Value chain · CLM-0461
In plain terms
The ionosphere absorbs about one part in a hundred thousand of the beam. It is not a meaningful loss.
The claim as recorded
By the knowledge base's three-layer estimate, ionospheric absorption of a space solar power beam is negligible as an energy loss, at a total fractional absorption of about 9.2e-6 at 2.45 GHz and 1.6e-6 at 5.8 GHz, which is roughly 18 kilowatts from a 2 gigawatt beam; the ratio of 5.60 between the two frequencies follows from the inverse-square frequency dependence of collisional heating.
Scope and limits
A crude three-layer slab, which is why it sits about a factor of three below SRC-105's full-path calculation. The agreement in order of magnitude with SRC-105 is the check that makes it usable; the frequency ratio is not an independent check, because the relation is inverse-square in frequency whenever collision frequency is far below wave frequency. The absolute figure should be quoted from SRC-105 rather than from here. The source of the absorption-coefficient form is not recorded. The 1978 NASA study's own table (SRC-108 printed p.4-7, Table 4-2) gives ionospheric loss from a 5 GW beam as 0.25 kW at 2450 MHz and 1 kW at 5800 MHz, a fraction of about 5e-11 at 2450 MHz (our arithmetic), about five orders of magnitude below this estimate, and rising rather than falling with frequency, against the same report's statement of inverse-square scaling (printed p.4-1); the table shows no working, so the disagreement is unresolved.
What it assumes
representative layer densities and collision frequencies rather than modelled profiles; vertical incidence
Where it comes from
This is the project's own working, shown in full:
Our calculation: non-deviative absorption coefficient kappa = (e^2/(2 eps0 me c)) x Ne nu/(omega^2 + nu^2), evaluated over a three-layer slab: D region 1e9 per cubic metre and 1e6 per second over 10 km, E region 1e11 and 1e5 over 20 km, F region 1e12 and 1e3 over 200 km. Independently corroborated by SRC-105, which computes 29.4 kW at 2.45 GHz and 5.11 kW at 5.8 GHz from a 1 GW beam, a fractional loss of 2.9e-5 (our arithmetic), the same order as this estimate and about three times larger. A 1978 NASA study states that "ohmic heating scales as the inverse square of frequency" (SRC-108 printed p.3-3) and gives the 2450 to 5800 MHz reduction as "a factor of 5.6" (printed p.4-1).
Related records
- Answers question
- QST-009 not published in this release
- Supersedes
- CLM-0099 not published in this release
Cite this
energyaperture.com/c/clm-0461
CLM-0461, Energy Aperture, as of 2026-09.
Connected records
Other published records linked to this one. A list, not a judgement.
- Also from SRC-105
- CLM-0058 (low confidence)A 2026 modelling paper finds that a reference space solar power beam stays well below the instability thresholds at both candidate...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.CLM-0440 (low confidence)A 2026 computer model of a gigawatt-class space solar power beam finds it would barely disturb the density of the upper atmosphere's...
- 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.