Laser acceleration of protons from near critical density targets for application to radiation therapy

TL;DR

This paper demonstrates that laser pulses with relatively small power can accelerate protons to energies suitable for medical applications by interacting with near-critical density plasmas, offering potential advancements in radiation therapy.

Contribution

It introduces a novel method of proton acceleration using low-power laser pulses and near-critical density targets, with detailed simulations and scaling laws for optimal conditions.

Findings

Protons can reach energies of 250 MeV with 100 TW laser pulses.

Self-generated magnetic and electric fields facilitate ion acceleration and collimation.

Scaling laws for proton energy based on laser and target parameters are established.

Abstract

Laser accelerated protons can be a complimentary source for treatment of oncological diseases to the existing hadron therapy facilities. We demonstrate how the protons, accelerated from near-critical density plasmas by laser pulses having relatively small power, reach energies which may be of interest for medical applications. When an intense laser pulse interacts with near-critical density plasma it makes a channel both in the electron and then in the ion density. The propagation of a laser pulse through such a self-generated channel is connected with the acceleration of electrons in the wake of a laser pulse and generation of strong moving electric and magnetic fields in the propagation channel. Upon exiting the plasma the magnetic field generates a quasi-static electric field that accelerates and collimates ions from a thin filament formed in the propagation channel. Two-dimensional Particle-in-Cell simulations show that a 100 TW laser pulse tightly focused on a near-critical density target is able to accelerate protons up to energy of 250 MeV. Scaling laws and optimal conditions for proton acceleration are established considering the energy depletion of the laser pulse.