An americium‐fueled gas core nuclear rocket

A gas core fission reactor that utilizes americium in place of uranium is examined for potential utilization as a nuclear rocket for space propulsion. The isomer 242mAm with a half life of 141 years is obtained from an (n, γ) capture reaction with 241Am, and has the highest known thermal fission cross section. We consider a 7500 MW reactor, whose propulsion characteristics with 235U have already been established, and re‐examine it using americium. We find that the same performance can be achieved at a comparable fuel density, and a radial size reduction (of both core and moderator/reflector) of about 70%.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87734/2/585_1.pd

Anisotropic geometry-conforming d-simplicial meshing via isometric embeddings

We develop a dimension-independent, Delaunay-based anisotropic mesh generation algorithm suitable for integration with adaptive numerical solvers. As such, the mesh produced by our algorithm conforms to an anisotropic metric prescribed by the solver as well as the domain geometry, given as a piecewise smooth complex. Motivated by the work of Lévy and Dassi [10-12,20], we use a discrete manifold embedding algorithm to transform the anisotropic problem to a uniform one. This work differs from previous approaches in several ways. First, the embedding algorithm is driven by a Riemannian metric field instead of the Gauss map, lending itself to general anisotropic mesh generation problems. Second we describe our method for computing restricted Voronoi diagrams in a dimension-independent manner which is used to compute constrained centroidal Voronoi tessellations. In particular, we compute restricted Voronoi simplices using exact arithmetic and use data structures based on convex polytope theory. Finally, since adaptive solvers require geometry-conforming meshes, we offer a Steiner vertex insertion algorithm for ensuring the extracted dual Delaunay triangulation is homeomorphic to the input geometries. The two major contributions of this paper are: a method for isometrically embedding arbitrary mesh-metric pairs in higher dimensional Euclidean spaces and a dimension-independent vertex insertion algorithm for producing geometry-conforming Delaunay meshes. The former is demonstrated on a two-dimensional anisotropic problem whereas the latter is demonstrated on both 3d and 4d problems. Keywords: Anisotropic mesh generation; metric; Nash embedding theorem; isometric; geometry-conforming; restricted Voronoi diagram; constrained centroidal Voronoi tessellation; Steiner vertices; dimension-independen

Magnetic fuel containment in the Gas Core Nuclear Rocket

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76911/1/AIAA-1993-2368-519.pd

A laser driven fusion plasma for space propulsion

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76316/1/AIAA-1992-3023-320.pd

Some physics issues facing the open cycle Gas Core Nuclear Rocket

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76323/1/AIAA-1991-3650-874.pd

Gas core fission and inertial fusion propulsion systems - A preliminary assessment

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76205/1/AIAA-1991-1833-546.pd

Mars missions with the MICF fusion propulsion system

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76184/1/AIAA-1988-2926-630.pd

The Conservation Equations for a Magnetically Confined Gas Core Nuclear Rocket

A very promising propulsion scheme that could meet the objectives of the Space Exploration Initiative (SEI) of sending manned missions to Mars in the early part of the next century is the open‐cycle Gas Core (GCR) Nuclear Rocket. Preliminary assessments of the performance of such advice indicate that specific impulses of several thousand seconds, and thrusts of hundreds of kilonewtons are possible. These attractive propulsion parameters are obtained because the hydrogen propellant gets heated to very high temperatures by the energy radiated from a critical uranium core which is in the form of a plasma generated under very high pressure. Because of the relative motion between the propellant and the core, certain types of hydrodynamic instabilities can occur, and result in rapid escape of the fuel through the nozzle. One effective way of dealing with this instability is to place the system in an externally applied magnetic field. In this paper we formulate the appropriate conservation equations that describe the dynamics of GCR in the presence of magnetic fields, and indicate the role such fields play in the performance of the system.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87618/2/1097_1.pd

Fuel confinement and stability in the gas core nuclear propulsion concept

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/76935/1/AIAA-1992-3818-773.pd

A preliminary comparison of gas core fission and inertial fusion for the space exploration initiative

Potential utilization of fission and fusion‐based propulsion systems for solar system exploration is examined using a Mars mission as basis. One system employs the open cycle gas core fission reactor (GCR) as the energy source, while the other uses the fusion energy produced in an inertial Confinement Fusion (MICF) concept, to convert thermal energy into thrust. It is shown that while travel time of each approach may be comparable, the GCR must overcome serious problems associated with turbulent mixing, fueling and startup among others, while the fusion approach must find ways to reduce the driver energy required for ignition.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/87495/2/1078_1.pd