Modelling of MAST upgrade neutral beam re-ionization and the impact on the beamline ducts and in-vessel components

• Published in: Fusion engineering and design 2019-09, Vol.146, p.765-769
• Main Authors: Shepherd, Alastair John, Akers, R., Barth, A., Day, I.E., Fishpool, G., McAdams, R., Tivey, R., Verhoeven, R.
• Format: Article
• Language: English
• Subjects: Coinjection; Computer simulation; Duct liners; Ducts; Graphite; Ionization; Linings; MAST-U; Modelling; Monte Carlo simulation; Neutral beam injection; Neutral beams; Re-ionization; Structural analysis; Thermocouples; Vessels
• ISSN: 0920-3796; 1873-7196
• DOI: 10.1016/j.fusengdes.2019.01.076

•MAST-U NBI beamline re-ionisation modelled for early operation plasma scenarios.•Monte Carlo modelling has derived the heat loading on the beamline duct liners.•New graphite tiles added to catch in-vessel re-ionisation.•ANSYS analysis confirms suitability for initial MAST-U campaigns.•Re-ionisation modelling benchmarked using the fast ion code LOCUST. We describe modelling of neutral beam re-ionization along the MAST-U beamlines and into the MAST-U vessel, within a field envelope applicable to the operational space of the machine. Monte-Carlo simulations using the MAGNET code give the re-ionized power loading on both beamline ducts, which was used to position thermocouples on the duct liners. Thermal and structural analysis of the duct liners has been carried out using ANSYS. The potential for significant amounts of re-ionized power entering the MAST-U vessel has resulted in the installation of graphite tile plating at the end of the ducts, compatible with co-injection. The power loading on these plates and other in-vessel components as modelled by MAGNET has been compared to the LOCUST code. Analysis has confirmed that the graphite tiles are compatible with core scope operation.