The impact of plasma physics on the timescale to a tokamak fusion power plant

Abstract

Some of the main plasma physics challenges associated with achieving the conditions for commercial fusion power in tokamaks are reviewed. The confinement quality is considered to be a key factor, having an impact on the size of the reactor and exhaust power that has to be managed. Plasma eruptions can cause excessive erosion if not mitigated, with implications for maintenance and availability. Disruptions are a major concern—one large disruption could terminally damage the reactor so it is important to understand the loads they impart to the structure, and put in place appropriate protection and an effective avoidance/mitigation strategy. Managing the exhaust of heat and particles from the plasma is likely to be a significant issue, which may be mitigated if an advanced confinement regime can be identified. The advanced divertor structures that may be required to handle the exhaust have a significant impact on the design of a fusion reactor. Three strategies can be identified to take account of the physics challenges, with different implications for the timescale to fusion power: (1) a staged approach with the size of each step determined by our confidence in the predictive capability of our models; (2) a single, big step with contingency built into the design where possible to accommodate the uncertainty in physics predictions and (3) a single big step with optimistic physics assumptions and no contingency, accepting the increased financial and reputational risk that comes with such an approach. This article is part of a discussion meeting issue ‘Fusion energy using tokamaks: can development be accelerated?’.

Can the development of fusion energy be accelerated? An introduction to the proceedings

“…Since the 1957 ZETA experiments at Harwell, plasma instabilities have been the bugbear of fusion. Howard Wilson's paper [32] gives us hope that fusion theory could help to mitigate their…”

“…Since the 1957 ZETA experiments at Harwell, plasma instabilities have been the bugbear of fusion. Howard Wilson's paper [32] gives us hope that fusion theory could help to mitigate their [33] speaks of the very exciting UK Atomic Energy Authority (UKAEA) scene at present, including the role of JET and its programme in support of ITER. The MAST upgrade is due to be running later this year and the meeting wished it good fortune!…”

A high-k mm-wave scattering diagnostic for measuring binormal wavenumber electron scale turbulence on MAST-U

“…Plasma turbulence plays a key role in determining the spatial-temporal evolution of plasmas in astrophysical, geophysical and laboratory contexts. In particular, turbulence on disparate spatial and temporal scales limits the level of confinement achievable in magnetic confinement fusion experiments and therefore limits the viability of sustainable fusion power [1]. MAST-U is a well-equipped experimental facility having instruments to measure ion-scale turbulence throughout the plasma and electron scale turbulence at the plasma edge.…”