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Conceptual Design of a Moving-Ring Reactor

Adrian C. Smith, Jr., Gustav A. Carlson, William S. Neef, Jr., Clinton P. Ashworth, Kenneth E. Abreu, Hans H. Fleischmann, Kenneth R. Schultz, Clement P. C. Wong, Dilip K. Bhadra, R. Lewis Creedon, Edward T. Cheng, George R. Hopkins, William Grossmann, Jr., David M. Woodall, Terry Kammash

Fusion Science and Technology

Volume 9 / Number 1 / January 1986 / Pages 136-170


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A design of a prototype moving-ring reactor was completed, and a development plan for a pilot reactor is outlined. The fusion fuel is confined in current-carrying rings of magnetically field-reversed plasma (“compact toroids”). The plasma rings, formed by a coaxial plasma gun, undergo adiabatic magnetic compression to ignition temperature while they are being injected into the reactor's burner section. The cylindrical burner chamber is divided into three “burn stations.” Separator coils and a slight axial guide field gradient are used to shuttle the ignited toroids rapidly from one burn station to the next, pausing for one-third of the total burn time at each station. Deuteriumthtium-3He ice pellets refuel the rings at a rate that maintains constant radiated power. The fusion power per ring is ∼105.5 MW. The burn time to reach a fusion energy gain of Q = 30 is 5.9 s. The fusion plasma rings are assumed to be of the field-reversed mirror type with some spheromak-like imbedded toroidal magnetic field. A magnetic/thermal energy ratio of one-third and an average ⟨β⟩ = 0.67 is presumed. Initial plasma ion (electron) temperatures are assumed to be 75 (50) keV, with an initial (final) plasma average radius of 39 (57) cm. The ion energy confinement is assumed to be classical and the electron energy confinement is one-tenth that of the ions. The rings are assumed to be tilt stabilized with ∼20% of the ring current carried by “fast,” axis-encircling particles. The first-wall and tritium breeding blanket designs make credible use of helium-cooling, silicon carbide, and Li2O to minimize structural radioactivity. “Hands-on” maintenance is possible on all reactor components outside the blanket. The first wall and blanket are designed to shut the reactor down passively in the event of a loss-of-coolant or a loss-of-flow accident. Helium removes heat from the first wall, blanket, and shield and is used in a closed-cycle gas turbine to produce electricity. Energy residing in the plasma ring at the end of the burn is recovered via magnetic expansion. Electrostatic direct conversion is not used in this design. The reactor produces a constant net power of 99 MW(electric).

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