With the naked eye, you wouldn't see anything. Yet, what comes out of Apollo is anything but trivial: light beams of such power that they can reproduce the conditions inside a star or even cause effects... in a vacuum.
A concentration of light and science
Apollon is a technological monster installed at the Orme des Merisiers, on the Saclay plateau. It occupies 4,000 m², and its beams exceed 4 petawatts (or four million billion watts). Soon, it will reach 10 PW. In other words: it's the most powerful laser in the world. And it's French!
To generate its pulses, Apollon uses a method called CPA (Chirped Pulse Amplification), developed by Gérard Mourou and Donna Strickland, Nobel Prize winners in 2018. This technique stretches a laser pulse, amplifies it, and then compresses it again in a fraction of a second. The result: a discharge of energy that is tiny in duration, but colossal in impact.
These shots allow researchers to test physical theories under extreme conditions. For example, they can observe effects predicted by quantum electrodynamics—a field where light and matter mix in somewhat crazy ways. Apollo is also capable of producing particles (protons, electrons, X-rays, etc.) that are used in all sorts of experiments, including biomedical ones.
Apollon isn't just a toy for physicists. It's also a tool for understanding how chemical elements form in the universe, or what happens at the heart of planets and stars. And for once, this type of facility isn't in California or China, but in France.
Internationally, the United States is not far behind: at SLAC in California, researchers have developed a system to generate petawatt pulses from a particle accelerator. A great achievement, but still far from what Apollon can do in terms of raw power. Their method, called "flipper," is interesting because it could make lasers more adaptable to suit needs.
In the meantime, Apollon continues to operate, and teams from all over the world come to conduct experiments there. The idea is to push the limits of what can be done with a beam of light a little further.
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