Electromagnetic stabilization of tokamak microturbulence in a high-β regime
2014 (English)In: 41st EPS Conference on Plasma Physics, EPS 2014, European Physical Society (EPS) , 2014Conference paper (Refereed)
The impact of electromagnetic stabilization and flow shear stabilization on ITG turbulence is investigated. Analysis of a low-β JET L-mode discharge illustrates the relation between ITG stabilization, and proximity to the electromagnetic instability threshold. This threshold is reduced by suprathermal pressure gradients, highlighting the effectiveness of fast ions in ITG stabilization. Extensive linear and nonlinear gyrokinetic simulations are then carried out for the high-β JET hybrid discharge 75225, at two separate locations at inner and outer radii. It is found that at the inner radius, nonlinear electromagnetic stabilization is dominant, and is critical for achieving simulated heat fluxes in agreement with the experiment. The enhancement of this effect by suprathermal pressure also remains significant. It is also found that flow shear stabilization is not effective at the inner radii. However, at outer radii the situation is reversed. Electromagnetic stabilization is negligible while the flow shear stabilization is significant. These results constitute the high-β generalization of comparable observations found at low-β at JET. This is encouraging for the extrapolation of electromagnetic ITG stabilization to future devices. An estimation of the impact of this effect on the ITER hybrid scenario leads to a 20% fusion power improvement.
Place, publisher, year, edition, pages
European Physical Society (EPS) , 2014.
Electric discharges, Fighter aircraft, Magnetoplasma, Plasma simulation, Shear flow, Electromagnetic instability, Fast ions, Flow shear, Fusion power, Gyrokinetic simulations, Hybrid discharges, L-mode discharges, Microturbulence, Stabilization
Fusion, Plasma and Space Physics
IdentifiersURN: urn:nbn:se:kth:diva-201853ScopusID: 2-s2.0-85002594955OAI: oai:DiVA.org:kth-201853DiVA: diva2:1079505
41st EPS Conference on Plasma Physics, EPS 2014, 23 June 2014 through 27 June 2014
QC 201703082017-03-082017-03-082017-03-08Bibliographically approved