The cheapest, smallest reactors will emerge from the so-called magneto-inertial fusion (MIF) parameter space. This physics regime is a hybrid between the low density magnetic confinement and beyond solid density inertial confinement. Many of the smallest proposed fusion propulsion systems are in fact MIF systems, consistent with this recent study. (The Case and Development Path for Fusion Propulsion by Jason Cassibry, Ross Cortez, Milos Stanic)
Among the various MIF confinement schemes, we observe that pulsed z-pinch based approaches have potentially solved many of the perceived problems associated with instabilities, and that breakeven systems may require only ~60 MA of current. Such a current level is only a factor of 3 away from current capabilities at the Sandia Z Machine and a factor of 30 away from a new pulsed power facility being reassembled at the University of Alabama in Huntsville in collaboration with NASA MSFC and The Boeing Company. We offer a potential development path to a TRL 9 flight system, including potential side experiments that can be done to help pay for the development and upgrades to facilites.
* Magnetic fields can make laboratory fusion easier
* Magnetically driven targets driven by pulsed power drivers are energy efficient and could be a practical and cost effective path to significant fusion yields over 100 megaJoules per pulse. Z today couples ~0.5 MJ out of 20 MJ stored to MagLIF target (0.1 MJ in DD fuel)
The pulsed z-pinch approach is perhaps the most direct route to development of fusion propulsion.
Z-pinch yields have been found to scale as ~I^4, where I is the current supplied by the pulsed power system.
5 to 10% of the implosion energy will be transferred to the central hotspot.
SOURCES – Sandia National Lab, University of Alabama