Master's Thesis : Design, realization and test of a Travelling-Wave Tube collector load

Abstract

Thales Alenia Space is a company producing electronic equipment for space vehicles. In regards to the cost of space programs, the reliability is a main concern. Thus, their products are intensively tested to ensure the long-term performance. Thales Alenia Space is a reference producer of power supply for Traveling-Wave Tube Amplifier (TWTA). The TWTA are used in telecommunication to amplify Radio Frequency (RF) electro-magnetic waves. The power supply is tested with a dynamic load made of several collector loads. These collector loads are specially designed to simulate electrically the behaviour of the TWTA. The goal of this master thesis is to design a collector of the TWTA dynamic load. The collector load acts as a variable current source. Several challenges appear in the design of such a device. The collector load combines high voltage input and power dissipation while a good accuracy in the load current is required. In order to achieve a collector load that simulates accurately the TWTA, this work starts with the derivation of the specification from the TWTA behaviour. Then, the loading circuit which sinks the current and manages the voltage is studied. A control feedback circuit is designed to regulate the current in the loading circuit. High voltage isolation is considered to ensure safety while providing power dissipation. In this work, a prototype was built to verify the collector load design. Several tests were performed including the current accuracy, control bandwidth and other technical considerations. Finally, the results and improvements are discussed.