Development of a NdFe-steel Hybrid Wiggler For SSRL

Abstract

A NdFe-steel hybrid configured permanent magnet wiggler is being developed for insertion in the SPEAR ring at the Stanford Synchrotron Radiation Laboratory, SSRL. Featuring 15 complete periods, a 12.9-cm magnetic period length, and a peak magnetic field range of 0.01-1.4 Tesla, the wiggler was designed to provide an intense radiation source for the National Laboratory/University of California participating research team (PRT) facility on Beam Line VIII-W. A new permanent magnet material, neodymium-iron (NdFe), is being used in the magnetic structure instead of rare-earth cobalt, REC, used previously in the 27-period wiggler now on Beam Line VI. NdFe advantages include a 16% higher coercive force (10.6-kOe vs. 9.0-kOe) and lower cost. The wiggler design features a thin walled, rigid vacuum chamber with pole pockets on opposing surfaces allowing a 2.1-cm minimum magnetic gap with a 1.8-cm beam vertical aperture. At 3 GeV the wiggler at peak field is expected to radiate approximately two kilowatts in a 5-mrad horizontal fan with a 7.8 keV critical energy. Calculations are in progress to model the wiggler radiation spatial and spectral radiation emission.