will@anasazi.UUCP (Will Fuller) (01/14/86)
<REPLACE THIS LINE WITH YOUR FINGERS>
One means of creating the temperatures and pressures necessary for
nuclear fusion is atmospheric ablation.
In this scenario a ceramic sphere containing a mixture of hydrogen
isotopes would be made to enter the atmosphere with a large initial
velocity. As the ceramic ablates away the temperatures and pressures
in the core of the sphere climb (this is a similar mechanism as the
one currently practiced for sustained fusion reactions via high
power laser). Another (more tasteful) application might be to use
the ceramic pellets as a fuel for a *very fast* ramjet.
I would like to see anybody's SDI knock out half a mole of billiard balls
traveling at tens of kilometers per second.
--
William H. Fuller
{decvax|ihnp4|hao}!noao!terak!anasazi!willtim@ism780c.UUCP (Tim Smith) (01/18/86)
>I would like to see anybody's SDI knock out half a mole of billiard balls >traveling at tens of kilometers per second. > Lets see, 1/2 mole ~= 1E23 = 4.6E7^3. A billiard ball is about 3 inches in diameter. This gives us a cube of billiard balls ~2000 miles on a side. I don't think this is practical. :-) -- Tim Smith sdcrdcf!ism780c!tim || ima!ism780!tim || ihnp4!cithep!tim
will@anasazi.UUCP (Will Fuller) (01/20/86)
In article <8601182109.AA26118@s1-b.arpa> dietz@SLB-DOLL.CSNET (Paul Dietz) writes: >The idea of using very high velocity projectiles to initiate fusion has >been considered. It isn't too terribly feasible. One would have to >ram projectiles together at > 100 km/sec; just hitting air would do >nothing. Ramming objects together is quite another matter entirely. What was origionally proposed was to use the heat generated by aerobraking for ablation. I have no idea what temperatures would be required to obtain the desired combination of temperature and pressure inside a ceramic sphere by the ablation process. Seems like some of you laser fusion experts out there could hang some numbers on this one. Further, I have no idea what sort of atmospheric impact velocities would be required to achieve the above temperatures. Perhaps some of the NASA types on the net could fill in some numbers. The only "wow" number that I can think of off hand is that the Soviet Vennera lander was subject to temperatures in excess of the surface temperature of the sun (far cry from the interior) when it entered the Venusian atmosphere. Seems like ~6-7 years back some fellow writing in Mercury or Icarus or maybe even the Ap. J., tried to show that a meteorite with trace hydrogen isotopes might have caused the Siberian Tenchutka (spelling?) meteoritic devestation. Unfortunately, the only journals I have available any more are the UN*X Reveiw, etc., (gek!) or I would try to find the article again. -- William H. Fuller {decvax|ihnp4|hao}!noao!terak!anasazi!will
henry@utzoo.UUCP (Henry Spencer) (01/21/86)
> One means of creating the temperatures and pressures necessary for > nuclear fusion is atmospheric ablation. Alas, it won't work. Yes, you can get heat and pressure that way, but nowhere near *enough* of either. The energy is coming from the kinetic energy of the projectile, so the maximum heating can be calculated by assuming that all the kinetic energy is instantly turned into heat and none of the energy is lost to the atmosphere. You end up with temperatures of tens of thousands of degrees, tops. Not good enough, by orders of magnitude. -- Henry Spencer @ U of Toronto Zoology {allegra,ihnp4,linus,decvax}!utzoo!henry
franka@mmintl.UUCP (Frank Adams) (01/28/86)
In article <497@anasazi.UUCP> will@anasazi.UUCP (Will Fuller) writes: >The only "wow" number that I can think of off hand is that the Soviet >Vennera lander was subject to temperatures in excess of the surface >temperature of the sun (far cry from the interior) when it entered the >Venusian atmosphere. This is not really very impressive. I believe a welding torch does the same. Anything which is heated enough to glow white is at about solar surface temperature. Frank Adams ihpn4!philabs!pwa-b!mmintl!franka Multimate International 52 Oakland Ave North E. Hartford, CT 06108
dgary@ecsvax.UUCP (01/31/86)
In article <1080@mmintl.UUCP> franka@mmintl.UUCP (Frank Adams) writes: [remarking on Will Fuller's observation that the Soviet Venera lander was subjected to temperatures on the order of the sun's surface] >This is not really very impressive. I believe a welding torch does the >same. Anything which is heated enough to glow white is at about solar >surface temperature. I believe you're correct. In fact, carbon arcs burn hotter than the surface temperature of the sun. In color photography (particularly cinematography) it is not unusual to see "color temperature" meters that rate the overall color of incident light by comparison to the temperature of a black body emitting a similar spectrum. The meters are rated in degrees Kelvin. For incandescent sources (including light bulbs and the sun) they fairly accurately reflect the actual temperature of the glowing surface. For photographic floods the temperature is usually 3200 K or 3400 K (depending on the type). Arc lamps are around 5800 K. Of course, filtration can change the color temperature up or down without altering the actual temperature. You can buy blue frosted incandescent floodlamps rated at about 5800 K despite the fact that the filament's around 3200. A color temperature meter can read several hundred degrees hotter than the solar surface because of light from the blue sky. And a color temperature reading from fluorescent light is meaningless. Instead of an incandescent glow, fluorescent tubes produce light by a two-step process: A gas discharge (like a neon sign's) excites a phosphor on the tube's interior, and the superimposed spectra of the two, riddled with spikes, resembles not at all the smooth hump of black body radiation. -- D Gary Grady Duke U Comp Center, Durham, NC 27706 (919) 684-3695 USENET: {seismo,decvax,ihnp4,akgua,etc.}!mcnc!ecsvax!dgary