Design and fabrication of a prototype planar undulator

Abstract

The main goal of this work is to get the fabrication technology of the insertion devices. A prototype undulator with the period of 48mm and the peak magnetic field of 0.75 T has been fabricated using NdFeB-SH35 magnets based on the cooperation between ILSF and NSTRI. The total magnet length is 483 mm and the number of periods is 8. The magnetic parameters of the undulator are determined in order to reach the first and third harmonics. The photon energy should cover 260 eV to 2000 eV range. In order to control the strong attractive magnetic force between the upper and lower arrays, a special mechanical mechanism has been designed and fabricated. The source of errors in the magnetic field has been discussed. The share of each errors has been investigated in the total magnetic field and their effects on the harmonics intensity have been studied. The RMS field error has been obtained to be 0.4%; also, the first and third harmonics intensity reached to more than 80% of the ideal intensities in the presence of the real magnetic field.

Keywords

• planar undulator
• permanent magnets
• synchrotron radiation
• field error
• Hall probe