Value chain · CLM-0083
In plain terms
The 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 times the plasma frequency. The field's own 2007 review says the case is unclear.
The claim as recorded
No source examined bounds the self-focusing relation's validity quantitatively across the underdense range; underdense is used only as a qualitative label meaning wave frequency above plasma frequency, whereas at 2.45 GHz the ratio is about 200, and the URSI report states it is unclear how important the effect is for an underdense plasma where the microwave frequency is much greater than the plasma frequency; the 1978 report states that no underdense self-focusing experiment had been attempted, and no source examined reports one that verifies the theory for the SPS case.
T3 government or agency report · high confidence · as of 2007 · VER-2636 CONFIRMED 2026-10-22 (audit fix, set AF2); VER-704 CONFIRMED 2026-09-04 · VC06
Evidence behind this: RE-GRADED T2 to T3 on 2026-09-11, under the weakest-source rule. SRC-108 is NASA-CR-151821, a NASA contractor report - an agency report with named authors and a published method, which is T3, and not a peer-reviewed venue. The claim's verbatim quote is confirmed at PDF p.8, word for word.
Scope and limits
A negative finding over the sources examined, which do not include Perkins and Valeo 1974 or Perkins and Goldman 1981 in full, both paywalled. Either might state a domain.
What it assumes
No assumptions are recorded against this claim.
Where it comes from
SRC-108 Ionosphere/Microwave Beam Interaction Study, NASA-CR-151821, 1978
SRC-100 URSI White Paper on Solar Power Satellite Systems (clean full text, 194 pp), 2007-06
SRC-104 Ionospheric interactions with high-power microwave beams, ESA/University of Leicester review,...
p1-1 verbatim: "The theory and observations of thermal self-focusing are in agreement when the ionospheric plasma is overdense... However, there are no observations available to compare with the theory of thermal self-focusing for the SPS case, underdense ionospheric plasma (the local plasma frequency is less than the heating frequency), and these observations, supplemented by full diagnostics, are needed to verify the frequency and power density scaling relationships." SRC-100 p148 verbatim: "Such effects are well known and have been studied from HF-heating experiments, but it is unclear how important this is for an underdense plasma where the microwave frequency is much greater than the plasma frequency." The 2004 review's only stated caveat concerns the arbitrary growth-rate criterion defining threshold, not a frequency domain. THE SOURCE SUPPORTS THIS CLAIM MORE STRONGLY THAN THE CLAIM WAS QUOTING IT, found 2026-09-11. The record rested on a passage that only CALLS FOR observations. At PDF p.35 the same report states the thing directly: "Although results of overdense self-focusing experiments agree with theory, underdense heating is sufficiently different that experimental work is needed to verify frequency and power density scaling relationships. No underdense self-focusing experiment has been attempted, primarily because diagnostics were not capable of detecting the large-scale irregularities should they form." That is a first-hand statement of the claim's no-experimental-verification half, from the source already cited. At PDF p.23 the report gives the threshold relation itself without bounding its domain of validity, which is what supports the claim's separate point that no source bounds the relation quantitatively.
Related records
- Answers question
- QST-009 not published in this release
- Contradicts
- CLM-1013 By 1980 the programme had made the upper ionosphere ripple with a heater running at what it... on the "never attempted" half - DOE's August 1980 summary reports two underdense-mode self-focusing experiments at Platteville with irregularities and LES-8 scintillation observed uninterpretable for SPS pending the 1/f^3 law
Cite this
energyaperture.com/c/clm-0083
CLM-0083, Energy Aperture, as of 2007.
Connected records
Other published records linked to this one. A list, not a judgement.
- Also from SRC-100
- CLM-0032In 2007 the international radio science union published a white paper saying that nobody had measured this heating effect from the ground...CLM-0047Heating falls with the square of frequency. In 2007 no ground-based measurement of it was available at gigahertz frequencies, and...CLM-0048An international scientific body reviewed the proposed figures, found them ranging from 230 to 1,000 watts per square metre, and chose 300...CLM-0049The stated design intent in a 2007 URSI white paper is that the beam would be shaped to fall to 10 watts per square metre by the edge of...CLM-0067According to a 2007 international report, Japanese designs of the time chose their beam strength on cost and land grounds; the report does...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-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...More on the source page.
- Also from SRC-104
- CLM-0042The 230 watts per square metre figure applies to one frequency and one design lineage. Japanese designs at a higher frequency allow up to...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-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.
- 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-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.
- Contradicted by
- CLM-1013By 1980 the programme had made the upper ionosphere ripple with a heater running at what it reckoned was four to twelve times the beam's...