The world’s most powerful X-ray laser

LCLS – the world’s most powerful X-ray laser located at the SLAC National Acceleration Laboratory in the US. When completed, the upgrade will allow scientists to explore atomic-level processes to answer many questions in the fields of biology, materials science, quantum physics, Interesting Engineering reported on September 27.

LCLS, built with funding from the US Department of Energy (DOE), is the first machine to create high-energy X-rays (hard X-rays) using a free electron laser. The facility began operations in 2009 but was upgraded in 2023. LCLS has an additional superconducting accelerator and magnetic structure called a rippler that can produce both soft and hard X-ray beams. Dubbed LCLS-II, the latest upgrade enables the facility to generate one million X-ray pulses per second.

Currently, DOE has approved the next upgrade called LCLS-II HE (high energy), which aims to double the energy of the electron beam coming from the superconducting accelerator, thereby doubling the X-ray energy. The superconducting accelerator in the LCLS-II upgrade includes 37 deep cold modules that can cool to -271 degrees Celsius to promote electrons to high energies with minimal energy loss.

With the new HE upgrade, LCLS will have 23 new deep cryogenic modules, each containing 8 superconducting radio frequency cavities to help provide optimal performance. The modules are produced by DOE’s Fermi National Accelerator Laboratory (Fermilab) and the Thomas Jefferson National Accelerator Facility (Jefferson Lab).

According to Greg Hays, LCLS-II-HE project manager, the first deep cryogenic module was a prototype manufactured from LCLS-II spare parts, so they had all the parts on hand. Once the production line is up and running, they can build a unit in an average of about 6 weeks. All modules are scheduled to be installed in the accelerator tunnel in 2026.

It is expected that LCLS-II-HE will produce its first X-rays between late 2027 and 2030. The first operation will determine how well the new laser beam performs, according to Mike Dunne, director of LCLS. During the upgrade, LCLS-II will still serve scientific experiments. Since the facility has two accelerators and only the superconducting accelerator has been upgraded, it can continue to operate with a regular accelerator.