On the robustness of spin polarization for magnetic vortex accelerated proton bunches in density down-ramps

TL;DR

This study uses particle-in-cell simulations to examine how density down-ramps affect the spin polarization and collimation of proton beams accelerated via Magnetic Vortex Acceleration, revealing robustness and beam dynamics insights.

Contribution

It demonstrates the robustness of proton spin polarization in density down-ramps during MVA and explores how ramp length influences beam collimation and polarization distribution.

Findings

Spin polarization remains around 80% across various ramp lengths.

Longer ramps lead to collimation of low-polarization protons.

Highly polarized protons exhibit large transverse spread.

Abstract

We investigate the effect of density down-ramps on the acceleration of ions via Magnetic Vortex Acceleration (MVA) in a near-critical density gas target by means of particle-in-cell simulations. The spin-polarization of the accelerated protons is robust for a variety of ramp lengths at around 80%. Significant increase of the ramp length is accompanied by collimation of low-polarization protons into the final beam and large transverse spread of the highly polarized protons with respect to the direction of laser propagation.