A Fusion Hybrid Reactor Based on the Gasdynamic Mirror (GDM)

A fusion-fission hybrid reactor whose fusion component is the gasdynamic mirror (GDM) is proposed for power production that could meet the world's energy needs of the next several decades. The choice of the GDM is based on the fact that it is linear, axisymmetric and can operate in steady state. Since the primary role of the fusion component is to supply neutrons to the blanket, it can operate at or near “breakeven” condition, a much less stringent condition than that required for a pure fusion reactor. A large aspect ratio GDM is desirable because of MHD stability considerations, and if we choose such a geometry then a cylindrically symmetric plasma with a surrounding blanket can be treated as semi-infinite cylinders, allowing for the reactor performance to be determined by two, one-dimensional equations: one describing the time evolution of the fissile material density bred in the fertile blanket, and another describing the diffusion of fast neutrons in that region. Our choice for the blanket material is thorium-232 in order to take advantage of the thorium fuel cycle that leads to the breeding of uranium-233. Such a fuel cycle is known to be resistant to proliferation and clandestine operations. We choose to operate the GDM at 0.10 of breakeven, using deuterium-tritium (DT) plasma at a density of 10¹⁶ cm^-3, and a temperature of 10keV. We find that for a reasonable design, such a reactor can generate tens of megawatts of thermal power per cm “safely” because it is “subcritical”, and “securely” because of our choice of the fuel cycle. A systems analysis reveals that about 2% of the net electric power is needed to sustain the fusion component. Moreover, we find that it takes approximately 4 months to reach steady state due to the several steps involved in the breeding cycle.