26th IAEA Fusion Energy Conference - IAEA CN-234

Global stabilization effect of Shafranov shift on the edge pedestal plasmas in JET and JT-60U

20 Oct 2016, 08:30

4h

Kyoto International Conference Center

Poster EXC - Magnetic Confinement Experiments: Confinement Poster EX/3, EX/4, PPC/1

Speaker

Dr Hajime Urano (QST)

Description

Here we report the global stabilization effect of Shafranov shift on the edge pedestal plasmas. Experimental observations show that (i) the increased Shafranov shift stabilizes the ballooning component of the peeling-ballooning mode (PBM) so that the edge pressure gradient is raised together with the expansion of the edge transport barrier (ETB) and (ii) when the Shafranov shift is fixed the increased collisionality reduces the edge pressure gradient whereas the ETB expands. This physics process has been examined using JET and JT-60U, in both of which the Shafranov shift stabilizes the pedestal most effectively because the pedestal plasmas in these devices are constraint systematically by the ballooning component of the PBM instability. The results will give a physics picture of H-mode edge and core interplay which contributes to an accurate prediction of the ETB structure in ITER.