Eur. Phys. J. D (2015) 69: 265
https://doi.org/10.1140/epjd/e2015-60109-5

Regular Article

Experimental observation of the ion energy spectra of Al, Co, and Cu laser produced plasmas

¹ Centro de Láseres Pulsados (CLPU), Parque Científico USAL, M5 building 37185 Villamayor, Salamanca, Spain
² Chemical Physics department, University of the Basque Country UPV/EHU, Apartado 644, 48080 Bilbao, Spain

^a e-mail: japinaniz@clpu.es

Received: 18 February 2015
Received in final form: 17 May 2015
Published online: 3 December 2015

Abstract

It is well known that nanosecond laser produced plasmas (LPPs) produce high kinetic energy ions when they expand to vacuum. The acceleration process is nowadays accepted to be due to the formation of a sharp double layer (DL) in the plasma-vacuum boundary. With the purpose of studying this acceleration process, kinetic energy spectra of the plasma ions are measured for each charge state separately. Experimental results are obtained by irradiating planar targets of Cu, Co and Al at a laser wavelength of 532 nm and fluences up to 58.1 J cm^-2. The obtained results show two new insights in the ion energy spectra. Firstly, they are non-maxwellian despite the widely accepted local thermal equilibrium in these type of plasmas. Secondly they show non-expected bicomponents distributions. The average energy of each species does not vary linearly with the charge state, suggesting complex acceleration processes.