Correct on both points. I started with a uniform field because it requires 10% of the energy- it would mean building a distributed network of satellites, but if we're inserting exajoules of energy into near-mars orbit, making a lot of satellites is probably within our means.
50,000 nT was their suggestion of what actually starts providing relevant protection. 5,000 nT was where they started seeing it at all, which would be 10^16 joules/2 megatons of TNT. I believe the massively stronger field is needed because the protection they are looking at for terraforming would need to be much better than Earth's. We still lose 94,608 tonnes of hydrogen annually to atmospheric escape, despite having 263% stronger gravity.
50,000 nT was their suggestion of what actually starts providing relevant protection. 5,000 nT was where they started seeing it at all, which would be 10^16 joules/2 megatons of TNT. I believe the massively stronger field is needed because the protection they are looking at for terraforming would need to be much better than Earth's. We still lose 94,608 tonnes of hydrogen annually to atmospheric escape, despite having 263% stronger gravity.