Direct imaging of plasma waves using ultrafast electron microscopy

• DOI: 10.1063/4.0000044
• Publication Date: 2020-12-28T16:48:48Z
• Authors: Shuaishuai Sun; Xiaoyi Sun; Daniel Bartles; Elliot Wozniak; Joseph Williams; Peng Zhang; Chong-Yu Ruan
• Keywords: ARTICLES; Crystallography; QD901-999; 0103 physical sciences; 01 natural sciences

A femtosecond plasma imaging modality based on a new development of ultrafast electron microscope is introduced. We investigated the laser-induced formation of high-temperature electron microplasmas and their subsequent non-equilibrium evolution. Based on a straightforward field imaging principle, we directly retrieve detailed information about the plasma dynamics, including plasma wave structures, particle densities, and temperatures. We discover that directly subjected to a strong magnetic field, the photo-generated microplasmas manifest in novel transient cyclotron echoes and form new wave states across a broad range of field strengths and different laser fluences. Intriguingly, the transient cyclotron waves morph into a higher frequency upper-hybrid wave mode with the dephasing of local cyclotron dynamics. The quantitative real-space characterizations of the non-equilibrium plasma systems demonstrate the feasibilities of a new microscope system in studying the plasma dynamics or transient electric fields with high spatiotemporal resolutions.