Dr
Seung-Hoe Ku
(Princeton Plasma Physics Laboratory)
24/10/2018, 16:40
THC - Magnetic Confinement Theory and Modelling: Confinement
Oral
Despite over 30 years of routine H-mode operation in all the major tokamaks, there has not been a fundamental understanding at the kinetic level on how the H-mode turbulence bifurcation occurs. This is a concern over ITER’s achievability of the H-mode operation with available heating power when the ∇𝑝-driven neoclassical ExB shearing rate is expected to be weak due to smallness of ρ*=ρi/a. The...
Dr
Jon Hillesheim
(Culham Centre for Fusion Energy)
24/10/2018, 17:00
EXC - Magnetic Confinement Experiments: Confinement
Oral
Unraveling the conditions that permit access to H-mode continues to be an unresolved physics issue for tokamaks, and accurate extrapolations are important for planning ITER operations and DEMO design constraints. Experiments have been performed in JET, with the ITER-like W/Be wall, to increase the confidence of predictions for the L-H transition power threshold in ITER. These studies have...
Dr
Lothar Schmitz
(University of California-Los Angeles)
24/10/2018, 17:20
EXC - Magnetic Confinement Experiments: Confinement
Oral
Quantitative proof is presented that the ion polarization current [1] dominates the evolution of the radial electric field E_r across the L-H transition, and needs to be properly taken into account in Ohm’s law. This is an important step towards developing a physics-based reduced L-H transition model, which in addition needs to include at a minimum the poloidal momentum balance, and evolution...
Dr
Mike Kotschenreuther
(Institute for Fusion Studies)
24/10/2018, 17:40
THC - Magnetic Confinement Theory and Modelling: Confinement
Oral
Major progress has been made in understanding the pedestal transport in several areas. 1) For the first time, the instabilities that dominate energy transport in present experimental pedestals are determined, using identifying ratios of the transport they produce in different channels - their “transport fingerprint”. These are derived from the drift kinetic equation for pedestal parameters,...
Dr
Joseph McClenaghan
(Oak Ridge Associated Universities)
24/10/2018, 18:00
EXC - Magnetic Confinement Experiments: Confinement
Oral
Shafranov shift stabilizes turbulence and creates a bifurcation in kinetic ballooning mode(KBM) transport that enables high performance ITB plasmas to be sustained at reactor relevant $q_{95}$. On DIII-D, the internal transport barrier (ITB), high $\beta_N$ ~3, and very high normalized confinement $H_{98,y2}$~1.6 of the high $\beta_p$ scenario has been achieved at $q_{95}$~6.5. This is...
Dr
Tuomas Tala
(VTT)
24/10/2018, 18:20
EXC - Magnetic Confinement Experiments: Confinement
Oral
Core density profile peaking has been extensively studied by performing several dimensionally matched collisionality scans in various plasma operation scenarios on JET as well as by executing a 3-point collisionality scan on DIII-D and a 2-point collisionality scan in I-mode on C-Mod.
In L-mode, D and V are large in all cases even if the NBI power is much smaller than in the H-mode cases....
