Thermal structures and their relation to magnetic topology in RFX-mod

The study examines the thermal properties of reversed-field pinch plasmas in the RFX-mod experiment [1] in Padova, Italy, and their relationship with magnetic topology. A database of 328 discharges providing 69,054 temperature profiles was analyzed. Temperature profiles are obtained with the Diagnostic soft X-ray 3-arrays (DSX3) diagnostic while tearing mode dynamics from saddle loops.  Key findings include the observation of high-quality thermal structures with electron temperatures up to 1200 eV, spanning up to 50% of the vessel radial extent, even without a well-organized magnetic topology. This is presumed to be due to the interaction among the various tearing modes. This is a novel discovery compared to previous results [2]. This work identifies three specific cases of non-linear dynamics among dynamo modes that enhance thermal structures. These cases will be presented here and will also be the subject of a future publication.

[1] P. Sonato et al 2003 Fus. Eng. Des., 66–68, pp. 161-168

[2] P. Franz et al 2013 Nucl. Fusion 53 053011