Design and test of an RF acceleration system loaded with magnetic alloy for the proton synchrotron of the Xi'an Proton Application Facility

The Xi'an Proton Application Facility(XiPAF)is a facility dedicated to the experimental simulation of the space radiation environment.The facility uses a compact synchrotron as its final-stage accelerator.The synchrotron can accelerate a proton beam from 7 to 230 MeV.Physical design results show that the radio frequency(RF) acceleration system should work in the frequency range of 1—6 MHz and provide a maximum voltage of >800 V.To dilute the strong space charge effect during the injection period,we also aim to achieve multiharmonic acceleration.A compact RF acceleration system loaded with magnetic alloy cores has been designed and developed to fulfill these requirements.The preliminary test results show that the system can work normally with a gap voltage of 800 V.With a further RF power upgrade,the voltage can be improved to >1:2 kV.

Beam position monitors as precise phase pickups for beam energy measurement at the Compact Pulsed Hadron Source

The 13-MeV proton linac of the Compact Pulsed Hadron Source(CPHS) at Tsinghua University, China,is composed of a 50-keV electron cyclotron resonance proton source, a 3-MeV four-vane-type radio-frequency quadrupole(RFQ) accelerator, and a drift tube linac(DTL). Precise measurement of the beam energies at the exit of the RFQ and the DTL is critical for DTL commissioning. Two button-type beam position monitors(BPMs) installed downstream of the RFQ are used to perform the measurement using a time-of-flight method. The effects of several factors on phase measurement accuracy are analyzed. The phase measurement accuracy of the BPMs at CPHS is better than ± 1.03° at 325 MHz after corrections,corresponding to an energy measurement error of± 0.07%. The beam energy measured at the exit of the RFQ is 2.994 ± 0.0022 MeV,which is consistent with the design value.

Analysis and simulation of the tune ripple effect on beam spill ripple in RF-KO slow extraction

Tune ripple has a significant influence on beam spill ripple in RF-knockout(RF-KO)slow extraction.In this study,a model was proposed to explain how the tune ripple affects the beam spill in RF-KO slow extraction;consequently,a simulation was performed using the lattice of the Xi’an Proton Application Facility(XiPAF)synchrotron to verify the model.The simulation demonstrates that the tune ripple influences the beam spill in two ways.On the one hand,the tune ripple causes a direct fluctuation in the separatrix area,which induces beam spill ripple.On the other hand,the tune ripple influences the emittance growth rate in RF-knockout slow extraction.These two aspects simultaneously contribute to the beam spill ripple.