When Captain Ramart of the Antares tried to contact Captain James T. Kirk of the USS Enterprise and warn him of Charles Evans, Evans used his psionic powers to remove a warped baffle plate from the generator which subsequently destroyed the Antares. (TOS - Star Trek 1 novelization: Charlie X) The name appears to be a misspelling of Nernst generator, which appeared in several of James Blish's other works.