Re: Hole in a box

From: Eugene Leitl (
Date: Fri Feb 15 2002 - 09:16:39 MST

On Fri, 15 Feb 2002, Robert J. Bradbury wrote:

> I don't think the standard heat engine concepts apply to photon
> harvesting. If your radiators are at the background temperature once
> you get above a few thousand degrees as an input you are getting
> 99.9+% efficiency anyway.

I don't think anything harder than soft xRays is utilizable in solid state
photodiodes. Peak efficiency would be probably in the UV range (diamond,

> Probably a fair amount of transmutation going on as well. So I suspect
> you are going to have rather hefty recycling costs associated with
> harvesting any energy produced as gamma rays.

You don't need a lot of gas to attenuate hard photons, though. See nukes:
the conversion efficiency of shortware photons into VIS and IR requires
negligable distances in atmosphere at ~1 atm pressure.

> > but there might be some interesting nuclear photovoltaics that
> > catch gammas and use them to do charge separation.
> I'd be interested in any references where people actually try to do this.
> Given the lack of powerful gamma ray sources that exist in our
> neighborhood, I would doubt much work has been done in this area.

Radioisotope batteries. Not all of them are radiothermal.

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