Probably meant more conductive because the walls inherently have to be thicker, so if the atmospheric side remains barely below melting, the interior of a thick

Probably meant more conductive because the walls inherently have to be thicker, so if the atmospheric side remains barely below melting, the interior of a thicker wall will be cooler. Rocket engines have the same problem. Thats why no one ships a 50000 PSI chamber pressure rocket engine, it would work great (Well, I wouldn't want to design the pumps...) but we just don't have the metallurgy to make a chamber that wouldn't melt. Aside from the Isp not going up fast enough to make a heavier engine worth it. Although there is also truth in that higher temp materials tend to be bad conductors. Tungsten is like what 4 times worse than copper as an engineering estimate? You don't use pure W or Cu anyway, but the general idea holds.