Analytical, numerical and experimental approach to thermal analysis and design of a travelling wave tube

Simulation of thermal energy transport in complicated structures is usually a challenge. An example of such problem is heat generation and transfer through microwave delay structure in the travelling wave tube (TWT) device. A high level of microwave power and considerable energy of electrons intercepted by the delay line leads to the increase of local temperature of the microwave structure. Determination of the heat transfer from the hot spots is essential for the proper design of the delay line and assisting cooling system. This problem has been investigated by means of a combined: analytical, numerical and experimental approach. Such methodology does not require expensive equipment and is much faster than the pure experimental analysis. Presented analytical model is focused on evaluation of the electron beam power dissipation and microwave losses along the delay line, which is not uniform and most of the power is dissipated at terminal part of the delay line. The analytically evaluated power dissipation was used in numerical simulation in order to assess the temperature distribution. Finally the results were validated experimentally using a designed measuring setup. One of the final conclusions was that the temperature distribution has a nonuniform character and the resulting high temperatures at the delay line output can significantly influence the device reliability parameters.