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UKAEA-CCFE-PR(22)402022
In this paper, we review the confinement and transport properties observed and predicted in low aspect ratio tokamaks, or spherical tokamaks (STs), which can depart significantly from those observed at higher aspect ratio. In particular, thermal energy confinement scalings show a strong, near linear dependence of energy confinement time on toroidal…
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UKAEA-CCFE-PR(22)282022
A new quasilinear saturation model SAT3 has been developed for the purpose of calculating radial turbulent fluxes in the core of tokamak plasmas. The new model is shown to be able to better recreate the isotope mass dependence of nonlinear gyrokinetic fluxes compared to contemporary quasilinear models, including SAT2 [1], whilst performing at least…
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UKAEA-STEP-PR(22)012022
Spherical tokamaks (STs) have been shown to possess properties desirable for a fusion power plant such as achieving high plasma β and having increased vertical stability. To understand their confinement properties in a reactor relevant regime a 1GW fusion power spherical tokamak plasma equilibrium was analysed using linear gyrokinetics to deter…
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UKAEA-CCFE-PR(23)1022021
We present the results of GENE gyrokinetic calculations based on a series of JET-ILW type I ELMy H-mode discharges operating with similar experimental inputsbut at different levels of power and gas fuelling. We show that turbulence due to slab electron-temperature-gradient modes (sETGs) produces a significant amount of heat flux in four JET-ILW …
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UKAEA-CCFE-CP(22)032021
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UKAEA-CCFE-PR(22)012021
Electromagnetic instabilities and turbulence driven by the electron-temperature gradient are considered in a local slab model of a tokamak-like plasma, with constant equilibrium gradients (including magnetic drifts but no magnetic shear). The model describes perturbations at scales both larger and smaller than the electron inertial scale de…
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UKAEA-CCFE-CP(21)082021
The pedestal plays an important role in determining the confinement in tokamak H-mode plasmas. However, the steep pressure gradients in this transport barrier also lead to edge localized modes (ELMs) [1]. There is good understanding of the pedestal in type I ELM regimes [2], however, type I ELMs are known to damage plasma facing components and f…
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UKAEA-CCFE-PR(21)352021
Sustained operation of high-performance, ITER-baseline scenario plasmas at the high levels of input power (~< 40MA) required to achieve ~ 15 MW of D-T fusion power in JET-ILW requires careful optimisation of the fuelling to avoid an unacceptable disruption rate due to excessive radiation, primarily from W impurities, which are sputter…
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UKAEA-CCFE-PR(20)212020
Local linear gyrokinetic simulations show that electron temperature gradient (ETG) instabilities are the fastest growing modes for kyρi >~ 0.1 in the steep gradient region for a JET pedestal discharge (92174) where the electron temperature gradient is steeper than the ion temperature gradient. Here, ky is the wa…
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UKAEA-CCFE-PR(19)792019
The exhaust (loss) power components due to ELMs, radiation and heat transport across the edge transport barrier (ETB) between ELMs are quantifed for H-mode plasmas in JET-C and JET-ILW to provide data for comparison with simulations of pedestal heat transport. In low-current, JET-ILW pulses with a low rate of gas fuelling, the pedestal heat tran…
Showing 11 - 20 of 51 UKAEA Paper Results