Stochastic Cooling Pickup/Kicker Developments for the High-Precision Spectrometer Ring in the HIAF Project at IMP

Zhixue Li,Jiawen Xia,Long Jing,Xuejing Hu,Junxia Wu,Xin Zhang,Jiancheng Yang,Yuan Wei,Fritz Caspers,Guangyu Zhu,Jun Meng,Ze Du,Yong Zhang,Hongming Xie

doi:10.1109/tns.2020.3038525

Abstract

Stochastic cooling of the spectrometer ring (SRing) at the High Intensity Heavy-Ion Accelerator Facility (HIAF) project in China, which is used mainly for experiments with radioactive fragment beams, is applied to speed up the cooling process of a stored ion beam. In this study, both a Faltin traveling wave structure and a novel slot-ring standing wave structure based on a ceramic vacuum chamber are discussed and evaluated for the pickup/kicker of the SRing stochastic cooling system. The slot-ring structure should significantly improve the shunt impedance due to the Cherenkov effect. For the Faltin-type structure, the results for the pickup shunt impedance obtained from simulations and from beam measurements agree well. Good agreement is also found between the simulated and measured results for the pickup shunt impedance of the slot-ring structure. Cooling process simulations using the Fokker-Planck equation based on the shunt impedance results for the Faltin- and slot-ring-type pickups are also presented.

Highlights

T HE High Intensity Heavy-Ion Accelerator Facility (HIAF) project was proposed by the Institute of Modern Physics (IMP) of the Chinese Academy of Sciences (CAS) in 2009
The development, performance, and testing of both a Faltin prototype traveling wave structure and a novel slot-ring prototype standing wave structure based on a ceramic vacuum chamber for the HIAF spectrometer ring (SRing) stochastic cooling system are presented in this article
This article introduces in detail and systematically describes how to design a Faltin-type and slot-ring-type pickup/kicker using the High Frequency Structure Simulation (HFSS) software

Summary

INTRODUCTION

We changed the operating bandwidth to 0.6–1.2 GHz where the beam spread fits inside the acceptance of the TOF cooling system when the energy is 400 MeV. 2) The blue solid curve does not changes sign when |δ( p)/ p)| ≤ 0.004 This means that TOF 0.6–1.2 GHz cooling will work to cool the beam momentum spread of 0.004. 3) The black dotted curve changes sign outside |δ( p)/ p)| = 0.0027 This means that the acceptance of TOF cooling is smaller than the beam momentum spread (|δ( p)/ p)| = 0.004) if the cooling bandwidth is 1–2 GHz. The behavior of an electrode system when it functions as a pickup is intimately related to its behavior as a kicker due to the reciprocity between the kicker and the pickup. The commercial simulation software ANSYS HFSS [18] was used for the longitudinal and transverse numerical simulations

Faltin Structure

SIMULATION CALCULATIONS OF THE COOLING PROCESS

Findings

CONCLUSION