title: Coherence imaging of scrape-off-layer and divertor impurity flows in the Mega Amp Spherical Tokamak (invited).
abstract: A new coherence imaging Doppler spectroscopy diagnostic has been deployed on the UK's Mega Amp Spherical Tokamak for scrape-off-layer and divertor impurity flow measurements. The system has successfully obtained 2D images of C III, C II, and He II line-of-sight flows, in both the lower divertor and main scrape-off-layer. Flow imaging has been obtained at frame rates up to 1 kHz, with flow resolution of around 1 km/s and spatial resolution better than 1 cm, over a 40° field of view. C III data have been tomographically inverted to obtain poloidal profiles of the parallel impurity flow in the divertor under various conditions. In this paper we present the details of the instrument design, operation, calibration, and data analysis as well as a selection of flow imaging results which demonstrate the diagnostic's capabilities.
authors.affiliation: Centre for Advanced Instrumentation, Department of Physics, Durham University, Durham DH1 3LE, United Kingdom.
authors.forename: S A
authors.initials: SA
authors.lastname: Silburn
authors.affiliation: CCFE, Culham Science Centre, Abingdon, Oxon OX14 3DB, United Kingdom.
authors.forename: J R
authors.initials: JR
authors.lastname: Harrison
authors.affiliation: Plasma Research Laboratory, Australian National University, Canberra, ACT 0200, Australia.
authors.forename: J
authors.initials: J
authors.lastname: Howard
authors.affiliation: York Plasma Institute, Department of Physics, University of York, Heslington, York YO10 5DD, United Kingdom.
authors.forename: K J
authors.initials: KJ
authors.lastname: Gibson
authors.affiliation: CCFE, Culham Science Centre, Abingdon, Oxon OX14 3DB, United Kingdom.
authors.forename: H
authors.initials: H
authors.lastname: Meyer
authors.affiliation: CCFE, Culham Science Centre, Abingdon, Oxon OX14 3DB, United Kingdom.
authors.forename: C A
authors.initials: CA
authors.lastname: Michael
authors.affiliation: Centre for Advanced Instrumentation, Department of Physics, Durham University, Durham DH1 3LE, United Kingdom.
authors.forename: R M
authors.initials: RM
authors.lastname: Sharples