Toshiya Tanabe

X-25 Cryo-ready In-vacuum Undulator at the NSLS

The existing 15‐year‐old hybrid wiggler at the NSLS has been replaced by a state‐of‐the‐art, cryo‐ready in‐vacuum undulator optimized for a dedicated macromolecular crystallography program. The device is a 1m long, 18mm period, hybrid PM‐type with a minimum operating gap of 5.6mm, and has provision for cryo‐cooling to 150K. Unlike the original SPring‐8 cryo‐PM undulator proposal, we use a new high‐remanence, high‐temperature grade of NdFeB (NEOMAX 42AH with Br=1.3T and Hcj=24 kOe) that can be baked to 100°C to be UHV‐ready in case of cooling system failure. A novel optical gap measurement system using a LED‐based product ensures gap accuracy of ±2 micro meter. A friction stir welding technique is used for the first time in an accelerator UHV device to minimize stress and deformation of the magnet arrays due to temperature gradients. This paper describes design issues of the device and other considerations such as magnetic measurement at low temperature.

Cryogenic Field Measurement of Pr2Fe14B Undulator and Performance Enhancement Options at the NSLS-II

Short period (14.5mm) hybrid undulator arrays composed of Praseodymium Iron Boron (Pr2Fe14B) magnets (CR53, NEOMAX, Inc.) and vanadium permendur poles have been fabricated at Brookhaven National Laboratory. Unlike Neodymium Iron Boron (Nd2Fe14B) magnets which exhibit spin reorientation at a temperatures below 150 K, PrFeB arrays monotonically increase performance with lower operating temperature. It opens up the possibility for use in operating a cryo‐permanent magnet undulator (CPMU) in the range of 40 K to 60 K where very efficient cryocoolers are available. Magnetic flux density profiles were measured at various temperature ranges from room temperature down to liquid helium (LHe) using the Vertical Testing Facility (VTF) at the National Synchrotron Light Source‐II (NSLS‐II). Temperature variations of phase error have been characterized. In addition, we examined the use of textured Dysprosium (Dy) poles to replace permendur poles to obtain further improvement in performance.

Magnetic Measurement System for the NSLS Superconducting Undulator Vertical Test Facility

One of the challenges of small-gap superconducting undulators is measurement of magnetic fields within the cold bore to characterize the device performance and to determine magnetic field errors for correction or shimming, as is done for room-temperature undulators. Both detailed field maps and integrated field measurements are required. This paper describes a 6-element, cryogenic Hall probe field mapper for the NSLS superconducting undulator Vertical Test Facility (VTF) [1]. The probe is designed to work in an aperture only 3 mm high. A pulsed-wire insert is also being developed, for visualization of the trajectory, for locating steering errors and for determining integrated multi-pole errors. The pulsed-wire insert is interchangeable with the Hall probe mapper. The VTF and the magnetic measurement systems can accommodate undulators up to 0.4 m in length.

Parametric Optimization of Undulators for NSLS‐II Project Beamlines

General optimization procedure, computation methods used, and the obtained optimal parameters of undulators for the NSLS‐II project beamlines are reported. The optimization starts with high‐accuracy calculation of undulator magnetic fields, using Radia magnetostatics code, for a large set of periods and vertical gaps of a given undulator type, given magnetic materials and a scalable magnet geometry. From the resulting magnetic fields, a sub‐set of undulator periods and the corresponding vertical gaps, providing the required low‐energy cut‐off values of spectral harmonics for each particular beamline, is determined. In parallel, from the same Radia undulator models, angular magnetic kick maps are calculated, and the insertion device effect on electron beam is simulated using Tracy‐2 tracking code based on symplectic integrator. After these simulations, magnet parameters are fine‐tuned and the maximal acceptable undulator lengths are determined for different straight sections, as functions of minimal gap an...

