High-power brazed-helix telecommunications TWT´s

Described is a new class of high-power traveling-wave tubes (TWT\´s) for telecommunications transmitters, which employ an advanced helix technology to enable operation at higher output-power levels than would be possible with the "conventional" helix technology. The helix technology used to make these tubes includes a copper helix, which is brazed to beryllium-oxide dielectric support rods, themselves being brazed to an outer copper sleeve. The resulting structure is characterized by low thermal contact resistance, superior heat-dissipation capacity and low RF losses. Experimental results presented show the advantages of this technology as compared to the earlier one. The output-power limits of brazed-helix TWT\´s are also estimated. Finally, the main brazed-helix telecommunications TWT\´s manufactured by THOMSON-CSF are described briefly, to give an idea of the performances that can be achieved with this advanced technology.