P. Helander S. L. Newton A. Mollén
A potential threat to the performance of magnetically confined fusion plasmas is the problem of impurity accumulation, which causes the concentration of highly charged impurity ions to rise uncontrollably in the center of the plasma and spoil the energy confinement by excessive radiation. It has long been thought that the collisional transport of i…
Preprint PublishedS. L. Newton P. Helander A. Mollén H. M. Smith
The accumulation of impurities in the core of magnetically confined plasmas, resulting from standard collisional transport mechanisms, is a known threat to their performance as fusion energy sources. Whilst the axisymmetric tokamak systems have been shown to benefit from the effect of temperature screening, that is an outward flux of impurities dri…
Preprint PublishedM.Y. Lavrentiev D. Nguyen-Manh S.L. Dudarev
Using an ab initio approach, we explore the stability of small vacancy and vacancychromium clusters in dilute body-centred cubic Fe-Cr alloys. To explain experimental observations described in C.D. Hardie et al., J. Nucl. Mater. 439, 33 (2013) and showing the occurrence of Cr segregation in low-Cr alloys, we investigate if chromium can form stable …
Preprint PublishedL. Piron B. Zaniol D. Bonfiglio L. Carraro A. Kirk L. Marrelli R. Martin C. Piron P. Piovesan M. Zuin
This work presents the first evidence of helical flow in RFX-mod q(a) < 2 tokamak plasmas. The flow pattern is characterized by the presence of convective cells with m = 1 and n = 1 periodicity in the poloidal and toroidal direction, respectively. A similar helical flow deformation has been observed in the same device when operatedfas a Reversed…
Preprint PublishedH. T. Kim M. Romanelli X. Yuan S. Kaye A.C.C. Sips L. Frassinetti J. Buchanan JET Contributors
This paper presents for the first time a statistical validation of predictive TRANSP simulations of plasma temperature using two transport models, GLF23 and TGLF, over a database of 80 baseline H-mode discharges in JET-ILW. While the accuracy of the predicted Te with TRANSP-GLF23 is affected by plasma collisionality, the dependency of predictions o…
Preprint PublishedM. Gorley M. Fursdon M. Kalsey
Fusion demonstration (DEMO) concepts are facing challenges in safety and licensing in part due to uncertainties with in-vessel components validation, which relate directly to the materials and design criteria used for assessments. These challenges come from the designed operation under unprecedented environmental conditions and reliance on the perf…
Preprint PurchaseJ. Fikar R. Schäublin D.R. Mason D. Nguyen-Manh
The vacancies produced in high energy collision cascades can form in irradiated tungsten vacancy clusters or vacancy prismatic dislocation loops. Moreover, vacancy loop can easily transform to a planar vacancy cluster. We investigated the formation energies of these three types of vacancy defects as a function of number of vacancies using three EAM…
Preprint PublishedE.J. du Toit M.R. O'Brien R.G.L. Vann
Tokamak plasma current start-up assisted by Electron Bernstein waves (EBW) has been demonstrated successfully in a number of experiments. The dynamic start-up phase involves a change in field topology, as the initially open magnetic field lines form closed flux surfaces (CFS) under the initiation of a plasma current. This change in field topology w…
PreprintI. Balboa S. Silburn P. Drewelow V. Huber A. Huber D. Kinna M. Price G. F. Matthews S. Collins J. Fessey M. Rack P. Trimble K.D. Zastrow
Recent improvements in software tools and methodology have allowed us to perform a more comprehensive in-vessel calibration for all mid-infrared camera systems at JET. A comparison of experimental methods to calculate the non-uniformity correction is described as well as the linearity for the different camera systems. Measurements of the temperatur…
Preprint PublishedJ. Lovell G. Naylor A. Field P. Drewelow R. Sharples JET Contributors
A new resistive bolometer system has been developed for MAST-Upgrade. It will measure radiated power in the new Super-X divertor, with millisecond time resolution, along 16 vertical and 16 horizontal lines of sight. The system uses a Xilinx Zynq-7000 series Field-Programmable Gate Array (FPGA) in the D-TACQ ACQ2106 carrier to perform real time data…
Preprint Published