Initial results from an in-vacuum undulator in the NSLS X-ray ring

A short‐period in‐vacuum undulator for the NSLS X‐ray Ring has been developed in a collaboration between SPring‐8 and the NSLS, and has achieved its project design goals during commissioning studies. The device is called IVUN (in‐vacuum undulator) and employs magnet arrays (31 periods, with an 11 mm period) developed at SPring‐8, while the requisite vacuum chamber and mechanical systems were developed at the NSLS. At a magnet gap of 3.3 mm, IVUN produces 4.6 keV radiation in the fundamental, with useful photon fluxes in both the second and third harmonics. The magnet gap is adjustable between 2 and 10 mm. A brief overview of IVUN is presented, together with initial commissioning results: the dependence of electron‐beam lifetime and bremsstrahlung on magnet gap, and the output radiation spectrum.