Gerald Nordley provided a mass beam propulsion overview at Space Access 2019.
There have been many kinds of mass beam propulsion. Use of mass beams, instead of light, allows great efficiency by adjusting the beam velocity so the redirected mass is left near zero velocity relative to the source. There is no intrinsic limit to the proper frame map velocity that can be achieved. To make a propulsion system, subsystems need to be developed to acquire propulsive energy, accelerate the mass into a collimated beam, insure that the mass reaches the spacecraft and redirect the mass. A number of approaches to these requirements have been proposed and are summarized here. Generally, no new scientific discoveries or breakthroughs are needed. These concepts are supported by ongoing progress in robotics, in nanometre scale technologies and in those technologies needed to use of space resources for the automated manufacture of space-based solar power facilities. For mass beams specifically, work in particle sizing, acceleration, delivery and momentum transfer is needed.
In 2002, Jordan Kare published High-acceleration Microscale Laser Sails for Interstellar Propulsion. Laser pushed micro-sails are used to propel a large spacecraft by impacting a pusher plate.
There is a recent NIAC study on combined laser-particle beam propulsion. A combined beam might be able to limit beam spread.
SOURCES – Live coverage of presentation by Gerald Nordley at Space Access 2019, Background papers by Gerald Nordley and Jordin Kare.
Written By Brian Wang, Nextbigfuture.com