the onion

[Dr_Barnowl]

I wonder if you could tune This for X-rays ; it would certainly make assembly easier.

[vansig]

since the x-rays probably cover a wide range of wavelengths, splitting the spectrum and processing different bands in different places would boost efficiency tremendously.

and that’s where this book will come in handy: http://www.porous-35.com/index.html

[KeithPickering]

The more I think about it … the less and less enamored I am of photovoltaics for x-ray capture. Huge cost, and yet-another untried technology are the barriers. Semiconductors for x-ray PV? Seriously? At ~$1 per Watt, haven’t we lost all cost advantage? And that’s not even accounting for the fact that nobody’s ever actually built an x-ray PV cell, as far as I’m aware, not even in the lab.

Meanwhile, as vansig’s equation shows, a nice source of HOT can make a fabulously efficient heat engine. Old, proven technology, and pretty cheap too. That’s where we need to be looking. And what we need to look FOR is a liquid (possibly a salt, possibly liquid only at high temps) that absorbs well in the FF’s Brehmstrellung band. Regarding materials for high temps, the actual temp of the absorbing liquid is easily controlled by engineering. You could build it for a lot of absorbing liquid at a lower temp, or less absorbing liquid at a higher temp. The temp of the liquid is also dependent on the distance from the x-ray source, which is another way of saying the same thing. These problems look a lot more solvable than x-ray PV’s, at least from where I sit.

[Aeronaut]

Agreed, Keith. Proven science and engineering is definitely the place to start when nobody even knows about aneutronic fusion. Anybody with a winter heating bill can appreciate the use of heat. The commercial electricity can come second and will almost certainly have to.

[Brian H]

Dr_Barnowl wrote: I wonder if you could tune This for X-rays ; it would certainly make assembly easier.

Fascinating and elegant. The component that I would worry about in that setup is the membrane; it would see a lot of throughput, non-stop!

[Brian H]

vansig wrote: since the x-rays probably cover a wide range of wavelengths, splitting the spectrum and processing different bands in different places would boost efficiency tremendously.

and that’s where this book will come in handy: http://www.porous-35.com/index.html

Here’s a firm using a technology called “Ovonics”, one application of which is thin-film PV. http://www.uni-solar.com/uni-solar-difference/technology/ . It uses 3 tuned layers on flexible steel substrate, total <1.0 mm.

More info: http://findarticles.com/p/articles/mi_m0KJI/is_7_118/ai_n26940431/

Stanford Ovshinsky, president, chief scientist and technologist at Energy Conversion Devices, Inc. (ECD Ovonics; http://www.ovonic.com; Rochester Hills, MI), says his firm has developed a nanocontrol device that has the potential to replace transistors. The all thin-film device is said to have significant multifunctional capabilities when compared to transistors, thanks to its high current carrying capacity and unique modulation gain.

The bio of the inventor is here: http://en.wikipedia.org/wiki/Stanford_R._Ovshinsky
He’s gone independent, again, to explore wider applications. “Ovshinsky Innovatons, LLC”. Might be worth giving a call (Troy, MI). (248) 408-3847

[vansig]

Most solar PV is concerned with colour temperature matching our sun (5770 kelvin).

Equipment operating temperature upper bound is well below that (700 .. 1500 kelvin), and
the xrays themselves also well outside that range (equivalent to ~500 million kelvin)

[Brian H]

vansig wrote: Most solar PV is concerned with colour temperature matching our sun (5770 kelvin).

Equipment operating temperature upper bound is well below that (700 .. 1500 kelvin), and
the xrays themselves also well outside that range (equivalent to ~500 million kelvin)

Ovonics and Ovshinsky are not like “most” anything. He’s now 88, widower-ed and re-married (to a physicist in ’07). Never went to university/college. Since ’06 has been awarded 6 honorary doctorates or so.

Read the bio. Notwithstanding that FF is a direct competitor to solar. Stan is a brilliant maverick, with contacts and (some?) resources, looking for excitement.

[vansig]

vansig wrote: probably not, unless we can force a situation where secondary electrons have exactly the right energy to be captured most-efficiently; eg: if the PV cell lases,
…which might be the case if, for a 215 nm band gap, for example, the semiconductor is, say, 215 nm thick, or forced to occupy a channel 215 nm wide.
perhaps something similar to this photonic crystal defect cavity : http://www.dtic.mil/cgi-bin/GetTRDoc?Location=U2&doc=GetTRDoc.pdf&AD=ADA471262

the above sounds really advanced, but it might be entirely feasible.
— http://www.osti.gov/bridge/servlets/purl/179272-kOZES2/webviewable/179272.pdf

[vansig]

photonic band gap materials could do a lot, for us.

“Unlike semiconductors, which facilitate the coherent propagation of electrons, PBG materials facilitate the coherent localization of photons. Applications include zero-threshold micro-lasers with high modulation speed and low threshold optical switches and all-optical transistors for optical telecommunications and high speed optical computers.

“In a PBG, lasing can occur with zero pumping threshold. Lasing can also occur without mirrors and without a cavity mode since each atom creates its own localized photon mode. This suggests that large arrays of nearly lossless microlasers for all-optical circuits can be fabricated with PBG materials.
— http://www.chem.utoronto.ca/staff/GAO/flashed/Si.htm

it also suggests that you can place photons where you want them, and that could improve efficiency of photo-voltaics quite a lot.

[vansig]

PV continues to make incremental advances. here is news of recent progress with thin-films:
“Plasmons are a type of wave that moves through the electrons at the surface of a metal when they are excited by incident light.”
“Catchpole’s experimental devices produce 30 percent more electrical current than conventional thin-film silicon cells.”
— http://www.technologyreview.com/energy/25083/

[Author]

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