Author:
Wolf V.,Zielke D.,Rauner D.,Briefi S.,Wimmer C.,Fantz U.
Abstract
Abstract
In NNBI ion sources neutral hydrogen atoms and positive ions impact
on low work function grid surfaces where they are converted to negative ions, and
subsequently extracted. Knowledge of the positive ions flux is
crucial for optimizing the negative ion yield, and also for benchmarking numerical
models. To this end a Mach probe (MP) diagnostic can be used, which determines the
direction and magnitude of the positive ion flux. The plasma in ion sources is typically
weakly magnetized, rendering the interpretation of Mach probe data difficult. For
this reason a two step approach is chosen, where at first a previously used Mach
probe is re-commissioned and applied in a well diagnosed and versatile laboratory
scale experiment. From these experiments important insights regarding the design
of a new combined Langmuir- and Mach probe, its calibration procedure, and data
interpretation are obtained.
Subject
Mathematical Physics,Instrumentation