Afterburner for ion propulsion?

Question

The ion particle are accelerated out the back of the space ship using a electrostatic grid. The ion particles are accelerated to a top speed of 100 000 km/h. If you are placing more electrostatic grids along the back of the engine, will the ion particles go faster then 100 000 km/h ?

Answer 1

Sure, there's no speed limit other than c. Of course it'll cost more power, which is proportional to the square of the ion speed.

Answer 2

no