RadiaBeam, Marina del Rey, California, USA
ANL, Lemont, Illinois, USA
UCLA, Los Angeles, USA
RadiaBeam, in collaboration with UCLA and Argonne National Laboratory (ANL), is developing a strongly tapered helical undulator system for the Tapering Enhanced Stimulated Superradiant Amplification experiment at 266 nm (TESSA-266). The experiment will be carried out at the APS LEA facility at ANL and aims at the demonstration of very high energy conversion efficiency in the UV. The undulator system was designed by UCLA, engineered by RadiaBeam, and is presently in fabrication at RadiaBeam. The design is based on a permanent magnet Halbach scheme and includes a short 30 cm long buncher section and four 1 m long undulator sections. The undulator period is fixed at 32 mm and the magnetic field amplitude can be tapered by tuning the gap along the interaction. Each magnet can be individually adjusted by 1.03 mm, offering up to 25% magnetic field tunability with a minimum gap of 5.58 mm. A custom designed 316L stainless steel beampipe runs through the center with a clear aperture of 4.5 mm. This paper discusses the design and engineering of the undulator system, fabrication status, and plans for magnetic measurements, and tuning.
ANL, Lemont, Illinois, USA
We present the results of experiments intended to show the effects of beam dumps on candidate collimator materials for the Advanced Photon Source Upgrade (APS-U) storage ring (SR). Due to small transverse electron beam sizes, whole beam loss events are expected to yield dose levels in excess of 10 MGy in beam-facing components, pushing irradiated regions into a hydrodynamic regime. Whole beam aborts have characteristic time scales ranging from 100s of ps to 10s of microseconds which are either much shorter than or roughly equal to thermal diffusion times. Aluminum and titanium alloy test pieces are each exposed to a series of beam aborts of varying fill pattern and charge. Simulations suggest the high energy/power densities are likely to lead to phase transitions and damage in any material initially encountered by the beam. We describe measurements used to characterize the beam aborts and compare the results with those from the static particle-matter interaction code, MARS; we also plan to explore wakefield effects. Beam dynamics modeling, done with elegant is discussed in a companion paper at this conference. The goal of this work is to guide the design of APS-U SR collimators.
Fermilab, Batavia, Illinois, USA
ANL, Lemont, Illinois, USA
One of the challenges of the injector for the Advanced Photon Source Upgrade (APS-U) is the measurement and monitoring of the required high charge electron beam at 6 GeV between the Booster synchrotron and the storage ring in the transport line (BTS. In APS-U charges of up to 17 nC per micropulse are specified with a beam geometrical horizontal emittance of 60 nm rad. Vertical beam sizes at the imaging station of ~80 µm (σ) are expected so system resolutions of <30 µm are warranted. A phased approach to enhance the imaging station performance has been initiated. Recently, the 20-year-old Chromox screen oriented at 45 degrees to the beam was replaced by a 100-micron thick YAG:Ce screen which gave an improved screen resolution of <10 micron(σ. However, the optical magnification of the system still needs to be increased. In addition, the high areal charge densities are expected to exceed the scintillator mechanism’s saturation threshold so an optical transition radiation (OTR) screen will be added to the station for high-charge studies. A final phase would be the use of optical diffraction radiation (ODR) as a non-intercepting, beam-size monitor during top-up injections.