Energy Spread and Emittance Simulation for RISP RFQ Cooler

Young-Ho Park,Won Joo Hwang,Yong Kyun Kim,Hyung-Joo Woo,Ju Hahn Lee,Gi Dong Kim

doi:10.1051/epjconf/20146611027

Abstract

RFQ cooler of RAON facility is a device to enhance the quality of ion beam. It is to secure the resolving power of high resolution mass separator by reducing the energy spread and the emittance of ion beam. Key components of this device are deceleration optics for ions with kinetic energy of up to 40 keV, segmented RFQ electrodes for trapping and cooling, and extraction optics for reacceleration. Using SIMION simulation code, we could test the device and characterize the output beam quality. Output emittance of less than 3  mm mrad and energy spread of less than 1 eV were obtained in this simulation.

Highlights

Ions with well-defined position and momentum are inevitable for precision measurement and separation
As ions are thermally cooled by buffer gas collision in a radio frequency quadrupole trap, they come to have better beam quality than the ones that were originally generated from an ion source
We report the performance of our RFQ cooler based on the calculation from SIMION code [4]

Summary

Introduction

Ions with well-defined position and momentum are inevitable for precision measurement and separation. RFQ cooler [1] is to prepare ion beam with precise physical properties concerning emittance, energy spread, and temporal spread etc. In RAON facility [2], an RFQ cooler will be installed in between pre-separator of ion source and high resolution mass separator of low energy beam line. The target specifications of this device are as follows: output emittance of 3 mm mrad, energy spread of less than 1 eV, and transmission efficiency of more than 60 % in DC mode operation. We started our study with a design similar to TITAN RFQ cooler [3]. The space charge effect from the Coulomb repulsion between individual ions was not taken into account in this study. We report the performance of our RFQ cooler based on the calculation from SIMION code [4]

RFQ Cooler Design

Simulation using SIMION code

Findings

Summary and discussion