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visits member for 2 years, 3 months
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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.


Aug
24
comment Using ion beam to create strong magnetic field
actually, my original motivation was reading about self-compressing magnetized plasma in plasmoids (e.g. here bigbangneverhappened.org/… ) which is however dynamic process. So I was thinking it should be possible to make it more stable (continually) using some external solid state magnetic coils outside of the focus.
Aug
24
comment Using ion beam to create strong magnetic field
In principle instead of electron/ion beam it should be possible to make something similar also just with some current loop in high-temperature low density plasma, considering very long mean free path ( several meters ) to avoid much scattering so that particles in plasma move almost ballistically governed exclusively by Lorenz force.
Aug
24
comment Using ion beam to create strong magnetic field
ad "the use of the beam repulsion (space charge) in the inner region just does not work." ... I was not considering any space charge repulsion ... the beams with opposite direction of current repel each other by magnetic field ( I was considering just magnetic field.)
Aug
24
comment Using ion beam to create strong magnetic field
True, that particle accelerators have usually very low current. However, this would be a bit different because, it is enclosed loop. The particles does not have to be accelerated at each obrit (just refocused because of some scattering )
Aug
19
revised Using ion beam to create strong magnetic field
added NOTE about refocusation and reacceleration
Aug
18
asked Using ion beam to create strong magnetic field
Aug
18
accepted Electron beam in magnetic field - increase or decrease the field?
Aug
18
comment Electron beam in magnetic field - increase or decrease the field?
OK, so using it for creation of intense magnetic field is probably not possible, or at least very hard? I mean, in "field reversed configuration" the plasma is stabilized, but the magnetic field is decreased (at least in the centre of coil.) It does not produce intense magnetic field in any particular spot.
Aug
17
revised Electron beam in magnetic field - increase or decrease the field?
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Aug
17
asked Electron beam in magnetic field - increase or decrease the field?
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?
added 117 characters in body
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
edited body