Editing Gaseous fission reactor (section)

== Reasoning for He-4 addition ==
<sup>4</sup>He may be used in increase the ability of the design to extract energy and be controlled. A few sentences from Anghaie et al. sheds light on the reasoning:

:"The [[power density]] in the MHD duct is proportional to the product of [[electrical conductivity]], velocity squared and [[magnetic field]] squared σv²B². Therefore, the [[enthalpy]] extraction is very sensitive to the MHD input-output fluid conditions. The vapor core reactor provides a hotter-than-most fluid with potential for adequate thermal equilibrium conductivity and duct velocities. Considering the product v² × B², it is apparent that a light working fluid should dominate the thermal properties and the UF<sub>4</sub> fraction should be small. Additional electrical conductivity enhancement might be needed from [[thermal ionization]] of suitable seed materials, and from non-equilibrium [[ionization]] by fission fragments and other [[ionizing radiation]] produced by the fissioning process."<ref>Anghaie, S., Pickard, P., Lewis, D. (unknown date). Gas Core & Vapor Core Reactors—Concept Summary</ref>