Value chain · CLM-0042
In plain terms
The 230 watts per square metre figure applies to one frequency and one design lineage. Japanese designs at a higher frequency allow up to about eight times as much.
The claim as recorded
The 23 mW/cm2 figure is not a universal physical constraint on beam power density but the value specific to 2.45 GHz operation in the NASA/DOE design lineage, since three JAXA designs at 5.8 GHz specify 1.1 to 7.8 times that figure at the rectenna, which is consistent with ionospheric absorption falling with frequency.
Scope and limits
Confidence MED. The causal link is inferred, not sourced. The JAXA figures may differ for reasons unrelated to the ionosphere - rectenna cost, land area, or a different risk appetite. Establishing which requires the primary JAXA design documentation, which is not held. This claim may NOT be used to assert that 5.8 GHz permits a higher ionospheric threshold; it establishes only that different programmes use materially different figures and that the difference correlates with frequency. The held 5.8 GHz theory estimates do not sit above all three JAXA figures: 26 mW/cm2 is below both 67 mW/cm2 (runaway) and 42.2 mW/cm2 (422 W/m2, self-focusing at one assumed condition), while 100 and 180 mW/cm2 are above both.
What it assumes
that the JAXA figures were set with ionospheric constraints in mind rather than for unrelated reasons; that ionospheric heating falls with frequency, which is physically expected but not quantified here
Where it comes from
This is the project's own working, shown in full:
Ratios from CLM-0041: 26/23 = 1.1; 100/23 = 4.3; 180/23 = 7.8. The three higher figures are all at 5.8 GHz; the 23 mW/cm2 figure is at 2.45 GHz. CLM-0039 records that the 1978 threshold was derived for 2450 MHz specifically. Theory thresholds at 5.8 GHz do exist: SRC-108 gives approximately 67 mW/cm2 for thermal runaway (CLM-0072), and SRC-104 PDF p12 (printed p8) gives 422 W/m2 for the thermal self-focusing instability at 5.8 GHz against 33 W/m2 at 2.48 GHz, for an electron density of 10^12 m-3 and an electron temperature of 1500 K.
Related records
- Answers question
- QST-001 not published in this releaseQST-009 not published in this release
Cite this
energyaperture.com/c/clm-0042
CLM-0042, Energy Aperture, as of 2026-09.
Connected records
Other published records linked to this one. A list, not a judgement.
- Also from SRC-104
- CLM-0057There is a formula for the instability threshold. It depends on electron density cubed, electron temperature to the fourth power, and...CLM-0059The two fields were largely the same people from the 1970s, and papers linking them were still appearing after 1991.CLM-0075When ESA revisited the question in 2004 it used the 1978 theory and did not cite the 1979-81 Platteville tests or NASA's 1981 revision of...CLM-0079The 1978 paper modelled both a ground facility and a satellite case, and its 500 watts per square metre figure is a power flux for a given...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-0108A 2004 ESA review found that during the October 2003 solar storm, just under 20 per cent of a space solar power beam would have been...CLM-0109In normal conditions the ionosphere takes essentially none of the beam. In a severe solar storm it could take a little under a fifth of it.CLM-0130The quiet-condition absorption figures from four sources do not disagree. One of them states an upper bound and the others sit inside it.More on the source page.