Precision alignment and tolerance of a plasma wakefield accelerator in a laser-ionized plasma source

TL;DR

This paper introduces a new method for precisely aligning a laser-ionized plasma source with electron beams in a plasma wakefield accelerator, achieving micrometer and microradian accuracy, crucial for collider and light source applications.

Contribution

A novel plasma afterglow light analysis technique for high-precision alignment of plasma sources with electron beams in PWFA systems.

Findings

Achieved 10 μm and 10 μrad alignment accuracy.

Verified alignment through beam energy loss and gain measurements.

Determined alignment tolerances for collider design.

Abstract

We present a novel method for aligning a laser ionized plasma source to a pair of ultra-relativistic electron beams that comprise a plasma wakefield accelerator (PWFA). We achieve alignment by analyzing the plasma afterglow light observed at two longitudinal locations as the plasma column is scanned across the electron beam. By analyzing the relative plasma light intensity at the two locations, we aligned an 85-cm plasma source to a 10 GeV, 1.6 nC electron beam to within 10 um offset, 10 urad tilt. The alignment is verified by analyzing the drive beam energy loss, energy transfer efficiency, and the witness beam energy gain as a function of the misalignment between the beams and the plasma. From this measurement, we extract the alignment tolerance required between the laser-ionized plasma source and electron beams, an important metric necessary for collider design studies or light source applications based on a laser-ionized plasma source.