Performance of the correlated painting based on the mechanical structure of the anticorrelated painting scheme

Abstract

The China Spallation Neutron Source (CSNS) accelerator consists of an 80 MeV ${H}^{\ensuremath{-}}$ Linac and a 1.6-GeV rapid cycling synchrotron (RCS). The painting scheme is one of the most important factors for the control of low beam loss at high beam power. In the painting injection of the CSNS/RCS, position scanning is used in both horizontal and vertical planes, and the anticorrelated painting is the design scheme. By using the anticorrelated painting, the beam power has successfully reached 50 kW. However, some problems have been found in the higher power beam commissioning, for instance, too large beam size after painting, nonuniform beam distribution, large transverse coupling effect, and so on, resulting in additional beam loss and making it difficult to satisfy the requirements of a high-power user mode. In order to solve these problems, flexibility in the CSNS design has been exploited to implement the correlated painting by using the rising current curve of the pulse power supply. The effectiveness of the new method has been verified in the simulation and beam commissioning, which can well control the full beam emittance and improve the beam distribution. By using the new method, the beam power on the target has successfully risen from 50 kW to the design value of 100 kW. Under the mechanical structure of the anticorrelated painting scheme where the position scanning is used in both horizontal and vertical planes, the correlated painting has been successfully achieved by using the rising current curve.