Electronic – Current capacity of copper wires in vacuum


I’d like to know the current carrying capacity of copper wires in vacuum.
The current plan (NPI) calls for sending ~3 amps through the vacuum space of a cryostat.
Has anyone done this? Have any references, links, or sage words of advice.
I found this,


and a few other references. (Kurt J. Lesker gives single numbers.) The slope of those curves in vacuum is about 2. Which at least makes some physics sense. Heat generated goes as I^2 and heat dissipated goes as T^4 (Assuming all the heat dissipation is by radiation… Stefan- Boltzmann law.)

Oh one kinda crazy idea would be to put a thick layer of heat shrink tubing over the wire. Better emmisivity and a larger area. (Perhaps something other than heat shrink.)

Best Answer

Since the current capacity of a wire increases in vacuum (about 20%, per your citation), you can use the design parameters allowed at 14.7 psi, and know that it will work safely in vacuum.