Hollow Plasma Channels for Positron Plasma Wakefield Acceleration

Plasma wakefield acceleration (PWFA) is a promising new acceleration technique that can accelerate charged particles to very high energies using plasma waves (wakefields) generated by a relativistic electron bunch. By using a concept called a plasma afterburner, PWFA has the potential of doubling the energy of the electrons from a linear accelerator. However, for a collider, the plasma afterburner would also need to efficiently accelerate positrons, which would require the plasma channel to be hollow or tubular in its radial density profile, and scalable to long lengths. This project will create a hollow plasma channel whose length is not limited by Rayleigh range constraints. The approach involves modifying the azimuthal phase distribution of a laser beam and focusing this beam inside a gas. During Phase I, existing models will be exercised to determine the system parameters needed to create a suitable hollow plasma channel for positron PWFA. The system will be built and tested during Phase II. Commercial Applications and other Benefits as described by the awardee: The primary application of this technology is for advanced accelerators using positron beams. Hollow plasma channels would enable positron PWFA to have efficiencies comparable to electron PWFA, which is critical for realizing the benefits of the plasma afterburner concept and its high potential cost savings. Long hollow plasma channels also should provide a new capability in plasma physics.