PROTO-SPHERA is an innovative Magnetic Confinement plasma experiment for Controlled Thermonuclear Fusion research, whose aim is to form a Spherical Torus confinement plasma not around a metal centerpost (as in Tokamaks), but around a plasma centerpost. The PROTO-SPHERA experiment (see last picture) is producing plasma since 2 years. Magnetic plasma instabilities will kink the plasma centerpost to a point such as to produce the Spherical Torus around it. This confinement scheme, if successful, will have advantages over Tokamaks: cylindrical and not toroidal geometry of the vacuum vessel (easing access and repairs), undefined sustainment of the toroidal current within the Torus, by DC voltage applied to the plasma centerpost (allowed by mixed magnetic and electrostatic plasma confinement and major role of plasma mass motion), finally high plasma beta (unitary ratio between plasma pressure and magnetic confinement pressure, which in Tokamaks is only a few %), that would minimize the size of a future Fusion reactor. The experiment is at the moment producing the plasma centerpost, and already exploring the initial phases of the kink instability, as shown in the following figures and pictures.
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Theory |
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Experiment |