Current beam bunch length monitors that measure the spectral content of beam-associated coherent radiation to determine the longitudinal bunch form factor usually require wide bandwidth detection, Fourier transformation of spectral or interferometric data, phase retrieval algorithms and multiple beam pulses to obtain the bunch length. In this paper we discuss progress in the development of a no...

A low energy electron beam can be used to characterize the high energy ultra-relativistic bunches. This technique allows one to obtain the bunch transverse profiles as well as the bunch length within a non-destructive single shot measurement. In this paper the bunch length measurement technique based on the interaction of the low energy electron beam with an ultra-relativistic bunch is describe...

A bunch-by-bunch measurement system has been developed at Pohang Light Source II. The system consists of a four-channel button pick-up, 20 GHz sampling oscilloscope and an 800 MHz low-pass digital filter. Upon measuring a bunch-by-bunch spatio-temporal beam motion matrix over many turns, singular-value decomposition analysis is used to reveal the dominant coupled-bunch modes. The system can dia...

Transverse bunch-by-bunch feedback systems for damping coupled-bunch instabilities in the KEKB rings have been working since the early stage of the commissioning of the rings. Stabilization of the beams with the system have been successful, permitting tests of higher beam currents and various filling patterns. The performance of these systems has been demonstrated under the normal physics run p...

A bunch-by-bunch longitudinal feedback system has been designed and built o control coupled-bunch instabilities in the PEP-I1 machine. A prototype system has been installed at the Advanced Light Source at LBNL. Programmable DSPs allow longitudinal feedback processing in conjunction with data acquisition or instrumentation algorithms. Here we describe techniques developed for different beam and ...

We derive analytical expressions for external fields of a charged relativistic bunch with a circular cross section. At distances far from the bunch, the field reduces to the relativistic modified Coulomb form and in the near region, reproduce the external fields of a continuous beam. If the bunch is surrounded by conducting surfaces, the bunch self-fields are modified. Image fields generated by...

The perturbative approach for describing the underdense plasma–ultrarelativistic electron bunch system is developed,using the ratio n0 nb as a small parameter (nb-bunch,n0plasma electron densities). Focusing of the electron bunch emerged in the first approximation of the perturbative procedure as a result of the plasma electrons redistribution.Focusing gradient and strength for ultrarelativisti...

The increase in single processor speed based on Moore’s law alone will not be able to deliver the dramatic speedup needed in many beam tracking simulations to uncover very slowly evolving effects in a reasonable time. SLAC has embarked on an effort to bring the power of parallel computing to bear on such computations with the goal to reduce the turnaround time by orders of magnitude so that the...

In CESR, 9 trains of 4 or 5 bunches of electrons and positrons collide at the interaction point, but bypass each other in the arcs of the storage ring using electrostatically separated orbits (pretzels). The parasitic bunch crossings resulting from the use of pretzel separation causes the bunches to have different orbits and, thus, the luminosity to be sensitive to the relative transverse posit...

In routine operation the Cornell Electron/positron Storage Ring, CESR, collides 9 trains of 4 or 5 bunches of electrons and positrons. The luminosity of individual bunch pairs can suffer if the transverse positions of those bunches are displaced differentially. This paper will present the results of studies of the effect of bunch–by–bunch or train– by–train variations in the luminosity by measu...