The Department of Energy sponsors a laboratory that is currently working on magnetic fusion devices based on what principle?
National Spherical Torus Experiment: The National Spherical Torus Experiment (NSTX) is an innovative magnetic fusion device based on the "spherical tokamak" concept. National Spherical Torus Experiment:  It was constructed by the Princeton Plasma Physics Laboratory (PPPL) in collaboration with the Oak Ridge National Laboratory, Columbia University, and the University of Washington at Seattle.
i don't know