Concept for a future high-energy electron-positron collider based on the staging of laser-plasma accelerator modules

LPAs can produce ultrahigh electric-field gradients of 10-100 GV/m, some three orders of magnitude beyond what conventional radio-frequency accelerators can achieve. They can also significantly reduce accelerator size, which is why they are being researched worldwide for high-energy colliders and a variety of other applications at lower particle beam energies (e.g., free-electron lasers).

However, there are limits to how much energy each LPA can impart to the beam. As shown above, a vision for an LPA-based collider involves coupling many individual LPA stages. Each LPA stage is driven by a laser with a pulse energy of tens of joules and boosts the particle beam energy by approximately 10 GeV.

The BELLA Petawatt laser system, which generates laser pulses of 40 J and 40 fs, enables research toward high-energy LPAs for future colliders. The laser system can drive single-stage and two-stage LPAs at the 10 GeV level. A new laser delivery beamline for driving a second acceleration stage is now operational to further explore staging.

Researchers observe the LPA plasma capillary (purple glow at far left) during an experiment.

To maximize beam energy, we employ laser guiding with pre-formed plasma waveguides to mitigate diffraction of the focused laser pulses, much like optical fibers for low-intensity beams.  To improve beam quality, we search for the best methods of generating the particle beams to be accelerated, such as using specially shaped plasmas or multiple laser pulses.

Applications will require a far higher repetition rate of 1 kHz, and colliders might require 10 kHz. We are developing high-repetition-rate lasers based on fiber technology to deliver high peak and average power in a compact, energy-efficient platform to address this need.