Showing 491 - 500 of 1892 UKAEA Paper Results
2019
UKAEA-CCFE-PR(19)69
Ruben Otin Robert Salmon
The equipment used in some welding techniques (e.g. tungsten inert gas alternating current welding or capacitor discharge stud welding) can induce high electromagnetic fields inside the operator due to the large time-varying electric currents involved in the process. The European Union (EU) Directive 2013/35/EU provides guidelines and recommendatio…
Preprint2019
UKAEA-CCFE-PR(19)68
Mikhail Yu. Lavrentiev Chu-Chun Fu Frédéric Soisson
We report a theoretical study of microstructure, magnetic properties, and their relationship in relatively concentrated Fe-Cr alloys in both Fe- and Cr-rich regions. Annealing of initially random systems at 500° C for times of the order of 106 s substantially changes their microstructure. In both systems, solute atoms form clusters with…
Preprint Published2019
UKAEA-CCFE-PR(19)67
Yasmin Andrew Jan-Peter Baehner Ronan Battle Tomas Jirman and the MAST team
Analysis of the L-H and H-L transition power thresholds (Pth) and pedestal parameters are presented for the Mega Ampere Spherical Tokamak (MAST). The dependencies of Pth on the average, core plasma electron density, X-point height and plasma current are described. Increasing X-point distance from the divertor floor over 10-12 cm, is found to inc…
Preprint Published2019
UKAEA-CCFE-PR(19)66
N. Boulle V. Dallas Y. Nakatsukasa D. Samaddar
We use deep neural networks to classify time series generated by discrete and continuous dynamical systems based on their chaotic behavior. Our approach to circumvent the lack of precise models for some of the most challenging real-life applications is to train different neural networks on a data set from a dynamical system with a basic or low-dime…
Preprint Published2019
UKAEA-CCFE-PR(19)65
Allah Rakha M.J. Mantsinen A.V. Melnikov S.E. Sharapov D.A. Spong A. Lopez-Fraguas F. Castejon
Alfven frequency sweeping modes in stellarator plasmas with normal and reversed shear rotational transform are modelled using a reduced MHD model. We focus on a TJ-II dynamic discharge in which a sequence of frequency sweeping modes with a frequency sweeping range from 20 kHz to 140 kHz (Melnikov A.V. et al 2014 Nucl. Fusion 54 123002) have been ob…
Preprint Published2019
UKAEA-CCFE-PR(19)64
B Chapman R O Dendy S C Chapman L Holland S W A Irvine and B C G Reman
Observations have recently been made of ion cyclotron emission (ICE) that originates from the core plasma in the DIII-D [1, 2] and ASDEX-Upgrade [3, 4] tokamaks. The ICE spectral peaks correspond to the local cyclotron harmonic frequencies of fusion-born ions close to the magnetic axis, in contrast to the hitherto usual spatial localisation of …
Preprint Published2019
UKAEA-CCFE-PR(19)63
Artem Lunev Robert Heymer
The laser flash method is highly regarded due to its applicability to a wide temperature range, from cryogenic temperatures to the melting point of refractory metals, and to extreme environments involving radioactive or hazardous materials. Although instruments implementing this method are mostly produced on a commercial basis by major manufactu…
Preprint Published2019
UKAEA-CCFE-PR(19)62
L. Horvath C.F. Maggi A. Chankin S. Saarelma A.R. Field E. Belonohy A. Boboc G. Corrigan E.G. Delabie J. Flanagan L. Frassinetti C. Giroud D. Harting D. Keeling D. King M. Maslov G.F. Matthews S. Menmuir S.A. Silburn J. Simpson A.C.C Sips H. Weisen K.J. Gibson JET Contributors
The pedestal structure, ELM losses and linear MHD stability are analysed in a series of JET-ILW H and D type I ELMy H-mode plasmas. The pedestal pressure (pPED) is typically higher in D than in H at the same input power, with the difference mainly due to lower density in H than in D. At the same input power, the pedestal electron pres…
Preprint Published2019
UKAEA-CCFE-PR(19)61
D. Patel M.D. Richardson B. Jim S. Akhmadaliev R. Goodall A.S. Gandy
A novel multicomponent alloy, V2.5Cr1.2WMoCo0.04, produced from elements expected to favour a BCC crystal structure, and to be suitable for high temperature environments, was fabricated by arc melting and found to exhibit a multiphase dendritic microstructure with W-rich dendrites and V-Cr segregated to the inter-de…
Preprint Published2019
UKAEA-CCFE-PR(19)60