The size of a laser with continuous output, to accelerate the payload to 13,500 km/sec in a year, is 3.75 Terra Watts. Since a micropulsed 1 Terra Watt laser has been developed, it is conceivable (although extremely unlikely) that the necessary laser could be invented within the next 20 years. The low feasibility, coupled with the lack of a system for decceleration[sic] into the Centauri System, led to the cancellation of this system's candidacy (see appendix for calculations).
3.2.2.2 Pulsed Fusion Microexplosion Drive
The Pulsed Fusion Microexplosion Drive is not a current, but rather an enabling technology. The system concept, modeled after the British Interplanetary Society's project DEADALUS, is to fire high energy particle beams at small fusionable pellets that will implode and be magnetically channeled out the nozzle (see Figs. 3.2b and 3.2c). The expected specific impulse is 1.02E6 seconds. The specific mass breakdown for separate sections (including fusion chamber, particle beam igniter system, and magnetic nozzle/inductor system) is included in the structures section (2.3.2). Finally, the entire system is expected to gimble a full degree in two axes to enable navigational corrections in three dimensions.
The type of fuel used in the pellets is of critical importance. Due to the extremes of temperatures and duress inherent in fusion reactions, a magnetic field is required to supplant the casing around the fusion
