Compact spin-polarized positron acceleration in multilayer microhole-array films

Compact spin-polarized positron accelerators play a major role in promoting significant positron application research, which typically require high acceleration gradients and polarization degrees, both of which, however, are still greatly challenging. Here, we put forward a spin-polarized positron acceleration method, which employs an ultrarelativistic high-density electron beam passing through any hole of multilayer microhole array films to excite strong electrostatic and transition radiation fields. Positrons in the polarized electron-positron pair plasma, filled in the front of the multilayer films, can be captured, accelerated, and focused by the electrostatic and transition radiation fields, while maintaining high polarization degrees of above $90%$ and high acceleration gradients of about $\mathrm{TeV}\text{/}\mathrm{m}$. A multilayer design allows for capturing more positrons and achieving cascade acceleration. Our method offers promising solutions to the issues of accelerator miniaturization, positron injection, and polarization preservation, and also can be used to accelerate other charged particles.