UCLA, Los Angeles, California, USA
ANL, Lemont, Illinois, USA
Dipole correctors and phase shifters are usually needed in the interspace of a permanent magnet (PM)-based undulator array for purposes of beam steering and phase matching when the field strength is changing. Unlike the PM-based undulators, the superconducting undulator (SCU) can change its end field with the help of varying currents in the end coils. By setting the end coil currents the beam-steering and the phase-matching could be realized, thus eliminating the need for standalone correctors and phase shifters, saving the interspace as well as reducing the mechanical complexity of an undulator array. We developed a procedure for determining the SCU end coil currents and verified it by numerical simulations. The procedure as well as the simulation results are described in this paper.
ANL, Lemont, Illinois, USA
An ANL-SLAC collaboration is working on design of a planar superconducting undulator (SCU) demonstrator for a FEL. As a part of this project, a SCU magnet prototype is planned to be built and tested. A planar SCU magnet consisting of a 1.0-m-long segment is being designed. Although OPERA is a standard tool for magnetic field calculation, ANSYS Maxwell 3D can also be used for a large and complex geometry. An ANSYS calculated magnetic field was benchmarked with the measured field profile of existing SCUs. This paper presents calculations of magnetic field and field integrals of 0.5-m-long and 1.0-m-long planar SCUs with a new end correction scheme. Then, an external phase shifter is also incorporated into the model. A cross-talk between a phase shifter and SCU magnetic structures is also presented.
RadiaBeam, Santa Monica, California, USA
UCLA, Los Angeles, USA
Beamline space is a very expensive and highly sought-after commodity, which makes the creation of compact integrated optics and diagnostics extremely valuable. The FAST- GREENS experimental program aims at demonstrating 10 % extraction efficiency from a relativistic electron beam using four helical undulators operating in the high gain TESSA regime. The inter-undulator gap needs to be as short as possible (17 cm in the current plans) to maximize the output power. Within this short distance, we needed to fit two focusing quadrupoles, a variable strength phase shifter, a transverse profile monitor consisting of a YAG-OTR combination for co-aligning the electron beam and laser, and an ion pump. By making the quadrupoles tunable with a variable gradient, in combination with vertical displacement, we can meet the optics requirements of matching the beam transversely to the natural focusing of the undulators. The two quadrupoles in conjunction with the electromagnetic dipole also serve as a phase shifter to realign the radiation and the bunching before each undulator section. This paper will discuss the mechanical design of this inter-undulator break section and its components.
SLAC, Menlo Park, California, USA
ANL, Lemont, Illinois, USA
We present connectable designs of superconducting undulators (SCU) and cryomodules (CM) based on previous SCU and CM designs at Argonne National Lab. The new SCU and CM designs will allow us to connect one CM to the next to form a contiguous line of SCUs with no breaks between the cryomodules. The SCU design will have correctors and phase shifters integrated into the main SCU magnet core, as well as external corrector magnets for trajectory corrections. There will also be a cryogenic magnetic quadrupole and a cold RF beam position monitor (BPM) integrated in the SCU CM. In addition to providing the usual FODO transverse focusing, the quadrupole and BPM will be used for the beam-based alignment technique that is critical for X-ray FEL operation. In this paper, we will present the conceptual design of the new SCU CM as well as results of FEL simulations using the SCUs as afterburners for the LCLS hard X-ray undulators.