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Author: Subject: A mini Sun from plasma or ... Polonium ?
metalresearcher
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[*] posted on 12-7-2016 at 10:37
A mini Sun from plasma or ... Polonium ?


Just a fantasy as such experiments cannot be performed as an amateur chemist. In a large professional lab like LANL or National Ignition Facility it would be possible.

I was thinking of how the Sun would be when downscaled 1 billion times.
That would result in a large skippy ball of 1.4m diameter and on a distance of 150m it would shine just like the real Sun. Same angular diameter and same brightness. According to the Boltzmann law the surface temperature of that skippy ball would be the same 5700K, thus scorching everything within a few tens of meters. The power would be (the Sun is 3.8e26 W) 3.8e26/(1 billion)^2 = 380e8 W = 380MW.

From plasma or radioactive elements. Polonium is such a candidate. According to world's largest chemistry textbook, Po-210 emits 140 W per gram, so to get 380 MW one needs to have 2.7 tons of Po which is infeasible as only 100 grams a year are produced, mostly in Russia.
Downscaling another 100 times would shrink the ball to 1.4cm diameter, emitting 380e6/(100^2) = 38kW which is within reach.

Such a ball of 14mm diameter of Po weighs 13 grams. That yields 13*140W = 1.8kW so far less than the downscaled Sun. But, according to Boltzmann's law, the surface temperature of that ball will yet be ((1800/38000)^1/4)*5700 = 2700 K == 2400 C. Far too hot to keep Po in solid or liquid state. But within a container of Ir, Ta or even WC or diamond it will remain solid. Not like a mini-Sun, but a mini red dwarf.

But is there any material (probably plasma as no solids exist at 5400 C, unless at Earth's core pressures) to make such a mini-Sun ?
Or a radioisotope which emits more power per volume ? I think Po-210 has the highest energy density.
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Sulaiman
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[*] posted on 12-7-2016 at 11:55


Wikipedia: Po, m.p. = 254C, b.p. = 962C

so you'd be dealing with one of the most toxic substances on earth in the vapour phase :D
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PHILOU Zrealone
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[*] posted on 12-7-2016 at 15:00


Maybe a stupid remark, but hasn't Polonium a critical mass (like other very radioactive materials) at what it does start the cascade nuclear chain reaction?



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[*] posted on 12-7-2016 at 15:41


The sun only produces a few watts per m^3. (from memory) Thats less than a compost heap.

I think you forget the cube factor in your calculation.
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[*] posted on 12-7-2016 at 15:59


Quote: Originally posted by PHILOU Zrealone  
Maybe a stupid remark, but hasn't Polonium a critical mass (like other very radioactive materials) at what it does start the cascade nuclear chain reaction?


You need a Be target to be hit by alpha particles Po decay releases in order to generate neutrons, as in the "urchin" or "screwball" neutron sources of early fission weapons- Po is not fissile in and of itself.




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[*] posted on 13-7-2016 at 10:18


Quote: Originally posted by wg48  
The sun only produces a few watts per m^3. (from memory) Thats less than a compost heap.

I think you forget the cube factor in your calculation.

That is right.

But I assumed the same brightness on the same scaled distance, hence the square factor.
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[*] posted on 13-7-2016 at 11:11


Make a gas core fission reactor- this could have the necessary power density.

Of course the temperature of the sun is above the melting point of any known material, so how it would be built is mysterious. Usually proposals for such devices assume it is contained in a magnetic field, but it would then be surrounded by a containment structure housing the field coils, with free radiation only in one direction.

But the "decay sun" has the same problem, plus the problem of producing an implausibly large amount of a short-lived nuclide.
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