Value chain · CLM-0947
In plain terms
A 1982 Japanese review calculates that the ionosphere absorbs about one part in fifty thousand of a 2.45 GHz power beam - around 0.1 MW from a 5 GW beam. That is nothing to the power system. The same sentence says it is still enough to warm the E-region, especially at night.
The claim as recorded
A 1982 Japanese assessment puts ionospheric collisional absorption of a 2.45 GHz power beam at about 2 x 10^-5 of incident power - roughly 0.1 MW out of 5 GW - and says in the same breath that this is negligible for power transmission and not negligible for the ionosphere. It states that collisional absorption near 2.45 GHz varies as the inverse square of frequency, that daytime D-region and E-region absorption dominates, and that the resulting absorbed energy flux density of about 1 erg/cm2 is expected to produce an E-region heating effect particularly at night.
Evidence behind this: T3, from SRC-141's own row. A national laboratory's quarterly review article, primary for what that laboratory assessed and not a measurement.
Scope and limits
THIS IS AN ASSESSMENT, NOT A MEASUREMENT, and the record must not be read as an observed absorption figure. NO UNCERTAINTY IS STATED and the paper gives none. THE SECOND HALF OF THE SENTENCE IS THE PART MOST EASILY LOST: anyone quoting the 2 x 10^-5 as "absorption is not a problem" would be dropping the clause that says it is a problem for the ionosphere, and the two clauses are joined by a single concessive in the original. IT IS ALSO NOT THE ABSORPTION PERCENTAGES SCN-003 DISPUTES. If that dispute concerns figures in the tens of per cent, this document states 0.002 per cent at 2.45 GHz and so contradicts them rather than sourcing them. AND IT DOES NOT CLOSE CLM-0557. The inverse-square law here is COLLISIONAL absorption; CLM-0557 concerns a frequency-scaling law for THERMAL SELF-FOCUSING, a different phenomenon with a different exponent - Duncan's threshold goes as f^+3. A microwave-frequency statement about one is not the missing derivation for the other.
What it assumes
No assumptions are recorded against this claim.
Where it comes from
Read first-hand at PDF p.4, printed p.726, section 2.4 (absorption), and transcribed from the Japanese with the raw rendering shown where the text layer is corrupt. Verbatim: "電子の衝突による吸収は，電波の周波数が2.45GHz付近では周波数の自乗に反比例し，日中のD領域及びE領域での吸収が主要なものである。マイクロ波ビームの吸収電力は入射電力の2x10-5程度，つまり伝送電力5GWのうち約O.lMWが吸収されることになる。" "O.lMW" is letter-for-digit corruption of "0.1 MW" and is shown unrepaired; the arithmetic confirms the reading independently of any judgement, since 2 x 10^-5 of 5 GW is 0.1 MW exactly. The second half, same paragraph: "この吸収量はマイクロ波の電力伝送にとっては問題とはならないが，吸収エネルギー束密度は約1 erg/cm2となるのでE領域での特に夜間における加熱効果としての影響が現れると考えられる。" THE EXTRACTOR MATTERS HERE AND IS NAMED: PyMuPDF decodes this document's Shift-JIS correctly, while pypdf emits mojibake - see pdfnorm class 10, which is a property of the extractor and not of the document.
Related records
- Answers question
- QST-009 not published in this releaseQST-017 not published in this release
Cite this
energyaperture.com/c/clm-0947
CLM-0947, Energy Aperture, as of 1982.
Connected records
Other published records linked to this one. A list, not a judgement.
- Also from SRC-141
- CLM-0126The 1982 source behind the disputed 10 per cent absorption figure actually says absorption is 0.002 per cent, and never mentions solar...CLM-0149A 1982 Japanese government radio-research review says the famous 230 watts-per-square-metre figure was only ever a theoretical calculation...CLM-0150A 1982 Japanese review notes that, at the time, the American and Soviet safety limits for microwave exposure were far apart (1000 times, by...