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 PublishedB Chapman R O Dendy S C Chapman K G McClements G S Yun S G Thatipamula M H Kim
Intense bursts of suprathermal radiation, with spectral peaks at frequencies corresponding to the deuteron cyclotron frequency in the outer midplane edge region, are often detected from deuterium plasmas in the KSTAR tokamak that are heated by tangential neutral beam injection (NBI) of deuterons at 100 keV. Identifying the physical process by wh…
Preprint PublishedJ.Galdon-Quiroga M.Garcia-Munoz S.Sharapov L.Sanchis-Sanchez L.Chen M.Dunne J.Gonzalez-Martin M.Hoelz A.S.Jacobsen K.G.McClements M.Nocente F.Orain J.F.Rivero-Rodriguez D.A.Ryan M.Salewski P.Schneider A.Snicker W.Suttrop Y.Todo M.A.Van Zeeland E.Viezzer M.Willensdorfer D.Zarzoso F.Zonca The ASDEX Upgrade Team MST1 Team
An edge resonant transport layer has been found to explain many aspects of fast-ion confinement under symmetry breaking 3D edge perturbations, such as edge localized modes (ELMs) and externally applied magnetic perturbations (MPs). Experimental measurements in the ASDEX Upgrade (AUG) tokamak show that fast-ion losses in the presence of symmetry bre…
Preprint PublishedK.G. McClements
Detailed in situ studies of magnetic reconnection and particle acceleration, which play a crucial role in the release and redistribution of energy in solar flares, can be performed in tokamak plasmas under conditions resembling those of the flaring solar corona. Recent measurements and modelling of fast particle production during reconnection event…
Preprint PublishedK. G. McClements A. Brisset B. Chapman S. C. Chapman R. O. Dendy P. Jacquet V. G. Kiptily M. Mantsinen B. C. G. Reman JET Contributors
Measurements are reported of electromagnetic emission close to the cyclotron frequency of energetic ions in JET plasmas heated by waves in the ion cylotron range of frequencies (ICRF). Hydrogen was the majority ion species in all of these plasmas. The measurements were obtained using a sub-harmonic arc detection (SHAD) system in the transmission li…
Preprint PublishedB. Chapman R. O. Dendy S. C. Chapman K. G. McClements G. S. Yun S. G. Thatipamula M. H. Kim
Chirping observed in ion cyclotron emission (ICE) from the KSTAR tokamak at sequential proton harmonics in the range 200 to 500 MHz has recently been interpreted (B. Chapman et al., Nucl. Fusion 57, 124004 (2017)) as due to fast, sub-microsecond, evolution of the local deuterium plasma density. This density evolution changes the plasma environment …
Preprint PublishedB. Madsen M. Salewski J. Huang A. S. Jacobsen O. Jones K. G. McClements the MAST team
Velocity-space tomography provides a way of diagnosing fast ions in a fusion plasma by combining measurements from multiple instruments. We use a toroidally viewing and a vertically viewing fast-ion D-alpha (FIDA) diagnostic installed on the spherical tokamak MAST (before the upgrade) to perform velocity-space tomography of the fast-ion distributio…
Preprint PublishedK. G. McClements K. Tani R. J. Akers Y. Q. Liu K. Shinohara H. Tsutsui S. Tsuji-Iio
The application of non-axisymmetric resonant magnetic perturbations (RMPs) to low current plasmas in the Mega Amp Spherical Tokamak (MAST) was found to be correlated with substantial drops in neutron production, suggesting a significant degradation of fast ion confinement. The effects of such perturbations on fast ions in MAST have been modelled us…
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 PublishedK.G. McClements J. Allen S.C. Chapman R.O. Dendy S.W.A. Irvine O. Marshall D. Robb M. Turnyanskiy R.G.L. Vann
The merging-compression method of plasma start-up in the Mega Amp Spherical Tokamak (MAST) involved the creation of two plasma tori with parallel currents, which merged at the vacuum vessel midplane due to their mutual attraction. Magnetic reconnection occurred in this process causing strong heating of both ions and electrons on millisecond timesca…
Preprint Published