Journals

Showing 11 - 20 of 1592 Journals Results
2019
UKAEA-CCFE-PR(20)120

A Doppler coherence imaging spectroscopy diagnostic has been developed on the HL- 2A tokamak for scrape-off-layer impurity plasma flow measurements. Two- dimensional imaging of line-averaged C2+ flow in the high-field-side scrape off layer with time resolution up to 1 ms, has been achieved successfully by this system. The spatial angular resolut…

Preprint Published
2019
UKAEA-CCFE-PR(20)121

Effects of parallel and poloidal flows, as well as the flow shear, on the resistive wall mode (RWM) instability have been numerically investigated in toroidally rotating plasmas, utilizing a recently updated version of the MARS-F code (Liu Y Q et al 2000 Phys. Plasmas 7 3681). A significant difference between these flow…

Preprint Published
2019
UKAEA-CCFE-PR(20)122

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…

Preprint Published
2019
UKAEA-CCFE-PR(20)123

We propose a method for data-driven modelling of the temporal evolution of the plasma and neutral characteristics at the edge of a Tokamak using neural networks. Our method proposes a novel fully convolutional network that is capable of predicting the time evolution of the physics parameters along the two-dimensional representation of the poloid…

Preprint Published
2018
UKAEA-CCFE-PR(20)124

NBI-heated L-mode plasmas have been obtained in JET with the Be/W ITER-like wall (JET-ILW) in H and D, with matched profiles of the dimensionless plasma parameters in the plasma core confinement region and same Ti/Te and Zeff. The achieved isotope identity indicates that the confinement scale invariance principle is satisfied in the core confine…

Preprint Published
2019
UKAEA-CCFE-PR(20)127

The self-consistent core-pedestal prediction model of a combination of EPED1 type pedestal prediction and a simple stiff core transport model is able to predict type I ELMy pedestals of a large database JET-ILW (ITER-like wall) at the similar accuracy as is obtained when the experimental global plasma b is used as input. The neutral penetration …

Preprint Published
2020
UKAEA-CCFE-PR(20)131

This paper presents a dedicated study of plasma-antenna (PA) coupling with the Alfvén Eigenmode Active Diagnostic (AEAD) in JET. Stable AEs and their resonant frequencies f, damping rates < 0, and toroidal mode numbers n are measured for various PA separations and limiter versus X-point magnetic con gurations. Two stable AEs are observed to …

Preprint
2020
UKAEA-CCFE-PR(20)134

Divertor Monitoring Pulses (DiMPle) have been run in JET from the C35 campaign onwards. They provide an opportunity to study the impurity contamination of the plasma when it is limited by different surfaces within the machine, as well as the longer term behaviour of the impurities. In these discharges the plasma is first limited on the outer wal…

Preprint
2020
UKAEA-CCFE-PR(20)133

Future experimental scientific facilities, energy generation assets, and nuclear decommissioning facilities will require increasing levels of remote maintenance, which must be facilitated by robotic systems. Moreover, these long-lived (30+ years) maintenance systems will, themselves need to maintained and upgraded in order to deal with lifespan …

Preprint
2018
UKAEA-CCFE-PR(20)129

Typically applied to non-linear simulations of MHD instabilities relevant to magnetically confined fusion, the JOREK code was originally developed with a 2D grid composed of isoparametric bi-cubic Bezier finite elements, that are aligned to the magnetic equilibrium of tokamak plasmas. To improve the applicability of these simulations, the grid-gene…

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