Laboratory Study of Ion-Neutral Collisions at Suprathermal Energies.

摘要

A double mass-spectrometer system for the study of the dynamics of ion-neutral collisions at suprathermal energies is described in detail. The system consists of a Wien Filter, which acts as a source of mass-selected and velocity analyzed ions, coupled to a static-pressure collision chamber followed by a quadrupole mass filter, which acts as a mass analyzer for the products and the projectile ions. This apparatus has been used to measure ion-neutral collision cross sections and ion product times-of-flight. The methods utilized in the processing of raw experimental data are also described. The raw cross section data is corrected with respect to the collection efficiency, yielding integral cross sections which can be used in codes designed to predict the environment of spacecraft in low earth orbit. The performance of the experiment is demonstrated by measuring the known ion-neutral collision systems: N2(+) + Ar, N2(+) + D2, and O+ + H2O. Keywords: Ion neutral collisions; Mass spectrometry; Space effects. (JHD)