Investigations on radio-frequency components and the multipactor phenomenon in high-power space applications

Resumen

The present doctorate falls under the umbrella of the Networking/Partnering Initiative (NPI) program of the European Space Agency (ESA) and has been co-funded with the University of Cartagena, Spain. The PhD student joined the Information and Communications Technologies research department in September 2007 under the supervision of Professor A. Alvarez Melcón. He took a PhD Master on the subject of Integral Equation and Method of Moments techniques, and in September 2008 he joined the NPI in the topics of Multipactor and Radio frequency (RF)-breakdown phenomena. Since then, the student has combined academic stays at the University of Valencia, Spain and at ESA/ESTEC center in Noordwijk, The Netherlands. In Valencia, he studied RF-breakdown phenomena from a theoretical point of view at the Applied Physics department, under the supervision of Professor B. Gimeno Martínez. The student was introduced to multipactor testing on real RF components at the High Power RF Laboratory of the Payload SystemDivision at ESA/ESTEC center, under the supervision of Mr. D. Raboso and Mr. C. Miquel-España. The objective of this work is to study the electromagnetic radiation of charged particles within waveguides. The main motivations of this research are the prediction of the multipactor effect within waveguide components for space applications, and the study of the electromagnetic fields created by moving charges for particle accelerators. The electromagnetic radiation of a charge particle as well as a charge distribution within a waveguide region or a resonator cavity has been extensively treated in the literature. Several authors have investigated the radiation of electron beams in metallic waveguides and cavities for the study of RF photo-injectors [1, 2]. Other classical problem related with this topic is the evaluation of the wakefields generated by particles moving linearly at constant velocity [3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14]. The study of the radiated fields left behind by a charged particle is particularly important because they influence the motion of the charged particles that follow them. The rigorous analysis of the wakefields is a non-trivial issue, and critically depends on the geometry and materials of the accelerator structure. In most of the current models found in the technical literature, the particles move linearly at constant velocity [4, 5, 6, 7, 8, 9, 11, 12, 14].