“高端外国专家引进计划”系列报告——D. F. Escande

==== Academic Seminars No.128 ====

时间：2022年9月26日  周一   14:30

方式：Zoom会议     848 7553 0521（密码：261137）

链接：https://us06web.zoom.us/j/84875530521?pwd=WHhleWZvelloZ1A0OE5xZDJLVm16dz09

邀请人：朱平 教授

报告人：D. F. Escande (Aix-Marseille Université)

题目：Intuitive introduction to Landau damping, Debye shielding, and Coulomb scattering

摘要：

Several aspects of weakly coupled and collisional plasmas can be described by N-body mechanics, increasing the simplicity and rigor of calculations, and coming with intuitive aspects. This seminar addresses three of them: Debye shielding, Coulomb scattering, and Landau damping and growth of Langmuir waves. Debye shielding is shown to result from collisions (see section 8 of [1]). As to Coulomb scattering, the N-body approach provides its first description incorporating all impact parameters without any ad hoc cut-off, and with a clear physical justification (see section 10 of [1]). The simultaneous average synchronization of almost resonant passing particles with the wave is the mechanical origin of Landau damping and growth, and implies that a single formula applies to both phenomena. This synchronization was shown experimentally too (see section 3.2 of [1]). Landau damping form the viewpoint of the wave, results from the phase mixing of beam modes, as shown in 1955 by Van Kampen in a Vlasovian frame (see section 5 of [1]). One of the derivations of Landau damping and growth is accessible to people who only know Newton’s second law and elementary calculus. It does not use Vlasov equation, Laplace transform, contour integration, or statistical settings, and is shorter than the usual Landau derivation of textbooks (see section 3.1 of [1]). A striking outcome of the N-body approach is to reveal the essential role of collisions in a « collisionless » plasma.

References:

[1] D.F. Escande, D. Bénisti, Y. Elskens, D. Zarzoso, and F. Doveil, Basic microscopic plasma physics from N-body mechanics A tribute to Pierre-Simon de Laplace, Rev. Mod. Plasma Phys. 2, 9 (2018).

报告人简介：

Dominique Escande 教授是国际著名磁约束等离子体理论物理学家，法国保罗-朗之万奖（法国物理学会理论物理奖）获得者，在RFP等离子体准单螺旋态自组织过程等诸多基础与聚变等离子体物理领域都有原创性贡献，曾担任法国Tore Supra实验室、马赛大学离子与分子物理实验室（LPIIM）主管，意大利RFX实验室顾问，欧盟EUROATOM聚变技术指导委员会主席等，主持多次重要国际学术会议，目前任法国马赛大学高等研究员，国家科学研究中心荣誉退休研究主任等。