Alex Picksley, a Research Scientist at the Accelerator Technology & Applied Physics Division’s Berkeley Lab Laser Accelerator (BELLA) Center, has been awarded the Institute of Physics Culham Thesis Prize: Plasma Physics Group for his Ph.D. thesis; the research for which was conducted at the laser-plasma accelerator group at the University of Oxford in the U.K..

The prestigious prize recognizes excellence in the scientific method and is awarded to theses that are well-explained, demonstrate a good understanding of the subject, and show significant new work and originality.

“I was amazed and extremely pleased to have received the award,” says Picksley. “The research described in the thesis involved a lot of experimental work, which always requires a team effort, and so the award reflects the hard work of the whole group at Oxford and the great support I received from my supervisors, Simon Hooker and Roman Walczak.”

Alex’s thesis, titled “Low-density plasma waveguides for multi-GeV laser Wakefield accelerators,” demonstrates how an auxiliary laser beam can create “plasma channels” for guiding high-intensity laser pulses through plasma. These channels are a critical component of next-generation accelerators that use intense laser bursts passing through a plasma to create a moving wave capable of accelerating charged particles at rates of up to a thousand times greater than conventional approaches.

These accelerators, called laser-plasma accelerators (LPAs), promise more compact and powerful machines that are much less expensive to build and operate than current technologies.

While we may be some way off from realizing the full potential of LPAs, Picksley’s research shows how these plasma channels, or plasma waveguides, prevent the high-intensity laser pluses from spreading out—a process called diffraction—when they are focused down to a small spot. This diffraction reduces the intensity of the pulses, making them unsuitable for producing the high energy gain required to drive an LPA.

“Although this technique has been around since the 1990s, we were able to adapt the approach for low-density plasmas and demonstrate that it can successfully maintain a high-intensity laser pulse over the meter-scale to accelerate electrons to multi-GeV energies,” explains Picksley.

He is now working with colleagues at the BELLA Center to create laser-driven plasma channels for producing a 10-GeV particle acceleration stage, which he says “has been the center’s goal since its inception, and is a critical milestone for the development of LPAs.”

Commenting on the award, BELLA Staff Scientist Anthony Gonsalves says that: “Finding a waveguide suitable for future high energy LPAs has been a significant challenge. Alex’s Ph.D. work changed the game with low-loss, meter-scale waveguides operating with optimal density for the first time.”