• S. Chunjarean
  SLRI, Nakhon Ratchasima
• C.-S. Hwang, J.C. Jan, F.-Y. Lin, P.H. Lin
  NSRRC, Hsinchu

Highest photon beam brightnesses are achieved in radiation from undulators. Very short period length and high fields, reached only in superconducting undulators, are desired to produce hard X-rays. In lower energy storage rings this is not enough, but radiation at higher harmonics(7th and up) are desirable. This is possible only if the undulator fields and periods are near perfect. Shimming methods as applied for room temperature permanent magnet undulators cannot be used for such superconducting magnets. The effect of field and period tolerances on higher harmonics photon beam brightnesses will be presented and limiting tolerances will be discussed. A variety of different field optimization techniques together with some measurements on test magnets will be discussed and evaluated to their usefulness as a high photon energy and high brightness radiation source.