High-degree spin-polarized sub-femtosecond electrons generated in situ in a beam-driven plasma wakefield accelerator

The generation and acceleration of an electron beam with a high degree of spin polarization desired for high-energy collider application is still an outstanding scientific problem for plasma-based accelerators. Based on and further improving our previous work [1], we propose that both the plasma wake and a highly polarized electron beam suitable for injection into such a wake can be produced by using an ytterbium (Yb) plasma. While the nonlinear wake is produced by ionizing both 6s electrons using a drive electron beam, the injection is achieved by ionizing 4f14 electrons of the resultant Yb III ions in-situ using a circularly polarized ultrashort laser pulse. By using the Time-dependent Schrödinger equation (TDSE) and the 3D Particle-in-cell (PIC) code, we show the generation of a sub-femtosecond, high-current (4 kA), low-normalized-emittance (180 nm), and high-energy (15 GeV) electron beam within ~41 cm distance, with up to 56% net spin polarization.

References:

[1] Z. Nie, et. al., Phys. Rev. Lett. 126, 054801 (2021).