A Hellbore is a heavy weapons system for starships or large ground vehicles, originally of Jurvain design, but now also used by the K'Nes and (occasionally) by humans. A Hellbore is basically a plasma cannon on steroids, but instead of a chemical reaction producing the plasma, powerful magnetic and/or gravitational fields squeeze a pocket of hydrogen gas until it undergoes atomic fusion, then allow the resulting fusion explosion to expand only in one narrow direction down the barrel of the weapon and at the target. The incredibly powerful bolt of plasma and radiation that results can cause massive damage to almost any target, and is even capable of firing through planetary atmospheres and still retaining enough energy to do substantial damage when being fired between orbiting spacecraft and ground installations. Hellbores were used as the main battery of the Mobile Siege Fortresses produced by Project Bolo. As seen during the Battle of St. Michael's Star in 2265, Hellbores can even dump so much energy into the gravity shield of a starship that the bleedthrough can still damage or destroy the vessel inside the shield.