[Show abstract][Hide abstract] ABSTRACT: The mechanism of forming negative ions in cesium sputter negative ion sources is studied by means of a modified dipole layer model and quantum theory. Formulas of the change of work function on the metal surface adsorbing cesium layer and the electron transfer probability are given. The formation probabilities of the negative ions are derived using a quantum tunneling model. The negative ion yield is also calculated. The calculated results are in essential agreement with the experimental data. The philosophy described in this paper may offer a useful theoretical model for the mechanism study of cesium sputter negative ion sources.
No preview · Article · May 1992 · Review of Scientific Instruments
[Show abstract][Hide abstract] ABSTRACT: The thermophysical characteristics of the ionizer in cesium sputter-type negative ion sources is studied by means of the heat transfer theory in this paper. A heat transfer model is given and theoretical calculations are performed. The theoretical calculations are in good agreement with experimental results. Based on the theoretical analysis the configuration of the source is improved and the calorific efficiency is increased, so that the temperature of the ionizer can reach up to 1300 K and the lifetime of the heater core of the ionizer is prolonged. The theoretical model can serve as the basis for the ionizer design of the cesium sputter-type negative ion sources. In addition, the study is also helpful for the design of the heater in the similar ion sources.
No preview · Article · Apr 1992 · Review of Scientific Instruments