Pepperpot emittance measurements of ion beams from an electron beam ion source

J Pitters,M Breitenfeldt,S Duarte Pinto,H Pahl,A Pikin,A Shornikov,F Wenander

doi:10.1016/j.nima.2018.12.072

Abstract

A pepperpot emittance meter was used to measure the transverse emittance of multiply charged beams from REXEBIS, an Electron Beam Ion Source (EBIS) used for charge breeding of radioactive ion beams. The emittance meter is equipped with a Micro Channel Plate (MCP), a phosphor screen and a CCD camera for detection of the ion signal. The pulsed beam structure of low duty cycle imposes challenging constraints on the detector settings. In this article we give a careful analysis of the optimal operating parameters of the pepperpot emittance meter for ion beams of varying intensities. Emittance values for mass-separated and non-separated beams for different operating modes of the EBIS are presented. Furthermore we report on aberrations created in our injection∕extraction system.

Highlights

REXEBIS [1] is used to perform charge breeding of ISOL-produced (Isotope Separation On-Line) beams [2]
A pepperpot emittance meter was used to measure the transverse emittance of multiply charged beams from REXEBIS, an Electron Beam Ion Source (EBIS) used for charge breeding of radioactive ion beams
The emittance of the EBIS is strongly governed by the thermal energy of the ions in the radial potential well, while the contribution from the magnetic field strength of the EBIS solenoid is relatively small

Summary

Introduction

REXEBIS [1] is used to perform charge breeding of ISOL-produced (Isotope Separation On-Line) beams [2]. The emittance of the EBIS is strongly governed by the thermal energy of the ions in the radial potential well, while the contribution from the magnetic field strength of the EBIS solenoid is relatively small. The normalized RMS emittance contribution from the radial ion temperature εT [3] and magnetic field εmag [4] can be estimated by the following equations: √ εT = re− 2. With q, mion and kTion being the ion’s charge, mass and transverse temperature, re− , the electron beam radius and B, the magnetic field strength in the EBIS trapping region. The values above are typical numbers for our setup, assuming, ions with mass number A = 20, charge state Q = 5, temperature kTion = 200 eV and a 2 T solenoidal field

Methods

Results

Conclusion