M. R. Gilbert J.-Ch. Sublet
The processing code SPECTRA-PKA produces energy spectra of primary atomic recoil events (or primary knock-on atoms, PKAs) for any material composition exposed to an irradiation spectrum. Such evaluations are vital inputs for simulations aimed at understanding the evolution of damage in irradiated material, which is generated in cascade displacement…
Preprint PublishedT. D. Swinburne S. Dudarev
The line tension model of obstacle hardening is modified to account for the thermally activated, kink-limited glide of 1=2h111i screw dislocations, allowing application to the plastic flow of bcc metals. Using atomistically-informed dislocation mobility laws, Frenkel-Kontorova simulations and a simplified dislocation obstacle model, we identify a …
Preprint PublishedS. L. Dudarev Pui-Wai Ma
Density functional theory (DFT) calculations show that self-interstitial atom defects in nonmagnetic body-centred cubic (bcc) metals adopt strongly anisotropic configurations, elongated in the h111i direction1–4. Elastic distortions, associated with such anisotropic defect configurations, appear similar to the distortions around small prismatic d…
Preprint PurchaseN. R. Walkden J. Harrison S. A. Silburn T. Farley S.S. Henderson A. Kirk F. Militello A.Thornton the MAST Team
Using high speed imaging of the divertor volume, the region close to the X-point in MAST is shown to be quiescent. This is confirmed by three different analysis techniques and the quiescent X-point region (QXR) spans from the separatrix to the N = 1.02 flux surface. Local reductions to the atomic density and effects associated with the camera vie…
Preprint PublishedA. De Backer D.R. Mason C. Domain D. Nguyen-Manh M.-C. Marinica L. Ventelon C.S. Becquart S.L. Dudarev
In a fusion tokamak, the plasma of hydrogen isotopes is in contact with tungsten at the surface of a divertor. In the bulk of the material, the hydrogen concentration profile tends towards dynamic equilibrium between the flux of incident ions and their trapping and release from defects, either native or produced by ion and neutron irradiation. The …
Preprint PublishedV. G. Kiptily M. Fitzgerald V. Goloborodko S. E. Sharapov C. D. Challis D. Frigione J. Graves M. J. Mantsinen P. Beaumont M. Garcia-Munoz C. Perez von Thun J. F. R. Rodriguez D. Darrow D. Keeling D. King K. G. McClements E. Solano S. Schmuck G. Sips G. Szepesi JET contributors
During development of a high-performance hybrid scenario for future deuterium–tritium experiments on the Joint European Torus, an increased level of fast ion losses in the MeV energy range was observed during the instability of high-frequency n = 1 fishbones. The fishbones are excited during deuterium neutral beam injection combined with…
Preprint PublishedS. C. Chapman P. T. Lang R. O. Dendy L. Giannone N. W. Watkins ASDEX 4 Upgrade Team
The ITER tokamak needs to sustain a plasma in a regime of high energy confinement (H-mode) to exceed fusion breakeven where power output exceeds input. H-mode plasmas are typically unstable to edge localised modes (ELMs), in which plasma escapes and strikes the plasma facing components. Scaled up to ITER, the energy released by ELMs can cause criti…
PreprintM.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 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 PublishedP. 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 Published