Generation of negative ions in a magnetic multipole plasma source with combined inductive and capacitive high frequency excitation
Abstract
Negative hydrogen and deuterium ions extracted from plasma sources have the potential for high-current charged and neutral particle beams for accelerator systems. Negative ions in the MeV energy range are of particular relevance for neutral beam plasma heating in fusion devices. Magnetic multipole plasma sources with filaments have been found to have a high content of negative ions. Plasma ion sources for long-term operation with fusion devices require, however, electrodeless excitation for various reasons. Inductively excited plasma sources generate ions but due to the absence of a high-energetic electronic component in the EEDF those sources do not operate at optimum. A combined inductive and capacitive high frequency excitation can be used to obtain both a high plasma density and high-energy electrons. Our aim is to control the electron energy distribution function of the plasma in such a way that the rovibronic states of the hydrogen and deuterium molecules in the electronic ground state are over-thermally populated. Dissociative attachment of low-energy electrons to rovibronic highly excited molecules leads to the desired negative ions. We present first results on the detection of vibrationally excited electronic ground-state molecules by laser induced fluorescence with VUV radiation. This work is supported by the Deutsche Forschungsgemeinschaft DFG.
- Publication:
-
APS Annual Gaseous Electronics Meeting Abstracts
- Pub Date:
- October 2003
- Bibcode:
- 2003APS..GECNWP062M