Driving electron beams to 1 GeV

Progress continues apace in the development of laser wakefield accelerators, which produce high-energy beams of electrons, atoms and molecules using the extreme fields generated in a plasma by high-power lasers. But for the potential of these devices to be realized — in practical applications that range from studying the behaviour of matter under extreme conditions to proton therapy for the treatment of deep-seated tumours — the energy of the particle beams they produce must reach the giga-electronvolt range. Initial estimates had suggested that reaching such energies would require lasers capable of producing pulse powers of the order of petawatts. But Wim Leemans and colleagues have proved the predictions wrong by producing 1-GeV electron beams using only 40 terrawatts of laser power — the trick being to focus the laser into a 3.3-cm-long gas-filled capillary discharge tube.

Nature Physics 2, - pp696 - 699 (2006)