Craig H. Williams

Realizing "2001: A Space Odyssey": Piloted Spherical Torus Nuclear Fusion Propulsion

A conceptual vehicle design enabling fast, piloted outer solar system travel was created predicated on a small aspect ratio spherical torus nuclear fusion reactor. The initial requirements were satisfied by the vehicle concept, which could deliver a 172 mt crew payload from Earth to Jupiter rendezvous in 118 days, with an initial mass in low Earth orbit of 1,690 mt. Engineering conceptual design, analysis, and assessment was performed on all major systems including artificial gravity payload, central truss, nuclear fusion reactor, power conversion, magnetic nozzle, fast wave plasma heating, tankage, fuel pellet injector, startup/re-start fission reactor and battery bank, refrigeration, reaction control, communications, mission design, and space operations. Detailed fusion reactor design included analysis of plasma characteristics, power balance/utilization, first wall, toroidal field coils, heat transfer, and neutron/x-ray radiation. Technical comparisons are made between the vehicle concept and the interplanetary spacecraft depicted in the motion picture 2001: A Space Odyssey.

A spherical torus nuclear fusion reactor space propulsion vehicle concept for fast interplanetary travel

A conceptual vehicle design enabling fast outer solar system travel was produced predicated on a small aspect ratio spherical torus nuclear fusion reactor. Initial requirements were for a human mission to Saturn with a>5% payload mass fraction and a one way trip time of less than one year. Analysis revealed that the vehicle could deliver a 108 mt crew habitat payload to Saturn rendezvous in 235 days, with an initial mass in low Earth orbit of 2,941 mt. Engineering conceptual design, analysis, and assessment was performed on all major systems including payload, central truss, nuclear reactor (including diverter and fuel injector), power conversion (including turbine, compressor, alternator, radiator, recuperator, and conditioning), magnetic nozzle, neutral beam injector, tankage, start/re-start reactor and battery, refrigeration, communications, reaction control, and in-space operations. Detailed assessment was done on reactor operations, including plasma characteristics, power balance, and component design.A conceptual vehicle design enabling fast outer solar system travel was produced predicated on a small aspect ratio spherical torus nuclear fusion reactor. Initial requirements were for a human mission to Saturn with a>5% payload mass fraction and a one way trip time of less than one year. Analysis revealed that the vehicle could deliver a 108 mt crew habitat payload to Saturn rendezvous in 235 days, with an initial mass in low Earth orbit of 2,941 mt. Engineering conceptual design, analysis, and assessment was performed on all major systems including payload, central truss, nuclear reactor (including diverter and fuel injector), power conversion (including turbine, compressor, alternator, radiator, recuperator, and conditioning), magnetic nozzle, neutral beam injector, tankage, start/re-start reactor and battery, refrigeration, communications, reaction control, and in-space operations. Detailed assessment was done on reactor operations, including plasma characteristics, power balance, and component design.

Commercially‐driven human interplanetary propulsion systems: Rationale, concept, technology, and performance requirements

Previous studies of human interplanetary missions are largely characterized by long trip times, limited performance capabilities, and enormous costs. Until these missions become dramatically more ‘‘commercial‐friendly’’, their funding source and rationale will be restricted to national governments and their political/scientific interests respectively. A rationale is discussed for human interplanetary space exploration predicated on the private sector. Space propulsion system requirements are identified for interplanetary transfer times of no more than a few weeks/months to and between the major outer planets. Nuclear fusion is identified as the minimum requisite space propulsion technology. A conceptual design is described and evolutionary catalyzed‐DD to DHe3 fuel cycles are proposed. Magnetic nozzles for direct thrust generation and quantifying the operational aspects of the energy exchange mechanisms between high energy reaction products and neutral propellants are identified as two of the many key sup...

Space Propulsion via Spherical Torus Fusion Reactor

A conceptual vehicle design enabling fast outer solar system travel was produced predicated on a small aspect ratio spherical torus nuclear fusion reactor. Analysis revealed that the vehicle could deliver a 108 mt crew habitat payload to Saturn rendezvous in 204 days, with an initial mass in low Earth orbit of 1630 mt. Engineering conceptual design, analysis, and assessment were performed on all major systems including nuclear fusion reactor, magnetic nozzle, power conversion, fast wave plasma heating, fuel pellet injector, startup/re-start fission reactor and battery, and other systems. Detailed fusion reactor design included analysis of plasma characteristics, power balance and utilization, first wall, toroidal field coils, heat transfer, and neutron/X-ray radiation.

