Experimental demonstration of a compact stellarator magnetic trap using four circular coils

An experimental demonstration of a compact stellarator magnetic trap created from four circular coils is presented. The coil manufacturing and assembly tolerances were on the order of 0.5–1%, far less stringent than most other stellarators. The simplicity, loose mechanical tolerances, and low cost of the trap design makes it feasible for stellarators to be used for a variety of novel physics experiments, in addition to their present use for magnetic confinement fusion. The experiment, the Columbia Non-neutral Torus, has several other desirable features such as no significant internal island chains and the lowest aspect ratio, A⩽1.9, of any stellarator built to date.