Insertion Devices at the National Synchrotron Light Source-II

The NSLS-II storage ring completed commissioning in 2014 and all project-beamline IDs have also been commissioned. As of February 2015, six beamlines are about to finish commissioning. By the end of 2015, the ring is expected to store 300 mA with top-up injection capability and 500 mA with a second superconducting RF cavity installed in the following year. The design principle of the NSLS-II ring is to employ low-field BMs and simultaneously install high-field wigglers in non-dispersive straights to reduce the horizontal emittance. The more wigglers are installed, the smaller the horizontal electron beam emittance becomes. At this stage, six 3.4-m-long wigglers with 1.8 T effective field and 100 mm period length have been installed in three straight sections, which could reduce emittance in a bare lattice from 2.1 nm.rad to approximately 1.0 nm. rad. Two 2.0-m-long EPU49s are installed for the coherent soft X-ray (CSX) beamline in a short straight (SS) section also known as the low-βx straight section. These are Apple-II-type devices with four movable arrays. Two 3.0-m-long IVU20s are installed in two SSs, one for the Hard X-ray Nano-Probe (HXN) beamline and the other for the Coherent Hard X-ray (CHX) beamline. One 1.5-m-long IVU21 is installed in a canted short straight section for the Sub-Micron Resolution X-ray Spectroscopy (SRX) beamline. Its canting angle is 2 mrad outboard in the center of the straight section. The first ID for this beamline is installed in the downstream portion of the straight section. Another 3.0-m-long IVU22 is installed in a long straight section (LS: high-βx) where a second device is planned to be added in the future. Three 2.8-m-long IVU23s are planned to be installed in long straight sections, either in an asymmetric canted configuration or in a straight configuration. One 1.4 m EPU57 and one 2.8 m EPU105 are planned for the Electron Spectro-Microscopy (ESM) beamline in a SS, while one 3.5m EPU57 in a LS is planned for the Soft Inelastic X-ray Scattering (SIX) beamline. Table 1 shows the specifications of all the IDs funded so far.

NSLS-II Injection Concept

Currently the facility upgrade project is in progress at the NSLS (at Brookhaven National Laboratory). The goal of the NSLS-II is a 3 GeV ultra-low-emittance storage ring that will increase radiation brightness by three orders of magnitude over that of the present NSLS X-ray ring. The low emittance of the high brightness ring’s lattice results in a short lifetime, so that a top-off injection mode becomes an operational necessity. Therefore, the NSLS-II injection system must provide, and efficiently inject, an electron beam at a high repetition rate. In this paper, we present our concept of the NSLS-II injection system and discuss the conditions for, and constraints on, its design.

Initial performances of first undulator-based hard x-ray beamlines of NSLS-II compared to simulations

Commissioning of the first X-ray beamlines of NSLS-II included detailed measurements of spectral and spatial distributions of the radiation at different locations of the beamlines, from front-ends to sample positions. Comparison of some of these measurement results with high-accuracy calculations of synchrotron (undulator) emission and wavefront propagation through X-ray transport optics, performed using SRW code, is presented.

Insertion device R&D for NSLS-II

NSLS-II is a medium energy storage ring of 3 GeV electron beam energy with sub-nm.rad horizontal emittance and top-off capability at 500 mA. Damping wigglers will be used not only to reduce the beam emittance but also for broadband sources for users. Cryo-permanent magnet undulators (CPMUs) are considered for hard X-ray planar device, and permanent magnet based elliptically polarized undulators (EPUs) are for soft X-ray polarization control. Rigorous R&D plans have been established to pursue the performance enhancement of the above devices as well as building new types of insertion devices such as high temperature superconducting wiggler/undulators. This paper describes the details of these activities and discuss technical issues.

Refurbishment of a used in-vacuum undulator from the National Synchrotron Light Source for the National Synchrotron Light Source-II ring

The National Synchrotron Light Source (NSLS) ceased operation in September 2014 and was succeeded by NSLS-II. There were four in-vacuum undulators (IVUs) in operation at NSLS. The most recently constructed IVU for NSLS was the mini-gap undulator (MGU-X25, to be renamed IVU18 for NSLS-II), which was constructed in 2006. This device was selected to be reused for the New York Structural Biology Consortium Microdiffraction beamline at NSLS-II. At the time of construction, IVU18 was a state-of-the-art undulator designed to be operated as a cryogenic permanent-magnet undulator. Due to the more stringent field quality and impedance requirements of the NSLS-II ring, the transition region was redesigned. The control system was also updated to NSLS-II specifications. This paper reports the details of the IVU18 refurbishment activities including additional magnetic measurement and tuning.

Recent Magnetic Measurement Activities at NSLS-II Insertion Device Laboratory

National Synchrotron Light Source II (NSLS-II) at Brookhaven National Laboratory (BNL) is a new 3 GeV third generation electron storage ring designated to provide extremely intense beams of X-ray, ultraviolet, and infrared light for basic and applied research. Insertion devices (IDs) play a significant role in achieving the high performance demands of NSLS-II. An accurate magnetic characterization and proper corrections of these devices are essential activities in the development of a state-of-the-art light source facility. This paper describes the results of the latest magnetic measurement activities at the NSLS-II ID laboratory.