A Prognostic Launch Vehicle Probability of Failure Assessment Methodology for Conceptual Systems Predicated on Human Causal Factors

Lessons learned from past failures of launch vehicle developments and operations were used to create a new method to predict the probability of failure of conceptual systems. Existing methods such as Probabilistic Risk Assessments and Human Risk Assessments were considered but found to be too cumbersome for this type of system-wide application for yetto-be-flown vehicles. The basis for this methodology were historic databases of past failures, where it was determined that various faulty human-interactions were the predominant root causes of failure rather than deficient component reliabilities evaluated through statistical analysis. This methodology contains an expert scoring part which can be used in either a qualitative or a quantitative mode. The method produces two products: a numerical score of the probability of failure or guidance to program management on critical areas in need of increased focus to improve the probability of success. In order to evaluate the effectiveness of this new method, data from a concluded vehicle program (USAF’s Titan IV with the Centaur G-Prime upper stage) was used as a test case. Although the theoretical vs. actual probability of failure was found to be in reasonable agreement (4.46% vs. 6.67% respectively) the underlying sub-root cause scoring had significant disparities attributable to significant organizational changes and acquisitions. Recommendations are made for future applications of this method to ongoing launch vehicle development programs.

Multi‐Megawatt MPD Plasma Source Operation and Modeling for Fusion Propulsion Simulations

The expansion of a high temperature fusion plasma through an expanding magnetic field is a process common to most fusion propulsion concepts. The efficiency of this process has a strong bearing on the overall performance of fusion propulsion. In order to simulate the expansion of a fusion plasma, a concept has been developed in which a high velocity plasma is first stagnated in a converging magnetic field to high (100’s of eV) temperatures, then expanded though a converging/diverging magnetic nozzle. A Magnetoplasmadynamic (MPD) plasma accelerator has been constructed to generate the initial high velocity plasma and is currently undergoing characterization at the Ohio State University. The device has been operated with currents up to 300 kA and power levels up to 200 MWe. The source is powered by a 1.6 MJ, 1.6 ms pulse‐forming‐network. In addition to experimental tests of the accelerator, computational and theoretical modeling of both the accelerator and the plasma stagnation have been performed using the...

Fusion Propulsion Through a Magnetic Nozzle and Open Divertor

A revised magnetic nozzle and open poloidal bundle divertor concept is proposed for a small aspect ratio, spherical torus reactor to be used in direct nuclear fusion space propulsion. A preliminary analysis of convergent/divergent flow through a magnetic nozzle illustrated the importance of high efficiency, where a power conversion efficiency of only 75% could lead to a doubling of exit area ratio requirements over ideal conditions. Preliminary MHD simulations have shown that as much as 50% of the mass flow could penetrate into the plasma‐magnetic field boundary layer, leading to a thermal‐to‐directed jet power loss of 30% and a spacecraft payload mass ratio loss of ∼ 60% of ideal. The importance of understanding the plasma‐magnetic field interface and the inability of space/time dependent MHD simulations to resolve fine‐scaled, gradient‐driven micro‐instabilities is currently under study. Preliminary plasma interface broadening mechanism studies have concluded that significant attachment of the plasma on...

FAST INTERPLANETARY PROPULSION USING A SPHERICAL TORUS NUCLEAR FUSION REACTOR PROPULSION SYSTEM

LWlkg respect&ely2s4., Although contestable, it is the A conceptual. vehicle de&n enabling fast outer solar system travel was produced predicated on a. small aspect ratio sphekical torus nuclear fusion reactor. .Analysis revealed that the vehicle could deliver a 108 mt crew habitat payload to Saturn rendezvous "in 214 days, with an initial mass in low Earth orbit of 2,640 mt. Engineering conceptual design, analysis, and assessment was performed on all major systems including payload, central truss, nuclear fusion reactor, power, magnetic nozzle, fast wave plasma" heating, tankage, startup/re-start fission reactor and battery, refrigeration, communicationS, reaction control, mission design, and space operations. Detailed fusion reactor design analysis included plasma characteristics, power balance/utilization, first wall, toroidal field coils, and heat transfer. judgment of the a&hors and m&y in the field that only a single space propulsion t&hnology exists at this time. that can reasonably be expected to offer this capability: nuclear fusion, &her magnetic or inertial cotimement. Based in part on the results of previous s&lies2,5 of the ,attributes and shortcomings of various classes of reactor "towards space propulsion, a closed magnetic syskm was chosen for this design concept. The high power density achievable in closed systems, improved confinement, spin polarization of the fuel, density and temperature profile peaking provided a distinct advantage @ their application towards space propulsion. The small aspect ratio spherical torus was chosen to serve as the basis for the vehicle concept.