Talk:Sodium Scenario

Thinking Moon

The Sodium entry is a good example of thinking Moon. That is, looking at ideas that are insignificant when used on Earth but could really save the day when used on the Moon. It does take a rather long scenario to show how Sodium could be used, but this is part of the process needed to compare complicated technical ideas.

--Jriley 13:25, 11 May 2007 (UTC)

The only problem I see is that sodium/potassium may not be suitable for buried wires, as described in the Sodium Scenario, as they can be easily scooped with a spoon or cut with a knife. Even if the wire is re-enforced with fibers and an iron core, malleability of the conductive layer could prove to be an issue in high use areas. Excavations and geologic settling would need to be very closely monitored. Long term studies of this kind of buried wire combo may have very interesting results. Would Na and K slowly mix and produce NaK? Would there be enough heat or tension to meld them together? How would the wire deform under varying subterranean pressures? I also cannot help my curiosity about the rate of loss experienced by bare cable buried in lunar regolith, as it will be interesting to see what effects the nano-phase surface iron may have on an uninsulated circuit. How could all of the above effects be mitigated? Oh, what I would give for a bag of mare simulant and a couple of vacuum chambers in a real lab right about now.

Jarogers2001 17:22, 12 May 2007 (UTC)

I thought they got somewhat cold winters where you live. Have you never seen condensation on windows and walls in winter? (Not usually prevalent in modern homes, but was quite a problem in older stone, brick and block buildings in much of Europe)

Luna's not very cold, but it's not very warm underground either, certainly not warm enough to eliminate the possibility of condensation. So I don't think sodium is suitable for indoors. Outdoors there's the problem of the daytime heat, more than enough to melt sodium.

If you're going to go to the trouble of using an iron core, I don't think sodium offers enough of an advantage over just using iron on it's own. And remember, they only use conductive skins to mitigate skin effect, something that's not particularly bad over relatively short spans at high voltage and low frequency. Basically your common HT cable on Earth is steel, they just put an aluminum skin on it to reduce losses.

Technically these two posts should be moved to Talk:Sodium_Scenario. If you move yours, I'll move mine. Using export - import isn't worth the headache for two posts. :)

-- Mdelaney 01:25, 13 May 2007 (UTC)

Just a fairly minor nitpick, technically 2 kHz qualifies as RF, but it's ULF band, very specialized and very narrow bandwidth. According to http://en.wikipedia.org/wiki/Radio_frequency it's listed for use in: Communication within mines. Not too sure if they mean mines(boom) or mines(coal) if you know what I mean. But if they mean the latter, we might need to keep that clear for our own mining ops.

2 kHz would definitely be subject to skin effect though so the point of using a better conductor in the skin is well taken. But might it not be just as effective to use a lower frequency and a slightly thicker iron cable? (We can probably get away with iron dust transformer cores at frequencies as low as 400 Hz).

2 kHz 3 phase would produce a full-wave-rectified power-supply ripple frequency of 12 kHz, should be easy enough to filter out, but could be very irritating in the wrong place if a smoothing capacitor(condenser) goes open circuit (nowhere near as likely as a short circuit with electrolytics).

-- Mdelaney 04:02, 13 May 2007 (UTC)