The quest for a brighter and more compact light source has been a long-standing challenge in the field of radiation physics. Currently, the most powerful light sources are free electron lasers, which are several kilometers long, making them unsuitable for use in smaller labs and industries. However, a recent study by B. Malaca, M. Pardal, D. Ramsey et al. suggests a new approach to this problem by introducing a concept of quasi-particle-based light sources that rely on the collective and macroscopic motion of an ensemble of light-emitting charges.
Free-electron lasing of plasma-accelerated electrons has already been demonstrated using conventional magnetic undulators. However, these sources are still limited in size and have only produced temporally incoherent radiation. In contrast, the researchers focus on a new approach that would bring temporal coherence and superradiance to plasma accelerator laboratories. Temporal coherence and superradiance require a localized current density with a near-constant profile, which can be generated in the wake of intense lasers and particle bunches in plasma.
The flexibility to control the quasiparticle trajectory opens up new possibilities in radiation physics that feature temporal coherence and superradiance. One of the examples they focus on is superradiant Cherenkov emission from superluminal quasiparticles. This quasiparticle Cherenkov radiation exhibits a superradiant and single-cycle optical shock directed along the Cherenkov cone-angle, and the peak intensity of this optical shock scales with the square of the number of radiating particles, making it brighter than the radiation produced by conventional light sources.
The study also highlights that the number of photons produced can provide a clear experimental signature, making it easier to verify the results of the experiments. The spectral density of the emitted radiation exhibits the typical superradiant scaling, which makes it easier to identify the radiation produced by the plasma accelerator.
The concept of quasi-particle-based light sources provides a new approach to creating brighter and more compact light sources. The researchers demonstrate that it is possible to bring temporal coherence and superradiance to plasma accelerator laboratories and that the number of photons produced can provide a clear experimental signature. This new approach opens up new possibilities in radiation physics, making it easier to conduct experiments and explore new possibilities in the field.
Source : Malaca, B. et al. “Coherence and superradiance from a plasma-based quasiparticle accelerator.” (2023) https://doi.org/10.48550/arXiv.2301.11082