Tunable High Spatio-Spectral Purity Undulator Radiation from a Transported Laser Plasma Accelerated Electron Beam

Abstract

Undulator based synchrotron light sources and Free Electron Lasers (FELs) are valuable modern probes of matter with high temporal and spatial resolution. Laser Plasma Accelerators (LPAs), delivering GeV electron beams in few centimeters, are good candidates for future compact light sources. However the barriers set by the large energy spread, divergence and shot-to-shot fluctuations require a specific transport line, to shape the electron beam phase space for achieving ultrashort undulator synchrotron radiation suitable for users and even for achieving FEL amplification. Proof-of-principle LPA based undulator emission, with strong electron focusing or transport, does not yet exhibit the full specific radiation properties. We report on the generation of undulator radiation with an LPA beam based manipulation in a dedicated transport line with versatile properties. After evidencing the specific spatio-spectral signature, we tune the resonant wavelength within 200–300 nm by modification of the electron beam energy and the undulator field. We achieve a wavelength stability of 2.6%. We demonstrate that we can control the spatio-spectral purity and spectral brightness by reducing the energy range inside the chicane. We have also observed the second harmonic emission of the undulator.

Electron Beam Brightness and Undulator Radiation Brilliance for a Laser Plasma Acceleration Based Free Electron Laser

“…The brilliance is also computed using SRW, where it is found to be 1.4 × 10 22 ph/s/mm 2 /mrad 2 /0.1%bw for the total beam case and 7.6 × 10 22 ph/s/mm 2 /mrad 2 /0.1%bw for the slice one. However, during the COXINEL experiment, the electron beam exhibited quite different qualities [66] and the brilliance is found to be of the orders of 10 17 ph/s/mm 2 /mrad 2 /0.1%bw [53], 3 orders of magnitude lower than the calculated one.…”

“…In addition, new electron beam optics has been adopted afterward, that enabled to reduce the energy spread of the electron beam arriving at the undulator more efficiently. This enabled us to reach a minimum undulator radiation bandwidth of 2% [53].…”

Small Signal Bi-Period Harmonic Undulator Free Electron Laser

“…Insertion devices are the key components of the synchrotron radiation and free electron laser sources. There are interests and technology upgrades of undulator technology for synchrotron radiation source (SRS) and free electron laser (FEL) for producing tunable electromagnetic radiation over the desired electromagnetic spectrum [1][2][3][4][5][6][7][8][9][10][11][12]. In the synchrotron radiation source, the relativistic electron beam propagates in the magnetic undulator field and emits spontaneous radiation.…”

Water-Window X-Ray Pulses from a Laser-Plasma Driven Undulator

“…To date, only few experiments [42][43][44][45][46][47] have experimentally shown undulator radiation from a laser-plasma accelerated electron beam. Plasma-driven undulator radiation was generated first in the visible 42 at 740 nm with 7.5% FWHM bandwidth, using electron beams of 65 MeV energy and achieving a beam brightness of 6.5 × 10 16 photons/s/mrad 2 /mm 2 /0.1% bandwidth.…”

“…We have recently been made aware of ref. 47 , which provides a more detailed study of the undulator radiation presented in ref. 46 .…”