Historical research guide · 0359 · 2010
DIRD Inertial Electrostatic Confinement Fusion
DIA / AAWSAP contractor
In one minute
Inertial electrostatic confinement is the fusion machine Philo Farnsworth — the inventor of electronic television — sketched in 1955, and this Defense Intelligence Agency report is its state of the art. The idea is disarmingly simple: hang a negatively charged wire grid inside a vacuum sphere, and ions fall inward, overshoot, come back, and recirculate through a dense core about a thousand times before they are lost. Because the ions are accelerated directly instead of heated as a crowd, a table-top device already reaches fusion energies: the author’s laboratory runs about a hundred million fusion reactions a second, and sealed units have been sold commercially to inspect ore on conveyor belts. The report then walks through the competing theoretical verdicts on whether this can ever reach net power, argues that the pessimistic ones assumed the wrong ion distribution, and closes with a concrete proposal — twelve radio-frequency ion guns aimed at one core to demonstrate breakeven on hydrogen-boron fuel, which returns only charged particles.
Connection
Chapter 12’s argument is that aneutronic fusion is the door worth walking through, and this is the Defense Intelligence Agency’s own survey of the one confinement scheme built around it — small, non-Maxwellian, and already producing fusion on a laboratory bench rather than in a building-sized machine. Its potential-well physics, where a dense self-organised charged core holds itself together, is the laboratory cousin of chapter 9’s plasmoids and charge clusters.
From the source
The inertial electrostatic confinement machine gets its fusion temperature for free: because the ions are accelerated directly by the grid rather than heated as a whole population, ions arriving at the core carry about 80 percent of the applied voltage, so a grid at roughly 25 kV already meets the Lawson temperature condition for deuterium-tritium — while a magnetic machine struggles to reach 10 keV. Trapping then comes from recirculation, typically about a thousand passes through the core, and star-mode operation sends the ion beams through the grid openings so they rarely strike the wires.Section I, IEC Basics, pp. 1-3; Discharge Modes in Gridded Devices, pp. 8-9
Earnshaw’s theorem, which had written electrostatic confinement off, assumes a steady state — and Farnsworth saw in 1955 that dynamically moving, inertially confined ions can electrostatically confine electrons. Hirsch’s calculation for monoenergetic ions with no angular momentum gives nested virtual anodes and cathodes around the centre of the sphere, the structures Farnsworth called poissors, in which the ion density rises without limit at the origin. In practice the spread in energy and angular momentum limits this to a single well, and how deep that well can be made is the field’s central open question.Section I, IEC Background, pp. 3-4; IEC Basics, pp. 5-8; Figure 1.2
The devices are real and measured: Hirsch’s six-gun ion-injected machine exceeded 10⁹ deuterium-tritium neutrons per second at 150 kV — above what simple beam-background reactions predict, implying beam-beam reactions in a potential well, and supported by his collimated neutron and gamma measurements — while gridded devices at Illinois routinely produce about 10⁸ deuterium-deuterium neutrons per second at 80 kV. Sealed getter-pumped units were licensed and used by Daimler-Chrysler on ore delivery belts in Germany, directly replacing californium-252 sources and allowing on-off operation.Section II, Select Experiments, pp. 14-17; Figures 2.1-2.3
The pessimistic theory verdicts rest on assumptions the machine does not satisfy. Nevins calculated a gain of about 0.21 for a 50 kV square well and concluded the scheme shows little promise for power, and Rider found bremsstrahlung prohibitive for the advanced fuels — but both used Maxwellian-averaged rates and a square well. Chacon’s bounce-averaged Fokker-Planck model, with those restrictions relaxed, finds gains in the hundreds provided the well is deeper than about 100 kV, the confinement time is long enough and the ion source strength is moderate; a parabolic well gives gains three to five times a square well’s.Section IV, IEC Theory, pp. 34-44; Table 4.1; Figure 4.3
Aneutronic proton-boron-11 fuel is the target, and the machine’s beam-like plasma is what makes it reachable: the reaction returns three alpha particles and no neutrons, and it needs ion energies near 150 keV, which an inertial electrostatic device supplies simply by applying about 180 kV, where a Maxwellian machine would have to heat an entire distribution to get there. Circulating ion energies at the required 150 keV have already been achieved at Illinois and several other laboratories; what remains is confinement time.Section III, Scale-up to p-11B IEC Space Power Unit, p. 28; Section VI, pp. 60-62; Figure 6.1
The named next measurement is specific. Today’s single-gun device runs about 2 recirculations at 50 mA and a gain near 10⁻⁶. Because the gain scales as recirculations times injected current divided by the square of the core radius, going to 12 differentially pumped radio-frequency ion guns — raising recirculations to about 1,000, current to 6,000 mA and shrinking the core spot tenfold — predicts a 10⁸ increase, that is breakeven for proton-boron-11. The proposal is to demonstrate it first in a hydrogen plasma with a 1 MW, 1 millisecond Marx-bank pulse at 0.01 Hz, measuring the density-time product directly.Section VI, Proposed Breakeven Experiment, pp. 62-64; Figures 6.2-6.4
The way in
https://documents2.theblackvault.com/documents/dia/AAWSAP-DIRDs/DIRD_09-DIRD_Inertial_Electrostatic_Confinement_Fusion.pdfHow to cite it
DIA / AAWSAP contractor (2010) DIRD Inertial Electrostatic Confinement Fusion https://documents2.theblackvault.com/documents/dia/AAWSAP-DIRDs/DIRD_09-DIRD_Inertial_Electrostatic_Confinement_Fusion.pdf