I'm not familiar with the design, but where are you getting the "millions of km" from? I didn't see that in the article, and my quick skim of the paper[1] sugge

I'm not familiar with the design, but where are you getting the "millions of km" from? I didn't see that in the article, and my quick skim of the paper[1] suggested that that Ls (the length of the coil) would need to 200 km (given shortly after equation 15). [1] https://reader.elsevier.com/reader/sd/pii/S0094576521005804 https://reader.elsevier.com/reader/sd/pii/S0094576521005804