  Observation of Interplanetary Scintillation (IPS) provides an important and
effective way to study the solar wind and the space weather. A series of IPS
observations were conducted by the Five-hundred-meter Aperture Spherical radio
Telescope (FAST). The extraordinary sensitivity and the wide frequency coverage
make FAST an ideal platform for IPS studies. In this paper we present some
first scientific results from FAST observations of IPS with the L-band
receiver. Based on the solar wind velocity fitting values of FAST observations
on September 26-28, 2020, we found that the velocity decreases with increasing
frequency linearly, which has not yet been reported in literature. And we have
also detected a variation of solar wind velocity on a timescale of 3-5 minutes,
which imply the slow change of the background solar wind, a co-existence of
high- and low-speed streams, or a reflect of the quasi-periodic
electron-density fluctuations.
