Attenuator And Research. Helix Traveling Wave Tube

Traveling Wave Tube (TWT), one of the most important types of microwave/millimeter wave vacuum tubes, is widely used in telecommunications, radars and electronic warfare applications. As the key component of the TWT, the slow-wave structure (SWS) essentially determines the performance of the TWT. While the helix SWS in helix TWT is the most widely implemented which determine the broad bandwidth, high gain, output power and high efficiency of the tube. The stability of traveling wave tube is closely related to the attenuator that used in the traveling wave tube. Therefore, we must study the attenuator in depth.How to measure the distribution of the attenuation of the clamp-pole, at present, we only estimate the distribution of coat roughly by measuring the DC resistance, this method have much error. The traditional measurement methods rely on the accumulated experience that make the attenuation on the concentrated attenuator as a constant to be test. This method does not take into account the changes in the frequency of the attenuation and ignores a lot of external factors on the attenuation. In addition, using probe to test the distribution of the attenuation of the clamp-pole that in the slow wave structure has problem itself such as not easy to control, this will lead to inaccurate results. Therefore, we must find a more accurate way to measure the distribution of the attenuation of TWT.This paper analyses the distribution of the attenuator-coated in TWT, by using HFSS. We hold a certain thickness of carbon that is in the rod equivalent to a conductivity or loss tangent of material. It avoids the cumbersome of analyzing the boundary conditions by setting the material properties. Based on this idea, we get the test curve by using waveguide method to testing a single rod. Then, we using equivalent conductivity and loss tangent as a bridge made a model of single rod and a helix slow wave structure by HFSS. By analyzing the results of the test and simulation, we accurate simulated the distribution of the attenuator in helix TWT. This study plays an important role in estimating the distribution of attenuation in TWT, and it also contributes to do further research on the beam-wave interaction in helix traveling wave tubes.Finally, we deduced the high-frequency parameter: dispersion and coupe impedance of the Helix TWT on the base of the equivalent. We written the formula into code, and compared the theoretical results with the simulated results. We find that the two results have the error which is acceptable. As a new approach, this part of the work for the study of helix TWT interaction is very meaningful.