Here are some useful links for references.
NIAC (NASA Innovative Advanced Concepts) funds studies in many fields, included advanced and future flight propulsion. A number of papers have been published over the years:
| Gradient Field Imploding Liner Fusion Propulsion System | Raymond Sedwick, Robert Adams | ||
| Pulsed Fission-Fusion (PuFF) Propulsion System | Raymond Sedwick, Robert Adams | 2013 | |
| Continuous Electrode Inertial Electrostatic Confinement Fusion | Raymond Sedwick, Robert Adams | 2018 | |
| Nuclear Propulsion Through Direct Conversion of Fusion Energy | John Slough | MSNW LLC phase 1 and 2 | |
| Aneutronic Fusion Spacecraft Architecture | Alfonso Tarditi | University of Houston at Clear Lake | |
| Fusion-Enabled Pluto Orbiter and Lander | Stephanie Thomas | Princeton Satellite Systems, Inc. phase 1 and 2 | |
| Fusion-Enabled Comprehensive Exploration of the Heliosphere | Setthivoine You | Helicity Space LLC | |
| Radioisotope Positron Propulsion | Ryan Weed | Positron Dynamics | |
| Aerogel Core Fission Fragment Rocket Engine | Ryan Weed | Positron Dynamics | |
| Proposal for a Concept Assessment of a Fission Fragment Rocket Engine (FFRE) Propelled Spacecraft | Robert Werka | NASA Marshall Space Flight Center | |
| Deceleration of Interstellar Spacecraft Utilizing Antimatter | Gerald Jackson | Hbar Technologies, LLC | |
| Pulsed Plasma Rocket (PPR): Shielded, Fast Transits for Humans to Mars | Brianna Clements | Howe Industries | |
| Pulsed Plasma Rocket: Shielded, Fast Transits for Humans to Mars | Howe, Steven | Howe Industries LLC |
