Speaker
Description
The negative ion formation in caesium sputter ion sources occurs on the surface of a cathode covered by a thin caesium (Cs) layer that lowers the surface work function and enhances the negative ion yield. It has been demonstrated that laser irradiation of the cathode can significantly increase the extracted negative ion current. The laser enhancement often exhibits a transient nature suggesting that the irradiation affects the caesium coverage of the cathode.
In this work we investigate the effects of laser irradiation, Cs+ ionizer power, and cathode voltage on the cathode temperature, cathode current, and Cu− beam production in a Multi-Cathode Source of Negative Ions by Caesium Sputtering (MC-SNICS). It is shown that the beam current correlates strongly with the cathode temperature, which determines the desorption rate of caesium from the sputter target surface. It is concluded that laser irradiation, ionizer power, and cathode voltage strongly influence the Cs coverage on the cathode surface, which is essential for optimized negative ion production, and thus explains the earlier observations where the laser exposure has been shown to boost the extracted beam currents.
| Email address | mikko.i.laitinen@jyu.fi |
|---|---|
| Visitor's Visa | no |
| Classification | Caesium management |