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2019年10月17日 五室第119期研讨会

20191017 五室第119期研讨会

题 目: 简介集成工作流引擎的设计与实现

报告人于治

主持人:李德徽

时  间:2019年10月17日(星期四)  15:00—16:00

地  点:4楼中间会议室

摘  要:

集成建模和模拟过程中,需要在多个计算程序按照复杂的逻辑关系传递数据,并依次执行,这被称为“工作流”。由于历史原因,目前广泛使用的程序所需的计算资源和输入、输出数据格式具有明显的差异,将这些程序整合起来是一个复杂的系统工程。因而,需要引入‘工作流引擎’,通过构建统一的数据和程序调用接口,统筹调度、管理计算程序和计算资源。本研究主要究目标是为满足现代面向集成应用需求,开发高效、灵活、易用的物理理论模拟、实验数据分析环境。本报告将简要介绍目前项目开发进展和下一步规划。

2019年10月11日 五室第118期研讨会

2019年10月11 五室第118期研讨会 

题 目:Numerical study of m/n=3/1 pressure driven mode in the presence of weak magnetic shear

报告人:马骏

主持人:于治

   间: 2019年10月11日(星期五)  15:00—16:00

   点: 6楼中间会议室

  要:

An m/n=3/1 unstable mode can be driven by pressure in the presence of a reversed shear in a cylinder, in which the magnetic shear is small near rational surfaces since qmin = 2.99. The linear mode can be considered as an ideal mode since the resistivity has very little effects upon the mode structure and growth rate for eta <= 10^-7. In nonlinear stage, after long time evolution the mode behaves as a tearing type mode, with final quasi-stationary m/n=3/1 islands. The pressure profile also reaches a new 0/0 state, which is flattened in the vicinity of weak shear region.

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2019年9月20日 五室第117期研讨会

2019920 五室第117期研讨会 

题  目:Radial electrical field evolution in ITG turbulence with source simulated by NLT code

报告人:肖小涛

   间: 2019年9月20日(星期五)  15:00—16:00

   点: 4楼中间会议室

  要:

Radial electric fields is important in regulating the plasma turbulence and confinement improvement. External heating or momentum injection contribute to radial electrical field. The contribution of source term to radial electrical field in ITG turbulence is studied by NLT code. It is found only pressure gradient term contribute significantly at linear phase, while toroidal flow term will also contribute a lot at nonlinear phase. The contribution of momentum source term needs more check.

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2019年9月12日 五室第116期研讨会

2019912 五室第116期研讨会 

题  目: Numerical study on nonlinear growth of m/n=3/1 double tearing mode in high Lundquist number regime

报告人:郭文峰

   间: 2019年9月12日(星期四)  15:00—16:00

   点: 4楼中间会议室

  要:

   The nonlinear growth of the m/n=3/1 double tearing mode (DTM) is numerically investigated in cylinder geometry with non-monotonic radial profiles of the equilibrium safety factor, having two q=3 surfaces. The formation of plasmoids is found in high Lundquist number regime in such configurations for the first time. During the nonlinear growth of DTM, long and thin Sweet–Parker current sheets are formed near the original inner and outer rational surfaces and become tearing unstable for a large enough Lundquist number, leading to secondary and tertiary magnetic islands which accelerate the magnetic reconnection. The plasmoids also affect the magnetic topology at nonlinear mode saturation. The system can eventually saturate at a quasistationary state with small island pairs. The simulation results show that the Lundquist number and the distance between two rational surfaces have important effects on plasmoids formation

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2019年7月31日 五室第115期研讨会

2019年7月31日 五室第115期研讨会  

题  目:Computing the Double-Gyroaverage Term Incorporating Short-Scale Perturbation and SteepEquilibrium Profile by the Interpolation Algorithm

报告人:张双喜 博士

   间: 2019年7月31日(星期三)  9:00—10:30

   点: 4楼中间会议室

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2019年7月26日 五室第114期研讨会

题 目:The Geodesic Acoustic Eigenmode in toroidally rotating tokamaks 报告人: 周登 研究员
时 间: 2019年7月26日(星期五) 14:30—15:20
地 点: 4楼中间会议室

2019年7月17日 五室第113期研讨会

题  目:The correct cutoff vsriable for integrals with the Rutherford differential cross-section.

