The propulsion plant of the Zheng He is a Barr Fusion Industries type 702 milspec helium-3/deuterium fusion tandem mirror stardrive with a Al-Qawiyy Fleet Systems direct conversion electrical generator.
History
In the late 2470s, The Allied Worlds Space Force desired a new high-performance stardrive (a term indicating any high-efficiency propulsion system capable of a 10% g acceleration) to improve its capabilities to respond rapidly to distant emergencies without keeping large numbers of ships forward-deployed throughout the Allied Worlds' jurisdiction, an expensive proposition.
The BFI-702-M stardrive was designed to the AWSF's specifications by Barr Fusion Industries of Heidelberg, a leader in the fusion sector, the contract for its development being awarded after a competitive process which concluded in 2481 AE. Legendary chief designer Shi-tsen Jiang worked with the synthetic intelligence Heidelberg Q37 'Quint' and a team of engineers for six years on the design, simulations and engineering prototypes. Construction (in orbit) of the full prototype began in orbit in 2487 and was completed in early 2489, achieving first ignition later in the year after extensive testing. AWSF's Materiel Command engineering inspectors deemed the prototype to meet the space force's specifications and officially accepted it on behalf of the Allied Worlds on 6/2490 AE. A production line was established and the first regular production drive was delivered to the orbital shipyard where the future AWS Buraq was being constructed in 2492, with the capacity being four per year.
In 2500, the AWSF cut its order from four drives per year to two. In 2505, the AWSF's cut its order entirely, but paid BFI a lump sum for its remaining parts inventory and to preserve the production tooling and documentation for future reactivation. The tooling remains in a large warehouse owned by BFI. Spare parts inventory was taken by the AWSF into its maintenance and logistics system.
The BFI-702-M was used in the Buraq class of rapid response ships, for which it was designed, the Miri class of fast transport ships. A light drone carrier was planned, and drives were purchased in anticipation of it, but the project was canceled. In total, 33 of the production drives BFI produced were used in AWSF ships, out of 48 built. (10 were intended for the light drone carrier that failed to materialize; the other 6 were for replacements or additional ships.)
31 BFI-702-M drives remain either in active service or mothballed in the reserve fleet. One was destroyed with the fast transport ship using it, the AWS Ridge Ten in the Dirac civil war intervention, by an antisatellite rocket launched by the Empire of Dirac. Another was deemed beyond economical repair after an accident in which a metal object, thought to have been a trim weight and structural parts, found its way inside the drive of the AWS Senrima while the ship was docked to an orbital station around Rosmerta for an overhaul. The shipyard's reactor operators tried to start the drive unsuccessfully, and did not investigate the cause of the failure until after they had repeatedly attempted startup (on station power.) The result was that high-Z elements from the debris were sputtered onto the plasma-facing material, heavily contaminating the drive with long-lived radioisotopes and creating a persistent plasma contamination problem. A technician sent to inspect the drive after the shipyard operators finally gave up received a lifetime radiation dose and was forced into early retirement. The incident resulted in the cancellation of Rosmertine Space Yards' maintenance contract with the AWSF, citing the incident as evidence of poor safety practices and operator training. There were several lawsuits and firings. RSY filed for bankruptcy six years later. Some former RSY employees claim that the debris was placed in the drive as an act of sabotage by a disgruntled former shipyard worker. The Senrima had a new drive installed and was returned to service, before being removed from active service in 2507.
The prototype propulsion plant was used for training purposes until 2502, at which point in was sold to the United Cities of Heidelberg for use in a new Presidential Starship. The President found the fueling costs prohibitive and the planetary government paid BFI to convert it for deuterium/deuterium fusion, which was successfully accomplished, but at a severe performance cost, because it was limited by the increased neutron radiation of D/D fusion and could only be operated at fractional power.
The Space Force Oversight Committee, in its Deccenial Report, considered the Advanced Helium-3 Stardrive project of which the BFI-702-M was the main product, to have been a qualified success. The AWSF was criticized for having ordered too many of them, however.