From nature.com, 27 March 2013
The challenge of producing the next generation of particle accelerators, for both fundamental research at laboratories such as CERN and more applied tasks such as proton therapy and nuclear transmutation, has been taken up by the high-intensity laser community. With the advent of chirped pulse amplification (CPA) in 19851 came the ability to generate ultrashort laser pulses with intensities in excess of 1018 W cm−2. At these intensities, the electromagnetic field drives electrons into relativistic motion, opening the door to useful effects like wakefield acceleration2 and hard X-ray production by bremsstrahlung, Compton or betatron emission3. Ion motion becomes relativistic4 at intensities above 1022 W cm−2 — an intensity regime demonstrated or anticipated with development projects for very-large-scale lasers like the HERCULES laser at the University of Michigan in the USA, which has generated some of the highest peak intensities ever delivered to a target5, and ELI6 (the Extreme Light Infrastructure project), which will create four linked high-intensity laser facilities across Europe. In recent experiments7, electrons have been accelerated by laser wakefield schemes to gigaelectronvolt energies over distances of just a few centimetres — a length that is orders of magnitude smaller than that required by conventional radiofrequency-based accelerators. These exciting developments suggest that, in principle, laser-based schemes could offer a far more compact, cost-effective approach to making high-energy particle accelerators in the future. Read more >>