报告人:常永斌 教授

时  间:2019年7月17日(星期三)  9:00—10:00

地  点:4楼中间会议室

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2019年7月5日 五室第112期研讨会

201975 五室第112期研讨会

题  目:日韩模拟会议简单介绍

报告人夏天阳

时  间:2019年7月5日(星期五)  14:30—15:30

地  点:6楼中间会议室

摘  要:

  汇报本次参加Japan-Korea workshop on “Modeling and Simulation of Magnetic Fusion Plasmas”的会议内容。主要是日本方面的报告内容。日本目前的模拟工作基本上都是基于自己开发的程序,本次会议的主要报告内容偏重于动理学问题,具体研究方向涵盖了磁约束等离子体中的湍流,新经典输运以及合成诊断等。希望通过本次介绍,让大家了解日本同行的部分研究进展,并讨论可能开展的合作方向。

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2019年7月2日 五室第111期研讨会

201972 五室第111期研讨会

题  目:Plasma Theory Connections to Quantum Information Science

报告人Prof. Scott Parker  ( University of Colorado)

 时  间:2019年7月2日(星期二)  14:00—15:00

地  点:601会议室

摘  要:

The potential impact of quantum information science (QIS) on large-scale computing is tantalizing due to the capability to manipulate 2^N complex numbers where N is the number of qubits.  Even for N=60, one approaches exascale. Additionally, Moore’s law scaling, nearing 5 nm scale, is approaching physical limits. Present day experimental quantum computers are very modest in terms of size and general capability. Whether they may someday be useful for large-scale computation is unknown due to fundamental constraints.  Efficient operations are linear.  Copying data is approximate.  Measurement, or obtaining output is expensive. Here we present two research areas where QIS and plasma theory overlap in interesting ways: 1) quantum algorithms solving the Vlasov equation, and 2) direct numerical simulation of ultra-cold non-neutral ion plasmas used in QIS.  We have developed a quantum algorithm that time evolves the linear Vlasov equation with an exponential speed up, thereby, directly addressing the computational demands of the 6D phase space.  Progress is being made on developing strategies for the nonlinear problem.  A series expansion with good convergence properties using the Homotopy Analysis method (HAM)[1] allows formulation of the nonlinear problem as a large number of matrix multiplies suitable for an efficient quantum algorithm.  Additionally, we will discuss how plasma theory can help support QIS via many-particle simulation of ultra-cold non-neutral ion plasmas.  A Penning trap is being used to simulate 100’s of interacting quantum spins using an ultracold 2D crystal of singly-ionized Beryllium ions[2].  The simulation obtains excellent agreement with linear eigenmode analysis and includes a fairly detailed laser doppler cooling model that allows prediction of the ultracold plasma steady state, and shows agreement with experimentally observed temperatures.

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2019年6月29日 五室第110期研讨会

2019629 五室第110期研讨会

题  目:A relativistic model of electron cyclotron current drive efficiency in tokamak plasmas

报告人胡业民

时  间:2019年6月29日(星期六)  9:00—9:50

摘  要:

Electron cyclotron current drive (ECCD) has been considered an im-portant tool for current profile control to achieve high performance in ITER operation owing to its ability to drive local current on- and off-axis. An accurate and computationally efficient model of ECCD efficiency is highly desirable for the purpose of performing scenario modeling and in-between shots data analysis for EC experiments on ITER. From theoret-ical studies in the past, it is clear that both momentum-conserving and relativistic characteristics are needed in the electron-electron collision op-erator to appropriately describe the collisional relaxation [1, 2, 3]]processes in the high temperature plasmas. In this work, numerical calculations of the current drive efficiency in a tokamak by using the variational approach are performed. A fully relativistic extension of the variational principle with the modified test function for the Spitzer function with momen-tum conservation in the electron-electron collision is described in general tokamak geometry [4, 5, 6]]. The model developed has generalized that of Marushchenko’s[2], which is extended for arbitrary temperatures and covers exactly the asymptotic for u  1 when Zeff  1, and suited to ray-tracing calculations. Also the wave-particle interaction is modeled by the relativistic generalization of the local Kennel-Engelman wave-induced dif-fusion operator in velocity space [7]. The theoretical results obtained here have been used to upgrade the current drive package in the ray-gracing code TORAY-GA, the benchmark has been made and the calculated re-sults were in good agreement with that using CQL3D. The upgraded code can also be used in other EC ray-tracing codes.

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