  We study in detail the dynamics of a scalar field in thermal bath with
symmetry breaking potential. In particular, we focus on the process of trapping
of a scalar field at an enhanced symmetry point through the thermal/non-thermal
particle production, taking into account the interactions of produced particles
with the standard model particles. As an explicit example, we revisit the
saxion dynamics with an initial amplitude much larger than the Peccei-Quinn
scale and show that the saxion trapping phenomenon happens for the most cases
and it often leads to thermal inflation. We also study the saxion dynamics
after thermal inflation, and it is shown that thermal dissipation effect on the
saxion can relax the axion overproduction problem from the saxion decay.
