Electromagnetic design, development and testing of 2T-XMCD dipole magnet

X-Ray absorption spectroscopy beamlines BL-08 and BL-09 cover an energy range of 5-25 KeV and are being used extensively. These beam-lines can also be used for X-ray Magnetic Circular Dichorism (XMCD) measurements. XMCD is the difference in spectrum of the X-ray absorption spectra, taken in the magnetic field, of the left circularly polarized light with the right circularly polarized light. XMCD is a useful technique to find the spin and orbital polarization components of different atoms present in the sample and is evolving as a very popular technique to for characterization of magnetic material with synchrotron radiation. To carry out the above experiments, a dipole electromagnet has been designed and developed. The magnet produces a field of 2 Tesla in a good field volume of 125 mm³ . The large air-gap dipole magnet can accommodate a cryostat to carry out the XMCD experiments at low temperatures. The electromagnet size is 500 x 500 x 400 mm³ and it weighs about 400 Kgs. Water cooled hollow copper conductors have been used for the magnetic coils which are arranged in a Helmholtz configuration. Pole shape optimization has been done to achieve a field uniformity of 100 ppm in the GFR. Motorized motion stages have been used for alignment and rotation of the electromagnet axis with the beam line to facilitate studies at different magnetization angles of the sample. (author)