The LCLS-II Photo-Injector Drive Laser System

Abstract

We present the new drive laser system for the photo-injector of the LCLS-II XFEL at SLAC, including the first commissioning results and challenges encountered due to high power, high repetition rate ultraviolet laser operation.

Formation of Temporally Shaped Electron Bunches for Beam-Driven Collinear Wakefield Accelerators

“…Ultimately, the laser pulse shape can only be controlled on a time scale δt ≥ 1/(2πδf L ) limited by the bandwidth of the photocathode laser δf L . Contemporary laser systems are capable to δt ≤ 150 fs (RMS) [48]. Additionally, the electron bunch shape is also affected by the time response of the photoemission process.…”

A new integrated machine learning framework for advanced photoemission

“…Herein, to better fill the gap for generating a universal framework for designing ultrafast pulse shaping procedures, we present a new framework for photoemission laser systems and dynamic laser shaping. To showcase the effectiveness of our approach in system optimization, reverse engineering, and design, we conducted a case study on the LCLS-II photo-injector laser 12 . This laser is a representative example of a complex and high-power system used to achieve spectro-temporally non-trivial performance.…”

High repetition-rate photoinjector laser system for S3FEL

“…This high repetition rate soft-Xray super-conducting free-electron laser facility consists of a 2.5 GeV CW superconducting linear accelerator and four initial undulator lines, which aims at generating X-Rays between 40 eV and 1 keV at rates up to 1 MHz. Photoinjectors are often exploited as the initial electron source for many FEL facilities, like for instance FLASH [1], SPARC [2], LCLS [3], LCLS-II [4], SwissFEL [5], FERMI [6], SHINE [7] and European XFEL [8]. Photoinjector is a device that produces high-quality electron beams by using drive laser to extract electrons from the cathode material.…”

“…In order to be operating at a high repetition rate (adjustable up to 1 MHz), Cs 2 Te photocathode will be used to produce the initial electron bunches because of high quantum efficiency (~10%) [14,15]. For efficient emission of electron bunches, UV laser pulses should be exploited to illuminate the photocathode [16,17], for instance fourth harmanic of Yb:fiber laser [4] and Nd:YLF laser [8]. According to design specifications of the S 3 FEL, 0.2 μJ UV laser pulse with sharp temporal and spatial edges is required to generate 200 pc charge and its pulse width should be between 10 and 60 ps.…”