title: Extending helium partial pressure measurement technology to JET DTE2 and ITER.
abstract: The detection limit for helium (He) partial pressure monitoring via the Penning discharge optical emission diagnostic, mainly used for tokamak divertor effluent gas analysis, is shown here to be possible for He concentrations down to 0.1% in predominantly deuterium effluents. This result from a dedicated laboratory study means that the technique can now be extended to intrinsically (non-injected) He produced as fusion reaction ash in deuterium-tritium experiments. The paper also examines threshold ionization mass spectroscopy as a potential backup to the optical technique, but finds that further development is needed to attain with plasma pulse-relevant response times. Both these studies are presented in the context of continuing development of plasma pulse-resolving, residual gas analysis for the upcoming JET deuterium-tritium campaign (DTE2) and for ITER.
authors.affiliation: Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6169, USA.
authors.forename: C C
authors.initials: CC
authors.lastname: Klepper
authors.affiliation: Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6169, USA.
authors.forename: T M
authors.initials: TM
authors.lastname: Biewer
authors.affiliation: CCFE, Culham Science Centre, Abingdon, Oxon OX14 3DB, United Kingdom.
authors.forename: U
authors.initials: U
authors.lastname: Kruezi
authors.affiliation: IRFM, CEA Cadarache, 13108 St-Paul-Lez-Durance Cedex, France.
authors.forename: S
authors.initials: S
authors.lastname: Vartanian
authors.affiliation: IRFM, CEA Cadarache, 13108 St-Paul-Lez-Durance Cedex, France.
authors.forename: D
authors.initials: D
authors.lastname: Douai
authors.affiliation: Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6169, USA.
authors.forename: D L
authors.initials: DL
authors.lastname: Hillis
authors.affiliation: Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6169, USA.
authors.forename: C
authors.initials: C
authors.lastname: Marcus
authors.affiliation: EUROfusion Consortium, JET, Culham Science Centre, Abingdon OX14 3DB, United KingdomOak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6169, USACCFE, Culham Science Centre, Abingdon, Oxon OX14 3DB, United KingdomIRFM, CEA Cadarache, 13108 St-Paul-Lez-Durance Cedex, France.