s" title="Permalink to this headline">¶</a></h2>
<p>The focusing elements can be: solenoids and magnetic quadrupole lenses.</p>
<div class="section" id="Solenoids">
<h3>Solenoids<a class="headerlink" href="#Solenoids" title="Permalink to this headline">¶</a></h3>
<p><span class="math notranslate nohighlight">\(k_x = k_y = k_s\)</span> - stiffness of the solenoid:</p>
<div class="math notranslate nohighlight">
\[k_s = \left (\frac {eB_z} {2m_ec \beta \gamma} \right) ^ 2 = \left (\frac {e B_z} {2 \beta \gam