Center for Exotic Nuclear Studies

KoBRA Wien Filter Project

1. Wien filter (Velocity filter)

• Ion optical element that can select the ions having the target velocity
• Perpendicular electric and magnetic fields
  ► Net force normal to the beam direction
• 
  
• Mass Spectrometer, Monochromator, etc.

Principal of the Wien filter

2. Purpose of the project

• Introducing a Wien Filter to the KoBRA beamline, the low-energy beamline at RAON
• Determining the specification of a Wien Filter considering the cost and ion optical performance
• Managing the purchase procedure and installation

3. Design

Top and side view of the Wien filter

Good-Field Region (GFR) of the Wien filter

Schematic view of the Wien filter

4. KoBRA Beam line

• Ion optical element that can select the ions having the target velocity
• Perpendicular electric and magnetic fields
  ► Net force normal to the beam direction
• 
  
• Mass Spectrometer, Monochromator, etc.

Install location of the Wien filter at KoBRA

5. Specifications

• Dipole magnet
• Vacuum chamber including electrodes
• Magnet power supply, HV power supply x 2

Field specifications

6. Performance Estimation

• Primary beam: 20Ne6+ (33 A∙MeV)
• Secondary beam: 18Ne (6 A∙MeV)
• Check the horizontal separation at the final focal plane (F3).
• Wien Filter can improve the beam purity with clear separation and better focusing.

Performance estimation results using LISE++

Optimal ion optics of KoBRA with Wien filter

KOSYG: KoBRA optics code for cOSY with Gui

Ion optics results with 14O8+ at 2.5 A∙MeV beam which is a typical beam produced by CRIB , RIKEN-CNS

Ion optics resu