Solving Cancer Tumours w/ High Energy Ions

[acpyrus]

I would appreciate some hints in how to get started with this problem:

You are asked to consult for the city's research hospital, where a group of doctors is investigating the bombardment of cancer tumours with high energy ions. The ions are fired directly toward the center of the tumour at speeds of 5.0 x 10^6 m/s. To cover the entire area, the ions are deflected sideways by passing them between two charged metal plates that accelerate the ions perpendicular to the direction of their initial motion. The acceleration region is 5.0 cm long, and the ends of the acceleration plates are 1.5 m from the patient. What acceleration is required to move an ion 2.0 cm across the tumour?

 

[Fermat]

Let $$a_p$$ be the acceleration across the plates.
When the electron has reached the end of the plates, what is the sideways deflection ?
What are its velocities at this point, and at what direction, to the inital direction of motion, is it traveling ?
After having passed through the plates, what is the motion of the electron now ?
Can you track this motion such that the total sideways deflection is 2.0 cm ?