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 ...

Compensation of multi-bunch beam loading is of great importance in the main linac of the Compact Linear Collider (CLIC). The bunch-to-bunch energy variation has to stay below 1 part in 10. In CLIC, the RF power is obtained by decelerating a drive beam which is formed by merging a number of short bunch trains. A promising scheme for tackling beam loading in the main linac is based on varying the...

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...

Head erosion is one of the limiting factors in plasma wakefield acceleration (PWFA). We present a study of head erosion with emittance growth in field-ionized plasma from the PWFA experiments performed at the FACET user facility at SLAC. At FACET, a 20.3 GeV bunch with 1.8×10 electrons is optimized in beam transverse size and combined with a high density lithium plasma for beam-driven plasma wa...

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...

We design a single bunch transverse beam size monitor which will be tested to measure the 28.5 GeV electron/positron beam at the SLAC FFTB beam line. The beam size monitor uses the CCD images of the interference pattern of the optical diffraction radiation from two slit edges which are placed close to the beam path. In this method, destruction of the accelerated electron/positron beam bunches d...

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...

Nothing epitomizes the mystery of life more than the spatial organization and dynamics of the cytoplasm. How can a bunch of molecules, no matter how sophisticated, generate spatially complex behavior on a scale that is much larger than the molecules themselves? In my view, we will be done as cell biologists when we can predict the structure and dynamics of cells from DNA sequence. That goal is ...

We have directly measured the mm-wave wake fields induced by subpicosecond, intense relativistic electron bunches in a diamond loaded accelerating structure via the dielectric wake-field acceleration mechanism. Fields produced by a leading drive beam were used to accelerate a trailing witness electron bunch which followed the driving bunch at an adjustable distance. The energy change of the wit...