
UKAEACCFEPR(23)882020
The pellet cycle of a mixed isotope tokamak plasma is successfully reproduced with reduced turbulent transport modelling within an integrated simulation framework. In JET tokamak experiments, deuterium pellets with reactorrelevant deposition characteristics were injected into a pure hydrogen plasma. Measurements of the isotope ratio profile inf…

UKAEACCFEPR(23)872020
The isotope dependence of plasma transport has a significant impact on the performance of future DT experiments in JET and ITER and eventually on the fusion gain and economics of future reactors. In preparation for future DT operation on JET, dedicated experiments and comprehensive transport analysis were performed in H, D and HD mixed plasma…

UKAEACCFEPR(20)1222019
We present an ultrafast neural network (NN) turbulent tokamak transport model, QLKNN, for heat and particle ﬂuxes. QLKNN is a surrogate model based on a database of 3 · 108 ﬂux calculations of the quasilinear gyrokinetic transport model QuaLiKiz. To ensure accurate reproduction of the underlying model, we include known features of the…

UKAEACCFEPR(20)172019
Core turbulent particle transport with multiple isotopes can display observable diﬀerences in behaviour between the electron and ion particle channels. Experimental observations at JET with mixed HD plasmas and varying NBI and gaspuﬀ sources [M. Maslov et al., Nucl. Fusion 7 076022 (2018)] inferred source dominated electr…

UKAEACCFEPR(18)132018
For the ﬁrst time, over ﬁve conﬁnement times, the selfconsistent ﬂux driven time evolution of heat, momentum transport and particle ﬂuxes of electrons and multiple ions including Tungsten (W) is modeled within the integrated modeling platform JETTO [Romanelli M et al PFR 2014], using ﬁrst principlebased codes : namely, QuaLiKiz [Bourd…

UKAEACCFEPR(18)102018
In IonTemperatureGradient (ITG) driven turbulence, the resonance condition leads to ion particle turbulent transport coeﬃcients signiﬁcantly larger than electron particle turbulent transport coeﬃcients. This is shown in nonlinear gyrokinetic simulations and explained by an analytical quasilinear model. It is then illustrated by JETTOQuaLi…

CCFEPR(17)422017
Quantitative comparisons are presented between gyrokinetic simulations and experimental values of the carbon impurity peaking factor in a database of JET Hmodes during the carbon wall era. These plasmas feature strong NBI heating, hence high values of toroidal rotation and correponding gradient. Furthermore, the carbon profiles present particularl…

CCFEPR(17)472017
Heavy impurities, such as tungsten (W), can exhibit strongly poloidally asymmetric density profiles in rotating or radio frequency heated plasmas. In the metallic environment of JET, the poloidal asymmetry of tungsten enhances its neoclassical transport up to an order of magnitude, so that neoclassical convection is expected to dominate over turbul…

CCFEPR(16)452016
It is shown that ITG turbulence close to the threshold exhibits a long time behaviour, with smaller heat fluxes at later times. This reduction is connected with the slow growth of long wave length zonal flows and, consequently, the numerical dissipation on these flows must be sufficient small. Close to the nonlinear threshold for turbulence generat…

CCFEPR(15)892015
The interplay between toroidal rotation u, parallel flow shear u? and perpendicular flow shear ?E in the stabilisation of tokamak turbulence is investigated in nonlinear fluxtube gyrokinetic simulations with the GKW code. The nonlinear simulations are performed for a reference Lmode DIIID plasma (the socalled shortfall case) at r/a = 0.8, var…
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