Discrete Logarithms in Generalized Jacobians

D\'ech\`ene has proposed generalized Jacobians as a source of groups for public-key cryptosystems based on the hardness of the Discrete Logarithm Problem (DLP). Her specific proposal gives rise to a group isomorphic to the semidirect product of an elliptic curve and a multiplicative group of a finite field. We explain why her proposal has no advantages over simply taking the direct product of groups. We then argue that generalized Jacobians offer poorer security and efficiency than standard Jacobians

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

A laser driven fusion plasma for space propulsion

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

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

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

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

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