Value chain · CLM-0401
In plain terms
A 2004 review calculated that, under some of the most extreme conditions measured during a large solar storm in October 2003, only just over four fifths of a microwave power beam would get through the ionosphere and atmosphere to the ground, against more than 99.7 per cent normally. The storm lasted more than a day, but conditions varied, so a loss that large probably (our inference) did not last throughout. The standard 1978 efficiency figures include no allowance for it.
The claim as recorded
A severe ionospheric disturbance can be a power availability event for a space solar power station: the 2004 ESA review, using one of the extreme electron density profiles measured during the late October 2003 coronal mass ejection event, calculated that only just over 80 per cent of the power of a 2.48 GHz beam would reach ground level, against over 99.7 per cent under normal conditions; the review states that the event lasted for over 24 hours and produced highly variable conditions in the ionosphere. The 1978 reference efficiency chain carries no ionospheric term.
Scope and limits
The assumption above is doing real work and is not supported by the source. The review applies "one of the extreme density profiles" from a 24-hour event, so 20 per cent is most likely a peak rather than an average. The duty cycle is therefore unknown, and this claim establishes that the effect exists and is material in magnitude, NOT its expected annual energy impact. Severe storms of that class are infrequent. No source reviewed gives a loss-versus-activity-index relation. THE SOURCE CONTRADICTS ITSELF ON THE TWO RECTENNA TERMS, and this record transcribes the labels as printed. DOE-ER-0023's own stage power levels are 6.58, 5.79 and 5.15 GW. 6.58 x 0.88 = 5.7904, matching the printed 5.79 exactly, while 6.58 x 0.89 = 5.8562 does not; the two step ratios are 0.87994 then 0.88946. So the design values are collection 0.88 and rf-dc conversion 0.89, the reverse of the printed labels. SRC-107 (NASA RP-1076, 1981) Table III-1 prints the same power levels with the labels the other way round and states the same 790 MW and 640 MW stage losses, which the subtractions confirm. The 63 per cent overall product is unaffected, because the two terms multiply. The transcription is faithful; the defect is the source's, which is a different defect from a claim misreporting its source and has a different fix.
What it assumes
that the 20 per cent figure would persist across the event rather than only at its peak, which the review does not state and which the phrase "highly variable conditions" argues against
Where it comes from
PDF p8 (printed p4): "Using one of the extreme density profiles from the EISCAT radar, illustrated in Fig. 1, the absorption levels for a 2.48 GHz signal were recalculated. The absorption levels under the enhanced conditions were now found to be significant, with only just over 80% of the SPS beam power reaching ground level". Same page: "The event lasted for over 24 hours and produced highly variable conditions in the ionosphere." Against CLM-0100's finding that the 1978 reference efficiency chain contains no ionospheric term at all, its stages being DC to RF 0.85, antenna 0.965, atmosphere 0.98, rectenna collection 0.89 and RF to DC 0.88.
Related records
- Answers question
- QST-009 not published in this release
- Supersedes
- CLM-0110 not published in this release
Cite this
energyaperture.com/c/clm-0401
CLM-0401, Energy Aperture, as of 2004.
Connected records
Other published records linked to this one. A list, not a judgement.
- 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-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.More on the source page.