O. P. Bardsley J. L. Baker
Power exhaust is a critical challenge for spherical tokamak reactors, making the design, optimisation and control of advanced divertor configurations crucial. These tasks are greatly simplified if the poloidal magnetic fields in the core and divertor regions can be varied independently. We present a novel method which fixes the core plasma equil…
Preprint PublishedP.-Y. Li D. R. Hatch B. Chapman-Oplopoiou S. Saarelma C. M. Roach M. Kotschenreuther S. M. Mahajan the MAST Team
The results of a recent gyrokinetic analysis of turbulent transport driven by the electron temperature gradient (ETG) in the MAST pedestal are presented. During the inter-ELM period, the buildup rate of the electron density gradients is faster than that of the electron temperature gradients, possibly indicating the presence of an active electron th…
PreprintV.G. Kiptily P.J. Bonofiglo T. Craciunescu J. Eriksson M. Fitzgerald V. Goloborodko M. Nocente S. Menmuir M. Podestà M. Poradzinski D. Rigamonti Z. Stancar S.E. Sharapov H. Sun D.M. Taylor M. Tardocchi P. Beaumont F. Belli F.E. Cecil C.D. Challis R. Coelho M. Curuia R. Dumont J. Garcia M. Garcia-Munoz Z. Ghani Ye. Kazakov D. Keeling E. Lerche C.F. Maggi J. Mailloux P. Mantica M.J. Mantsinen D. Marocco C. Perez von Thun F. Rimini
The fusion reaction between deuterium and tritium, D(T,n)4He is the main source of energy in future thermonuclear reactors. Charged fusion products of this reaction, α-particles (4He-ions), are born with an average energy of 3.5 MeV. Transferring energy to the thermal plasma during their slowing down, the…
PreprintPeng Shi Yuhan Wang Li Gao Hongjuan Sun Qinghu Yang Xin Xu Chengshuo Shen Yanqiu Chen Qinlin Tao Zhipeng Cheng Haosheng Wu Lu Wang Zhongyong Chen Nengchao Wang Zhoujun Yang Jingchun Li Yonghua Ding Yuan Pan J-TEXT team
This article presents an in-depth study of the sequence of events leading to density limit disruption in J-TEXT tokamak plasmas, with an emphasis on boudary turbulent transport and the high-field-side high-density (HFSHD) front. These phenomena were extensively investigated by using Langmuir probe and Polarimeter-interferometer diagnostics. The res…
PreprintD. 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…
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