Energy and particle confinement in JET H-mode plasma

Energy and particle confinement in JET H-mode plasma

Energy and particle confinement in JET H-mode plasma 150 150 UKAEA Opendata
UKAEA-CCFE-PR(19)52

Energy and particle confinement in JET H-mode plasma

This work describes the behaviour of the global energy and particle confinement on JET observed in a massive database of H-mode plasmas covering almost whole lifetime of JET operations, both with carbon and metal wall. The analysis is focused on type I ELMy H-modes in stationary phases. It is shown that plasma density in that regime is determined mainly by the plasma current, edge safety factor, triangularity of the last closed flux surface and the hydrogenic isotope mass. That behaviour is consistent for the whole database regardless of divertor configuration or the plasma facing materials. On average, thermal energy confinement time in JET with carbon wall (JET-C) is accurately predicted by the IPB98y,2 scaling. For JET with the ITER-like wall the energy confinement is found to be lower than expected from the scaling. The difference is found to be much stronger in divertor configuration with outer strike point at vertical target and pumping throat at the private flux. Observed lower confinement in JET-ILW can partially be attributed to the additional operational constraints of the metal wall machine, i.e. the avoidance of heavy impurity accumulation via additional gas dosing, but not in full. The isotope effect on the energy confinement in M=1-2 range is found to be the same in JET-C and JET-ILW, thus independent of the wall material, if correlation with plasma density is accounted for. The effect of toroidal magnetic field on the confinement is between zero and slightly negative. Triangularity has generally favourable effect on the energy confinement, but the magnitude changes across the database. Effect of triangularity on plasma density although is always much stronger, therefore plasmas with high triangularity are in general more dense and colder than at the lower triangularity. The work described in this paper is done under the EUROfusion global confinement database project, and the data shown here will be available to the EUROfusion collaborators shortly. It is also either already a part of the international H-mode confinement database or will be in the future updated version.

Collection:
Journals
Journal:
Nuclear Fusion
Publisher:
IOP (Institute of Physics)
Published date:
27/09/2021