R. T. Osawa D. Moulton S. L. Newton S. Henderson B. Lipschultz A. Hudoba
To mitigate the issue of plasma exhaust in reactor scale tight aspect ratio tokamaks such as STEP (Spherical Tokamak for Energy Production), a double-null (DN) configuration is thought to be advantageous over a single-null (SN) configuration. However, practical control of the plasma vertical stability will likely lead to an oscillation around th…
PreprintA. Valentine T. Berry S. Bradnam H. Chohan T. Eade C. Grove J. Hagues K. Hearn J. Hodson K. Lennon J. Naish J. Neilson C. Nobs L. Packer A. Turner T. Turner L. Woodall R. Worrall
Global research programmes seeking to achieve a commercially viable model of a fusion power plant are being accelerated at an unprecedented rate. One critical element to the design and licensing is an accurate understanding of the radiation environment throughout the plant lifetime and subsequent decommissioning phase. The radiation field which res…
PreprintL. Howlett I. Cziegler S. Freethy H. Meyer
A comprehensive L-H power threshold study of MAST data is presented, with a detailed categorisation of transition and intermediate behaviour and a comparison of the results to scaling laws. Preliminary studies into the ion and electron heat flux for transitions at different densities are introduced. The first results of an L-H transition study o…
PreprintM. Kryjak B. Dudson D. Power S. Mijin C. Ridgers
The study of plasma exhaust remains a core focus of current efforts towards viable DEMO-class magnetically confined fusion devices. The scrape-off layer (SOL) features complex physics. This is especially true for detachment, a mechanism where a cloud of neutrals forms at the divertor target and becomes a sink of plasma energy, momentum and part…
PreprintR. Scannell the MAST Upgrade EUROfusion Tokamak Exploitation Teams
MAST Upgrade (MAST-U) is a new low aspect ratio device (R/a = 0.85/0.65 ~ 1.3) based on the MAST tokamak that started plasma operations in October 2020. It has substantial new capabilities compared with the original MAST device, with 19 new poloidal field coils (14 of which are within the vacuum vessel) and new, closed, up-down symmetric diverto…
PreprintHendrik Meyer the STEP Plasma Control Heating & Current Drive Team
With steady progress on ITER project and the design of DEMO, the international community is now entering an era in which fusion power on the grid could become a reality within the next 20 – 30 years. In this environment the UK has started the ambitious Spherical Tokamak for Energy Production (STEP) programme, aiming to develop a compact protot…
PreprintGuoliang Xia T.C. Hender Yueqiang Liu E. Trier
The Spherical Tokamak for Energy Production (STEP) is a UKAEA program that aims to deliver a prototype fusion energy plant and a path to commercial viability of fusion [1]. The low aspect ratio spherical tokamak is attractive because of its potential to achieve high normalized beta βN operation, and the fusion power ~β…
PreprintM. Kong E. Nardon M. Hoelzl D. Bonfiglio D. Hu U. Sheikh A. Boboc P. Carvalho T.C. Hender S. Jachmich K.D. Lawson S. Silburn Ž. Štancar R. Sweeney G. Szepesi the JOREK team JET contributors
Shattered pellet injection (SPI), with research started in recent years, is the current concept for the ITER disruption mitigation system (DMS) to prevent disruption-related damage. Compared with impurity SPI, pure deuterium (D2) SPI could contribute to runaway electron (RE) avoidance in ITER via a strong dilution cooling before the thermal quen…
PreprintK. G. McClements M. Fitzgerald H. J. C. Oliver A. P. Prokopyszyn
The UK has launched a programme to build a prototype fusion power plant, the Spherical Tokamak for Energy Production (STEP), by 2040. It is intended that the STEP prototype will generate fusion power of the order of 1 GW and net electrical power of the order of 100 MW. Plasma scenarios that could be compatible with these design requirements and wit…
PreprintM.Yu. Lavrentiev A. Hollingsworth J. Hess S. Davies A. Wohlers B. Thomas H.Salter A. Baron-Wiechec I. Jepu Y. Zayachuk N. Peng
Molybdenum is used as plasma-facing material in tokamaks and as material for plasma optical diagnostic mirrors. Harsh conditions of neutron irradiation, exposure to hydrogen isotopes and helium, and high temperature result in degradation of molybdenum surface and ultimately limit the lifetime of fusion power plant. In the current paper, we inves…
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