BESSY VSR, a scheme where 1.7 ps and 15 ps long bunches (rms) can be stored simultaneously in the BESSY II storage ring has recently been proposed [1]. The strong longitudinal bunch focusing is achieved by superconducting high gradient RF cavities. If the bunch fill pattern exhibits a significant inhomogeneity, e.g. due to gaps, transient beam loading causes a distortion of the longitudinal pha...

In a plasma wakefield accelerator in the nonlinear regime the accelerated bunch electrons oscillate in a pure ion column. They emit strong synchrotron, also known as betatron radiation, in the keV to MeV photon range [1]. In previous experiments with a single electron bunch the oscillating electrons where distributed symmetrically about the beam axis or the ion column axis. However, with a driv...

The TTF Free Electron Laser needs very short bunches to produce self-amplified spontaneous emission (SASE). This short bunch length is produced in a magnetic bunch compressor where the trajectories of particles with different energy have different path length in a way that the bunch is longitudinally compressed. As a parasitic effect the wake fields produced by the passing bunch will have the p...

A dual-axis, synchroscan streak camera was used to measure longitudinal bunch profiles in three storage rings at SLAC: the PEP-II lowand high-energy rings, and SPEAR3. At high currents, both PEP rings exhibit a transient synchronous-phase shift along the bunch train due to RF-cavity beam loading. Bunch length and profile asymmetry were measured along the train for a range of beam currents. To a...

For several years, a large variety of beams have been prepared in the LHC injectors, such as single-bunch and multi-bunch beams, with 25 ns, 50 ns and 75 ns bunch spacings, nominal and intermediate intensities per bunch. As compared to the nominal LHC beam (i.e. with nominal bunch intensity and 25 ns spacing) the other beams can be produced with lower transverse emittances. Beams of low transve...

In order to achieve high luminosity in CLIC, ultra-low emittance bunches have to be generated in both electron and positron damping rings. To achieve this goal, big energy loss per turn in the wigglers has to be compensated by the RF system. This results in very strong beam loading transients affecting the longitudinal bunch position and bunch length. In this paper, the conceptual design of the...

Multi-bunch instabilities degrade beam quality through increased beam emittance, energy spread and even beam loss. Feedback systems are used to suppress multi-bunch instabilities associated with the resistive wall of the beam ducts, cavity-like structures, and trapped ions. A new digital transverse bunch-by-bunch feedback system has recently been commissioned at the Taiwan Light Source, and has...

This paper presents the measurement of sub-picosecond relativistic electron beam bunch length by analyzing the spectra of the coherent terahertz pulses through Kramers-Kronig transformation. The results are compared with autocorrelation from a scanning polarization autocorrelator that measures the coherent optical transition radiation. The limitations of the different methods to such a characte...

For the successful operation of various accelerator facilities a detailed bunch characterization is required. A complete description can be achieved using various diagnostic systems installed along an accelerator beamline. Ideally the diagnostic should be able to measure parameters of a single bunch in a non-destructive manner. For bunch length measurements this results in a complicated task es...

This paper discusses various aspects of multibunch motion in thepresence of nearest neighbor wakefield coupling. Included are the solution to the problem for smooth focusing with equal bunch energies, an explanation for the apparent &mping of the bunch amplitudes that is observed for weak coupling, and a treatment of the problem for discrete focusing based on the moments of the wakefield distri...