On the link between the q-profile and internal transport barriers
Numerous experiments were performed on JET to clarify the link between rational q, magnetic shear and internal transport barriers (ITBs) by varying the q-profile from a monotonic one to one with a central reversed shear (Challis et al 2002 Plasma Phys. Control. Fusion 44 1031). The q-profile was found to be crucial in two cases: for ITB formation in the presence of a strong negative magnetic shear and for ITBs in the vicinity of low order rational q surfaces with a small magnetic shear. The ITBs of these two types have been modelled and analysed in this work using transport codes (TRANSP, JETTO, TRB). Transport coefficients were calculated using several widely used theories of micro-turbulence and compared with data deduced from the experiment to verify the applicability of the theories. Different underlying physical mechanisms were found to be responsible for ITB formation in a negative magnetic shear and in the vicinity of a rational minimum q.
Bibliographic Reference: An article published in: Plasma Physics and Controlled Fusion 46 (2004) 1181�1196
Availability: This article can be accessed online by subscribers, and can be ordered online by non-subscribers, at: stacks.iop.org/PPCF/46/1181
Record Number: 200517960 / Last updated on: 2005-03-08
Original language: en
Available languages: en