An investigation of the emittance of escaping fast electron beams from planar and nanowire targets

Year: 2025

Authors: Hume EJ., Koester P., Baffigi F., Brandi F., Calestani D., Cristoforetti G., Fulgentini L., Labate L., Marasciulli A., Morris S., Palla D., Salvadori M., Villani M., Gizzi L.A., Lancaster K.L.

Autors Affiliation: INO CNR, Intense Laser Irradiat Lab ILIL, I-56124 Pisa, Italy; IMEM CNR, Parma, Italy; Univ Warwick, Dept Phys, Coventry, England; Univ York, York Plasma Inst, York, England; LNGS INFN, Assergi, AQ, Italy.

Abstract: Fast electron generation and transport in high-intensity laser-solid interactions induces X-ray emission and drives ion acceleration. Effective production of these sources hinges on an efficient laser absorption into the fast electron population and control of divergence as the beam propagates through the target. Nanowire targets can be employed to increase the laser absorption, but it is not yet clear how the fast electron beam properties are modified. Here we present novel measurements of the emittance of the exiting fast electron beam from irradiated solid planar and nanowire targets via a pepper-pot diagnostic. The measurements indicate a greater fast electron emittance is obtained from nanowire targets. Two-dimensional particle-in-cell simulations support this conclusion, revealing beam defocusing at the wire-substrate boundary, a higher fast electron temperature and transverse oscillatory motion around the wires.

Journal/Review: HIGH POWER LASER SCIENCE AND ENGINEERING

Volume: 13      Pages from: e14-1  to: e14-10

More Information: We acknowledge financial support from the NextGenerationEU (PNRR) Integrated Infrastructure Initiative in Photonic and Quantum Sciences (IPHOQS) (CUP B53C22001750006, ID D2B8D520, IR0000016) and EuPRAXIA Advanced Photon Sources (EuAPS) (CUP I93C21000160006, IR0000030). We also acknowledge support and funding from the Engineering and Physical Sciences Research Council (EP/L01663X/1) and the Royal Society International Exchange (IES/R3/170248). Computing resources were provided by STFC Scientific Computing Department’s SCARF cluster. This work was in part funded by the UK EPSRC (grants EP/G054950/1, EP/G056803/1, EP/G055165/1 and EP/ M022463/1).
KeyWords: emittance; fast electrons; femtosecond; particle-in-cell; pepper-pot
DOI: 10.1017/hpl.2025.5