The effect of Coulomb binary collisions and the measured tempo-spatial profiles of laser pulses on ion acceleration

Abstract We conducted particle-in-cell (PIC) simulations to investigate the impact of measured tempo-spatial profiles of laser pulses on ion acceleration in laser-solid target interactions for up to 27 ps. In our simulations, we modeled the evolution of preplasma when prepulses reached the target 25 ps before the peak pulse, whose intensities were about I <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:mo>≃</mml:mo> </mml:mrow> </mml:math> 10 13 <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mrow> <mml:msup> <mml:mrow> <mml:mi>Wcm</mml:mi> </mml:mrow> <mml:mrow> <mml:mo>−</mml:mo> <mml:mn>2</mml:mn> </mml:mrow> </mml:msup> </mml:mrow> </mml:math> , which is close to the ionization threshold of plastic targets. By incorporating measured tempo-spatial profiles of laser pulses, collisional ionization (CI), and Coulomb binary collisions (BC) into our simulations, we were able to reproduce proton and carbon ion spectra that better match experimental data. Our findings reveal that CI and Coulomb BC play crucial roles in the dynamics of particle acceleration. Notably, Coulomb BC significantly influence the ionization charge states and the energy distributions of ions. By spatially resolving the anticipated ion scatter angle, we observed that Coulomb interactions are predominant in the whole plasma domain specifically in the cold and dense regions inside and near the target on either side. These results contribute to more realistic PIC simulations, bringing them closer to experimental conditions, which we refer to as EXPIC.