R. Ochoukov V. Bobkov H. Faugel M. García-Muñoz B. Geiger D. Moseev K. G. McClements S. Nielsen P. Schneider M. Weiland J.-M. Noterdaeme ASDEX Upgrade Team MST1 Team
Ion cyclotron emission (ICE) is a commonly observed feature of magnetized toroidal plasmas in the presence of fast ions. It is generally agreed that this emission is caused by a strongly inverted (in the velocity space) population of confined fast ions originating from either neutral beam injection (NBI), fusion reactions, or acceleration by waves …
Preprint PublishedYasmin 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 PublishedAllah 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 PublishedB 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 PublishedL. 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 PublishedA. Dvornova G.T.A. Huijsmans S. Sharapov F.J. Artola P. Puglia M. Hoelzl S. Pamela A. Fasoli D. Testa
Toroidal Alfven Eigenmode (TAE) excitation can be caused by fusion-born or Ion Cyclotron Resonance and neutral beam heating fast particles through wave-particle resonance. TAEs may affect fast particle confinement, reduce heating and current drive efficiency, cause damage to the first wall, and decrease overall plasma performance. Excitation of TA…
Preprint PublishedJ. P. Martin-Collar B. F. McMillan S. Saarelma A. Bottino
We perform a study of system-scale to gyro-radius scale electromagnetic modes in a pedestal-like equilibrium using a gyrokinetic code ORB5, and compare to the results of a local gyrokinetic code, GS2, and an MHD energy principle code, MISHKA. In the relevant large-system, short wavelength regime, good agreement between the gyrokinetic codes is foun…
Preprint PublishedS. Buller A. Mollén S.L. Newton H.M. Smith I. Pusztai
In toroidal magnetic confinement devices, such as tokamaks and stellarators, neoclassical transport is usually an order of magnitude larger than its classical counterpart. However, when a high-collisionality species is present in an stellarator optimized for low Pfirsch-Schlüter current, its classical transport can be comparable to the neoclassica…
Preprint PublishedA. Fil D. Moulton B. Dudson B. Lipschultz K. Verhaegh O. Février O. Myatra C. Theiler M. Wensing EUROfusion MST1 teams the TCV team
In ITER and DEMO, achieving detachment at lower densities would allow to reduce the amount of impurity seeded and to improve confinement by running at lower separatrix densities. Analytic models predict that a increase of total flux expansion would allow such a reduction in upstream density at detachment. However, both experiments and modelling …
Preprint Published