Bead-Pull measurements techniques and Multipole components of DQW crab-cavity

The main goal of this document is to characterize the electric and magnetic field with all their components and find the best way to do it. The first part of this document will present basic bead-pull measurements. This will be done with the aim to validate this measurement method; i.e. that the different components of the eletric and magnetic fields can be measured precisely. Then, the multipole components of this crab-cavity will be investigated with the use of the Panofsky-Wenzel theorem. The goal is to answer the question: "Is it possible to measure accurately these multipoles, in particular B1, B2 and B3?". Finally, some new shapes of beads, needles, discs will be produced in order to measure longitudinal or transverse fields only without perturbating other components.