High-Energy Laser-Proton Acceleration from Cryogenic Hydrogen

Stanford University, Stanford CA

Investigators

Abstract

The proposed research will apply high-power lasers to irradiate a microscopic ice layer and accelerate particles to high speeds. The goal is to demonstrate the highest acceleration efficiency known to date and to deliver particle beams suitable for applications. Similar to x-rays, particles of high speed penetrate through tissue but deposit most of their energy only at one point deep inside the human body. Thus, they are extremely well suited to destroy cancer cells. The laser-driven particle beams are expected to have the required properties so that they can be further developed for tumor therapies. The added advantage that they are compact will make them widely available for hospitals and research centers. If successful, the project will have high pay-off for society. The award will provide full-time support for a graduate student and part-time support for a postdoctoral associate at Stanford University, in keeping with the goals of the program toward preparation of a much-needed workforce in accelerator science. This research project will produce pure high-energy proton beams from the interaction of a high-intensity short-pulse laser with cryogenic hydrogen. These experiments utilize a novel continuously flowing cryogenic micro-jet that was recently developed at Stanford. Thus, the project is in the unique position to achieve simultaneously all the requirements on energy, charge, purity, beam emittance and repetition rate that up to now have been elusive in this field. Existing particle-in-cell simulations show that liquid hydrogen will become transparent during the interaction with the laser thus enhancing the sheet electric fields and resulting in nearly mono-energetic proton beams of energies larger than 50 MeV. Experimentally demonstrating the predicted proton beams will be a very important achievement, and a demonstration of new accelerator physics. Furthermore, these beams will be suitable for injection and will consequently motivate new studies of hybrid accelerators that have tremendous potential to deliver the urgently needed 230 MeV and above regime for applications in proton radiography, imaging and tumor therapies.