The Astra Gemini laser in the CLF has entered a new regime by turning on its second beamline. Gemini becomes a unique facility with two synchronized, independently controllable, 0.5 Petawatt beamlines. This opens up a new regime in laser-plasma physics: Gemini will enable UK and European scientists to study ultra-relativistic laser plasma interactions with femtosecond temporal accuracy.

This is also a major leap in Gemini’s capability in producing secondary sources. Scientists now will be able to make one beam interact with the plasma produced by the other, giving rise to bright sources of short-wavelength radiation.

An international team of researchers from UK and Japan have just finished a successful experiment investigating relativistic effects that occur when the second laser beam is reflected from a wave in a plasma produced by the first beam. The wave, travelling at nearly the speed of light, is known as a 'flying mirror', and the light reflected from it has its wavelength shortened to about 1 percent of its original value, blue-shifting the infra-red laser photons into the extreme ultraviolet.

The experimenters also studied the generation of extremely short wavelengths by harmonic processes in the plasma, in a relativistic regime that had not previously been explored. Several important observations were made during the run, and are expected to result in high impact publications.

The Astra Gemini laser was commissioned in September 2007, and the first experiment began in January 2008. There were so many requests for access to the new facility that the CLF agreed to begin operations with only one of the two beams. This allowed the initial demand to be met, and the commissioning of the second beam was delayed until July 2010. A second dual-beam experiment is already in progress acquiring useful data.