Compact magnetic confinement fusion:Spherical torus and compact torus

The spherical torus(ST)and compact torus(CT)are two kinds of alternative magnetic confinement fusion concepts with compact geometry.The ST is actually a sub-category of tokamak with a low aspect ratio;while the CT is a toroidal magnetic configuration with a simply-connected geometry including spheromak and field reversed pinch.The ST and CT have potential advantages for ultimate fusion reactor;while at present they can also provide unique fusion science and technology contributions for mainstream fusion research.However,some critical scientific and technology issues should be extensively investigated.