Structured Laser Pulses to Accentuate Signatures of Collective QED-Plasma Effects

An intense laser  experiences a change in frequency when it passes through plasma with a time-varying plasma frequency, such as through plasma undergoing ionization. Alternatively, passing through a plasma composed of relativistic electrons, that are slowing down or accelerating , will similarly cause a change in frequency. These effects might be exploited by counterpropagating a relativistic electron beam with an intense laser in order both to produce (via a QED cascade) and to observe (via laser frequency shifts) collective behavior in a pair plasma  [1]. We explore here whether introducing temporal or spatial structure to the counterpropagating laser might make these collective pair plasma effects more easily detectable.

 

[1] Qu, K., Meuren, S. and Fisch, N.J., 2020. Signature of Collective Plasma Effects in Beam-Driven QED Cascades. arXiv preprint arXiv:2001.02590.