A quasi-particle accelerator in plasmas to miniaturize coherent light sources

Published on Oct. 19, 2023, 12:13 p.m.

An international team of researchers led by Bernardo Malaca (PhD student in the Lasers and Plasmas Group, Institute of Plasmas and Nuclear Fusion), under the guidance of Jorge Vieira (professor in the Physics Department of the Instituto Superior Técnico), has determined how collective movements can radiate as single particles. The team also included Miguel Pardal (PhD student at GoLP/IPFN) and Ricardo Fonseca (researcher at GoLP/IPFN and professor at ISCTE). The article was published in the journal Nature Photonics (see article here).

What would be the radiation emitted by a superluminous particle? And how would it radiate under arbitrarily high accelerations? It is not usually possible to investigate these questions: as far as we know, there are no individual particles that can travel faster than light. Furthermore, technology limits the maximum acceleration to which we can subject charged particles in a laboratory context. What researchers have now recognized is that these exotic radiation regimes are perfectly accessible to collective excitations. An example of these collective excitations is the Mexican waves in a soccer stadium, where something that appears to go around the stadium is made up of people who just sit down and stand up at the appropriate times.

As an illustration, the researchers carried out numerical simulations on the LUMI supercomputer (Finland) to study the radiation emitted by quasi-particles in plasma accelerators (plasma is the state of matter where the atoms have already been ionized), which are much more compact than conventional ones.

This technique makes it possible to obtain coherent radiation from THz to the extreme ultraviolet with brightness as high as free electron lasers operating in the same frequency range. This work was carried out in collaboration with researchers from the Laboratoire d'Optique Appliquée (France), the University of Rochester (USA) and the University of California Los Angeles (USA), and funded by FCT/Portugal and the European Plasma Research Accelerator with eXcellence in Applications (EuPRAXIA) project.

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