Groundbreaking helix slow-wave structures with diamond heat sinks for power TWTs

The helical slow-wave structure (HSWS) is the pioneering and prevailing type of slow-wave structure for traveling-wave tubes. One serious drawback found in the conventional HSWS is low heat removal, which limits tube output power. Attempts at improving heat removal by employing soldered helixes or support rods made of beryllium oxide or diamonds usually result in very complicated production processes and higher costs. Apart from that, the net effect is less than expected. For diamond support rods this is due in particular to the small surface and large thermal resistance in the area of the helix in contact with the rod. We propose a new design and technology for manufacturing HSWS employing CVD diamonds. The proposed design offers excellent thermal properties and high interaction impedance over extensive bandwidths.