Abstract
A fusion technology development and demonstration concept is conceived using a plasma based volumetric neutron source capable of providing a range of fusion power and wall loading levels during testing, developing, and demonstration stages of operation. The high performance anticipated for the spherical torus (ST) plasma permits large physics margins for the initial neutron wall loading of 0.5 MW/m(2), while still allowing a long-term power reactor relevant physics performance goal of 5 MW/m(2) with reduced margins. An ST-VNS takes advantage of low magnetic field and compact plasma to implement full remote replacement of the center leg of the toroidal field coil, the divertor, the first wall, the shield, and the test blanket modules. At the initial stage of operation, only modest neutron wall loading (0.5 MW/m(2)) would be attempted. Success in achieving reliable operations at 2 MW/m(2) in wall loading at a later stage would fulfill the goals of the VNS; success at 5 MW/m(2) would permit component testing for the demonstration power plants. This approach of ST-VNS provides a realistic opportunity for the ultimate demonstration of safe, reliable, and environmentally attractive fusion systems.