Value chain · CLM-1094
In plain terms
The 1978 Rice report the archive holds is the follow-on to the 1977 one that the reference system cites, and the 1977 report, obtained the same day, gives about 20 milliwatts per square centimetre with no band and no derivation. The 12 milliwatts per square centimetre figure is worked out in the 1978 report from a simple heating-versus-cooling balance, and the authors say their simplifications make the real threshold higher, not lower, and that nobody had observed the effect.
The claim as recorded
The held Duncan and Gordon report (CR-151821, July 1978, STI accession N78-30475) is the successor to DOE/ER-0023's reference 26, not reference 26: the held report refers to "the previous report on this contract" and cites "Duncan and Gordon, 1977" three times, and ER-0023 cites September 1977 with the 1977 accession N77-33389. In the held body the 12 mW/cm2 thermal runaway threshold is derived analytically (equation 9, F = 2.8e-13 f0^2 Tn^(-1/2) erg/cm2 s, 1.2e5 at 2.45 GHz and 200 K, 67 mW/cm2 at 5.8 GHz) from ohmic heating against rotational cooling of N2 and O2 alone, and the "factor of two" is the report's stated accuracy, "about the same accuracy to which the cooling reaction rates are known"; the report says its neglect of O(3P) fine-structure cooling and of a model ionosphere makes the estimate an underestimate of the true threshold, increasingly so with altitude, and that "no experimental observations of electron thermal runaway in the ionosphere have been reported".
Evidence behind this: T3-the report's own body, title page and STI label read at the render, against the reference list that cites it.
Scope and limits
The September 1977 report (N77-33389, NASA-CR-151517, NTRS 19770026445) was obtained 2026-09-19 and carries no 12 mW/cm2, no factor of two and no analytic derivation; its runaway threshold is "approximately 20 mW/cm2" (PDF p.12 / 3-3, render), scaled from a 15 MHz, 1 MW Arecibo experiment. So the 12 mW/cm2 and its band are July 1978 work that DOE/ER-0023 (October 1978) does not cite; against the document it does cite, the adopted 23 is 15 per cent above the reference's 20. The held 1978 file's contents page lists a REFERENCES section at R-1 that is not in the 66 pages, and its STI label says "53 p". The sources row's "NTRS 19780022532" is the 1978 report's own id (accession 78N30475 on the NTRS record), so the row's pairing of it with N77-33389 joined two documents.
What it assumes
No assumptions are recorded against this claim.
Where it comes from
PDF p.2, render: "July 1978", "N78-30475", "(NASA-CR-151821) ... Final Report (Rice Univ.) 53 p", "SEP 1978 RECEIVED NASA STI FACILITY". p.5, normalised: "proposed in the previous report on this contract". p.13, normalised: "theoretically studied (Duncan and Gordon, 1977; Duncan and Zinn, 1978)". p.16, raw: "has been reported previously (Duncan and Gordon, 1977)". p.63, normalised: "An extension of the experiment proposed by Duncan and Gordon (1977)". p.4, render: "power density threshold of 12 mW/cm2 (within a factor of two)". p.8, render: "Thermal runaway is predicted within a factor of two to occur at a power density of 12 mW/cm2 for the 2.45 GHz SPS frequency (see Section 3.2)". p.18, normalised: "our calculation does yield a threshold value which is probably accurate to within a factor of 2, about the same accuracy to which the cooling reaction rates are known"; render: "our calculated thresholds will underestimate the true threshold predictions established through sophisticated numerical computations including a detailed model ionosphere". p.19, render: equation (9) with the exponent printed as -1/2; "F = 1.2 x 10^5 erg/cm2 s = 12 mW/cm2"; "approximately F = 67 mW/cm2". p.20, render: "we have underestimated the instability threshold, with the amount of error again becoming larger with increasing altitude"; raw: "with an accuracy of about a factor of 2". SRC-085 PDF p.97, text layer: "26. "Ionosphere/Microwave Beam Interaction Study," L. M. Duncan and W. E. Gordon, Rice University, Contract NAS9-15212, September 1977 (N77-33389)"; the same entry on p.199. Equation (9) reproduced from equations (6) and (8): the runaway condition Q+ > Q- for all Te gives F/f^2 > (5.4e-26/7.4e-14) x max[(Te - Tn)/Te^(3/2)] = 7.30e-13 x 0.3849 Tn^(-1/2), coefficient 2.81e-13 against the printed 2.8e-13; 2.8e-13 x (2.45e9)^2 x 200^(-1/2) = 1.19e5 erg/cm2 s.
Basis: mW/cm2; erg/cm2 s
Related records
- Answers question
- QST-010 not published in this release
Cite this
energyaperture.com/c/clm-1094
CLM-1094, Energy Aperture, as of 1978-07.
Connected records
Other published records linked to this one. A list, not a judgement.
- Also from SRC-085
- CLM-0013The paper that modern UK studies rely on for the beam figure calls anything below 1 kilowatt per square metre safe, with 230 watts per...CLM-0020The original 1978 design set the beam at 230 watts per square metre in the middle of the receiving site, about one twenty-third of that at...CLM-0023In the 1978 reference design, two limits set the size of the transmitter and the receiving site: how much heat the transmitter can shed...CLM-0039The 1978 report set the figure to protect radio and navigation systems from a disturbed ionosphere, called the number theoretical and...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-0101The 1978 contract required the researchers to report fixes if ionospheric disturbance pushed the pilot-beam phase error past 2 to 3...CLM-0137In four major space solar power studies from 1978 to 2007, none put a number on how much of the beam's energy would be lost if the beam...CLM-0138The original 1978 government design for beaming power down from space adds up all the expected energy losses to get 63% overall efficiency...More on the source page.
- 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-0066The figure adopted in 1978 was higher than each of the lower figures in the studies it cited, though those figures were themselves...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...More on the source page.
- Also from SRC-587
- 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.