Superradiance and temporal coherence in plasma accelerators: New (conceptual) pathways towards FEL brightness
J. Vieira
GoLP/Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Lisbon, Portugal
Coherent light sources, such as free electron lasers, provide bright beams for
biology, chemistry, physics and advanced technological applications. As their
brightness increases, these sources are also becoming progressively larger, with the
longest being several km long (e.g. LCLS). Plasma accelerators, instead, are much
more compact, and can play a key role in bringing these sources to smaller
laboratories. Reaching this goal requires orders of magnitude increase on the
brightness delivered by plasma accelerator based light sources. In turn, such a
radical enhancement of beam brightness in plasma accelerator light sources
depends directly on the onset of temporal coherence and superradiance.
Here, we propose a new radiation emission mechanism that may bring temporal
coherence and superradiance to plasma accelerator based light sources, without the
onset of the so-called free-electron-laser instability. The mechanism is suitable for
experimental demonstrations in current plasma accelerator laboratories. Instead of
focusing on single particle motions, we investigate the radiation produced by an
ensemble of light emitting particles exhibiting collective, matter-wave effects. Such
collective motions, which can be as simple as a plasma wave, are pervasive in
plasmas and plasma based accelerators. We apply this concept to relativististic
electron bunches [1], and in plasma accelerator based-light sources, in order to
generate broadband and narrow bandwidth superradiant and temporally coherent
radiation in the XUV/soft-xray region [2]. We use theory and particle-in-cell
simulations complemented by the Radiation Diagnostic for Osiris (RaDiO)
Bibliography:
[1] J. Vieira et al, Nature Physics 17, 99 (2021).
[2] B. Malaca et al, submitted (2023); arXiv:2301.11082v1
[3] M. Pardal et al, Comp. Phys. Communs. 285, 108634 (2023)]