The following is a simulation for charged particle in $B_z =B e^{-\frac{x^2}{2*\sigma^2}}$
You can drag the changed particle and change it's velocity (drag red arrow).

Let me know what you need!

Click the eye (image) to display the simulation
[eye]

/htdocs/ntnujava/ejsuser/2/users/ntnu/fkh/changeGaussianField_pkg/changeGaussianField.propertiesFull screen applet or Problem viewing java?Add http://www.phy.ntnu.edu.tw/ to exception site list