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visits member for 2 years, 1 month
seen Jun 19 at 9:23

I'm PhD student of computational solid state physics. I'm mostly interested in molecular electronics. In spare time I'm interested in computer game development, computer graphics and painting.

I'm a big fan pf of aeronautics, astronautics, military technology and high performance computing.


Jun
19
comment buckling of tube - shell thickness vs. momentum of inertia optimum
I expected something more strightforward, but perhabs the topic is not so easy as it seems...
Jun
19
accepted buckling of tube - shell thickness vs. momentum of inertia optimum
May
10
asked are there known fundamental limits of quantum computer scaling?
May
2
comment How large should an optically large fusion reactor be?
Orion project is nice, but it has also many problems ( nuclear weapons are quite complex and expensive, does not have specific impulse as good as pure fusion etc. ). As I said - cooling is not a problem if you (1) cool it by exhaust of propellant itself (that is how chemical rocket engine achieve such high power density) and (2) if plasma cool itself by black-body radiation at ~10000K. If the plasma is kept by magnetic field in free space quite far form ship construction, not much of solid surface is irradiated so not much cooling is needed. 99.9% of waste heat does not touch solid surface.
May
1
comment How large should an optically large fusion reactor be?
I like fission, yet I disagree. The power densities required are HUGE ( like >1MW/kg of whole ship ). With electricity power generation as intermediate it is not feasible. Radiative cooling is effective at high temperatures ( > 5000 K ) where no solid material survives. The propellant exhaust itself is an effective cooling (of thermal rocket). So propellant exhaust directly from reactor core make sense. And fission gas-core or plasma-core nuclear reactors are not good, because low neutron cross-section of gas/plasma. There fusion make sense (more than on Earth)
May
1
revised How large should an optically large fusion reactor be?
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May
1
comment How large should an optically large fusion reactor be?
Please no flame-war. In context of spaceship propulsion is high power density (per mass) important, which Sun does not provide. Also it is hard to convert Sun power to propellant exhaust velocity ~1000 km/s, regulate the power or turn it on/off. I guess optically thick reactor can be still possibility for some large spacecraft ( say several kilometres in size )
May
1
asked How large should an optically large fusion reactor be?
Apr
13
revised nuclear fusion scaling with reactor size
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Apr
13
revised nuclear fusion scaling with reactor size
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Apr
13
comment nuclear fusion scaling with reactor size
Btw. one of my motivations for this question is that I like big spaceships in sci-fi movies, and scaling laws of fusion reactors can be good arguments why tu build spaceships really big :D :D
Apr
13
comment nuclear fusion scaling with reactor size
Floris > exactly, I heard that deliberately build smaller than planned to save 20-40% of money, but the original project (original size) would probably achieve self-sustained reaction and power production.
Apr
13
comment nuclear fusion scaling with reactor size
anna_v : yes, I like inertial confinement fusion, but perhaps it has also some scaling laws? (I read Bussard paper some time ago .. there was something about scaling with $R^4$)
Apr
13
asked nuclear fusion scaling with reactor size
Apr
12
comment General relation between power density of any engine and dissiapation rate and temperature
ok, this I know, my question was rather about the heat flow rate. At higher temperature or higher temperature gradient the heat flow is higher. ( eg. termal conduction scales as $ dQ/dt \propto (T_2-T_1) $, thermal radiation scales as $ dQ/dt \propto (T_2^4-T_1^4) $
Apr
7
awarded  Tumbleweed
Apr
1
revised General relation between power density of any engine and dissiapation rate and temperature
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Mar
31
asked General relation between power density of any engine and dissiapation rate and temperature
Mar
29
asked What is the limit for the size of a galaxy?
Feb
20
revised a question regarding Fourier transform in electron microscopy
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