Modeling of negative ion transport in a plasma source
- Laboratoire de Physique des Milieux Ionises, Laboratoire du CNRS, Ecole Polytechnique, 91128 Palaiseau (France)
- Departement de Recherches sur la Fusion Controelee CE Cadarache, 13108 St Paul lez Durance (France)
A code called NIETZSCHE has been developed to simulate the negative ion transport in a plasma source, from their birth place to the extraction holes. The ion trajectory is calculated by numerically solving the 3-D motion equation, while the atomic processes of destruction, of elastic collision H{sup -}/H{sup +} and of charge exchange H{sup -}/H{sup 0} are handled at each time step by a Monte-Carlo procedure. This code can be used to calculate the extraction probability of a negative ion produced at any location inside the source. Calculations performed with NIETZSCHE have allowed to explain, either quantitatively or qualitatively, several phenomena observed in negative ion sources, such as the isotopic H{sup -}/D{sup -} effect, and the influence of the plasma grid bias or of the magnetic filter on the negative ion extraction. The code has also shown that in the type of sources contemplated for ITER, which operate at large arc power densities (>1 W cm{sup -3}), negative ions can reach the extraction region provided if they are produced at a distance lower than 2 cm from the plasma grid in the case of 'volume production' (dissociative attachment processes), or if they are produced at the plasma grid surface, in the vicinity of the extraction holes.
- OSTI ID:
- 21199179
- Journal Information:
- AIP Conference Proceedings, Vol. 439, Issue 1; Conference: 8. international symposium on the production and neutralization of negative ions and beams; 7. european workshop on the production and application of light negative ions, Villagium of Giens (France), 14-19 Sep 1997; Other Information: DOI: 10.1063/1.56355; (c) 1998 American Institute of Physics; Country of input: International Atomic Energy Agency (IAEA); ISSN 0094-243X
- Country of Publication:
- United States
- Language:
- English
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