YBCO (updated)

6 02 2009

I’ve updated this post with help from Msimon.


Here is the spec sheet for the YBCO I ordered, specifically 13 meters of SCS4050i.

Icvalues range from 80 –110 Amps at 77 K in 4 mm width 

Engineering Current Density (Je) = 21 –29 kA/cm2 


Now I’m going to walk through some calculations(full code here) based on a dodecahedral bussard reactor core about the size of a basketball (outside diameter of core is ~200 mm). Dimensions:

outside_radius: 99.9393315967242 mm

torus_midplane_radius: 79.4172368111867 mm

torus_radius: 34.62 mm

torus_circumference: 217.524 mm


For now I’m ignoring the effects of the critical magnetic field. In these ruby code samples, the “>>” indicates converting physical units.


We have 13 meter of 4mm YBCO. This allows for 4 turns for each of the 12 coils:

turns = ((ybco_length >> Unit("mm"))/torus_circumference/12).floor # 4 turns for each coil


The superconducting tape supports a critical current of ~100 amps. So with 4 turns, we have 400 Ampere-turns per coil. Plug this into Ampère’s force law and you get 0.021912 N or force, or 2.235 grams. 

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