Aneutronic fuel and the compact machines that suit it

Why the library suggests it

TAE Technologies and Japan's National Institute for Fusion Science produced the first proton-boron-11 fusion inside a magnetically confined plasma, dropping boron powder into the edge of the Large Helical Device and firing three 2 MW hydrogen beams at 160 kilovolts; a silicon detector out of the plasma's direct line of sight counted about 150,000 fusion products a second with boron present and under a thousand without (First measurements of p11B fusion in a magnetically confined plasma, 2023). Their own conclusion names the lever this site cares about: the rate can be pushed by engineering the particle distribution rather than only by raising temperature. LPPFusion's dense plasma focus reports a mean confined ion energy of 240 kiloelectronvolts — inside the range proton-boron-11 needs — from a plasmoid only tens of microns across holding a large share of the machine's whole energy, with the products emerging as an ion beam one way and an electron beam the other so current is induced directly in a coil (Focus Fusion: Overview of Progress Towards p-B11 Fusion with the Dense Plasma Focus, 2023). The work order for the first decaborane shots, with the instruments already installed, is Preparations for pB11 tests in the FF-2B dense plasma focus (2024). On the compact side, Princeton's field-reversed configuration holds its plasma inside closed field lines the plasma largely makes for itself, in a tube four to eight metres long, heated by an odd-parity rotating magnetic field; PFRC-2 has heated electrons past 500 electronvolts and held plasmas for 300 milliseconds (The Princeton Field-Reversed Configuration for Compact Nuclear Fusion Power Plants, 2023), and Samuel Cohen makes the case for that whole size class to the committee that sets the decade's priorities in FESAC Decadal Study: Clean, multi-purpose fusion power from small field-reversed configuration reactors (2024).

The experiment or build

The near-term rung is direct conversion, not ignition. Take an existing machine that makes charged fusion products at any rate at all, and instrument the collection: put a coil or a set of biased grids in the product path and measure the electrical energy recovered per fusion event. The settling measurement is joules of electricity out per joule of fusion product energy, on a real machine, with the collection efficiency stated separately from the fusion yield. That number is the whole economic argument for aneutronic fuel and it is almost never published.