There are many applications for particle accelerators, even outside research facilities, but for the longest time they have been large, cumbersome machines, not to mention very expensive to operate. Here laser wakefield accelerators (LWFAs) are a promising alternative, which uses lasers to create accelerate particles along the wake in a plasma field. One of the major struggles has been with reinjecting the thus accelerated particles into another stage of a multi-stage accelerator, which would be required to obtain energies closer to one TeV. In this rea researchers have now demonstrated a way around this, by using curved channels for the laser beams (paywalled paper) which inject the laser beam into the continuous cavity.
Schematic diagram of the laser fabrication system (Credit: Hongyang Deng et al., 2023)
Their plasma wakefield acceleration system construction is described in an open access 2023 paper by Hongyang Deng et al., which covers the fabrication of the capillaries that contain the waveguides for these side-injection lasers. Each capillary is created in sapphire using femtosecond laser ablation technology to create a narrow channel with the appropriate properties. During the experimental phase, the researchers found a similar problem as with the previous multi-stage reinjection of accelerated particles, in that the injected laser beam had to be properly aligned with the main channel so as not to disturb the plasma wakefield.
As for why these multi-stage LWFAs are very interesting is covered in accelerating electrons levels using curved laser beams
