@article{7627,
  author = {G. A. van Swaaij and K. Bystrov and D. Borodin and A. Kirschner and L. B. van der Vegt and G. J. van Rooij and G. De Temmerman and W. J. Goedheer},
  title = {Dissociative recombination and electron-impact de-excitation in CH photon emission under ITER divertor-relevant plasma conditions},
  abstract = {For understanding carbon erosion and redeposition in nuclear fusion devices, it is important to understand the transport and chemical break-up of hydrocarbon molecules in edge plasmas, often diagnosed by emission of the CH A(2)Delta-X-2 Pi Gero band around 430 nm. The CH A-level can be excited either by electron-impact (EI) or by dissociative recombination (DR) of hydrocarbon ions. These processes were included in the 3D Monte Carlo impurity transport code ERO. A series of methane injection experiments was performed in the high-density, low-temperature linear plasma generator Pilot-PSI, and simulated emission intensity profiles were benchmarked against these experiments. It was confirmed that excitation by DR dominates at T-e < 1.5 eV. The results indicate that the fraction of DR events that lead to a CH radical in the A-level and consequent photon emission is at least 10%. Additionally, quenching of the excited CH radicals by EI de-excitation was included in the modeling. This quenching is shown to be significant: depending on the electron density, it reduces the effective CH emission by a factor of 1.4 at n(e) = 1.3 x 10(20) m(-3), to 2.8 at n(e) = 9.3 x 10(20) m(-3). Its inclusion significantly improved agreement between experiment and modeling.
},
  year = {2012},
  journal = {Plasma Physics and Controlled Fusion},
  volume = {54},
  pages = {095013},
  month = {Sep},
  isbn = {0741-3335},
  url = {http://arxiv.org/abs/1207.0736},
  doi = {10.1088/0741-3335/54/9/095013},
  language = {English},
}