Cascaded acceleration of proton beams in ultrashort laser-irradiated microtubes

TL;DR

This paper proposes a cascaded proton acceleration method using ultrashort laser-irradiated microtubes, enhancing proton energy and collimation through transient electric fields, effective at non-relativistic laser intensities.

Contribution

It introduces a novel cascaded acceleration scheme utilizing microtubes and transient electric fields, applicable to a broad proton energy range at non-relativistic laser intensities.

Findings

Proton beams can be further accelerated within microtubes by transient axial electric fields.

Radial electric fields improve the collimation of the injected proton beam.

The scheme is effective for proton energies from 1 to 100 MeV at non-relativistic laser intensities.

Abstract

A cascaded ion acceleration scheme is proposed by use of ultrashort laser-irradiated microtubes. When the electrons of a microtube are blown away by intense laser pulses, strong charge-separation electric fields are formed in the microtube both along the axial and along the radial directions. By controlling the time delay between the laser pulses and a pre-accelerated proton beam injected along the microtube axis, we demonstrate that this proton beam can be further accelerated by the transient axial electric field in the laser-irradiated microtube. Moreover, the collimation of the injected proton beam can be enhanced by the inward radial electric field. Numerical simulations show that this cascaded ion acceleration scheme works efficiently even at non-relativistic laser intensities, and it can be applied to injected proton beams in the energy range from 1 to 100 MeV. Therefore, it is particularly suitable for cascading acceleration of protons to higher energy.