It is most definitely possible to calculate the force, it is a simple application of the the Lorentz force.
Perhaps no one replied because you don't seem to have put any effort into trying to figure it out yourself.
This is the Lorentz formula. It requires me to know the electric field,the particle velocity, magnetic field and the electic charge. I know none of these values.
All I know is how many rpm are required for a certain voltage to be generated.
Is it possible to calculate the force generated with just this information?