Re: Six Places to Nuke When You're Serious


"Luke Campbell" <lwcamp@xxxxxxxxx> wrote in message
news:1155613893.693061.26700@xxxxxxxxxxxxxxxxxxxxxxxxxxxxxx

John Schilling wrote:

That only helps if your loss term is a surface effect. For deuterium
fusion on any practical scale, it isn't - deuterium plasma, even at
normal liquid density, is optically thin to fusion bremsstrahlung
X-rays.

The NIST x-ray mass attenuation database
http://physics.nist.gov/PhysRefData/XrayMassCoef/cover.html shows that
a 10 keV x-ray shows a penetration length of about 0.2 cm in water
http://physics.nist.gov/PhysRefData/XrayMassCoef/ComTab/water.html
(just multiply by 1 g/cm^3 to get the inverse attenuation length)
Since I don't see you getting bremsstrahlung radiation with higher
energies than k_B T, you're not going to get x-rays penetrating much
further than a few centimeters in water (heavy or not). Unless, of
course, there's something wrong with the NIST data?

No, there's nothing wrong with the NIST data - at room temperature and
with a very weak x-ray source. But the data changes considerably when
the hydrogen is entirely ionized, and the thermally generated x-rays
flood the system. The oxygen only gets ionized to it 4th or 5th
ionization state though, so it doesn't get completely x-ray
transparent, but will get bleached to the energy of the x-rays doing
the heating and thus become essentially transparent to them.

Or unless the
temperatures are around an MeV per degree of freedom or so?

Note that SNO is much larger than a few centimeters in diameter.

Some gargantuan fusion systems were proposed by Teller and others, at
least rhetorically, prior to the Ulam-Teller invention. It may be that
a very large container of deuterium or heavy water could be ignited. I
think the SNO is probably too small though. But even then you are
looking at a very, very large ignition source. Something able to heat
4000 cubic meters to fusion temperature simultaneously. I think you are
looking at something in the 100s of megaton range just for the ignition
source.

.

Relevant Pages

  • SNL x-ray or VuV source
    ... Sonoluminescence may produce fusion, and in fact, the most recent ... with blackbody temperatures in the low KeV region. ... such as x-ray or VuV lithography but are difficult to produce because ... conventional x-ray tube. ...
    (sci.optics)
  • Re: Age of weld
    ... slag entrapment in the weld area or lack of fusion. ... How would an X-ray show it was a casting? ... Mark ...
    (sci.engr.metallurgy)
  • Re: Six Places to Nuke When Youre Serious
    ... is optically thin to fusion bremsstrahlung ... The NIST x-ray mass attenuation database ... Note that SNO is much larger than a few centimeters in diameter. ...
    (rec.arts.sf.science)