From the article,
But it's not clear yet whether or not e-sails are feasible. An e-sailing probe would need to be equipped with a device called an electron gun to keep its wires positively charged (otherwise, electrons arriving via the solar wind would scuttle the propulsion system).
The team isn't sure how much energy would be required to run an electron gun on an e-sailing craft. Two competing models of how materials charge in a plasma give very different results, Johnson said: One model suggests it's a reasonable amount and the other implies that there's no realistic way to generate that much energy onboard.
Does anybody have any knowledge on the different models they are referring to and which one if any is more in line with EU model?
