  We study the dynamics of skyrmions in chiral magnets in the presence of a
spin polarized current. The motion of skyrmions in the ferromagnetic background
excites spin waves and contributes to additional damping. At a large current,
the spin wave spectrum becomes gapless and skyrmions are created dynamically
from the ferromagnetic state. At an even higher current, these skyrmions are
strongly deformed due to the damping and become unstable at a threshold
current, leading to a chiral liquid. We show how skyrmions can be created by
increasing the current in the magnetic spiral state. We then construct a
dynamic phase diagram for a chiral magnet with a current. The instability
transitions between different states can be observed as experimentally clear
signatures in the transport measurements, such as jumps and hysteresis.
