Transport and Non-Invasive Position Detection of Electron Beams from Laser-Plasma Accelerators

Abstract

Abstract. The controlled imaging and transport of ultra-relativistic electrons from laser-plasma accelerators is of crucial importance to further use of these beams, e.g. in high peak-brightness light sources. We present our plans to realize beam transport with miniature permanent quadrupole magnets from the electron source through our THUNDER undulator. Simulation results demonstrate the importance of beam imaging by investigating the generated XUV-photon flux. In addition, first experimental findings of utilizing cavity-based monitors for non-invasive beam-position measurements in a noisy electromagnetic laser-plasma environment are discussed.

Undulator-Based Laser Wakefield Accelerator Electron Beam Energy Spread and Emittance Diagnostic

“…A pair of quadrupole magnets 50 mm and 25 mm long have been installed on the beam line in order to collimate the electron beam and insert it into the undulator [7]. The magnets are each controlled by three motorized stages with micron resolution allowing for three axis independent alignment of each magnet with respect to the electron beam.…”

“…The design and current status of experiments to couple the Tapered Hybrid Undulator (THUNDER) [1] undulator to the Lawrence Berkeley National Laboratory (LBNL) laser plasma accelerator (LPA) are discussed Currently the LPA has achieved quasi-monoenergetic electron beams with energies up to 1 GeV [2] In principle, these ultra-short, highpeak-current, electron beams are ideal for driving a compact XUV free electron laser (FEL) [3], [4] Understanding the electron beam properties such as the energy spread and emittance is critical for achieving high quality light sources with high brightness By using an insertion device such as an undulator and observing changes in the spontaneous emission spectrum, the electron beam energy spread and emittance can be measured with high precision [5] A high resolution XUV spectrometer allowing for better than 0 1% (rms) energy spread measurements has been built and characterized at the Advanced Light Source(ALS) [6] and is currently being installed on the LOASIS beam line A pair of quadrupole magnets with three axis independent alignment have been installed on the beam line in order to collimate the electron beam and insert it into the undulator [7] The initial experiments will use spontaneous emission from 1 5 m of undulator Later experiments will use up to 5 m of undulator with as goal the demonstration of a high gain extreme ultraviolet (XUV) FEL…”