'Flying focus' laser overcomes key limitation in plasma-based particle accelerators
In a new Nature Physics study, researchers accelerated electrons to more than twice the energy predicted by the traditional dephasing limit for laser-plasma accelerators operating over the same distance. This was made possible by a specially engineered laser pulse called a flying focus, which counteracts a longstanding limitation known as "dephasing."
In a groundbreaking study published in Nature Physics, researchers have developed a new laser pulse called a flying focus that overcomes the dephasing limitation in laser-plasma accelerators. Traditional accelerators, which use intense laser pulses to propel electrons through a plasma, are limited in energy output due to the dephasing phenomenon.
This occurs when ultra-relativistic electrons accelerate in the plasma wave and catch up with the driving laser pulse, causing them to stop gaining energy. The flying focus laser pulse counteracts this limitation by sweeping forward at a speed independent of the laser pulse's group velocity in the plasma. This decouples the plasma wave's speed from the laser pulse, allowing electrons to remain in the accelerating region of the wave for a longer distance without losing energy.
The researchers achieved this by using a specially engineered axiparabola mirror to create the flying focus and employing ionization injection to introduce electrons directly into the plasma wave. Through extensive simulations and experimental testing, they demonstrated that dephasing can be eliminated within a narrow plasma density range.
This breakthrough could revolutionize particle accelerators, enabling them to deliver higher energies over shorter distances, potentially transforming fields such as medical imaging, cancer treatment, and particle physics research.
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