P. Helander S. L. Newton A. Mollén
A potential threat to the performance of magnetically confined fusion plasmas is the problem of impurity accumulation, which causes the concentration of highly charged impurity ions to rise uncontrollably in the center of the plasma and spoil the energy confinement by excessive radiation. It has long been thought that the collisional transport of i…
Preprint PublishedR. S. Hemsworth D. Boilson P. Blatchford M. Dalla Palma G. Chitarin H. P. L. de Esch F. Geli M. Dremel J. Graceffa D. Marcuzzi G. Serianni D. Shah M. Singh M. Urbani P. Zaccaria
The heating neutral beam injectors (HNBs) of ITER are designed to deliver 16.7MWof 1 MeVD0 or 0.87 MeVH0 to the ITER plasma for up to 3600 s. They will be the most powerful neutral beam (NB) injectors ever, delivering higher energy NBs to the plasma in a tokamak for longer than any previous systems have done. The design of the HNBs is based on the …
PublishedA. R. Field I. Balboa P. Drewelow J. Flanagan C. Guillemaut J. R. Harrison A. Huber V. Huber B. Lipschultz G. Matthews A. Meigs J. Schmitz M. Stamp N. Walkden JET contributors
The dynamics and stability of divertor detachment in N2 seeded, type-I, ELMy H-mode plasmas with dominant NBI heating in the JET-ILW device is studied by means of an integrated analysis of diagnostic data from several systems, classifying data relative to the ELM times. It is thereby possible to study the response of the detachment evolution to the…
Preprint PublishedD. Moulton J. Harrison B. Lipschultz D. Coster
We show that a central characteristic of Super-X divertors, parallel area expansion fR (de ned as the ratio of the elementary area normal to the magnetic field at the target to that at the X-point, also known as total flux expansion), significantly changes the characteristics of the target plasma for fixed upstream conditions. To isolate the effect…
Preprint PublishedW. Guttenfelder A.R. Field I. Lupelli T. Tala S.M. Kaye Y. Ren W.M. Solomon
Non-axisymmetric magnetic fields are used to perturbatively probe momentum transport physics in MAST L-mode plasmas. The low beta L-mode target was chosen to complement previous experiments conducted in high beta NSTX H-mode plasmas (ßN=3.5-4.6) where an inward momentum pinch was measured. In those cases quasi-linear gyrokinetic simulations of uns…
Preprint PublishedK.G. McClements E.D. Fredrickson
Spherical tokamaks (STs) typically have lower magnetic fields than conventional tokamaks, but similar mass densities. Suprathermal ions with relatively modest energies, in particular beam-injected ions, consequently have speeds close to or exceeding the Alfven velocity, and can therefore excite a range of Alfvenic instabilities. STs heated with neu…
Preprint PublishedJ. Omotani I. Pusztai S. Newton T. Fülöp
Neutral atoms can strongly influence the intrinsic rotation and radial electric field at the tokamak edge. Here, we present a framework to investigate these effects when the neutrals dominate the momentum transport. We explore the parameter space numerically, using highly flexible model geometries and a state of the art kinetic solver. We find that…
Preprint PublishedK. Tani K. Shinohara T. Oikawa H. Tsutsui K.G. McClements R.J. Akers Y.Q. Liu M. Suzuki S. Ide Y. Kusama S. Tsuji-Iio
A non-steady-state orbit-following Monte-Carlo code has been developed. As part of the verification and validation of the code, calculations of time dependent neutron rates have been made for a specific shot in the Mega Amp Spherical Tokamak (MAST) using three-dimensional fields representing vacuum resonant magnetic perturbations (RMPs) and toroida…
Preprint PublishedJ.E. Menard T. Brown L. El-Guebaly M. Boyer J. Canik B. Colling R. Raman Y. Zhai P. Buxton B. Covele C. D'Angelo A. Davis S. Gerhardt M. Gryaznevich M. Harb T.C. Hender S. Kaye D. Kingham M. Kotschenreuther S. Mahajan R. Maingi E. Marriott E.T. Meier L. Mynsberge C. Neumeyer M. Ono S.A. Sabbagh V. Soukhanovskii P. Valanju R. Woolley
A Fusion Nuclear Science Facility (FNSF) could play an important role in the development of fusion energy by providing the nuclear environment needed to develop fusion materials and components. The spherical torus/tokamak (ST) is a leading candidate for an FNSF due to its potentially high neutron wall loading and modular configuration. A key consid…
Preprint PublishedJ.R. Harrison W.A.J. Vijvers C. Theiler B.P. Duval S. Elmore B. Labit B. Lipschultz S.H.M. van Limpt S.W. Lisgo C.K. Tsui H. Reimerdes U. Sheikh K.H.A. Verhaegh M. Wischmeier The MST TCV Teams
Divertor detachment in the TCV tokamak has been investigated through experiments and modelling. Density ramp experiments were carried out in ohmic heated L-mode pulses with the ion B drift directed away from the primary X-point, similar to previous studies [pitts2001]. Before the roll-over in the ion current to the outer strike point, C III and D? …
Preprint Published