Drawing of a <a href="https://en.wikipedia.org/wiki/magnetron" class="extiw" title="w:magnetron">magnetron</a>, a <a href="https://en.wikipedia.org/wiki/vacuum_tube" class="extiw" title="w:vacuum tube">vacuum tube</a> used as an oscillator to generate <a href="https://en.wikipedia.org/wiki/microwave" class="extiw" title="w:microwave">microwaves</a> at high power levels, used in <a href="https://en.wikipedia.org/wiki/radar" class="extiw" title="w:radar">radar</a> sets and microwave ovens, from a 1984 Naval training text.  The tube is shown with part of the copper anode block cut away, revealing the cathode and <a href="https://en.wikipedia.org/wiki/cavity_resonator" class="extiw" title="w:cavity resonator">cavity resonators</a>.  The magnetron shown here is several decades old, and uses two <a href="https://en.wikipedia.org/wiki/alnico" class="extiw" title="w:alnico">alnico</a> horseshoe magnets.  Modern magnetrons use more compact <a href="https://en.wikipedia.org/wiki/rare_earth_magnet" class="extiw" title="w:rare earth magnet">rare earth magnets</a>.
Unknown author<span style="display: none;">Unknown author</span>
Retrieved June 20, 2014 from <a rel="nofollow" class="external text" href="http://www.rfcafe.com/references/electrical/NEETS-Modules/NEETS-Module-18-2-11-2-20.htm">NEETS  Navy Electricity and Electronics Training Series, published by Naval Education and Training Command, US Navy, 1984, NAVEDTRA 172-18-00-82 Module 18: Radar Principles, p. 2-14, fig. 2-9</a> on <a rel="nofollow" class="external free" href="http://www.rfcafe.com/">http://www.rfcafe.com/</a>