A team of French researchers said they have developed a compact laser-plasma accelerator that uses two colliding laser pulses to produce highly stable and reproducible electron streams. High-energy particle accelerators, which can generate focused beams of highly energetic electrons, currently exist only in large-scale facilities like the Stanford Linear Accelerator Center (SLAC) in California, the International Linear Collider (ILC) at Fermilab outside Chicago and CERN, the European Organization for Nuclear Research, in Geneva, Switzerland. But a team of researchers from the Optical Applications Laboratory in Pasaiseau, led by Victor Malka and Jerome Faure, report they have developed a smaller alternative, a laser-plasma-based accelerator that can fit within a large room.Schematic illustration of a colliding pulse injection mechanism. The collision of two short laser pulses creates an electron beam, which follows the main laser pulse. (Image: Agustin Lifschitz, SPL group at Laboratoire d'Optique Appliquee) The basic idea was proposed over a decade ago, but until now physicists have struggled to control the systems. Faure and his colleagues injected electrons into a plasma wave created in the wake of a propagating laser pulse, resulting in a stable compact electron accelerator that could one day be used in applications including radiation therapy, radiography and femtosecond chemistry. The work is described in the journal Nature. The team's result is an improvement on the principle of the laser wakefield accelerator, which was used in 2004 to produce electron beams of a single defined energy, according to Tom Katsouleas, a member of the Department of Electrical Engineering at the University of Southern California who wrote a commentary that accompanied the Nature research article. "This idea of using a second laser pulse to slingshot electrons into a plasma wake dates back to 1996," Katsouleas writes. "Several groups have attempted variations on the original idea, but Faure et al are the first to demonstrate high-quality beam injection." The research shows that "the widespread use of compact plasma accelerators for medicine, industry and research may be much closer than we think," Katsouleas writes. For more information, visit: www.nature.com