{2\pi\gamma m r ^ 2}) (\psi -\psi_0).\]</div>
</div>
<div class="section" id="Paraxial-Ray-Equation">
<h2>Paraxial Ray Equation<a class="headerlink" href="#Paraxial-Ray-Equation" title="Permalink to this headline">¶</a></h2>
<p>Here we write the equation of the paraxial ray in the form corresponding to a system with axial symmetry under the assumptions made earlier. To derive the equation of the paraxial ray, we equate the force of radial acceleration to the forces of electric and magnetic from the side of