hello I would like to propose a simulation, which I need so much :)
2D in a magnetic field that increases with the x axis, then has a maximum, and then returns to zero value as a function gaussina. see photo. the particle part in any point of this plane and with the direction to be set. also the speed and mass are to be set and charge.

on the 2D plane in the point x, y have the cmapo varies with xe, remains constant along y. you can set a starting point as the point (xo, yo) where B (tesla) is almost zero and choose the direction of the particle.

You can do the following:
1) Divide the plan, of length x and height y, in vertical strips of known width.
2) manually assign a value of the magnetic field in each strip
3)the field is constant in each vertical strip
4) manually select a point in the plane
5) manually choose a direction in the plane
6) assign charge, mass, velocity, to the particle
7) go the simulation!

then in fig1 explain what must do the program in steps. first step to divide the plane into strips of very great height and thickness of three or more mm and assign the field to each one. the field is constant in each strip but it is different from the strip and the strip. or it can be the same depending on the assignment. second step assign a point and a direction to the particle. third step, run the simulation.

in fig2 explain the graphical method for ottenre the result, in any direction goes away, the particle, the radius of curvature is always perpendicular to the direction of the particle. in the band starting the radius of curvature is constant. the particle is a portion of circumference. Now I draw the tangent line to the curve O | and the radius is perpendicalore to this line so the design and so on.

set the time in ns the lenght in mm velocity m/s field in tesla charge in coulomb mass in kg

the application is scientific to know if the particle at a given velocity and mass passes through the field or bounces back.