Progress on spin-polarized beams from plasma-based accelerators

With the on-going developments in the field of plasma-based accelerators towards high-energy particle beams, one beam property that becomes increasingly important forapplications is its polarization. These range from surface physics to deep-inelasticscattering experiments probing the proton’s nuclear structure, as well as searches forphysics beyond the Standard Model in axion-related studies.

Only more recently have plasma-based sources of spin-polarized beams gainedsubstantial attention [1]. A first experiment demonstrating the successful preservation ofthe nuclear spin of helium-3 ions has recently been conducted [2]. Such a proof-of-principle experiment is still outstanding for electrons. This is in parts due to target
constraints [3], as one of the leading approaches relies on the photo dissociation ofhydrogen halides and only yields comparatively low-density and narrow interactionvolumes from which the polarized electrons can be accelerated. This limits the choice offeasible injection mechanisms for subsequent wakefield acceleration significantly.

In this talk, we review the recent experimental and theoretical developments in the field ofplasma-based, polarized particle beams and discuss their prospects for applications like nuclear fusion [4].

[1] L. Reichwein et al., Rep. Prog. Phys. 88, 117001 (2025)
[2] C. Zheng et al., High Power Laser Sci. Eng., in press (2026),
doi:10.1017/hpl.2026.10140
[3] D. Sofikitis et al., Phys. Rev. A 111, 053119 (2025)
[4] R. M. Kulsrud et al., Phys. Rev. Lett. 49, 1248 (1982)