AMMONX: A kinetic ammonia production scheme for EIRENE implementation

Abstract

Until recently the EIRENE suite handled hydrogen chemistry (i.e. H atoms, H2 molecules, and H2+ molecular ions and their isotopomers). Extensions also exist for hydrocarbon chemistry, including CxHy species (H is any hydrogen isotope), but no kinetic scheme including NHx chemistry had been implemented. After a benchmarking of available schemes and kinetic data, a reduced scheme including 50 reactive processes is presented here, implying a large set of N-bearing species (N, N2, N2+, NHx radicals and ions). This mechanism is a part of a more complete scheme of 130 processes also including the metastable states of N2 and N. In a first time, this scheme has been validated by comparison with independent experimental works. In a second time the scheme was used in Eirene suite to model a type-case. First results confirm that under tokamak conditions, ammonia is produced in significative amount after N2 injection in the sub-divertor volume. Keywords: Modeling, Edge-plasma, Ammonia formation, Tokamak