BNL, Upton, New York, USA
Fermilab, Batavia, Illinois, USA
ANL, Lemont, Illinois, USA
A new magnetic measurement system is under construc-tion at BNL for accurate field harmonic measurements and fiducialization of magnets for a future upgrade of the NSLS- II storage ring. The entire storage ring is envi-sioned to be replaced with a new lattice concept, known as Complex Bend, which superimposes dipole and high-gradient quadrupole fields. The magnetic measurement system will use rotating wire and a PCB rotating coil specifically designed for small-aperture (< 15 mm) high gradient magnets. In this paper we describe in detail the mechanical design and the data acquisition hardware and software.
BNL, Upton, New York, USA
*S. Sharma, "Storage Ring Girder Issues for Low Emittance Storage Rings", Tutorial, Medsi School 2, Grenoble, France, October 2-25, 2019.
ANL, Lemont, Illinois, USA
The Advanced Photon Source Upgrade (APS-U) accelerator magnets have stringent stability requirement*. The project schedule and budget did not allow for full prototyping of the final design. Therefore, the engineers relied on accurate simulation to ensure that the design would meet the specifications. Recently, assembly and free-boundary vibration tests have been done on the first article of the upstream quadrupole Doublet, Longitudinal gradient dipole and Multipole module (DLM-A). The top surface flatness of the girder and the magnet alignment measurement results demonstrate the static positioning requirement of magnet-to-magnet is met. The free-boundary condition modal test results were used to validate the FEA analysis used in the DLM-A design. This validation then confirms the predicted performance of the magnet support system design. Mode shapes and corresponding frequencies from the FEA modal analysis agree with the experimental modal analysis within an acceptable tolerance. The validation approves not only the procedure for accurate modeling of magnet support system that APS-U has developed, but also provides confidence in predicting the accelerator performance.
*Advanced Photon Source. (2019). APS Upgrade Project Final Design Report (APSU-2.01-RPT-003). Retrieved from https://www.aps.anl.gov/APS-Upgrade/Documents
University of Tokyo, Kashiwa, Japan
KEK, Tsukuba, Japan
Sokendai, The Graduate University for Advanced Studies, Tsukuba, Japan
Tokyo University of Science, Noda, Japan
Yokohama National University, Yokohama, Japan
TIT, Tokyo, Japan
Yokohama National University, Graduate School of Engineering Science, Yokohama, Japan
Although nonevaporable getter (NEG) pumps are widely used in synchrotron radiation facilities, pure metal Titanium (Ti) has not been used as a NEG because the activation temperature of a Ti thin film deposited by DC magnetron sputtering was reported to be 350-400 °C*. Recently Miyazawa et al. found that high-purity Ti deposited under ultra-high vacuum (UHV) followed by N2 introduction works as a NEG with an activation temperature of 185 °C**,***. Since the concentration of impurities such as O, C, and N in the Ti thin film prepared by this method is 0.05% or less, we named this as oxygen-free Ti. In this study, we evaluated the pumping properties of oxygen-free Ti thin films after high-purity N2 introduction by total and partial pressure measurements. A vacuum vessel with oxygen-free Ti deposited on the inner walls was found to pump H2, H2O, O2, CO and CO2 even after 30 cycles of high purity N2 introduction, air exposure, pumping, and baking at 185 °C. Furthermore, we analyzed the oxygen-free Ti thin films after high-purity N2 or air introduction by synchrotron radiation X-ray photoelectron spectroscopy. The results show that more TiN was formed when high-purity N2 was introduced after oxygen-free Ti deposition. High purity of the Ti thin film and TiN formation on the surface seem to be responsible for the reduced activation temperature as low as 185 °C.
*C. Benvenuti et al., J. Vac. Sci. Technol. A 16, 148 (1998).
**T. Miyazawa et al., Vac. Surf. Sci. 61, 227 (2018).
***KEK, patent pending, WO2018097325 (Nov. 28, 2017).
ALBA-CELLS Synchrotron, Cerdanyola del Vallès, Spain
Technical University of Catalonia, The Biomaterials, Biomechanics and Tissue Engineering, Barcelona, Spain
ANL, Lemont, Illinois, USA
The Advanced Photon Source-Upgrade (APS-U) project* is under construction and will incorporate a new Multi-Bend Achromat (MBA) lattice. With this design, the new storage ring will require over 1320 new magnets that are being produced under build-to-print contracts to several vendors across the globe. Magnetic measurements are needed to characterize and fiducialize all these magnets to ensure field quality and alignment requirements are met. Seven specialized test benches were designed and built to meet the measurement requirements. These measurement benches may be classified into two groups. The first group is the field quality measurement that includes the strength of the main field and higher harmonics. The multipole magnets are measured using four rotating coil benches, whereas the longitudinal gradient dipoles are mapped using a Hall probe system. The second group is fiducialization that locates the magnetic center of the magnet using a rotating wire and relates it to magnet fiducials and reference surfaces using a laser tracker. This information accompanies each magnet through the module assembly and final installation in the ring to ensure that the magnet is aligned within the allowable tolerance. To date, about 65% of all magnets needed for the storage ring have been measured and fiducialized. Mechanical design of the measurement benches will be presented.
*Advanced Photon Source. (2017). APS Upgrade Project Preliminary Design Review Report (APSU-2.01-RPT-002). Retrieved from https://www.aps.anl.gov/APS-Upgrade/Documents.
ANL, Lemont, Illinois, USA
UW-Madison/PD, Madison, Wisconsin, USA
Argonne National Laboratory is developing a Sub-THz AcceleRator (A-STAR) for a future multiuser x-ray free electron laser facility. The A-STAR machine will utilize a compact collinear wakefield accelerator (CWA) based on a miniature copper (Cu) corrugated waveguide as proposed*. The accelerator is designed to operate at a 20-kHz bunch repetition rate and will utilize the 180-GHz wakefield of a 10-nC electron drive bunch with a field gradient of 100 MVm’1 to accelerate a 0.3-nC electron witness bunch to 5 GeV. In this paper, we discuss specific challenges in the mechanical design of the CWA vacuum chamber module. The module consists of series of small quadrupole magnets with a high magnetic field gradient that houses a 2-mm diameter and 0.5-m-long corrugated tubing with brazed water-cooling channels and a transition section. The 45-mm-long transition section is used to extract the wakefield and to house a beam position monitor, a bellows assembly and a port to connect a vacuum pump. The CWA vacuum chamber module requires four to five brazing steps with filler metals of successively lower temperatures to maintain the integrity of previously brazed joints.
*A. Zholents et al., "A conceptual design of a Compact Wakefield Accelerator for a high repetition rate multi user Xray Free-Electron Laser Facility," in Proc. IPAC’18, Canada, 2018, pp. 1266~1268.
ANL, Lemont, Illinois, USA
APS Upgrade selected the horizontal injection scheme which requires exchanging the x and y emittances in the BTS transport line through a series of six skew quadrupoles, as well as matching the beam parameters to the APS Upgrade storage ring through two dipoles and a conventional pulsed septum. This paper presents the layout of this BTS line section in the storage ring tunnel and key components in this section including the mechanical design of dipole magnet, quadrupole and skew quad magnets, the vacuum system, the diagnostics system, and the supports. Finally, detailed mechanical design of this BTS line section in modules and some consideration for fabrication and installation are addressed.