axial flow with magnetic containment, wheel flow, and coaxial flow (9,13,15,1.6). The vortex flow reactor illustrated in Figure 1 is designed to achieve fuel-propellant separation through use of centrifugal forces. Hydrogen propellant diffuses radially inward through the gaseous uranium vortex, with the centrifugal forces associated with the heavier uranium counteracting the diffusion drag of the hydrogen. The disadvantage of this concept is due to the hydrogen drag, which is great enough to cause large uranium losses except at very low hydrogen flow rates. Figure 2 illustrates the magnetic containment scheme. Magnetic fields of force confine the uranium plasma while the propellant flows axially around the fuel region. This concept involves the technical difficulties associated with magnetic containment, in addition to propellant drag problems similar to those of the vortex flow. Another variation is the wheel flow concept shown in Figure 3. Hydrogen propellant enters and leaves the reactor tangentially along the outer periphery after circulating around the inner cylindrical uranium region. In this concept the main difficulty still seems to be excessive fuel loss due to hydrogen-uranium mixing. The coaxial flow reactor is shown in Figure 4. This concept is based on the coaxial flow of a central cylindrical uranium mass

and a surrounding annulus of hydrogen. No vortex motion


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