Ion and electron heating/transport characteristics during high guide field reconnection experiments in the TS-6 and ST40 spherical tokamaks

Here we report ion and electron heating/transport characteristics of magnetic reconnection under the influence of high guide field (B_t > 3B_rec) in the ST40 and TS-6 experiments. In addition to the previously reported double-peak heating feature of ion temperature profile through the dissipation of reconnection outflow jet and the extension of ion heating scaling △T_i ∝ B_rec² in keV range, our recent experiments explored the following 3 new findings/achievements using 96CH/320CH ion Doppler tomography and 30CH/140CH Thomson scattering diagnostics in ST40 and TS-6 respectively: (i) formation of poloidally asymmetric global ion heating structure in TS-6 and highly localized electron heating around the X-point in ST40 via parallel electric field acceleration, (ii) update of the heating scaling to △U_i ∝ B_rec² in collaboration with Thomson scattering measurement: ~ 1kJ/m³ in MAST (B_rec ~ 0.1T) to 10 times higher regime ~ 10kJ/m³ (B_rec ~ 0.3T) in ST40, and (iii) quasi-steady sustainment/confinement of reconnection startup plasma after the end of merging.