bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dynamic systems modeling of the spallation neutron source cryogenic moderator system to optimize transient control and prepare for power upgrades
Authors: Goth N , Liu F , Maldonado B , Ramuhalli P , Howell M , Maekawa R , Cousineau S 
Published: July 2024

Abstract
Through support of the US Department of Energy’s Office of Basic Energy Sciences, Oak Ridge National Laboratory has begun applying machine learning methods to improve accelerator and target performance of the Spallation Neutron Source (SNS). These methods are being applied to the control optimization and power upgrade of the SNS Cryogenic Moderator System (CMS). A numerical model of the CMS has been developed to study these optimizations and system modifications using EcosimPro. This paper compares steady-state and transient numerical results with experimental data. Control optimization studies focused on dampening mass flow, temperature, and pressure fluctuations during sudden losses of accelerator beam power. This analysis was conducted by adjusting five proportional-integral-derivative controllers connected to four flow control valves and one heater. Future efforts include power uprate studies focused on increasing the CMS cooling capacity. The current accelerator power is 1.4 MW; the first target station is being upgraded to 2.0 MW as part of the Proton Power Upgrade effort. The CMS cooling capacity is sufficient for 2.0 MW operation.
Conservation of Helium while Maintaining High System Purity
Authors: White M , Theilacker J , Barba M 
Published: July 2024

Abstract
Recent helium shortages and helium price increases have lead to an increased emphasis being placed on conserving helium. The need to conserve helium must be balanced with need to maintain the high levels of purity necessary to prevent operational problems caused by contamination. Helium losses and contamination control are especially important for test stands that have cryogenic distribution systems operating continuously with frequent changeover of cryogenic temperature components that are being tested. This paper describes a mathematical model to estimate the quantity of helium lost and the purity of the helium after the pump and backfill procedure is complete. The process to determine the optimal time during pump down to cut off pumping and start backfilling is described. There is a tradeoff between trying to achieve the lowest possible pressure during pumping and the quantity of air leaking into the volume while pumping is occurring. An additional benefit of careful selection of pump and backfill parameters in conjunction with real-time pressure monitoring can reduce the labor and time required to complete a successful pump and backfill procedure. This paper is intended to be a tool for engineers to review their pump and backfill procedures and measured data to optimize helium losses, system purity, and labor required.
Cryostat Design for an FEL SCU Demonstrator
Authors: Fuerst J , Bouchard G , Gassner G , Hasse Q , Ivanyushenkov Y , Kasa M , Kraft E , Krejcik P , Nguyen D , Permanyer X 
Published: July 2024

Abstract
A design for a 4.2 K cryostat to support superconducting undulator (SCU) magnets is being developed as part of an SCU free electron laser (FEL) technology demonstrator. An array of several cryostats will be installed as an afterburner at the end of the existing hard x-ray beam line of the LCLS-II facility at the SLAC National Accelerator Laboratory (SLAC). Cryostat requirements include high operational availability, precision positioning and measurement capability to support beam-based alignment, high undulator magnet packing fraction, operational transparency to the electron beam, and compatibility with the existing LCLS hardware and space constraints. A cryocooler-based refrigeration system is appropriate given the scale and operational profile of the demonstration. The design is being developed as part of a collaboration between SLAC and Argonne National Laboratory (ANL) and draws on ANL’s experience with SCUs at the Advanced Photon Source.
Cryogenic infrastructure upgrade for crab cavities validation at TRIUMF
Authors: Koveshnikov A , Matheson B , Lang D , Laxdal R , Pearce C , Kishi D , Keir J , Cheung J , Kolb P , Li R , Bjarnason R , Yao Z 
Published: July 2024

Abstract
The High Luminosity (HL-LHC) upgrade of the Large Hadron Collider at CERN is an example of large-scale international scientific cooperation which spans multiple international partners. Canada through TRIUMF is making an in-kind contribution to the project with the delivery of five crab cavity cryomodules. The cryomodules will be delivered to CERN by 2026 for installation in the LHC. TRIUMF will receive the RF dipole (RFD) crab cavities from a consortium of US labs. In preparation for the assembly of the cryomodules, TRIUMF has undergone a number of upgrades. Chief among these is the preparation and commissioning of a new cryogenic insert for the TRIUMF multi-purpose cryostat to allow testing of the jacketed cavities at 2 K. The insert consists of a heat exchanger and a JT expansion valve. The 2 K pumping power has been augmented from 20 W to > 40 W with the addition of a booster sub-atmospheric pump.
Cryogenic and safety design of the future high field cable test facility at Fermilab
Authors: Bruce R , Tope T , Koshelev S , Theilacker J , Nikolic V , Velev G 
Published: July 2024

