Next year, the team will run an even bigger test, which aims to prove that the thruster can operate at full power for 100 hours. Gallimore said the engineers are also designing a special magnetic shielding system that would keep the plasma away from the walls of the thruster to prevent damage and enable the thruster to operate reliably for even longer periods of time. Gallimore said that without the shielding a flight version X3 would probably start experiencing problems after several thousand hours of operations.
In addition, there is the problem of generating 500 kw of power. At 20 watts per square foot it would require a massive solar array.
I would assume that nuclear power will be used to power the half megawatt rated ion thrusters.