I believe that is the Radiation trooper.
Radiation zone assault troopers, also known as radiation troopers or simply radtroopers, were an elite Imperial stormtrooper division. They were well equipped to operate in one of the deadliest terrain types. A lead-polymer substrate in the modified plastoid armor gave protection needed to withstand lethal Grade 5 radiation zone for several hours. Only the radtrooper suits were proof against extended operations in deadly environments. The Galactic Empire deployed them into radiation-filled zones that contained assets the Empire wanted to claim or defend. The Empire was known to employ neutron bombs, which killed or maimed a large number of the local population. Radtroopers were normally equipped with vibroblades, force pikes and grenades, as blasters lost their effectiveness in high rad conditions. Some special, high output blasters were issued to radtroopers