Speaker
Description
CSNS ion source, similar to ISIS ion source is a type of penning surface plasma ion source, which can produce 50 mA H$^{-}$ beam. The commissioning of CSNS front end including ion, LEBT and RFQ has been finished. Above 15 mA H$^{-}$ beam is obtained at the exit of RFQ, which meets the requirement of CSNS phase I. However, the improvement of both, beam performance and operation stability, is desirable to be studied further. Some modifications have been performed, including penning field, extraction optics, post acceleration, and power supply. A new ceramic insulator is designed. A cap is added into the end of insulator, which increase insulated distance in vacuum side with no influence on beam optics. The permanent magnet is tried to produce penning field instead of pole tip mounted on the analyzing magnet top surface. Some simulations are done using PBGUNS and CST. Various extracted structure are simulated aiming to make the beam through the extracted electrode without loss. Furthermore, a new extraction power supply is designed, which can offer associate pulse power supply. During non-pulse extraction, this associate power supply is created to extract negative beam, which will loss on the surface of extraction electrode largely. In this case, the surface temperature of extraction electrode will be heated to over a hundred degree. And the cesium vapor from the discharge chamber will and not deposit on this surface. The stability of ion source thus is improved further. The commissioning of ion source shows a good result within 48 hours. The plasma emission spectrum is also applied to diagnose the plasma discharge.
