Effective shielding to measure beam current from an ion source

Area of Science:

• Particle Accelerator Physics
• Electromagnetism
• Materials Science

Background:

• Beam current transformers (BCTs) are susceptible to saturation from stray magnetic fields generated by solenoids, quadrupoles, and RFQ structures.
• Accurate beam current measurements are vital for accelerator operation and research.
• Limited space in accelerator beamlines necessitates compact shielding solutions.

Purpose of the Study:

• To develop and describe compact, effective magnetic shielding for BCTs in particle accelerator environments.
• To ensure BCTs maintain functionality and accuracy despite high external stray fields.
• To present measurement data validating the shielding performance.

Main Methods:

• Design and fabrication of concatenated magnetic shields tailored for specific accelerator components (IFMIF-EVEDA LIPAc LEBT/MEBT, FAIR Proton Linac).
• Analysis of magnetic field distribution and shielding material properties.
• Experimental validation of shield effectiveness through measurements on the SILHI source.

Main Results:

• The developed compact concatenated magnetic shields effectively protect ACCT Current Transformers from radial external fields exceeding 37 mT.
• Shielding performance was validated through measurements at Saclay.
• The shields are designed to fit within the constrained space along the beam pipe.

Conclusions:

• Compact, effective magnetic shielding is achievable and essential for protecting beam current transformers in high-stray-field accelerator environments.
• The described shielding techniques are applicable to various accelerator projects, including IFMIF-EVEDA and FAIR.
• Understanding field distribution and material properties is key to designing successful magnetic shields.