Nice and very enthusiastic article. At first I thought its about the solar sail idea (which is around for a while) but its kind of an update. The novel thing with the e-sail is that it works (potentially) further out than the solar sail. From your reference 2:

"This increase in area would lead to continued acceleration much longer than comparable propulsion technologies. For example, when solar sail spacecraft reach the asteroid belt at 5 AU, the energy of the solar photons dissipates and acceleration stops. Wiegmann believes the E-Sail would continue to accelerate well beyond that.

“The same concerns don’t apply to the protons in the solar wind,” he said. “With the continuous flow of protons, and the increased area, the E-Sail will continue to accelerate to 16-20 AU -- at least three times farther than the solar sail. This will create much higher speeds.”"

I just wanted to post this to prevent people mixing this up with ("conventional") solar sails.

Ok, one added info: The e-gun is to make sure that the sail stays charged positively (see ref 2).