The Design And Study Of The High-energy Acceleration Period For SSC-LINAC

In order to alleviate the operating pressure of the Sector Focusing Cyclotron(SFC),improve beam quality and increase the operation efficiency,a linac injector(SSCLINAC)is designed by Institute of Morden Physics(IMP)to make it possible to work in parallel for SFC,SSC,CSR.The SSC-LIANC plays an important role in enhancing the overall performance both in the injection of CSR and in experiments on high current heavy ion beam.As an injector of SSC,SSC-LINAC can provide CW heavy-ion beams with the energy of 0.58 Me V/u and 1.025 Me V/u respectively.The SSC will boost energies of the output beams up to 5.5 Me V/u and 10.7Me V/u for various experimental terminals and CSRm.The SSC-LIANC is composed of the superconducting ECR ion source,LEBT,4-rod RFQ,MEBT,IH-DTL cavities and HEBT.This thesis mainly focuses on the design and investigation of the IH-DTL3 in the high-energy acceleration section.Two operating frequencies that 53.667 MHz and 107.334 MHz were considered and compared in the design.The design indicators are as follows:1)The charge-to-mass ratio is from 1/7 to 1/3.2)Beam current is about 0.1m A,boosted from 0.58 Me V/u to 1.025 Me V/u.3)Continuous wave(CW)operation is required.4)The phase width at the exit of DTL3 should be less than ±20°.Therefore,the thesis firstly introduced the principles,current development of LINAC and corresponding theory about beam transmission.And then the details of beam dynamics design,simulation,optimization and the EM design are also presented.In the process of KONUS beam dynamics design,the period of acceleration,transverse focusing and longitudinal focusing are separated from each other.The accelerating in 0° will lead to the defocusing in transverse,causing different levels of the emittance increase in longitudinal and transeverse direction.Owing to the large longitudinal energy spread and phase width at the entrance,small longitudinal and transverse acceptance of SSC,it is difficult to match the two ends.So on the premise of meeting the beam energy requirement,the emittance increase and phase width at the exit are mainly concerned in the process of beam dynamics design.In the end,the relative emittance growth should be controlled in the range of 20%,while the phase width in the range of ±20°.By contrasting the two results of beam dynamics design at 53.667 MHz and 107.334 MHz,the design proposal at 53.667 MHz is selected to further optimize,which could be better to meet the practical requirements.In the course of EM design,the cavity characteristics,such as frequency,Q factor,effective shunt impedance,the field distribution,power consumption,the maximum surface electric field and the Kp value are considered.To begin with,based on the original design scheme,the effects on RF features of various components sizes are discussed.Some useful conclusions are obtained,which is significant for the actual optimization of the cavity design.And then according to the above results,the IH-DTL cavity at 53.667 MHz is optimized.The actually final design parameters,which meet the design requirement,are as follows: the Q factor is about 13800,the maximum axial electric field in the gap is about 3.683MV/m,the power consumption is about 24.6k W,the maximum surface electric field is about 11.96MV/m,the Kp value is about 1.3 and the effective shunt impedance is about 265M?/m.