A potentially attractive next-step towards fusion commercialization is a pilot plant, i.e., a device ultimately capable of small net electricity production in as compact a facility as possible and in a configuration scalable to a full-size power plant. A key capability for a pilot plant program is the production of high neutron fluence enabling fusion nuclear science and technology (FNST) research. It is found that for physics and technology assumptions between those assumed for ITER and nth-of-a-kind fusion power plant, it is possible to provide FNSTrelevant neutron wall loading in pilot devices. Thus, it may be possible to utilize a single facility to perform FNST research utilizing reactor-relevant plasma, blanket, coil, and auxiliary systems and maintenance schemes while also targeting net electricity production. In this paper three configurations for a pilot plant are considered: the advanced tokamak (AT), spherical tokamak (ST), and compact stellarator (CS). A range of configuration issues are considered including: radial build and blanket design, magnet systems, maintenance schemes, tritium consumption and self-sufficiency, physics scenarios, and a brief assessment of research needs for the configurations.

The general character of the magnetohydrodynamic flow past a non-conducting flat plate in the presence of transverse magnetic fields is analysed in some detail. The appropriate extension of the Rayleigh problem to the magnetohydrodynamic case is shown to yield solutions which correctly predict some features of the steady flow past a semi-infinite flat plate; in addition, it is shown that the knowledge of these significant features permits an easy evaluation of their magnitudes in other extensions of the Rayleigh problem. The flow past a semi-infinite flat plate is analysed by two methods. First, by linearizing the governing equations and incorporating the assumption of a low ratio of viscous to magnetic diffusivity, the results for skin friction and the normal component of magnetic field at the plate are obtained and are shown to be useful in interpreting the character of these low conductivity flows. Secondly, the complete set of governing equations is formulated as a finite difference problem and solved numerically on a digital computer. The results obtained, in addition to demonstrating feasibility of the numerical calculations, show that the disturbance produced by the plate is no longer confined to a thin viscous layer if the ratio of viscous to magnetic diffusivity is greater than 10−2, but that an appreciable Alfvén type disturbance is excited.

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The characteristics of the plasma around a slender, slightly blunted cone during re-entry are discussed in relation to the plasma sheath transmission problem.The flow field around the aforementioned vehicle is qualitatively described, and the plasma and collision frequency distribution around a perfectly sharp cone during re-entryis presented graphically. The methods employed in computing the presented values of the plasma parameters are outlined and referenced in the Appendix.