Berkeley Lab

BELLA Laser

Petawatt peak power at high repetition rate (1 Hz) driving multi-GeV LPAs

The BELLA laser bay at a late stage of construction, "front end" in foreground

The BELLA laser bay at a late stage of construction, “front end” in foreground

The BELLA Laser is a Ti:sapphire CPA laser providing laser pulses at petawatt-level peak power with a repetition rate, unprecedented at that power, of 1 Hz. It was designed, built and installed in collaboration with a commercial vendor (Thales).

The laser consists of a front end system that outputs ~1.4 joules/pulse (uncompressed) at 10 Hz, followed by two final amplifiers that operate at the final 1 Hz repetition rate. The final uncompressed pulse energy is > 65 J. This is sent to a grating-based optical compressor that produces >40 J compressed pulses which can be shorter than 30 femtoseconds, reaching a peak power of ~1 petawatt. The laser is subsequently focused with a long focal length off-axis paraboloid mirror into the target chamber.

From foreground to background, the plasma target chamber, part of the High Power Diagnostic system with the Electron Energy Spectrometer, and the Electron Beam Dump

From foreground to background, the plasma target chamber, part of the High Power Diagnostic system with the Electron Energy Spectrometer, and the Electron Beam Dump

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.

The primary activities are focused on the research and development of LPAs at energies expected to reach 10 GeV. This includes controlled production, detailed characterization, and applications of the electron beams.