What will the trajectory of a charged particle in a magnetic field look like?

Question

IT education

We have a medium - a vacuum. Let's take a Cartesian coordinate system. A charged particle moves in this system, and its velocity vector makes an acute angle with the z-axis of the chosen coordinate system. Suddenly, a homogeneous constant magnetic field appears instantly, the intensity vector of which is directed along z. How will the charged particle's trajectory look like in this field? Will it be a spiral stretched along the z-axis? Or a spiral stretched along the direction of the particle's velocity vector?