title: Divertor impurity injection using high voltage arcs for impurity transport studies on the Mega Amp Spherical Tokamak.
abstract: The operation of next-generation fusion reactors will be significantly affected by impurity transport in the scrape-off layer (SOL). Current modelling efforts are restricted by a lack of detailed data on impurity transport in the SOL. In order to address this, a carbon injector has been designed and installed on the Mega Amp Spherical Tokamak (MAST). The injector creates short lived carbon plumes originating at the MAST divertor lasting less than 50 μs. High voltage capacitor banks are used to create a discharge across concentric carbon electrodes located in a probe mounted on the Divertor Science Facility in the MAST lower divertor. This results in a very short plume duration allowing observation of the evolution of the plume and precise localisation of the plume relative to the X-point on MAST. The emission from the carbon plume was imaged using fast visible cameras filtered in order to isolate the carbon II and carbon III emission lines centered around 514 nm and 465 nm.
authors.affiliation: School of Physical Sciences and National Centre for Plasma Science and Technology, Dublin City University, Glasnevin, Dublin, Ireland.
authors.forename: H J
authors.initials: HJ
authors.lastname: Leggate
authors.affiliation: ITER Organisation, FST, Route de Vinon, CS 90 046, 13067 Saint Paul Lez Durance Cedex, France.
authors.forename: S W
authors.initials: SW
authors.lastname: Lisgo
authors.affiliation: CCFE, Culham Science Centre, Abingdon, Oxon OX14 3DB, United Kingdom.
authors.forename: J R
authors.initials: JR
authors.lastname: Harrison
authors.affiliation: CCFE, Culham Science Centre, Abingdon, Oxon OX14 3DB, United Kingdom.
authors.forename: S
authors.initials: S
authors.lastname: Elmore
authors.affiliation: CCFE, Culham Science Centre, Abingdon, Oxon OX14 3DB, United Kingdom.
authors.forename: S Y
authors.initials: SY
authors.lastname: Allan
authors.affiliation: CCFE, Culham Science Centre, Abingdon, Oxon OX14 3DB, United Kingdom.
authors.forename: R C
authors.initials: RC
authors.lastname: Gaffka
authors.affiliation: CCFE, Culham Science Centre, Abingdon, Oxon OX14 3DB, United Kingdom.
authors.forename: R C
authors.initials: RC
authors.lastname: Stephen
authors.affiliation: School of Physical Sciences and National Centre for Plasma Science and Technology, Dublin City University, Glasnevin, Dublin, Ireland.
authors.forename: M M
authors.initials: MM
authors.lastname: Turner