Nick_Janow@mindlink.bc.ca (Nick Janow) (06/16/91)
Non-imaging optics could also improve the thermal efficiency of generators. They could possibly turn a working fluid into plasma, driving an MHD generator. This needs a fair bit of work in developing large-scale non-imaging optics and in developing thermal radiators for use in space (though the techniques should work here just as well). I wonder how such a system would compare with other solar generation schemes. -- Nick_Janow@mindlink.bc.ca
printf@cix.compulink.co.uk (Ian Stirling) (06/16/91)
If you can make a workable solar sail how much more difficult is it to make a large parabolic mirror for melting large boulder size chunks of rock? Could you mine a asteroid my melting it and allowing the vapour that comes off to condense on nearby cooled surfaces,using a sort of fractional distilation to seperate the metals.Also could you get higher temperatures than the surface of the sun by filtering the incoming light at the mirror(diffraction grating ?)to leave only the higher energy photons,this does not seem to violate any laws as you are only able to use a small fraction of the incoming light to heat the object but most of the light goes past at lower overall energy. Mail to either |PLEASE do not send large Printf%cix@ukc.ac.uk |(>20K)mail messages as Printf@cix.compulink.co |I get charged for them. Printf@cix.uucp | one of these may work |
lsk91@campus.swarthmore.edu (06/17/91)
In article <1991Jun16.125917.7326@demon.co.uk>, printf@cix.compulink.co.uk (Ian Stirling) writes... >If you can make a workable solar sail how much more difficult is it >to make a large parabolic mirror for melting large boulder size >chunks of rock? It was pointed out to me last year that heating by solar flux doesn't work so well in space since there are no convection currents in the molten stuff (no gravity). I don't recall the specifics of this. If it could work some other way, you wouldn't want to use a parabolic mirror to focus an image of the sun on the rock, you'd want to use a light funnel. See _Scientific_American_ of a few months back for a good article on light funnels. They concentrate *all* the incident solar flux on a spot, a lens or mirror just focuses an image, and thus much flux does not help heating. >you get higher temperatures than the surface of the sun by filtering >the incoming light at the mirror(diffraction grating ?)to leave only the >higher energy photons,this does not seem to violate any laws as you >are only able to use a small fraction of the incoming light to heat >the object but most of the light goes past at lower overall energy. Huh? Even the low energy photons should help to heat up the rock, so no point in filtering them out. Leaving only high energy photons does not necessarily yield higher than surface of the sun temperatures, although you may change the energy distribution profile of your solar flux, you won't change its "temperature".