Method of processing ion energy distributions using a Thomson parabola ion spectrograph with a microchannelplate image converter camera

Abstract

A Thomson parabola ion spectrograph (TP) is a very useful tool for the investigation of pulsed laser ablation. Measurements performed with the TP give useful information about physical processes, ion species and their energy distributions, as well as charge states. For ions with the lower charge states, $\text{q<20,}$ complete information about energy distributions of all ionization states of ions can be obtained from a single laser shot. For ions with higher ionization states, parabolas generated in the TP interfere and it is impossible to get energy distributions for all the ion species. In this situation, the registered ions are composed of a few groups with different charge states and different energies. The TP enables the charge states and energetic ranges of different ion groups to be estimated. This presentation describes a method of processing experimental results, obtained from a TP, using a microchannelplate (MCP) image converter. Ion energy distributions for ${\mathrm{C}}^{\mathrm{1+}}{\mathrm{–C}}^{\mathrm{6+}}$ and ${\mathrm{Ta}}^{\mathrm{1+}}{\mathrm{–Ta}}^{\mathrm{12+}}$ are shown, and the effects of correcting the obtained ion energy distributions for the detection efficiency of the MCP are illustrated.