New energy-spread-feedback control system using nondestructive energy-spread monitors

Abstract

A new energy-spread feedback control system using nondestructive energy-spread monitors has been developed in order to control and stabilize the energy spreads of single-bunch electron and positron beams in the KEKB injector linac. A well-controlled feedback system has been successfully working in daily operation not only for keeping the injection rate higher along with the beam-orbit and energy-feedback control system, but also for reducing the background level to the KEKB collider experiment. The energy spreads of the injection beams have been well stabilized within 0:33 0:01% and 0:50 0:02% (0:55 0:06%) for the electron beam and the first (second) bunch of the high-current primary electron beam for positron production at the 180 arc, respectively, and within 0:39 0:01% (0:36 0:03%) for the first (second) bunch of the positron beam at the end of the injector linac through the energy-spread feedback control system under the nominal operation condition. In this report we describe in detail the energyspread feedback control system using nondestructive energy-spread monitors with multi -strip-line electrodes and their performance in KEKB operation.

Time dependent formulation of the energy loss by an accelerated intense electron beam just emitted by the cathode of RF-FEL photoinjector

“…Calculations of qq l qt , q l (t) and r l (t) By means of Eqs. (11), (12), (18) and (21) the terms qq l =qt and q l ðtÞ become for p ¼ 0:…”

“…As a consequence, these fields cause instabilities such as bunch lengthening, head-tail turbulence, energy dispersion and emittance growth which result in deterioration of the beam quality and can even affect strongly the lasing process. The conventional treatment of the wakefield [9,10], energy dispersion [11,12], and emittance growth [13] considers an ultrarelativistic beam of uniform density traveling at the speed of light. Although it does not take into account any axial energy dispersion inside the pulse, this treatment greatly simplifies the calculation and leads to ignoring the self-field.…”