Simulation analyses of 100-keV as well as low and high energy protons through insulating nanocapillary

Abstract

In order to clearly understand the physical images of incident ions passing through the insulating nanocapillary, in this work we establish a theoretical model, in which the matlab program is combined with the Monte Carlo method, to estimate the time evolution of transmission features, such as the angular and deposited charge distribution, three-dimensional (3D) trajectories of H+ particles with proton incident energies of 10 keV, 100 keV and 1 MeV at -1 title angle. The simulation results show that the transmission mechanism of 100 keV protons is different from those of 10 keV and 1 MeV protons. After a sufficiently charging and discharging stage, 10 keV H+ particles are guided along the direction of capillary axis, indicating that the guiding force from the surface charge patches is significant, and the small-angle scattering of 1 MeV protons under the capillary inner wall is a physical process that determines the transport of H+ particles through the nanocapillary. However, for 100 keV H+ particles, the centroid angle gradually shifts from the guiding direction to the direction close to the incident beam, which is attributed to the fact that the stochastic inelastic binary collision below the surface is the main transmission mechanism at the beginning. After the charging and discharging reach an equilibrium state, the H+ particles are likely to pass through the nanocapillary, and the main transmission mechanism is the charge-patch-assisted specular scattering. This mechanism deepens the understanding of the transport behavior of protons through the nanocapillary, which will contribute to the control and application of the 100 keV proton beam.