Historical research guide · 0882 · 2020
Twelve Axioms of Fusion Energy R&D
Daniel L. Jassby
In one minute
Daniel Jassby spent twenty-five years as a plasma physicist at the Princeton Plasma Physics Laboratory, and here he writes down twelve rules he believes seventy years of fusion research have demonstrated. Some are about hardware: the next machine costs three to five times its estimate; every device, with its cryogenics, vacuum and cooling systems, draws enormous electrical power; less than a tenth of the tritium injected into a magnetic device is actually burned, and nobody has yet run the experiment that would breed back more than is lost. Others are about people: proponents rarely concede a concept has failed, review committees approve almost every proposal, and press releases announce breakthroughs whether or not anything moved. His sharpest test is the simplest one — a fusion concept that cannot produce measurable deuterium-deuterium neutrons is not doing fusion, and the neutrons must come from the plasma or target gas rather than from stray ions striking the vessel wall. He wrote it as a checklist for funding agencies.
Connection
This is the hardest scorecard in chapter 1’s evidence ladder, and it is worth reading precisely because the fusion architecture this site follows survives it: NASA Glenn’s lattice confinement work passes Jassby’s neutron test with measured deuterium-deuterium yields, and aneutronic proton-boron-11 fuel steps around his tritium axiom entirely. Anyone building the chapter 12 case should be able to answer all twelve.
From the source
The load-bearing test of any fusion energy concept is measurable deuterium-deuterium fusion neutrons, and they must originate in a heated plasma or target gas rather than from wayward deuterons striking the wall of the reaction vessel; Jassby’s formulation is that no neutrons means no fusion.Axiom #2, Axiom of Manifest Fraud
By the end of 2019, Jassby records, none of the well-funded projects at General Fusion, Helion or Lockheed had produced a single fusion neutron and Tri-Alpha only token amounts, while Phoenix Nuclear Labs had announced peak deuterium-tritium neutron production of 4x10^13 per second, about 100 watts, sustained for more than 100 hours — the best non-government neutron source, built for isotope production and radiography rather than power.Axiom #1, Neutron Reformulation, and Axiom #8
The confinement triple product — plasma density times energy confinement time times ion temperature — is the measurement that ranks concepts: only the stellarator, the laser-heated fuel capsule and Sandia’s MagLIF have reached the 2x10^17 keV-s per cubic metre of the Soviet T-3 tokamak of 1969-70, and the best stellarator result is still at least twenty times below the best tokamak value of 1.2x10^21 keV-s per cubic metre.Axiom #3, The Supremacy Axiom
In any line of fusion energy research the actual cost to completion of the next device runs three to five times the original projection: ITER’s construction estimate grew from about 5 billion dollars to 20 billion and more, the NCSX stellarator was cancelled after a threefold increase, and NSTX-Upgrade needed a further 200 million dollars for rebuilding after 95 million had been spent.Axiom #4, Axiom of Escalating Cost
Counting the whole site’s power draw changes the accounting: TFTR and JET demonstrated Q values of 0.3 to 0.5 in the 1990s but the real energy ratio including facility power would have been of order 0.01, and NIF’s Q above 0.1 refers to energy absorbed by the fuel capsule, with the true ratio smaller by a factor of at least a thousand once laser generation efficiency is included. Jassby’s Electrical Appliance Corollary is that fusion generators turn electricity into neutron streams and will not turn neutrons into net electricity.Axiom #8, Axiom of Massive Electric Power Drain
Tritium is the fuel-cycle bottleneck: less than 10 percent of injected fuel is burned in magnetic confinement devices, up to 30 percent in inertial systems, and full recovery of the remainder is impossible because of trapping, implantation, permeation and radioactive decay — while no experiment to demonstrate a global tritium breeding ratio greater than one has yet been attempted anywhere.Axiom #9, The Tritium Deficit Axiom
The way in
https://doi.org/10.31224/osf.io/mhytuHow to cite it
Daniel L. Jassby (2020) Twelve Axioms of Fusion Energy R&D doi:10.31224/osf.io/mhytu