Positron Dynamics near term work to proving out antimatter
catalyzed deuterium fusion propulsion with over 100,000 ISP:
"Positron Dynamics is developing antimatter catalyzed fusion propulsion which they will
first demonstrate in a cubesat launch. They are getting around the still mostly unsolved
difficulties of storing antimatter. They are doing this by using Sodium 22 isotopes."
See:
http://www.nextbigfuture.com/2016/10...m-work-to.html