The Research Of The Cooling Beam Lifetime In HIRFL-CSR

In this thesis,the theory and experiments about beam lifetime in HIRFL-CSR accelerator were described.The main Cooling Storage Ring(CSRm)of HIRFL-CSR is used to accumulate,accelerate and extract the charged ion beam to experimental terminal.During accumulation in CSRm,the Multiple Multiturn Injection method with electron cooling is applied at the injection energy to increase beam intensity.On the one hand,electron cooling can quickly shrink the size,divergence and the momentum spread of stored ion beams,which is also used to reduce beam loss that caused by Intra Beam Scattering(IBS).On the other hand,electron cooling can improve the cumulative efficency.The heavy ion accelerators require an extrimenlly high vacuum,because the residual gas in the tube will lead to beam loss which is caused by the scattering and the charge exchange process.By the existing cross-section formula,the lifetime due to the residual gas was estimated in CSRm.A good lifetime of the beam is helpful for the accumulating and accelerate in CSRm,as well as,which will achieve a high beam luminosity for internal target experiments.The recombination effects between electrons and ions will result in the beam loss.Some experiments on C6+ beam and Ar15+ beam have been carried out in CSRm to investigate the relationship between electron cooler and beam lifetime.It is observed that the beam lifetime is remarkably increased when electron cooling is applied.The dependence of ion beam lifetime on the electron beam parameters(the density/the current/ the energy/the expansion factor)has been measured.The results of the measurement have been analyzed based on the electron cooling and recombination theory.The principle of how the electron cooling affect beam lifetime has aslo been studied.According to the measurement results and the analysis,the electron beam parameters were optimized to improve the stored ion beam to a optimal state.