Abstract:
To improve the capability and performance of
its light sources, the Duke FEL lab (DFELL)
is upgrading its storage ring based FEL. The
existing linearly polarized OK-4 FEL wigglers
are being replaced gradually by the next
generation OK-5 wigglers capable of producing
either linearly or circularly polarized
light. In the second phase of this upgrade in
2005, the OK-5 FEL consisting of two wigglers
is installed together with the OK-4 FEL in a
specially designed magnetic lattice. The
circularly polarized OK-5 FEL was first
brought to lasing on Aug. 14, 2005.
In the following days, the first distributed
optical klystron FEL with variable
polarization, the DOK-1 FEL, comprised of two
horizontal OK-4 wigglers and two circular
OK-5 wigglers, was brought to lasing for the
first time. In this paper, we report our
commissioning experience and initial
measurements of both the OK-5 FEL and DOK-1 FEL.