RF output multipaction margin of travelling wave tubes

The paper show the multipaction capability of Thales RF output solutions for today high power L- and S-Band TWTs. Thales accepts that a real prediction of the multipaction onset level of complex coaxial structures like in example a TNC connector, with dielectrics, air gaps and complex electric fields inside, is not possible with today knowledge. Therefore Thales prefers to qualify their RF output interfaces with different multipaction tests, which were assisted by ESA and their multipaction experience. We could demonstrate that our designs have a 6 dB multipaction margin by test and a new multipaction test for L-Band will show if our standard TNC connector will have the same margin or if for high power L-Band applications a SC connector has to be the preferred solution. For very high power S-Band applications we see definitely a WR340 ¼ height waveguide output as the best solution which is already today a standard interface at satellite level. In summary Thales has solved a very critical area for high power tubes in L- and S- band and is able to fulfill today multipaction requirements.