MAST Accomplishments and Upgrade for Fusion Next-Steps

Morris, W.; Milnes, J.; Barrett, T.; Challis, C.; Chapman, I. T.; Cox, M.; Cunningham, G.; Dhalla, Fahim; Fishpool, G.; Jacquet, Philippe; Katramados, Ioannis; Kirk, A.; McClements, K. G.; Martin, Richard L.; Meyer, H.; Romanelli, M.; Saarelma, S.; Sharapov, S. E.; Thompson, V.; Valovič, M.; Whitfield, G.; Wolff, Dan

doi:10.1109/tps.2014.2299973

Cited by 27 publications

(22 citation statements)

References 40 publications

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“…IX C. Off-axis current drive physics will be further investigated in NSTX-U and MAST-U, where significant off-axis current drive capabilities will be implemented. 22,23,370 As for plasma profile control, the profiles are largely determined by the confinement properties of the plasma. The H-mode produces much broader plasma pressure profiles, which enabled NSTX and MAST to explore high beta/performance regimes.…”

Section: Current and Plasma Profile Controlmentioning

confidence: 99%

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Recent progress on spherical torus research

Ono

Kaita

2015

Physics of Plasmas

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The spherical torus or spherical tokamak (ST) is a member of the tokamak family with its aspect ratio (A = R0/a) reduced to A ∼ 1.5, well below the normal tokamak operating range of A ≥ 2.5. As the aspect ratio is reduced, the ideal tokamak beta β (radio of plasma to magnetic pressure) stability limit increases rapidly, approximately as β ∼ 1/A. The plasma current it can sustain for a given edge safety factor q-95 also increases rapidly. Because of the above, as well as the natural elongation κ, which makes its plasma shape appear spherical, the ST configuration can yield exceptionally high tokamak performance in a compact geometry. Due to its compactness and high performance, the ST configuration has various near term applications, including a compact fusion neutron source with low tritium consumption, in addition to its longer term goal of an attractive fusion energy power source. Since the start of the two mega-ampere class ST facilities in 2000, the National Spherical Torus Experiment in the United States and Mega Ampere Spherical Tokamak in UK, active ST research has been conducted worldwide. More than 16 ST research facilities operating during this period have achieved remarkable advances in all fusion science areas, involving fundamental fusion energy science as well as innovation. These results suggest exciting future prospects for ST research both near term and longer term. The present paper reviews the scientific progress made by the worldwide ST research community during this new mega-ampere-ST era.

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Section: Current and Plasma Profile Controlmentioning

confidence: 99%

“…I A), the present facilities (Sec. I B), and the new 2 MA-class ST facilities NSTX-U 22 and MAST-U 23 presently under construction (Sec. I C).…”

Section: Introductionmentioning

confidence: 99%

Recent progress on spherical torus research

Ono

Kaita

2015

Physics of Plasmas

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“…It will be equipped with neutral beam heating, and a wide range of high resolution diagnostics with a strong emphasis on the scrape-off layer and divertor plasma, allowing new levels of detail in testing of models. Cryopumps have been installed in each divertor, and the large radius divertor targets (T5) have been specially designed to compensate power concentrations due to ripple effects, using a CAD-based optimisation tool [20] [24].…”

Section: A a Possible Research Strategy For Mast Upgradementioning

confidence: 99%

MAST Upgrade Divertor Facility: A Test Bed for Novel Divertor Solutions

Morris

Harrison

Kirk

et al. 2018

IEEE Trans. Plasma Sci.

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The challenge of integrated exhaust consistent with the other requirements in DEMO and power plant class tokamaks (ITER-like and alternative DEMOs, FNSF approaches) is wellknown and the exhaust solution is likely to be fundamental to the design and operating scenarios chosen. Strategies have been proposed such as high main plasma radiation (e.g. [1]), but improved solutions are sought and will require revised research methodologies. While no facility can address all the challenges, the new MAST Upgrade tokamak enables exploration of a wide range of divertor plasma aspects in a single device and their relation with the core plasma (e.g. access to H-mode), in particular the development of fundamental understanding and new ideas. It has a unique combination of closed divertor, capability of a wide range of configurations from conventional to long-leg (including Super-X), and fully symmetric double null (plasma and divertor structures). To extrapolate to DEMO and power plant scale devices where full integrated tests in advance are not feasible yet different physics mechanisms may dominate, theory-based models are likely to be essential, for confident performance prediction, optimisation, and a "qualification" of the concept. Development and validation of such models is at the heart of the programme around MAST Upgrade. Amongst the many areas to be explored, there will be a strong focus on the closely coupled topics of plasma detachment and cross-field transport mechanisms (e.g. plasma filaments), key ingredients of effective and reliable protection of the plasma facing components at DEMO-scale. Index Terms-Fusion reactor design, divertor, plasma exhaust, plasma filaments, super-X, tokamak devices. I. INTRODUCTION-ALTERNATIVE EXHAUST APPROACHES Tokamaks at reactor scale need effective and practical exhaust systems. An integrated exhaust solution accommodates both a high performance plasma and the engineering and materials requirements of reliably protected long-lifetime plasma-facing components (PFCs). Its many challenges are well documented-it involves far more than the divertor configuration. The fastest path would be to use the single-null divertor configuration (e.g. as implemented on ITER) accompanied by a highly radiating main plasma and a fully detached divertor [1]. However, while there is some basis for optimism, it is not yet clear whether such a constraint on the

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“…Previous studies have shown that the detached divertor regime reduces the plasma pressure and electron temperature at the divertor target which allows for higher radiative power fractions in the SOL. The divertor design on MAST-Upgrade [9,17] provides the first opportunity to investigate the effect of a Super-X configuration, in which access to the detached regime is largely aided by the increased connection length to the divertor [12]. For deriving electron temperature and densities it has been noted that during the onset of detachment, line ratios from the Balmer series show an increase, being clear indicator of very low electron temperature (≤ 1 eV).…”

Section: Modelling Transient Ionisation In a Tokamak Divertormentioning

confidence: 99%

Diagnosing transient plasma status: from solar atmosphere to tokamak divertor

Giunta

Henderson

O’Mullane³

et al. 2016

J. Inst.

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This work strongly exploits the interdisciplinary links between astrophysical (such as the solar upper atmosphere) and laboratory plasmas (such as tokamak devices) by sharing the development of a common modelling for time-dependent ionisation. This is applied to the interpretation of solar flare data observed by the UVSP (Ultraviolet Spectrometer and Polarimeter), on-board the Solar Maximum Mission and the IRIS (Interface Region Imaging Spectrograph), and also to data from B2-SOLPS (Scrape Off Layer Plasma Simulations) for MAST (Mega Ampère Spherical Tokamak) Super-X divertor upgrade. The derived atomic data, calculated in the framework of the ADAS (Atomic Data and Analysis Structure) project, allow equivalent prediction in non-stationary transport regimes and transients of both the solar atmosphere and tokamak divertors, except that the tokamak evolution is about one thousand times faster.

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MAST Accomplishments and Upgrade for Fusion Next-Steps

Cited by 27 publications

References 40 publications

Recent progress on spherical torus research

Recent progress on spherical torus research

MAST Upgrade Divertor Facility: A Test Bed for Novel Divertor Solutions

Diagnosing transient plasma status: from solar atmosphere to tokamak divertor

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