title: Direct experimental evidence of back-surface ion acceleration from laser-irradiated gold foils.
abstract: Au foils were irradiated with a 100-TW, 100-fs laser at intensities greater than 10(20) W/cm2 producing proton beams with a total yield of approximately 10(11) and maximum proton energy of >9 MeV. Removing contamination from the back surface of Au foils with an Ar-ion sputter gun reduced the total yield of accelerated protons to less than 1% of the yield observed without removing contamination. Removing contamination from the front surface (laser-interaction side) of the target had no observable effect on the proton beam. We present a one-dimensional particle-in-cell simulation that models the experiment. Both experimental and simulation results are consistent with the back-surface acceleration mechanism described in the text.
authors.affiliation: Department of Nuclear Engineering, University of California, Berkeley, California 94720, USA. mallen@nu.berkeley.edu
authors.forename: Matthew
authors.initials: M
authors.lastname: Allen
authors.forename: Pravesh K
authors.initials: PK
authors.lastname: Patel
authors.forename: Andrew
authors.initials: A
authors.lastname: Mackinnon
authors.forename: Dwight
authors.initials: D
authors.lastname: Price
authors.forename: Scott
authors.initials: S
authors.lastname: Wilks
authors.forename: Edward
authors.initials: E
authors.lastname: Morse