The ion heat pulse after a sawtooth crash is studied by a time-of-flig
ht (TOF) neutral measurement. A rapid change of the bulk ion energy di
stribution near the edge is observed after a sawtooth crash. The delay
time is measured, and the effective measuring position is estimated b
y a neutral transport code. Then a transient ion thermal conductivity,
chi(i)(HP), of about (7-18) m(2)/s is evaluated for the low confineme
nt mode (L-mode) plasma. The simple diffusive model with constant chi(
i)(HP), however, does not explain the amplitude of the pulse in the io
n energy distribution. (C) 1996 American Institute of Physics.