In beam-beam macroparticle simulations for collider rings, the accurate determination of the incoherent spectrum and potentially unstable coherent modes requires (1) large numbers of collisions, and (2) accurate electric field solutions at each collision. On a single processor, a selfconsistent simulation typically uses a 2D model of the beam-beam interaction in order to achieve a reasonable co...

In this study, Analytical work is carried out for static shape control of cantilever beam structure with a use of laminated piezoelectric actuator (LPA). The mathematical modeling of beam element covered with LPA based on Timoshenko beam element theory and linear theory of piezoelectricity has been used. This work shows how number of actuators, actuator size, actuator location on beam and contr...

Stretcher mode of KSR has been experimentally tested. Up to now, beam spill longer than 8 second has been attained by reducing RF knockout power. Improvement of extraction efficiency will be realized by ramping of betatron tune and formation of closed-orbit-distortion without the effect of non-linear sextupole magnets to make aperture minimum at the first septum for extraction.

An international team is currently investigating the best way to use Higher Order Modes (HOM) for beam diagnostics in 3.9 GHz cavities. HOMs are excited by charged particles when passing through an accelerating structure. Third harmonic cavities working at 3.9 GHz have been installed in FLASH to linearize the bunch energy profile. A proof-of-principle of using HOMs for beam monitoring has been ...