Talk:Nuclear lightbulb

thermodynamic limits

No thermodynamic limits sounds like wishful thinking to me. I think that a photovoltaic is limited by the carnot cycle like any other device. The advantage of the photovoltaic is that the hot side temperature is probably something like the equivalent blackbody temperature of the photon or something, which is quite hot for a 25000K blackbody (making the upper limit on efficiency around 24/25 = 96% say). I think Mr Carnot is a bit harder to escape than the article implies. (There are also technical issues like neutron poisoning and PV cooling which I suspect are more than just engineering) njh 05:19, 31 December 2005 (UTC)[reply]

Agreed, I think I'll pull the last few sentences. Modify if you think you can do better. Lcolson 06:50, 31 December 2005 (UTC)[reply]

Looks reasonable. If any technique has high potential, it is MHD (MHD_generator), which is a non-contact way of generating electricity directly from very hot plasma. I read a report years back about a technique whereby a super hot nuclear plasma is pulsed by injecting fuel in lumps, the pulses created magnetic pulses which were somehow coupled directly to a coil which was then suitably clarified for mains electricity. njh 09:02, 31 December 2005 (UTC)[reply]

Temperature

How con the reactor function at 25000ºC? The boiling point of silica is 2230ºC, so the container should melt, boil, and eventually turn into a plasma at that temperature, unless some form of magnetic confinement is used. It material would then cool down and the engine will cease to function. Polonium 21:40, 9 May 2006 (UTC)[reply]

Apparently the idea is to cool the outside of the silica bulb so it never gets too hot using hydrogen gas (which being your propellant is quite abundant). You'd probably get corrosion of the inside over time and of course loss in efficiency but it seems possible. OF course theoretically possible and practically possible are two very different things. http://www.nuclearspace.com/a_liberty_ship10.htm 128.12.194.96 22:17, 10 January 2007 (UTC)[reply]

From my understanding it is because the silica is transparent at that temperature so while it might be 25k all the energy just goes right through it so it doesn't melt —Preceding unsigned comment added by 76.125.0.97 (talk) 18:00, 30 October 2010 (UTC)[reply]

I think whoever wrote this misunderstood black-body radiation. Even if at 25000K most of the radiation is in the UV range, it's still emitting lots of radiation at longer wavelengths. Less radiation isn't emitted at longer wavelengths: it's that an increasing fraction is emitted at shorter ones, with more radiation being emitted overall. You're still getting all the IR radiation you'd emit at lower temperatures, and a great deal more. Wikifruta (talk) 02:32, 30 May 2011 (UTC)[reply]

Degradation of Fused Silica

Aren't there concerns over the transparency of fused silica degrading over time from exposure to high energy UV and to alpha and beta radiation? —The preceding unsigned comment was added by 65.5.3.112 (talk) 17:35, 25 January 2007 (UTC).[reply]

Fused silica transparency

Where does the idea that fused silica is transparent to extreme UV come from? The transmission drops to basically zero at 100 nm. It also melts at under 2,000 celsius. This really needs to be rewritten — Preceding unsigned comment added by 199.212.64.135 (talk) 01:12, 15 January 2020 (UTC)[reply]