Particle Acceleration and Advanced Light Sources (PAALS)

Dephasingless laser wakefield acceleration (LWFA) driven by an achromatic flying focus is an original concept that is a disruptive technology with the potential to transform the field of laser-plasma acceleration (LPA) and more broadly advanced accelerators. Conventional LWFA approaches can accelerate electrons to high energies, but the maximum energy is constrained by the low plasma densities required to limit dephasing between the laser pulse and accelerated electrons. The achromatic flying focus is a new spatiotemporal focusing system that provides the ability to propagate a high-intensity laser pulse over meters at any velocity while maintaining a small focal spot and a near-transform-limited pulse duration. By controlling the velocity of a focal spot propagating in a plasma, a wakefield can be driven at the speed of light, thus eliminating dephasing. Initial simulations of this “dephasingless” LWFA with no dephasing between the laser pulse and accelerated electrons suggests that a 20-fs, 500-J laser (NSF OPAL) would be capable of accelerating electrons to TeV-class energies in a one-meter stage. This flagship experiment seeks to successfully demonstrate such a TeV-class LPA.

The image above, from an article by Kyle G. Miller et al., shows an OSIRIS simulation of a dephasingless laser wakefield accelerator. Contours of laser intensity (red/yellow), electron density (gray), and accelerating/decelerating wakefield (teal/pink) are shown. The first bubble (white) trails the laser pulse and is devoid of all but the trapped electrons.