Quad magnetism

Quasi-magnetism was, according to the Fifth Doctor, "the only force known to shield anti-matter." It was created when a Q star burnt out. Omega once took advantage of quasi-magnetism, hiding behind it in the area of space known as Rondel or the Arc of Infinity. When the Doctor and Nyssa passed through the area, the TARDIS sensors detected quasi-magnetism. (DW: Arc of Infinity)