Acceleration on particle system in Fuse

Hello guys!
I would ask for your help :)

Using Fuse, I would like to create a particle system in which particles change velocity in relation to their position (a linear acceleration, for example).
I tried to do this by changing the strength of a force in relation to the distance between a point in the space and the position of particles (like in the picture) but it doesn’t work.

Here the patch
accelerationTest.vl (28.4 KB)

What am I doing wrong? :(

Thank you very much!!