Compact Efficient Polarizers for Relativistic Electron Beams

TL;DR

This paper introduces a compact, efficient method for directly polarizing relativistic electron beams using a novel beam-target interaction mechanism, enabling broader accessibility for advanced research and applications.

Contribution

The authors propose a new self-polarization technique utilizing simple beam-target interactions with a double-layer target to produce dense polarized electron beams.

Findings

The method achieves spontaneous radiative polarization of relativistic electron beams.

The double-layer target induces plasma effects that focus and reshape the polarized beam.

The approach is robust across various beam and target parameters.

Abstract

Relativistic spin-polarized electron beams are important for fundamental research and the industry, but their generation currently requires conventional accelerators or ultrastrong laser facilities, limiting their accessibility and broad applications. Here, we put forward a novel method for constructing a compact efficient "polarizer" that achieves direct ultrafast conversion of relativistic dense electron beams into polarized ones, based on the beam "self-polarization" mechanism via simple beam-target interactions. In this scheme, as the electron beam grazes through the polarizer (a double-layer solid target), it ionizes the target and excites an asymmetric plasma field due to the plasma backflows. This field then reacts on the beam itself, triggering spontaneous radiative polarization and reflection of the beam, and ultimately yielding a dense polarized electron beam. Moreover, the double-layer target setup induces a plasma bubble that focuses the polarized beam and reshapes its polarization distribution. Our method is robust with respect to the beam and target parameters, and opens a new avenue for relativistic beam polarization with compact accessible devices, which would facilitate their broad applications and the development of related experiments, such as in strong-field QED studies, and polarized electron-positron and electron-ion colliders.