Y. Liu S.A. Sabbagh I.T. Chapman S. Gerasimov Y. Gribov T.C. Hender V. Igochine M. Maraschek G. Matsunag M. Okabayashi E.J. Strait
The high-frequency noise measured by magnetic sensors, at levels above the typical frequency of resistive wall modes, is analyzed across a range of present tokamak devices including DIII-D, JET, MAST, ASDEX Upgrade, JT-60U, and NSTX. A high-pass filter enables identification of the noise component with Gaussian-like statistics that shares certain c…
Preprint PurchaseI.T. Chapman E. de la Luna P.T. Lang Y. Liang B. Alper P. Denner D. Frigione L. Garzotti C.J. Ham G.T.A. Huijsmans S. Jachmich G. Kocsis M. Lennholm I. Lupelli F.G. Rimini A.C.C. Sips JET Contributors
ELM control may be essential to develop ITER scenarios with a reasonable lifetime of divertor components, whilst ELM pacing may be essential to develop stationary ITER scenarios with a tungsten divertor. Resonant magnetic perturbations (RMPs) have mitigated ELMs in high collisionality plasmas in JET. The efficacy of RMPs in mitigating the ELMs is f…
Preprint PublishedS. Pamela T. Eich L. Frassinetti B. Sieglin S. Saarelma G. Huijsmans M. Hoelzl M. Becoulet F. Orain S. Devaux I. Chapman I. Lupelli E. Solano JET Contributors
A subset of JET ITER-like wall (ILW) discharges, combining electron density and temperature as well as divertor heat flux measurements, has been collected for the validation of non-linear MHD simulations of Edge-Localised-Modes (ELMs). This permits a quantitative comparison of simulation results against experiments, which is required for the valida…
Preprint PublishedC.J. Ham R.G.J. Cramp S. Gibson S.A. Lazerson I.T. Chapman A. Kirk
The magnetic perturbations produced by the resonant magnetic perturbation (RMP) coils will be rotated in ITER so that the spiral patterns due to strike point splitting which are locked to the RMP also rotate. This is to ensure even power deposition on the divertor plates. VMEC equilibria are calculated for different phases of the RMP rotation. It i…
Preprint PublishedL. Carbajal R. O. Dendy S. C. Chapman J.W. S. Cook
Ion cyclotron emission (ICE) offers a unique promise as a diagnostic of the fusion born alpha-particle population in magnetically confined plasmas. Pioneering observations from JET and TFTR found that ICE intensity PICE scales approximately linearly with the measured neutron flux from fusion reactions, and with the inferred concentration, na=ni, of…
Preprint PublishedS.C. Chapman R.O. Dendy P.T. Lang N.W. Watkins F.A. Calderon
We focus on JET plasmas in which ELMs are triggered by pellets in the presence of ELMs which occur naturally. We perform direct time domain analysis of signals from fast radial field coils and toroidal full flux azimuthal loops. These toroidally integrating signals provide simultaneous high time resolution measurements of global plasma dynamics and…
Preprint PublishedJ. W. S. Cook R.O. Dendy S.C. Chapman
A fast Alfven wave with a finite amplitude is shown to grow by a stimulated emission process that we propose for exploitation in toroidal magnetically confined fusion plasmas. Stimulated emission occurs while the wave propagates inward through the outer midplane plasma, where a population inversion of the energy distribution of fusion-born ions is …
Preprint PublishedC. J. Ham I. T. Chapman J. Simpson Y. Suzuki
Tokamaks are traditionally viewed as axisymmetric devices. However this is not always true, for example in the presence of saturated instabilities, error fields, or resonant magnetic perturbations (RMPs) applied for edge localized mode (ELM) control. We use the VMEC code (Hirshman and Whitson 1983 Phys. Fluids 26 3553) to …
Preprint PublishedW. N. Lai S. C. Chapman R. O. Dendy
The kinetic evolution in velocity space of a minority suprathermal electron population that is undergoing the anomalous Doppler instability (ADI) is investigated using the results from fully nonlinear numerical simulations that self-consistently evolve particles and fields in a plasma. Electron trajectories in phase space during different stages of…
Preprint PublishedH. Zhu R.O. Dendy S.C. Chapman S. Inagaki
It is known that rapid edge cooling of magnetically confined plasmas can trigger heat pulses that propagate rapidly inward. These can result in large excursion, either positive or negative, in the electron temperature at the core. A set of particularly detailed measurements was obtained in Large Helical Device(LHD) plasmas [S. Inagaki et al, Plasma…
Preprint Published