Value chain · CLM-1461
In plain terms
A 1981 computer model predicted that a space solar power beam would make electrons in the lower ionosphere two to three times hotter and change their number by up to half, and the study found that radio measurements during ground-based heater tests in Colorado broadly matched its model, though by day the heater could not reproduce the beam's full effect at the greater heights. A 1980 US government report said measurements during the Colorado tests showed the electrons' temperature changing while the heater was on, and that calculations by the same lead author matched another researcher's figure for how far such a heater can raise it; the memo behind that figure is not held, so whether it was measured cannot be checked.
The claim as recorded
Meltz, Rush and Violette (1981) model, for the nominal 23 mW/cm2 SPS design flux, an electron-temperature rise by a factor of 2 to 3, an electron-density decrease of up to 50% below 80 km and an increase of up to 20% above 80 km in the lower E-layer, and report that ionosonde phase and attenuation measurements made with the Platteville HF heater agree generally closely with their fluid model once differences between the model and the actual electron density distribution are allowed for, while absorption kept the heater below SPS-equivalent flux in the E-region, so the predicted E-layer density increases were not simulated by day. DOE/ER-10003-T2 (1980), in its account of cross-modulation measurements during the Platteville tests, says its experimental studies show the electron temperature was changing in the D and E regions while the heater operated, giving no size for the change, and reports that studies by Chilton, in the limited-distribution memo NTIA TM 79-4, "indicate that the electron temperature above Platteville can be raised" from a 200 K background to 300 to 500 K "using powers such as employed in the experiments", and calls this a very close match to the theoretical calculations of Meltz and Nighan (1980); it does not say whether the 300 to 500 K range was measured or calculated, and the density changes it gives are from those calculations.
Scope and limits
The Platteville tests used a ground-based HF heater as an analogue of the SPS beam, not a microwave beam at GHz frequency; the ionosonde comparison tests the model indirectly and is not a measurement of density change at SPS flux; SRC-109 PDF p.64 says the heater can simulate the SPS beam's effects in the D-region but, by day, not in the E-region. SRC-110 PDF p.53 gives no size for the temperature change its experimental studies showed. The p.12 figures are for a midday, solar-maximum case that the paper calls perhaps a worse case. Measured electron-temperature rises from the Arecibo heating experiments, up to a factor of two at 75 km, and the modellers' own report that Arecibo measurements validate the model, are in CLM-1068 (SRC-449, April 1980). The Chilton memo SRC-110 cites, NTIA TM 79-4, is not held; the held NTIA Report 81-66 of March 1981 by the same author on the same subject (SRC-737, CLM-1378) gives electron temperature against transmitter power from theory, and its measurements are 1973 cross-modulation data, so it does not settle whether the 300 to 500 K range was measured. The model's factor of 2 to 3 on a 200 K background is 400 to 600 K (our arithmetic), overlapping 300 to 500 K; SRC-110 calls the agreement very close.
What it assumes
The scaling of the Platteville HF facility's power to an SPS-equivalent 23 mW/cm2 is the sources' own and is not re-derived here.
Where it comes from
PDF p.12 (printed p.10): "the electron temperature is raised by a factor of 2 or 3"; "below 80 km, 3-body attachment to molecular oxygen decreases the electron density by as much as 50 percent"; the lower E-layer changes "cause electron density increases of up to 20 percent". PDF p.19 (printed p.17), at the 23 mW/cm2 design flux: "the temperature increase is between a factor of two to three times ambient". PDF p.64 (printed p.62): "Using the fluid theory results, we have made detailed comparisons of the predicted and observed ionosonde measurements. The agreement is generally close if one allows for the differences between the electron density model and the actual distribution."; "As a result the expected density increases are not simulated during the day". SRC-110 PDF p.53 (printed p.38), read at the page image: "The experimental studies show that the electron temperature was changing in the D and E regions during the time the Platteville Facility was operating. Studies by Chilton (NTIA TM 79-4, limited distribution) indicate that the electron temperature above Platteville can be raised from a background level of 200 ... K to between 300 and 500 ... K using powers such as employed in the experiments" (the page prints a degree sign before each K); "This change in electron temperature corresponds very closely to recent theoretical calculations"; "(Meltz and Nighan, 1980). The same studies show electron density increases of 10 - 20 percent in the E region and decreases of up to 50 percent below 80 km".
Basis: factor increase in electron temperature; percentage change in electron density; 23 mW/cm2 beam equivalent
Related records
- Answers question
- QST-001 not published in this release
- Supersedes
- CLM-0162 not published in this release
Cite this
energyaperture.com/c/clm-1461
CLM-1461, Energy Aperture, as of 1980-1981.
Connected records
Other published records linked to this one. A list, not a judgement.
- Also from SRC-110
- CLM-0102A 1979 field test found no heating effect on the two navigation systems tested, but did find cross-modulation on time-signal stations and...CLM-0103Solar flares during the same campaign disturbed the same navigation signals far more than any effect that could be put down to the heater...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...CLM-0139Real measurements at the Arecibo Observatory in 1980, in the same physical regime relevant to space solar power beams, found electron...CLM-0163On the exact same navigation-radio circuits used to test simulated space-solar-power heating of the upper atmosphere, a single ordinary...CLM-1378The 1981 report found online is by the same author about the same heating experiments, but it is not the 1979 memo the 1980 government...