Robert B. Adams

Case and Development Path for Fusion Propulsion

This paper discusses the importance of fusion propulsion for interplanetary space travel, illustrates why the magnetoinertial fusion parameter space may facilitate the most rapid, economic path for development, justifies the choice of pulsed Z pinch, and provides a potential development path leading up to a technical readiness level 9 system. Round trips of less than one year to Mars are only possible using fusion propulsion systems. Such a system will require an onboard nuclear fission reactor for reliable startups, and so fission and fusion developments for space are mutually beneficial. The paper reviews the more than 50 year history of fusion research and summarizes results from a recent study of the fusion parameter space for terrestrial power, which suggests magnetoinertial fusion can provide the smallest, most economical approach for a fusion propulsion system. Emerging experimental data and theory show pulsed Z-pinch fusion solves some of the most deleterious instabilities and scales to fusion bre...

Design of Z-pinch and Dense Plasma Focus Powered Vehicles

Z-pinch and Dense Plasma Focus (DPF) are two promising techniques for bringing fusion power to the field of in-space propulsion. A design team comprising of engineers and scientists from UAHuntsville, NASAs George C. Marshall Space Flight Center and the University of Wisconsin developed concept vehicles for a crewed round trip mission to Mars and an interstellar precursor mission. Outlined in this paper are vehicle concepts, complete with conceptual analysis of the mission profile, operations, structural and thermal analysis and power/avionics design. Additionally engineering design of the thruster itself is included. The design efforts adds greatly to the fidelity of estimates for power density (alpha) and overall performance for these thruster concepts

Planetary Defense: Options for Deflection of Near Earth Objects

Several recent near -miss encounters with asteroids and comets have focused attention on the threat of a catastrophic impact with the Earth. This document reviews the historical impact record and current understanding of the number and location of Near Earth Objects (NEO s) to address their impact probability. Various ongoing projects intended to survey and catalog the NEO population are also reviewed. Details are then given of an MSFC -led study, intended to develop and assess various candidate systems for protection of the Earth against NEOs. An existing program, used to model the NEO threat, was extensively modified and is presented here. Details of various analytical tools, developed to evaluate the performance of proposed technologies for protection against the NEO threat, are also presented. Trajectory tools, developed to model the outbound path a vehicle would take to intercept or rendezvous with a target asteroid or comet, are described. Also, details are given of a tool that was created to model both the un -defl ected inbound path of an NEO as well as the modified, post -deflection, path. The number of possible options available for protection against the NEO threat was too numerous for them to all be addressed within the study; instead, a representative selecti on were modeled and evaluated. The major output from this work was a novel process by which the relative effectiveness of different threat mitigation concepts can be evaluated during future, more detailed, studies. In addition, several new or modified ma thematical models were developed to analyze various proposed protection systems. A summary of the major lessons learned during this study is presented, as are recommendations for future work. It is hoped that this study will serve to raise the level atte ntion about this very real threat and also demonstrate that successful defense is both possible and practicable, provided appropriate steps are taken.

Planetary Body Maneuvering: Outbound Propulsion and Trajectory Analysis

This paper is part of a sequence of three documenting the work completed at the NASA Marshall Space Flight Center in the area of the defense of Earth from incoming Near Earth Objects (NEO). The work found herein can be found fully docum ented in reference 1 . I. Outbound Propulsion For both the interception and rendezvous techniques, neither fragmentation nor deflection can take place until the necessary system hardware is transported out to the approaching NEO. Some type of outbound pro pulsion system is required to accomplish this. Several propulsion systems are considered in this study; they were selected for their ability to meet the mission requirements, their level of technological maturity and development status.

Preliminary Analysis of the Gradient Field Imploding Liner Fusion Propulsion Concept [STUB]

The advancement of human deep space exploration requires the continued development of energetic inspace propulsion systems, advancing from current chemical engines to nuclear thermal rockets to future high energy concepts such as nuclear fusion. This paper presents the initial results of a NASA Innovative Advanced Concepts (NIAC) Phase I study funded to investigate the feasibility of a new pulsed fusion propulsion concept based on the rapid implosion of a fuel target injected at high velocity into a strong stationary magnetic field. The proposed concept takes advantage of the significant advances in terrestrial magneto-inertial fusion designs while attempting to mitigate the most common engineering impediments to in-space propulsion applications. A semi-analytic numerical model used to estimate target compression physics and energy release is presented, leading to estimates for engine performance. A preliminary vehicle design concept is outlined, and representative trajectory analyses for rapid Mars and Saturn missions are provided. The paper concludes with an overview of proposed next steps for theoretical and experimental validation of the concept.

Developing the Pulsed Fission-Fusion (PuFF) Engine

In September 2013 the NASA Innovative Advanced Concept (NIAC) organization awarded a phase I contract to the PuFF team. Our phase 1 proposal researched a pulsed fission-fusion propulsion system that compressed a target of deuterium (D) and tritium (T) as a mixture in a column, surrounded concentrically by Uranium. The target is surrounded by liquid lithium. A high power current would flow down the liquid lithium and the resulting Lorentz force would compress the column by roughly a factor of 10. The compressed column would reach criticality and a combination of fission and fusion reactions would occur. Our Phase I results, summarized herein, review our estimates of engine and vehicle performance, our work to date to model the fission-fusion reaction, and our initial efforts in experimental analysis.

Verification of a Multiphysics Toolkit against the Magnetized Target Fusion Concept

In the spring of 2004 the Advanced Concepts team at MSFC embarked on an ambitious project to develop a suite of modeling routines that would interact with one another. The tools would each numerically model a portion of any advanced propulsion system. The tools were divided by physics categories, hence the name multiphysics toolset. Currently most of the anticipated modeling tools have been created and integrated. Results are given in this paper for both a quarter nozzle with chemically reacting flow and the interaction of two plasma jets representative of a Magnetized Target Fusion device. The results have not been calibrated against real data as of yet, but this paper demonstrates the current capability of the multiphysics tool and planned future enhancements