What is an "arc of a helix"?

Question

I'm studying the trajectory of a subatomic particle inside a magnetic field, and I keep reading that it follows the track of an "arc of helix". But I can't seem to find the meaning of the "arc" of an helix on the internet. Anyone to point me to the right direction ?

Answer 1

A particle creates an arc of a helix when it has two non-zero velocity component $V_x$ and $V_y$. The $x$ component forces the particle to move in the straight line because it doesn't feel any force due to the magnetic field but the $y$ component does and moves in a circular motion so the particle follows the path of a helix The Helix can be uniform as well as nonuniform it depends on the velocity that is parallel to the magnetic field if the velocity is constant and nonzero helix is uniform but if the velocity is not constant the helix is nonuniform.

here is the diagram of the helix