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...

A mechanistic model for Botrytis cinerea on grapevine was developed. The model, which accounts for conidia production on various inoculum sources and for multiple infection pathways, considers two infection periods. During the first period ("inflorescences clearly visible" to "berries groat-sized"), the model calculates: i) infection severity on inflorescences and young clusters caused by conid...

BESSY II features sophisticated filling patterns as well as manipulation and separation techniques of custom bunches to serve both timing and photon hungry experiments at the same time [1]. Recently, the low-α operation mode [2], providing bunch lengths as short as 2 ps, was extended by pseudo single bunch options. A robust technique to excite one bunch with constant displacement and enlargemen...

The production of ultra-short x-rays in Cornell’s Energy Recovery Linac (ERL) requires electron bunch lengths of less than 100fs with minimal transverse emittance growth and energy spread. Because the linac consists of two sections separated by an arc, CSR forces limit the bunch length in the linac, and bunch compression has to be done after acceleration. Creation of such short bunches requires...