Simulation and reduction of longitudinal and transverse impedances of a collimation device with two beams in one vacuum chamber

The results of simulation of geometrical longitudinal impedance of TCDQ are presented. This impedance is related to the shape and not to the ohmic losses of the surface. In particular, contributions from the end transitions of the beam absorber blocks as well as from the transverse slots between the absorber blocks are calculated. Moreover, power loss due to presence of trapped modes in the transitions is estimated.