Influence of residence time and helium addition in the ammonia formation on tungsten walls in N2H2 glow discharge plasmas

The influence of the residence time for the active species and of the helium addition to the plasma in the ammonia formation in N2H2(He) Glow Discharge plasmas has been studied using differential pumped mass spectrometry. Three different residence times for the N2 molecule were studied: 25, 50 and 100ms. Other experiments scanning the helium plasma content (0–8%) were performed with a residence time of 100ms. While no difference in the ammonia formation yields was found between the cases of 25ms and 50ms, the ammonia yields were increased by a 25% in the case of 100ms. Additionally, an increasing helium plasma content enhances the ammonia formation yields up to 45%. Three different effects induced by the presence of helium in the plasma were analyzed: effects in mass spectrometry measurements, changes in the electron temperature and modification of the surface chemistry. The analyzes pointed out to an improved NH recombination on tungsten walls induced by helium presence as the key factor that could explain the higher ammonia yields experimentally found for the highest helium content in the plasma. Keywords: Nitrogen seeding, Ammonia, Tungsten, Helium, Residence time, Electron temperature

Abstract licence: CC BY-NC

A person counts once a day per paper. We keep no cookie and no address: a reader is a hash that changes every day. Any month under five reads shows no number.