Abstract
The CH A-X molecular band is measured upon seeding the hydrogen plasma in the linear plasma generator Pilot-PSI [electron temperature Te =0.1-2.5 eV and electron density ne = (0.5-5) × 1020 m-3] with methane. Calculated inverse photon efficiencies for these conditions range from 3 up to 106 due to a steeply decreasing electron excitation cross section. The experiments contradict the calculations and show a constant effective inverse photon efficiency of ∼100 for Te <1 eV. The discrepancy is explained as the CH A level is populated through dissociative recombination of the molecular ions formed by charge exchange. Collisional de-excitation is observed for ne 5× 1020 m-3 and 0.1 eV< Te <1 eV. These results form a framework for in situ carbon erosion measurements in future fusion reactors such as ITER.
| Original language | English |
|---|---|
| Article number | 151501 |
| Journal | Applied Physics Letters |
| Volume | 95 |
| Issue number | 15 |
| DOIs | |
| State | Published - 2009 |
| Externally published | Yes |
Funding
The authors acknowledge the assistance of R.S. Al and B. de Groot, H.J. van der Meiden, M.J. van de Pol, A.E. Shumack, W.A.J. Vijvers, and G.M. Wright with the experiments and the useful discussions with S. Brezinsek, D. Borodin, A. Kirschner, V. Philipps, and D.C. Schram. This work was supported by the European Communities under the contract of Association between EURATOM/FOM and carried out within the framework of the European Fusion Programme with financial support from NWO and the NWO Grant No. RFBR 047.018.002. The views and opinions expressed herein do not necessarily reflect those of the European Commission.
