Full sawtooth crashes in high temperature plasmas have been investigat
ed on the Tokamak Fusion Test Reactor (TFTR) [Plasma Phys. Controlled
Fusion 33, 1509 (1991)]. A strong asymmetry in the direction of major
radius, a feature of the ballooning mode, and a remaining m=1 region a
fter the crash have been observed with electron cyclotron emission ima
ge reconstructions. The TFTR data is not consistent with two-dimension
al (2-D) models; it rather suggests a three-dimensional (3-D) localize
d reconnection arising on the bad curvature side. This process explain
s the phenomenon of fast heat transfer which keeps the condition q(0)<
1. (C) 1996 American Institute of Physics.