D. Brunetti J. P. Graves C. J. Ham S. Saarelma
We propose a resistivity-beta driving mechanism aimed at explaining the appearance of free boundary long wavelength global instabilities in high-beta diverted tokamaks. These perturbations resemble very closely the RWM (resistive wall mode) phenomenon. Performing a proper toroidal analysis, we show that the magnetohydrodynamic stability is worsened…
PreprintJ W Berkery S A Sabbagh C Ham V Zamkovska J Butt J Riquezes M Tobin S Henderson L Kogan B Patel R Scannell E Trier B LeBlanc
Fusion power output from spherical tokamaks would benefit from increased confined plasma density, but there exists a limit on the density before confinement is lost and the plasma current is disrupted. This density limit has long been characterized by a simple, global Greenwald limit proportional to the plasma current and inversely proportional …
Preprint PurchaseJ. O. Allen S. Desai S. Freethy K. Hawkins M. A. Henderson E. Kaijanen C. Lechte J. Lovell E. Melidis A. Munasinghe J. Pearl B. Plaum A. Seidu H. Webster the MAST-U EBW Team
MAST-Upgrade (MAST-U) is undergoing several enhancements to deliver increased performance and functionality. One such enhancement is the design, development, and implementation of an Electron Bernstein Wave (EBW) Heating and Current Drive (HCD) System. The MAST-U EBW System aims to provide experimental data for model validation, and to provide a…
PreprintM. Fontana G. Giruzzi F. P. Orsitto E. de la Luna R. Dumont L. Figini D. Kos M. Maslov S. Schmuck L. Senni C. Sozzi C. Challis D. Frigione J. Garcia L. Garzotti J. Hobirk A. Kappatou D. Keeling E. Lerche C. Maggi J. Mailloux F. Rimini D. Van Eester
The present paper is dedicated to the study of the discrepancies encountered in electron temperatures (Te) measurements carried out with Electron Cyclotron Emission (ECE) and Thomson Scattering (TS) diagnostics in the core of the JET tokamak. A large database of discharges has been collected, including high-performance scenarios perform…
PreprintC J Ham P E Farrell
The Grad–Shafranov equation for axisymmetric MHD equilibria is a nonlinear, scalar PDE which in principle can have zero, one or more non-trivial solutions. The conditions for the existence of multiple solutions has been little explored in the literature so far. We develop a simple analytic model to calculate multiple solutions in the large asp…
PreprintA V Dudkovskaia J W Connor D Dickinson P Hill K Imada S Leigh H R Wilson
A nonlinear 4-dimensional drift island theory derived in (Imada et al 2019 Nucl. Fusion 59 046016 and references therein) provides qualitative predictions of the plasma response to a stationary neoclassical tearing mode (NTM) magnetic island in a low beta, large aspect ratio tokamak plasma. (Dudkovskaia et al 2021 Plasma Phys. Control. Fusion 63 05…
PublishedN.Osborne K.Verhaegh M.D.Bowden T.Wijkamp N.Lonigro P.Ryan E.Pawelec B.Lipschultz V.Soukhanovskii T.Biggelaar
High resolution D2 Fulcher band spectroscopy was used in the MAST-U divertors during Super-X and elongated conventional divertor density ramps with D2 fuelling from the mid-plane high-field side. In the Super-X case (density ramp from Greenwald fraction 0.12 to 0.24), the upper divertor showed ground state rotational tempe…
PreprintL. Horvath M. Maslov P.A. Schneider C.F. Maggi L.Frassinetti B. Lomanowski R.B. Morales D. Nina S. Saarelma J. Simpson G. Corrigan D.I. Refy M.Brix T. Pereira M. Vecsei JET Contributors
The relative role of particle transport and edge fuelling in setting the H-mode density pedestal is still a key open question [1]. Although reduced pedestal models have proven successful in predicting the pedestal pressure for a wide range of plasma scenarios [2,3,4], they lack a first principle based, predictive model for the edge density. Pred…
PreprintT. Gheorghiu F. Militello J. Juul Rasmussen
Shear flows in turbulent fluids have been known to act as transport barriers for some time. An example of a shear flow generating mechanism is the E×B shear in plasma, which has a substantial impact on the dynamics of magnetic confinement fusion devices. The influence of this may be seen in the scrape-off layer (SOL) where blobs or filaments may b…
Preprint Published