Investigation of the magnetic field oscillations and reversals

磁场振荡和反转的研究

• 批准号: 35696137
• 负责人: Dr. Alexander Pinter
• 金额: --
• 依托单位: Service de Physique Théorique
• 依托单位国家: 德国
• 项目类别: Research Fellowships
• 财政年份: 2007
• 资助国家: 德国
• 起止时间: 2006-12-31 至 2007-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/35696137?language=en
• 关键词: Investigation; magnetic; field; oscillations; reversals

The research proposal focuses on a numerical study of turbulent dynamo and magnetic field induction, so as to answer scientific issues raised by the Von Karman Sodiuna experiment (VKS). Following the observations of dynamo action in constraint flows of electrically conducting fluids (experiments in Riga, Karlsruhe, 2000), the extension to less constrained and turbulent flows was a natural next step, and it is actively studied by several groups worldwide. The Instrument built by the VKS team in CEA Cadarache produced new and original data about dynamo with magnetohydrodynamics turbulence.The first dynamo observation in an unconstrained, turbulent regime in 2006 in this setup was a worldwide noticed success expecting to shed new light on aspects relevant for astrophysics and geophysics. These hopes were confirmed by the recently first experimental observation of reversals of a dynamo field in a turbulent flow regime.Results are expected concerning open questions regarding the dynamo: what is the effect of turbulent fluctuations on the threshold value? How does the Saturation of the magnetic field depend on the kinetic Reynolds number? What are the statistical properties of the magnetic and velocity fields both before and after onset? And especially in this new particular project: How are the reversals and oscillations of the magnetic fields triggered?In the numerical studies, the influence of fluctuations and turbulence onto the dynamo threshold will be first explored. The response to an imposed magnetic field will then be studied, as a function of the distance to the dynamo threshold, in order to understand experimental results. Then the Saturation of the dynamo instability as a function of the Reynolds number will be explored. Finally, the reversals and oscillations of the magnetic fields will be investigated.

该研究计划的重点是湍流发电机和磁场感应的数值研究，以回答冯卡门钠实验（VKS）提出的科学问题。在导电流体的约束流中观察到发电机作用之后（在里加、卡尔斯鲁厄的实验，2000年），下一步自然是扩展到较少约束和湍流，世界各地的几个小组正在积极研究。由CEA Cadarache的VKS团队建造的仪器产生了关于磁流体动力学湍流发电机的新的原始数据。2006年，在该装置中首次在无约束的湍流状态下观测发电机，这是一个全球瞩目的成功，有望为天体物理学和天体物理学相关方面提供新的见解。这些希望证实了最近的第一次实验观察的逆转的发电机领域在湍流regime.Results预计有关公开的问题，发电机：什么是湍流波动的影响的阈值？磁场的饱和度如何依赖于动力学雷诺数？在开始之前和开始之后，磁场和速度场的统计特性是什么？特别是在这个新的特别项目中：磁场的反转和振荡是如何被触发的？在数值研究中，我们将首先探讨涨落和湍流对发电机阈值的影响。然后将研究对施加的磁场的响应，作为到发电机阈值的距离的函数，以理解实验结果。然后将探讨发电机不稳定性的饱和度作为雷诺数的函数。最后，将研究磁场的反转和振荡。