Value chain · CLM-0869
In plain terms
The 1978 reference report gives two different figures, 88 and 89 per cent, for how much of the beam lands inside the same 5 km circle on the ground.
The claim as recorded
The 1978 DOE/NASA reference system report gives its beam collection efficiency at the same aperture as two different values. Its body text at PDF p.37 states approximately 88 per cent of beam energy within a 5 km radius perpendicular to boresight, while two of its efficiency chains - Figure 5 at PDF p.25 and Figure 25 at PDF p.56 - each LABEL a box RECTENNA ENERGY COLLECTION 0.89. Figure 5's own arithmetic sides with the prose: its printed intermediate powers reproduce only if 0.88 is applied at that box. A third chain, Figure A-9 at PDF p.125, lists Rectenna Energy Collection 0.88 and RF-DC Conversion 0.89 in its Current Reference System column. So the division runs between the box labels of Figures 5 and 25 on one side and, on the other, the prose sentence, Figure 5's arithmetic and Figure A-9's column.
Scope and limits
THIS RECORDS THAT THE DOCUMENT DOES NOT SAY WHICH FIGURE IT MEANS, NOT THAT EITHER IS WRONG. The earlier suggestion that 88 and 89 are simply different roundings of one value is WITHDRAWN: a rounding does not transpose two adjacent boxes, and CLM-0872 shows the arithmetic and the labels disagree structurally rather than by precision. The three-line parenthetical beneath the rectenna row - 10 km rectenna diameter, sigma 10 degrees, plus or minus 1 dB, 2 per cent transmit-array tolerances - is a FIGURE-LEVEL note and not a label of any one box: three of its four conditions are transmit-side, so it cannot describe either the collection or the conversion term alone. It conditions the chain that contains the 0.89, and a 10 km diameter is the 5 km radius of the p.37 sentence.
What it assumes
No assumptions are recorded against this claim.
Where it comes from
Read directly from the held PDF and checked against it before this record was written. PDF p.37, verbatim: "This power beam has approximately 88% of its energy within a 5 km radius perpendicular to boresight, with a resultant beam width of 1.2 arc-minutes." PDF p.25 (printed p.13) Figure 5 carries adjacent boxes RECTENNA ENERGY COLLECTION 0.89 and RECTENNA ENERGY CONVERSION 0.88, with 6.58 GW, 5.79 GW and 5.15 GW printed above the atmospheric-losses, collection and conversion boxes; on our arithmetic 6.58 x 0.88 = 5.79 and 5.79 x 0.89 = 5.15, while 6.58 x 0.89 = 5.86. PDF p.56 (printed p.44) Figure 25 carries RECTENNA ENERGY COLLECTION 0.89 and RF-DC CONVERSION 0.88, the latter with an arrow on to DC POWER; centred below the whole row, under neither box, is "(10KM RECTENNA DIAMETER; sigma = 10 deg, +/- 1dB, 2% TOLERANCES ON TRANSMIT ARRAY)", the Greek sigma and degree sign given here in ASCII. PDF p.125 (printed A-26) Figure A-9, Current Reference System column, lists Rectenna Energy Collection 0.88 and RF-DC Conversion 0.89. The scan's text layer renders the digit 1 as a lower-case L in both the arc-minute figure and the rectenna diameter; the values above are as PRINTED, read from the rendered page, not as extracted.
Related records
- Answers question
- QST-001 not published in this release
Cite this
energyaperture.com/c/clm-0869
CLM-0869, Energy Aperture, as of 1978.
Connected records
Other published records linked to this one. A list, not a judgement.
- Also from SRC-085
- CLM-0013The paper that modern UK studies rely on for the beam figure calls anything below 1 kilowatt per square metre safe, with 230 watts per...CLM-0020The original 1978 design set the beam at 230 watts per square metre in the middle of the receiving site, about one twenty-third of that at...CLM-0023In the 1978 reference design, two limits set the size of the transmitter and the receiving site: how much heat the transmitter can shed...CLM-0039The 1978 report set the figure to protect radio and navigation systems from a disturbed ionosphere, called the number theoretical and...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-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...CLM-0138The original 1978 government design for beaming power down from space adds up all the expected energy losses to get 63% overall efficiency...More on the source page.