Abstract
The HFVMTF (High Field Vertical Magnet Test Facility) is a new experimental facility under development at Fermi National Accelerator Laboratory (FNAL) to test large superconducting magnets (up to 20 tons weight and 1.3 m diameter) in a double bath superfluid helium cryostat (1.9 K and 1.2 bar). Coupled with a superconducting dipole magnet fabricated by Lawrence Berkeley National Laboratory (LBNL), this facility will be able to test future high-temperature superconductor (HTS) cables under a background magnetic field of 15 T for fusion magnets. This paper describes the design of the cryostat and its 1.4-meter diameter lambda plate, as well as the different components for a safe operation of the facility, even during critical events such a magnet quench or a vacuum breaking situation. The project is funded by US DOE Offices of Science, High Energy Physics (HEP), and Fusion Energy Sciences (FES).
Mechanical and process design of the interface to a 20,000 liter liquid helium dewar
Authors: Wright M , Hasan N , Ganni V , Knudsen P , Jones S , Nguyen C 
Published: July 2024

Abstract
A new 20,000-liter (20 kL) liquid helium dewar is being integrated in to the existing cryogenic system at the Facility for Rare Isotope Beams at Michigan State University (MSU-FRIB). This dewar will mainly be used for the helium inventory management at FRIB (preserving helium inventory during unplanned / planned maintenance of the cryogenic system) and also in sharing the capacity to support the various cryogenic refrigeration systems to increase the operational efficiency and availability. It is also designed to interface to future cryogenic system upgrades (i.e., new 4.5 K refrigerators). This dewar has a single large penetration, or ‘neck’, that all the process lines and instrumentation pass through. On top of the ‘neck’ is a vacuum insulated interface box, or ‘neck can’, which houses all the connections between the dewar and the connecting distribution system. Though not generally common, this design approach has been successfully implemented on 5 to 10 kL liquid helium dewars at the Spallation Neutron Source (SNS), Jefferson Lab (JLab), and also at FRIB. It has been found that this approach greatly simplifies the mechanical design, while allowing for multiple process and instrumentation interfaces and still permitting a low heat in-leak. This paper presents an overview of the mechanical and process design of this neck can.
Pressure safety approach for PIP-II cryogenic distribution system and cryomodules
Authors: Soyars William , Banaszkiewicz Tomasz , Dhuley Ram 
Published: July 2024

Abstract
The Proton Improvement Plan-II (PIP-II) is a superconducting linear accelerator being built at Fermilab that will provide 800 MeV proton beam for neutrino production. The linac consists of a total of twenty-three (23) cryomodules of five (5) different types. Cooling is required at 2K, 5K and 40K. The Cryogenic Distribution System (CDS) consists of a Distribution Valve Box, ~285 m of cryogenic transfer line, modular Bayonet Cans to interface with cryomodules, and a Turnaround Can. The cryogenic system must provide protection from over-pressure by sizing pressure relief devices for all volumes and process line circuits. The cryomodule cavity circuits have dual pressure ratings, 4.1 bara when cold and 2.05 bara when warm (T>80K). Worst case relieving cases will be identified. The methods for determining heat flux will be presented. For the relieving occurring in the linac tunnel, flow must vent to outside to avoid an oxygen deficiency hazard. Also, we will present vacuum vessel relief sizing to protect the cryogenic distribution system vacuum shells from over pressure during an internal line rupture. The project is funded by US DOE Offices of Science, High Energy Physics.
Six years’ experience of the XFEL 2K operation
Authors: Barbanotti S , Bozhko Y , Jensch K , Schnautz T , Sellmann D 
Published: July 2024

Abstract
The European X-Ray Free Electron laser (XFEL) has successfully been operated for more than 5 years. The superconducting cavities and magnets being key components of the cryomodules constituting the XFEL linac and injector are operated at 2 K in a liquid helium bath. A four stages cold compressor system is used to return the vapor to the XFEL helium refrigerator with the capability of pumping up to 110 g/s for compensating static and dynamic heat losses at 2 K.
In this paper technical challenges with regard to the cold compressor system such as availability, 2K pressure stability and contamination of the 2K circuit are summarized. Influence of hydrostatic head on operation of all cooling circuits is analyzed. Issues related to the use of some kinds of instrumentation as pressure transmitters, flow meters and level sensors are discussed. The experiment regarding the future XFEL project as doubling of safety valves is described.
Spallation Neutron Source Hydrogen Relief Analysis for the Cryogenic Moderator System
Authors: DeGraff Brian , Howell Matthew , Dominguez-Ontiveros Elvis , Goth Nolan , Williams Wesley , Winder Drew 
Published: July 2024

