Stochastic Cooling Hardware System Development For CSRe

Stochastic cooling at the experimental Cooler Storage Ring,CSRe at the Institute of Modern Physics in China,is used mainly for experiments with radioactive fragment beams.According to the CSRe injection acceptance,CSRe stochastic cooling was designed to cool transverse emittances of up to 20-50πmm.mrad and momentum deviations of up to±0.5-1.0%.A combination of stochastic precooling and subsequent electron cooling is needed to get overall cooling times of the order of 10 seconds for injected secondary heavy ion beams and beams cooled by electron cooling to equilibrium phase space density.The study and design of CSRe stochastic cooling hardware system and the success of on-line beam experiments of its prototype are introduced in this thesis.In December 2015 stochastic cooling of heavy ions was successfully applied for the first time at the CSRe storage ring of IMP in Lanzhou,China.During four days of commissioning,transverse and longitudinal cooling could be observed.Both the time-of-flight and the notch filter methods were used for longitudinal cooling.The measured cooling rates are presented.The related work we did in this thesis has never been found in China before.A novel type of 2.76 m long perforated travelling wave pick-up/kicker structure which was originally proposed by F.Caspers at CERN was developed for CSRe stochastic cooling of medium energy heavy ion beams withβ≈0.7.It is installed inside a bending magnet vacuum chamber with the output signal taken from the downstream end.This slotted structure features a sufficiently broad bandwidth,good shunt impedance,low losses and a comparatively easy mechanical construction and installation into the CSRe dipole chamber.The simulated and measured results of shunt impedance of the slotted travelling wave pickup electrode are in reasonable agreement.The feasibility of this structure has been verified by beam cooling experiment on CSRe.The operating bandwidth from 100 MHz to 1200 MHz of the CSRe stochastic cooling hardware system is more than 3 octaves,which is different from any other facility in the world.The core microwave devices such as variable 0~0-360~0 wideband phase shifter,phase equalizer,notch filter and adjustable delay line are specially developed for the CSRe stochastic cooling hardware system.Three longitudinal cooling methods including TOF,Notch filter and Palmer were realized on a stochastic cooling hardware system.