Sawtooth control in JET with ITER relevant low field side resonance ICRH and ITER like wall
2014 (English)In: 41st EPS Conference on Plasma Physics, EPS 2014, European Physical Society (EPS) , 2014Conference paper (Refereed)
New experiments at JET with the ITER like wall show for the first time that ITER-relevant low field side resonance first harmonic ICRH with can be used to control sawteeth that have been initially lengthened by fast particles. In contrast to previous [J. P. Graves et al, Nature Communs 3, 624 (2012)] high field side resonance sawtooth control experiments undertaken at JET, it is found that the sawteeth of L-mode plasmas can be controlled with less accurate alignment between the resonance layer and the sawtooth inversion radius. This advantage, as well as the discovery that sawteeth can be shortened with various antenna phasings, including dipole, indicates that ICRH is a particularly effective and versatile tool that can be used in future fusion machines for controlling sawteeth. Without sawtooth control, NTMs and locked modes were triggered at very low normalised beta. High power H-mode experiments show the extent to which ICRH can be tuned to control sawteeth and NTMs while simultaneously providing effective electron heating with improved flushing of high Z core impurities. Dedicated ICRH simulations using SELFO, SCENIC and EVE, including wide drift orbit effects, explain why sawtooth control is effective with various antenna phasings, and show that the sawtooth control mechanism cannot be explained by enhancement of the magnetic shear. Hybrid kinetic-MHD stability calculations using MISHKA and HAGIS unravel the optimal sawtooth control regimes in these ITER relevant plasma conditions.
Place, publisher, year, edition, pages
European Physical Society (EPS) , 2014.
Antennas, Discovery wells, Magnetohydrodynamics, Plasma stability, Resonance, Shear flow, Drift orbit effects, Effective electrons, Fusion machines, High field sides, Low-field sides, Plasma conditions, Resonance layers, Sawtooth control, Plasma simulation
Fusion, Plasma and Space Physics
IdentifiersURN: urn:nbn:se:kth:diva-201854ScopusID: 2-s2.0-85006086292OAI: oai:DiVA.org:kth-201854DiVA: diva2:1079657
41st EPS Conference on Plasma Physics, EPS 2014, 23 June 2014 through 27 June 2014
QC 201703092017-03-092017-03-092017-03-09Bibliographically approved