Vacuum Tube Death Ray

[scott wurcer]

"you need to conduct the heat to an effective black body radiator" How is the accomplished?

Conduction would be via metallic or another thermally conductive material or other heat transport process to a large surface that radiates via black body radiation to essentially the 3 degree or so universal background temperature. A heatsink uses conduction, convection, and radiation. You can't conduct heat to a vacuum and there is certainly no convection. Heat sink fins that face each other don't help either because they both radiate and absorb. From the link below I get about 460W/sq meter at 300K so after you add the degrees C per Watt to get to the radiator you can compute how hot your tube is when in equilibrium. I just picked 300K you would need to start with a max temperature spec for the tube and the power dissipated and work forward.

https://en.wikipedia.org/wiki/Stefan–Boltzmann_law

I suppose you could evaporate a liquid into space but that is obviously not practical.

 

[WSJ]

Conduction would be via metallic or another thermally conductive material or other heat transport process to a large surface that radiates via black body radiation to essentially the 3 degree or so universal background temperature. A heatsink uses conduction, convection, and radiation. You can't conduct heat to a vacuum and there is certainly no convection. Heat sink fins that face each other don't help either because they both radiate and absorb. From the link below I get about 460W/sq meter at 300K so after you add the degrees C per Watt to get to the radiator you can compute how hot your tube is when in equilibrium. I just picked 300K you would need to start with a max temperature spec for the tube and the power dissipated and work forward.

https://en.wikipedia.org/wiki/Stefan–Boltzmann_law

I suppose you could evaporate a liquid into space but that is obviously not practical.

If this were built in the 40's, how would this have been done with glass vacuum tubes available at that time.

 

[scott wurcer]

If this were built in the 40's, how would this have been done with glass vacuum tubes available at that time.

No technology necessary just materials, sheets or hunks of metal of the right sizes and shapes connected together in the right arrangement.

Spacecraft Thermal Control Subsystem Description
Radiators

The radiators use primary heat rejection surfaces:

they support high dissipating electronic units (traveling wave tubes andconverters). The structural composition of these panels is generally aluminumface sheet and honeycomb core.
they are designed for a maximum thermal efficiency achieved by usingembedded heat pipes in association with a specific coating providing a highinfrared emittance with a low solar absorptance (so called Optical SolarReflectors). For end of life conditions, heat rejection capability may reach upto 350 W/m2 for a typical 40°C radiator temperature.