L. Horvath C.F. Maggi F.J. Casson V. Parail L. Frassinetti F. Koechl S. Saarelma M.G. Dunne K.J. Gibson JET Contributors
Recent studies have shown that on JET with the Be/W ITER-like wall (JET-ILW) in high beta discharges with high D2 gas rates the inter-ELM temperature pedestal growth is saturated half way through the ELM cycle, leading to plasmas with reduced confinement, and that the linear MHD stability of these pedestals is inconsistent with the Peeling-Ballooni…
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 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 PublishedK. Imada H. R. Wilson J. W. Connor A. Dudkovskaia P. Hill
A new drift-kinetic theory of the ion response to magnetic islands in tokamak plasmas is presented. Small islands are considered, with widths w much smaller than the plasma radius r, but comparable to the trapped ion orbit width ρ_bi. An expansion in w/r reduces the system dimensions from five down to four. In the absence of an electrostatic poten…
Preprint PublishedB. J. Ding P. T. Bonoli A. Tuccillo M. Goniche K. Kirov M. Li Y. Li R. Cesario Y. Peysson A. Ekedahl L. Amicucci S. Baek I. Faust R. Parker S. Shiraiwa G. M. Wallace A. Cardinali C. Castaldo S. Ceccuzzi J. Mailloux F. Napoli F. Liu B. Wan JET Contributors
Progress in understanding lower hybrid current drive (LHCD) at high density has been made through experiments and modeling, which is encouraging given the need for an efficient off-axis current profile control technique in burning plasma. By reducing the wall recycling of neutrals, the edge temperature is increased and the effect of parametric inst…
Preprint PublishedM. Maslov D. King E. Viezzer D. Keeling C. Giroud T. Tala A. Salmi M. Marin J. Citrin C. Bourdelle E. Solano JET contributors
Particle transport is of a great importance for understanding physics of tokamak plasmas and planning future experiments on larger machines such as ITER. The subject was intensively studied in the past, particularly in relation to density peaking and presence of anomalous inward particle convection in L- and H-mode. While in the L-mode case presenc…
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 PublishedH. Wilson
Some of the main plasma physics challenges associated with achieving the conditions for commercial fusion power in tokamaks are reviewed. The confinement quality is considered to be a key factor, having an impact on the size of the reactor and exhaust power that has to be managed. Plasma eruptions can cause excessive erosion if not mitigated, with …
Preprint PublishedC. Bourdelle Y. Camenen J. Citrin M. Marin F.J. Casson F. Koechl M. Maslov
In Ion-Temperature-Gradient (ITG) driven turbulence, the resonance condition leads to ion particle turbulent transport coefficients significantly larger than electron particle turbulent transport coefficients. This is shown in non-linear gyrokinetic simulations and explained by an analytical quasilinear model. It is then illustrated by JETTO-QuaLi…
Preprint PublishedL. Piron A. Kirk Y. Q. Liu G. Cunningham M. Carr G. Fishpool R. Gowland I. Katramados D. Luckin R. Martin
In magnetic fusion devices, unwanted non-axisymmetric magnetic eld perturbations, known as error fields (EF), can have detrimental effects on plasma stability and confinement. To minimize their impact on plasma performances and on the available operational space, it is important to identify the EF sources and develop EF control strategies. MAST Up…
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