Bunch-by-bunch feedback systems for curing coupled-bunch instabilities in the KEKB rings have been constructed. Even at a very early stage of the commissioning of the rings, strong transverse instabilities occurred in both rings which limited maximum storable currents. Stabilization of the beams with transverse feedback systems has been successful so far, enabling us to accumulate greater beam ...

In this method called Traveling Laser Focus (TLF), multi-cell microstructures scaled down to the laser wavelength-size. Each cell in these structures has an opening from the side. Special Electro-Optical device controllably sweeps focused laser spot along these openings in accordance with instant position of accelerated micro-bunch inside the structure. This arrangement reduces the illuminating...

A bunch-by-bunch longitudinal feedback system has been used to control coupledbunch longitudinal motion and study the behavior of the beam at ALS, SPEAR, PEP-II, and DA Φ NE. Each of these machines presents unique challenges to feedback control of unstable motion and data analysis. Here we present techniques developed to adapt this feedback system to operating conditions at these accelerators. ...

The bunch compression system in the TTF-FEL decreases the bunch length in order to achieve the high peak currents needed for the SASE FEL process. Along the curved trajectories in the bunch compressor magnet chicanes, these short bunches will start to radiate coherently. In this paper, a numerical calculation of the characteristics of this radiation is presented. One-dimensional bunch models ar...

We extend a recently introduced mapping model, which explains the bunching phenomenon in an ion beam resonator for two ions [Geyer, Tannor, J. Phys. B 37 (2004) 73], to describe the dynamics of the whole ion bunch. We calculate the time delay of the ions from a model of the bunch geometry and find that the bunch takes on a spherical form at the turning points in the electrostatic mirrors. From ...

Beam tests of the KEKB bunch by bunch feedback system prototypes have been performed in the TRISTAN-AR on both longitudinal and transverse planes. A two-tap FIR filter system consisting of hardware logic's realized the function of the phase shift by 90 degrees, the suppression of the static component and the delay of up to a few tens of turns in longitudinal plane with 508 MHz of system clock. ...

A Michelson interferometer was installed at the femtosecond (fs) terahertz (THz) Accelerator of Pohang Accelerator Laboratory(PAL) to measure a subpicosecond order electron bunch length. To measure an ultra-short electron bunch length, we use reconstruction process and fast fourier transform. Currently, we are generating THz radiation with the pulse energy of 7μJ by means of coherent transition...

A quasi-stationary electron cloud can drive single-bunch instabilities on a circulating beam through a head-tail coupling mechanism. The oscillation frequency of the electrons in the transverse field of the bunch, and how it can be expressed as a function of the bunch properties, is essential for the understanding of this instability. The process of the instability has been investigated via com...

The longitudinal and transverse space-charge effects on bunch rotation in the longitudinal phase space designed to produce an intense short proton bunch are discussed. A criterion for length broadening due to space-charge modification of the rf potential is given. As for the transverse effect, the incoherent space-charge tune shifts will affect the bunch rotation unless the chromaticities are p...