A neutronic wavefront is a plasma energy storm which can travel through space at high warp. These storms are saturated with radiolytic isotopes, which are harmful to a number of species, including humans and Vulcans. They also contain plasma eddies.
Sometime prior to 2052, the Vulcan starship T'Plana encountered a Class Five neutronic wavefront. Unable to outrun the wavefront, the ship was destroyed and all crewmembers were lost.
Over a century later, the Earth Starfleet vessel Enterprise encountered a neutronic wavefront that spanned more than half a dozen light years in diameter. Unable to outrun the wavefront, the Enterprise crew were forced to take refuge in the ship's inactive warp nacelles to prevent exposure to the deadly radiolytic isotopes. The Enterprise herself would be protected from destruction since the crew reinforced her structural integrity.
Setting up a command center in one of the nacelle's compartments, the crew were able to steer through the wavefront with little trouble. While the ship was within the wavefront, however, it was boarded by members of the Takret Militia who were searching for three deserters who had been brought aboard Enterprise. The Enterprise crew were able to drive the Militia officers away by steering the ship towards a plasma eddy. Following this incident, the Enterprise was able to leave the wavefront earlier than expected thanks to the piloting skills of Ensign Travis Mayweather. (ENT: "The Catwalk")