Showing 1 - 10 of 54 Journals Results
2021
UKAEA-CCFE-PR(21)30
N. Fil S.E. Sharapov M. Fitzgerald G.J. Choi Z. Lin R.A. Tinguely H.J.C. Oliver K.G. McClements P.G. Puglia R.J. Dumont M. Porkolab JET Contributors
Recent JET Deuterium experiments with an advanced internal transport barrier (ITB) scenario have been performed to clearly observe destabilised toroidicity-induced Alfvén eigenmodes (TAEs) by fast ions; interestingly, these also exhibit unstable electromagnetic (EM) perturbations in the sub-TAE frequency range. We identify such EM perturbations to…
Preprint2021
UKAEA-CCFE-PR(21)23
K G McClements J Young L Garzotti O M Jones C A Michael
The work reported in this paper has already been presented internally by placement student Jacob Young at a MAST Physics and Technology meeting on December 17 2020. Therefore it does not require a paper review presentation. Please also note that the paper is proposed for inclusion in a special issue of Plasma Research Express linked to the recent I…
Preprint2020
UKAEA-CCFE-PR(20)88
A. R. Jackson A. S. Jacobsen K. G. McClements C. A. Michael M. Cecconello
The efficient confinement of fast ions is crucial to the development of a fusion power plant. Sawtooth crashes are a manifestation of an internal kink instability, which can severely degrade this confinement. The effect of these on a fast ion population can be investigated using fast-ion deuterium-alpha (FIDA) spectroscopy, where charge exchange…
Preprint Published2019
UKAEA-CCFE-PR(19)08
B 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 Published2018
UKAEA-CCFE-PR(18)43
K.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 Published2018
UKAEA-CCFE-PR(18)14
K. 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 Published2018
UKAEA-CCFE-PR(18)11
B. 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 Published2018
UKAEA-CCFE-PR(18)6
B. 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 Published2018
UKAEA-CCFE-PR(18)4
K. 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 Published2017
CCFE-PR(17)76