution in the perpendicular velocity plane of oxygen ions. The oxygen bunch distribution can excite strong helium EMIC waves and weak oxygen and proton waves. The dominant helium EMIC waves are strong in quasi-perpendicular propagation and show harmonics in frequency spectrum of Fourier analysis. The proposed mechanism can explain the generation and some observed properties of helium and oxygen EMIC waves in the magnetosphere.
