HyperV Technologies is pursuing a unique “pulsed ignition” approach to fusion that has the promise to dramatically reduce the level of complexity, reliability and maintainability of the reactors. The HyperV approach will use an array of plasma jets to drive a pulsed implosion upon centimeter sized magnetized fuel targets in microsecond timescales.
MiniRailgun Accelerator for Plasma Liner Driven HEDP and Magneto-Inertial Fusion Experiments (21 pages) 36th ICOPS Meeting, June 1, 2009
A spherical array of minirailgun plasma accelerators is a potential driver for forming imploding spherical plasma liners that can reach HEDP-relevant ( about 0.1 Mbar) pressures upon stagnation. The liners would be formed via merging of 30 or more dense, high Mach number plasma jets (n about 10^16−17 cm−3, M about 10–35, v about 50–70 km/s, rjet about 5 cm) in a spherically convergent geometry. The small (typically 1-2 cm square bore x 15-50 cm length) parallel-plate railguns with ceramic insulators would use pulsed injection of high-Z gas at the breech via fast opening valves to produce high density plasma jets with velocity in the 50-100 km/s range. Recent tests at HyperV using a single pulsed capillary discharge injecting into the minirailgun breech have achieved plasma densities in the bore approaching 10^18 cm−3, with densities in the jet plume exceeding 1017 cm−3 at velocities above 50 km/s. Total plasma jet mass in these 1 cm square bore tests has not yet been determined, but similar tests of an earlier 6 mm square bore 13 cm long device, with a roughly 3 μs, 100 kA current pulse using an aluminized mylar fuse starting from rest, yielded 90 μg of plasma at 50 km/s, and about 40 μg at 63 km/s. A modest scaleup of the railgun to a 2 cm square bore operating at longer pulse widths of 200-300 kA should be capable of accelerating a few thousand micrograms of high-Z gas (e.g. xenon) to above 50 km/s. This performance should be sufficient for reaching HEDP-relevant pressures.
A series of MiniRailguns have been built and tested using plasma injection.
• 200 μg at 85 km/s with capillaries and fast gas valve
• 10^19 cm−3 in bore
• 10^16 - 10^17 cm−3 in plume
• 50 - 8000 μg
• crowbar operation
• rail current augmentation (effectively increases L′)
Initial tests with a Quad MiniRailgun configuration demonstrated with low jitter
Fast Gas Valves now working with Ar, He, N2