Articolo in rivista, 2017, ENG, 10.1016/j.nme.2017.05.009
Laguardia, L.; Caniello, R.; Cremona, A.; Gatto, G.; Gervasini, G.; Ghezzi, F.; Granucci, G.; Mellera, V.; Minelli, D.; Negrotti, R.; Pedroni, M.; Realini, M.; Ricci, D.; Rispoli, N.; Uccello, A.; Vassallo, E.
Consiglio Nazionale delle Ricerche; Istituto per la Conservazione e la Valorizzazione dei Beni Culturali, Sesto Fiorentino Istituto di Fisica del Plasma - CNR, Via R. Cozzi 53, 20125 Milan, Italy
Nitrogen used to reduce the power load onto the divertor in tokamak fusion devices (JET, AUG) has the drawback of ammonia formation. Non-negligible quantity of tritiated ammonia could be a serious concern for ITER, since it cannot be reduced through the presently designed fuel cycle loop. In this paper we report a study of the production of ND 3 as a function of the electron temperature (T e ) and neutral pressure in a N 2 /D 2 plasma mixture in the linear machine GyM. The nitrogenized compounds were monitored by Optical Emission Spectroscopy (OES) and Mass Spectrometry (MS). Measurements were performed at different values of T e ranging from 3 eV to 6 eV by varying the microwave power (2.45 GHz, up to 0.6 kW cw) that sustains the plasma, and for different neutral pressure at a constant ratio of nitrogen and deuterium partial pressures. The effect of introduction of He or Ar in the N 2 /D 2 mixtures has been also investigated. The ND 3 produced during plasma experiments has been quantified with a dedicated setup based on an in-line LN 2 trap and Liquid Ion Chromatography (LIC). Mass-spectrometry results showed that ND 3 is formed only during the plasma phase of the experi- ment while LIC showed that ammonia production increases with T e and with the total neutral pressure. Optical Emission Spectroscopy confirms the presence of ND species in all the cases studied. The addition of He and Ar in the N 2 /D 2 plasma, not modifing T e and n e , causes a reduction of ammonia formation, that is negligible in the case of Ar addition, while in the case of He reaches 80%. This suggests that He modifies the physical chemical process occurring at the wall, where the adsorbed He inhibits the reac- tions leading to ammonia formation at the metallic surface of the vessel. These results confirm the active role of a metallic surface in ammonia production and indicate He injection as a promising solution to limit the formation of the tritiated ammonia in the N seeded plasma of ITER. ©2017 The Authors. Published by Elsevier Ltd.
Nuclear materials and energy
Ammonia, Chromatography, Mass Spectrometer, Nitrogen seeding, Optical spectroscopy
Ricci Daria, Minelli Daniele, Caniello Roberto, Uccello Andrea, Pedroni Matteo, Vassallo Espedito, Realini Marco, Ghezzi Francesco Mauro, Gervasini Gabriele, Granucci Gustavo, Gatto Giuseppe, Rispoli Natale, Cremona Anna, Mellera Vittoria Antonia, Negrotti Riccardo, Laguardia Laura
ICVBC – Istituto per la conservazione e valorizzazione dei beni culturali, IFP – Istituto di fisica del plasma "Piero Caldirola", ISPC – Istituto di Scienze del Patrimonio Culturale
ID: 376167
Year: 2017
Type: Articolo in rivista
Creation: 2017-10-02 10:06:01.000
Last update: 2022-04-12 19:23:20.000
External links
OAI-PMH: Dublin Core
OAI-PMH: Mods
OAI-PMH: RDF
DOI: 10.1016/j.nme.2017.05.009
URL: http://www.scopus.com/record/display.url?eid=2-s2.0-85020786800&origin=inward
External IDs
CNR OAI-PMH: oai:it.cnr:prodotti:376167
DOI: 10.1016/j.nme.2017.05.009
Scopus: 2-s2.0-85020786800
ISI Web of Science (WOS): 000417293300037