TY - JOUR

T1 - The impact of contaminants on laser-driven light ion acceleration

AU - Petrov, G. M.

AU - Willingale, L.

AU - Davis, J.

AU - Petrova, Tz.

AU - Maksimchuk, A.

AU - Krushelnick, K.

PY - 2010/10

Y1 - 2010/10

N2 - The impact of contaminants on laser-driven ion acceleration is investigated using particle-in-cell simulations. The conventional ion acceleration mechanism, target normal sheath acceleration, has been revisited for targets with proton-rich contaminants in the form of water vapor. The targets considered have a deuterated plastic layer on the rear surface of an aluminum target, and the influence of the contaminant layer on the deuteron acceleration is investigated. In the early stage of ion acceleration, the space-charge electrostatic field on the rear target surface accelerates only the outermost, proton-rich layer of ions, which inhibits the deuteron acceleration by shielding it from the field. When the proton layer is depleted, the deuterons become exposed to the space-charge field and are promptly accelerated. This scenario was tested with a two-dimensional particle-in-cell simulation model by varying the contaminant layer thickness and laser fluence (laser energy per unit area). For laser fluences F(laser) <1 J/mu m(2), the contamination layer over the surface inhibits the deuteron acceleration from the rear surface, while in the opposite case of laser fluences F(laser) > 1 J/mu m(2) deuterons and heavier ions can be successfully accelerated with conversion efficiency of laser energy into ions of more than 1%. Experimental data from a 6 mu m thick aluminum foil coated with a 1 mu m deuterated plastic layer on the back surface are suggestive of the detrimental role of contaminants on deuteron acceleration. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3497002]

AB - The impact of contaminants on laser-driven ion acceleration is investigated using particle-in-cell simulations. The conventional ion acceleration mechanism, target normal sheath acceleration, has been revisited for targets with proton-rich contaminants in the form of water vapor. The targets considered have a deuterated plastic layer on the rear surface of an aluminum target, and the influence of the contaminant layer on the deuteron acceleration is investigated. In the early stage of ion acceleration, the space-charge electrostatic field on the rear target surface accelerates only the outermost, proton-rich layer of ions, which inhibits the deuteron acceleration by shielding it from the field. When the proton layer is depleted, the deuterons become exposed to the space-charge field and are promptly accelerated. This scenario was tested with a two-dimensional particle-in-cell simulation model by varying the contaminant layer thickness and laser fluence (laser energy per unit area). For laser fluences F(laser) <1 J/mu m(2), the contamination layer over the surface inhibits the deuteron acceleration from the rear surface, while in the opposite case of laser fluences F(laser) > 1 J/mu m(2) deuterons and heavier ions can be successfully accelerated with conversion efficiency of laser energy into ions of more than 1%. Experimental data from a 6 mu m thick aluminum foil coated with a 1 mu m deuterated plastic layer on the back surface are suggestive of the detrimental role of contaminants on deuteron acceleration. (C) 2010 American Institute of Physics. [doi: 10.1063/1.3497002]

KW - HIGH-INTENSITY LASER

KW - PLASMA INTERACTIONS

KW - PROTON-BEAMS

KW - TARGET INTERACTIONS

KW - FAST IGNITION

KW - GENERATION

KW - IRRADIATION

KW - SOLIDS

U2 - 10.1063/1.3497002

DO - 10.1063/1.3497002

M3 - Journal article

VL - 17

JO - Physics of Plasmas

JF - Physics of Plasmas

SN - 1070-664X

IS - 10

M1 - 103111

ER -