Measurements of the energy spectrum of electrons emanating from solid materials irradiated by a picosecond laser

Di Stefano, C. A. and Kuranz, C. C. and Seely, J. F. and Thomas, A. G. R. and Drake, R. P. and Keiter, P. A. and Williams, G. J. and Park, J. and Chen, H. and MacDonald, M. J. and Rasmus, A. M. and Wan, W. C. and Pereira, N. R. and Joglekar, A. S. and McKelvey, A. and Zhao, Z. and Klein, S. R. and Kemp, G. E. and Jarrott, L. C. and Krauland, C. M. and Peebles, J. and Westover, B. (2015) Measurements of the energy spectrum of electrons emanating from solid materials irradiated by a picosecond laser. Physics of Plasmas, 22 (4): 043113. ISSN 1070-664X

Abstract

In this work, we present the results of experiments observing the properties of the electron stream generated laterally when a laser irradiates a metal. We find that the directionality of the electrons is dependent upon their energies, with the higher-energy tail of the spectrum (similar to 1 MeV and higher) being more narrowly focused. This behavior is likely due to the coupling of the electrons to the electric field of the laser. The experiments are performed by using the Titan laser to irradiate a metal wire, creating the electron stream of interest. These electrons propagate to nearby spectator wires of differing metals, causing them to fluoresce at their characteristic K-shell energies. This fluorescence is recorded by a crystal spectrometer. By varying the distances between the wires, we are able to probe the divergence of the electron stream, while by varying the medium through which the electrons propagate (and hence the energy-dependence of electron attenuation), we are able to probe the energy spectrum of the stream. (C) 2015 AIP Publishing LLC.