Cryo-cooled, 60 terawatt at 10 Hz repetition rate, driving GeV LPAs
The TREX Ti:sapphire CPA laser system provides >60 terawatt laser pulses at 10 Hz repetition rate. The system was designed and built by staff of the Laser Optics and Accelerator Systems Integrated Studies (LOASIS) Program from 2001 through 2004. The energy of the amplified, uncompressed laser pulses reaches ~3.9 J in a cryogenically cooled and fully vacuum-enclosed final laser amplifier system. This is sent to a grating-based optical compressor that produce compressed pulses of ~35 femtoseconds, reaching a peak power of 60 terawatt. The laser is subsequently focused with a 2 m focal length off-axis paraboloid mirror into the target chamber.
The laser is equipped with sophisticated diagnostics and controls. Control systems safely operate and continuously monitor its important parameters from a centrally located control room. A magnetic electron spectrometer using phosphor screens and multiple CCD cameras allows high repetition rate analysis. This is backed up by on-line neutron and gamma ray monitoring. Optical diagnostics monitor the energy, spectrum, and other parameters of the transmitted laser to infer its coupling to the LPA.
TREX was used for the first capillary plasma channel LPA experiments between 2005-2010, reaching GeV electron beam energies in a structure of few-cm length. The TREX laser is currently used to drive two experimental beamlines: an undulator beam line where experiments test the ability of LPAs to drive seeded free electron lasers; and staging experiments to develop a modular approach to attaining higher energy in laser plasma accelerators.