Time of flight in electrostatic ion analyser for laser produced plasma ion resolving

摘要

This work addresses the use of an electrostatic analyser as a method of resolving ion species and charge state in theplasma ablation plume. Passing charged particles between a pair of electrodes at a known voltage and correlating withcharge to mass ratio Z/M and arrival time, allows one to perform ion spectroscopy. The time of flight showed adecrease in its value with the increase of the potential across the analyser plates. Higher plate voltage requires higherenergy particles to pass through, thus higher speed and lower arrival time. LORENTZ 3D numerical software wasused to model the trajectory of "test" ion beams and charged particles showed good agreement with simple modellingof the particles trajectory in an analytical description. The analysis of the experimental data was cross checked withthe modelling of the analyser and the simulated LORENTZ 3D results and revealed the same general trends. Smalldifferences were observed between the measured and simulated time of flight (< 1μs) which can be attributed to eitherthe electronics used which has to respond on the order of nanoseconds or the simulated data are imperfect models forphysical reality and can be reliable only if they demonstrate agreement with experimental results. This work presentsalso evidence on successfully resolving 15 of the distinct charged particle species (proton and ions released from theVHS tape used as the primary target in this work) emitted from the laser plasma.