Optimal shape of electrodes for high performance of inertial electrostatic confinement fusion

Inertial electrostatic confinement (IEC) fusion is a scheme of producing the ions between the anode and the hollow cathode in the concentric spheres by the glow discharge, accelerating the ions into the spherical center and giving rise to fusion reactions between the accelerated ions or between the accelerated ions and the background neutrals. A current feed-through is connected to the cathode through the anode to apply the negative high voltage. The existence of the feed-through breaks the spherical symmetry of the device and makes the lifetime of fast ions shorter since 50 % of the accelerated ions hit the feed-through and are lost. The optimal shapes of both of the cathode and the anode at the viewpoint of the long life of the fast ions are inquired by evaluating the lifetime of the ions by tracking the trajectories of the ions. Numerical results reveal that the lifetime of fast ions becomes twice by deforming a hemisphere of the anode pierced by the feed-through into an ellipsoid, although the shape of the cathode exerts less influence on their lives. The deformed anode reduces the heat load on the feed-through due to the ion bombardment and raises the neutron production rates due to longer life of the fast ions.