A conceptual design of a low resistance vaccum vessel for the steady state Tokamak reactor

Abstract

A design study on the vacuum vessel of the Steady State Tokamak Reactor has been performed in order to provide a realistic structural concept for a fusion reactor. The vacuum vessel and shield are integrated to form a double-thin-wall structure filled with stainless steel and water resulting in a low one-turn electric resistance of ∼4 μω without insulating breaks or bellows. The reinforcement plates are weleded between the inner and outer skins of the double-thin-wall structure, and shileding units are installed in every chamber with electrical insulation from these skins and plates. As a result, the requirements for the vacuum vessel can be realized by this simple structure alone. Transient electromagnetic and structural analysis has been performed for the three-dimensiona; shell model in the plasma disruption condition of plasma current 12 MA and current decay time 20 ms. An eddy current, about 95% of plasma current, is induced on the vacuum vessel, and a maximum magnetic pressure ∼ 5.8 MPa is caused by coupling with the toroidal field. The maximum stress intensity for the magnetic prerssure is about 216 MPa. This low resistance vacuum vessel is extremely effective in shielding the change of the magnetic field in the superconducting toroidal and poloidal field coils during a plasma disruption. In summary, the feasibility and features of this new type of vacuum vessel concept have been shown in this study.