Time: Thursday, Dec. 9nd, 4:00pm
Speaker: Yu Zhang
Title: On the Radiation Fields of Fast Radio Bursts Close to Sources
Abstract:
Fast radio bursts (FRBs) are coherent powerful radio transients with cosmological origins. The detected galactic FRB reveals that magnetars can generate FRBs, however the mechanism still remains enigmatic. Characteristics of FRBs are limited to observable quantities such as luminosity, duration, spectrum and repetition etc. Due to the uncertainties of triggering mechanisms and source sites within or out of magnetospheres of neutron stars, status of FRBs close to their sources are unknown. As an extreme astronomical event, FRBs could accompany with energy-comparable or even more powerful x/γ ray counterparts. Here, we study the interaction of ultrastrong radio pulses in GHz and high-energy photons in GeV. Particle-in-cell simulations show that at the field-strength of about 3×10^(12) V/cm, quantum cascade effects can generate dense pair plasmas and the radio pulses are significantly depleted. Therefore, GHz radio pulses of stronger than 3×10^(12) V/cm is difficult to escape from emitters if accompanying with GeV photons. This process could afford a limit to the FRB field strength nearby sources. Investigation on the toleration of 3×10^(12) V/cm radio waves for potential plasma/beam emitters in neutron-star scenarios should be helpful to distinguish the precise mechanism of FRBs.
Speaker: 王驰宇
Title:实验数据的“神”(慎)处理
Abstract:托卡马克每次放电均会产生大量的数据。在2010年JET一炮放电存储50-60GB数据。而根据预测,ITER一次放电需要采集480GB数据。面对如此庞大的数据,从中提取出关键信息并得出正确的物理结果并非易事。建立有效的诊断手段、积累相关的物理背景、掌握高效的实验数据处理方法、形成完善的数据分析系统,是对实验物理学的最有力支撑之一。本次报告主要介绍数据获取手段,数据分析的相关理论及方法并简述了数据处理的过程。
由于疫情原因,本次报告在钉钉群线上举行