  Local electron and ion heating characteristics during merging reconnection
startup on the MAST spherical tokamak have been revealed for the first time
using a 130 channel YAG-TS system and a new 32 chord ion Doppler tomography
diagnostic. 2D local profile measurement of $T_e$, $n_e$ and $T_i$ detect
highly localized electron heating at the X point and bulk ion heating
downstream. For the push merging experiment under high guide field condition,
thick layer of closed flux surface formed by reconnected field sustains the
heating profile for more than electron and ion energy relaxation time
$\tau^E_{ei}\sim4-10$ms, both heating profiles finally form triple peak
structure at the X point and downstream. Toroidal guide field mostly
contributes the formation of peaked electron heating profile at the X point.
The localized heating increases with higher guide field, while bulk downstream
ion heating is unaffected by the change in the guide field under MAST
conditions ($B_t>3B_{rec}$).
