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📰 Controlled acceleration of electrons in a fully optical plasma waveguide

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In the race for ultra-high-energy electron beams for particle physics, laser-plasma accelerators appear to be a promising compact solution. Physicists have greatly increased thepower (In common sense, energy means anything that allows you to do work, produce energy, etc.) electrons and improved the quality of the beams by managing to control theminjection (The word injection can have several meanings 🙂 electrons in a guidewave (A wave is the propagation of a disturbance that produces a variation in its path …) plasma (In physics, plasma describes a state of matter consisting of charged particles …) everything (The whole understood as the whole of what exists is often interpreted as the world or …) optical (Optics is the branch of physics that deals with light, radiation …).


Legend: a) Example of 10 angularly resolved electron spectra obtained during a series of 14 shots. b) Two examples of angularly integrated spectra corresponding to the spectra marked with blue and green lines in (a). Credit: Cédric Thaury.

Laser-plasma accelerators deploy extremely strong electric fields – 1000 times greater than those produced by conventional accelerators. They use very powerful femtosecond pulsed lasers that produce a plasma (electrons, ions) ionizing the it matters (Matter is the substance that makes up any body having a tangible reality. Its …) and that generate the fields that accelerate the electrons. To obtain a good quality, high energy electron beam, two conditions must be met: impulse driving laser (A laser is a device that emits light (electromagnetic radiation) …) to accelerate the electrons over the greatest possible distance, and the check (The word control can have several meanings. It can be used as a synonym for examination, for …) injection, i.e. the place where the electron beam originates, in order to have the most monokinetic beam possible. Although these conditions had been achieved separately for more than 15 years, they had never been achieved simultaneously before. Putting point (graphics) a fully optical guiding method for low densities of gas (A gas is a set of very loosely bonded atoms or molecules and …) adapted tolaser-plasma acceleration (Laser-plasma acceleration is a research topic aimed at development …) and associating it with an electron injection of shock (As soon as two entities interact violently, we say there is a shock, be it …)researchers of the Laboratory of Applied Optics (LOA, CNRS (The National Center for Scientific Research, better known by the acronym CNRS, is the largest …) / Ecole polytechnique / ENSTA) met both conditions and produced 1.1 GeV electron beams with unprecedented efficiency. This result removes an essential block that should significantly increase the performance of laser-plasma accelerators. These results are published in the journal Light sciences and applications.

To achieve these results, the scientists produced an all-optical plasma waveguide, that is, using a low-energy laser pre-pulse and focusing it into a gas jet by means of a new type of ‘optics. developed (In geometry, the evolution of a plane curve is the locus of its centers of …) for the experience. This pre-pulse generates a plasma channel whose density (The density or relative density of a body is the ratio of its density to the …) decreases towards the optical axis: the main impulse is then guided as in a optic fiber (An optical fiber is a very thin glass or plastic wire that has the property of …) with index gradient. This guide increases the distance over which the intense laser accelerates electrons and the final energy is then multiplied by 3. To obtain a beam whose radius dispersion (Dispersion, in wave mechanics, is the phenomenon that affects a wave in a …) in energy is low, it is necessary that the electrons accelerated by the laser pulse come from a well-defined region of the gas. To ensure this control of electron injection, the electron density of the plasma has been modeled by producing a shock in the gas, locally generating a strong density gradient that particularizes the electron region that will be accelerated. A good energy resolution is thus obtained (figure). The next step is to improve the laser targeting in the gas, the accuracy of which affects the intensity of the electron beam.

A big plus of the all-optical drive, the first of which demonstration (In mathematics, a proof allows us to establish a proposition from …) was performed here for theacceleration (Acceleration commonly refers to an increase in speed; in physics, …) plasma, is to greatly limit the damage related to power (The word power is used in several fields with a particular meaning 🙂 of the laser, thus allowing arbitrarily high energies and repetition rates. This approach therefore opens up promising prospects for the community. A country (The countryside, also called rural environment, designates all the cultivated areas …) of experiences at the Infrastructure of Research (Scientific research primarily refers to all actions undertaken with a view to …) (IR) Apollo (Apollo (in ancient Greek? Π? Λλων / Apóllôn, in Latin Apollo) is the god …)whose laser is 10 times more powerful will aim to triple the energy of the electron beam obtained. A particularly interesting final perspective is that of using Apollon for very fundamental studies such as those relating toquantum electrodynamics (Relativistic quantum electrodynamics is a physical theory that aims to reconcile …).

Reference:
Controlled acceleration of the GeV electron beams in a fully optical plasma waveguide.
Kosta Oubrerie, Adrien Leblanc, Olena Kononenko, Ronan Lahaye, Igor A. Andriyash, Julien Gautier, Jean-Philippe Goddet, Lorenzo Martelli, Amar Tafzi, Kim Ta Phuoc, Slava Smartsev & Cédric Thaury, Light: science and applicationspublished June 14, 2022.
DOI: 10.1038 / s41377-022-00862-0.
HAL and arXiv open the archives.

Contact:
– Cédric Thaury – CNRS Researcher, Applied Optics Laboratory – cedric.thaury on ensta.fr
Communication (Communication concerns both man (intrapsychic, interpersonal communication, etc.) INP – inp.com on cnrs.fr

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