Value chain · CLM-0066
In plain terms
The figure adopted in 1978 was higher than each of the lower figures in the studies it cited, though those figures were themselves uncertain by up to a factor of two.
The claim as recorded
The adopted 23 mW/cm2 figure exceeds each of the three lower figures in the studies cited for it: Duncan and Gordon's thermal runaway threshold of 12 mW/cm2 (within a factor of two); the Raytheon critical power of 15 mW/cm2; and 20 mW/cm2, which Duncan and Gordon's abstract reports as a previously predicted self-focusing threshold (within a factor of two) while their body says a self-focusing threshold cannot be determined in the usual sense, and which the Raytheon study gives as the level above which irregularities are possible.
Scope and limits
It remains inside Duncan and Gordon's stated factor-of-two band of 6 to 24 mW/cm2 (CLM-0045), so it is not outside the evidence. And Duncan and Gordon state their own simplifications bias the threshold low (CLM-0072), which argues the true value is higher than any of these central estimates. So exceeding them is not necessarily wrong. This claim establishes the arithmetic relationship only, and no source found explains the choice. The 1.15 ratio against 20 mW/cm2 is not a precise margin: that figure is stated within a factor of two, Duncan and Gordon's body says a self-focusing threshold cannot be determined in the usual sense (SRC-108 PDF p23, printed 3-10), and the Raytheon 20 mW/cm2 concerns possible irregularities, not self-focusing. Raytheon's own self-focusing figures are 70 to 200 mW/cm2 (SRC-112 p67).
What it assumes
No assumptions are recorded against this claim.
Where it comes from
This is the project's own working, shown in full:
23 against 12 is 1.9 times; against 15 is 1.5 times; against 20 is 1.15 times. Figures from CLM-0072, CLM-0065 and the adopted value in CLM-0020.
Related records
- Answers question
- QST-010 not published in this release
Cite this
energyaperture.com/c/clm-0066
CLM-0066, Energy Aperture, as of 2026-09.
Connected records
Other published records linked to this one. A list, not a judgement.
- Also from SRC-108
- CLM-0043The study the 1978 reference system cites put the level where the beam may start to disturb the ionosphere at about 20 milliwatts per...CLM-0045The apparent conflict between 12 and 23 was not an error. The underlying study gave a range, and the figure adopted sits near the top of it.CLM-0072The 1978 study gives 12 milliwatts per square centimetre for runaway, give or take a factor of two, and says no threshold can be set in the...CLM-0082The formula is the right one for the conditions space solar power would create. It was written for this case, not borrowed from a different...CLM-0083The formula is the right type but nobody has said how far it can be pushed, and at space solar power frequencies the wave is about 200...CLM-0085The 1978 formula does not give a threshold. It relates threshold power to the width of the plasma structures produced, so getting a single...CLM-0101The 1978 contract required the researchers to report fixes if ionospheric disturbance pushed the pilot-beam phase error past 2 to 3...CLM-0132A 1978 NASA-funded study calculated that a beam of about 12 milliwatts per square centimetre at 2.45 GHz would be the point where the...More on the source page.
- Also from SRC-112
- CLM-0065A Raytheon study eight months earlier, by the same authors as the lost memorandum, gave a critical power of 15 milliwatts per square...