Wakefield Generation in Hydrogen and Lithium Plasmas at FACET-II: Diagnostics and First Beam-Plasma Interaction Results

TL;DR

This paper reports on the development and initial results of diagnostics and beam-plasma interaction experiments in hydrogen and lithium plasmas at FACET-II, aiming to demonstrate high-gradient plasma wakefield acceleration with precise measurement capabilities.

Contribution

It introduces new diagnostics and experimental setups for measuring beam and plasma parameters critical for advancing plasma wakefield acceleration at FACET-II.

Findings

Initial beam ionized wake generation in hydrogen gas

Commissioning of plasma sources and diagnostics

Progress towards high-gradient acceleration demonstration

Abstract

Plasma Wakefield Acceleration (PWFA) provides ultrahigh acceleration gradients of 10s of GeV/m, providing a novel path towards efficient, compact, TeV-scale linear colliders and high brightness free electron lasers. Critical to the success of these applications is demonstrating simultaneously high gradient acceleration, high energy transfer efficiency, and preservation of emittance, charge, and energy spread. Experiments at the FACET-II National User Facility at SLAC National Accelerator Laboratory aim to achieve all of these milestones in a single stage plasma wakefield accelerator, providing a 10 GeV energy gain in a <1 m plasma with high energy transfer efficiency. Such a demonstration depends critically on diagnostics able to measure emittance with mm-mrad accuracy, energy spectra to determine both %-level energy spread and broadband energy gain and loss, incoming longitudinal phase space, and matching dynamics. This paper discusses the experimental setup at FACET-II, including the incoming beam parameters from the FACET-II linac, plasma sources, and diagnostics developed to meet this challenge. Initial progress on the generation of beam ionized wakes in meter-scale hydrogen gas is discussed, as well as commissioning of the plasma sources and diagnostics.