Abstract
The Spallation Neutron Source at Oak Ridge National Laboratory operates the Cryogenic Moderator System (CMS) which provides hydrogen cooling at 20K to three neutron moderators. Each hydrogen loop is protected by multiple burst discs and reclosing relief valves. As a result of the Proton Power Upgrade project, the CMS moderator loops will hold more hydrogen and thus require piping modifications. Operational experience has demonstrated that transient pressure increases in these hydrogen loops occasionally result in the rupture of the burst discs. The causes for pressure transients in the system that might lead to hydrogen venting are varied and complex, for example loss of vacuum or cooling. Dynamic simulation and analysis of the parameters considered as the worst-case relief venting scenario were performed and will be presented.
Dynamic simulation of CHL at SNS
Authors: Maekawa R , Howell M , Kim S H 
Published: July 2024

Abstract
A dynamic simulation model of Central Helium Liquefier (CHL) has been developed by the process simulation software; EcosimPro™. CHL consists of 4 K and 2 K cold boxes to sustain the operation of LINear ACcelerator (LINAC) which is composed of Superconducting Radio Frequency (SRF) cavities installed in the Cryomodules. 4 K cold box is a modified Claude cycle refrigerator, having LN2 precooler with two Brayton Cycle turbines, followed by the series connected Turbines (Tu3 and Tu4), and a Supercritical Helium (SHe) turbine (Tu5) for high thermodynamic efficiency. The product of 125 g/s of SHe is subcooled at the LHe immersed Heat eXchanger (HX) before supplying to Cryomodules, which has its own precooled HX for He II vapor vs. SHe, to have high liquid yield for He II at 2.1 K. Four series connected Cold Compressors (CCs) keep the LINAC pressure at 0.04 bar for the proton beam acceleration. The paper discusses the modeling of CHL, including four CCs. The benchmark of the model against a design specification of CHL and the validation of CC model is also described in detail.
Characterization of centrifugal compressors operating in FRIB’s sub-atmospheric compression system
Authors: Howard J , Engeda A , Knudsen P , Hasan N , Ganni V 
Published: July 2024

Abstract
Helium cryogenic systems operating below the normal boiling point (of 4.22 K) are required for many modern high-energy particle accelerators to achieve the necessary performance criteria. Temperatures below the normal boiling point are established by lowering saturation pressure below atmospheric conditions using vacuum equipment. FRIB operates a multi-stage string of cryogenic compressors (or ‘cold-compressors’) to achieve the sub-atmospheric pressures required (30 mbar) for the accelerator operating conditions of approximately 2 K. Housed within a vacuum insulated vessel (i.e., the sub-atmospheric cold box), the cold-compressor system re-pressurizes the helium from approximately 30 mbar to above atmospheric pressure condition before injecting the flow back into the helium refrigerator. Despite the implementation of cold-compressors in several existing large-scale cryogenic systems, openly available literature is insufficient to provide the information necessary for a general characterization of the performance and stability for these cold compressors. A one dimensional steady-state model to predict the performance of cryogenic centrifugal compressors has been developed. This model enables performance prediction by using optimally selected enthalpy loss correlations and basic impeller and diffuser geometrical data. The present work provides an initial comparison of the estimated performance of the individual and string of cryogenic centrifugal compressors to the operational / test data. With appropriate validation, the model is anticipated to allow assessment and prediction of optimal operational envelops that ensure stable and efficient operation at different operating conditions.
The SPARC cryogenic system
Authors: Dalesandro A , Weiner A , Kelley J P , Hall K , Trainor J , Herrmann J , Wilder D , Yung R , Quack H 
Published: July 2024

Abstract
The SPARC project at Commonwealth Fusion Systems (CFS) is a tokamak system designed to demonstrate commercially relevant fusion energy and achieve net fusion power output during the first operating campaign, with eventual fusion pulse energies exceeding 1 GJ. The SPARC tokamak includes eight magnet systems, three that use high-temperature superconducting (HTS) tapes. The SPARC cryogenic system (CRYO) consists of three supercritical helium cryogenic loops at nominal temperatures of 8 K, 15 K, and 80 K. CRYO 8 K and 15 K loops cool the HTS magnets to maintain thermal stability and prevent quench, while magnets cooled to 80 K are normally conductive. CRYO provides cold helium using a hybrid system that includes a Brayton-cycle-based cryoplant supporting all CRYO temperature loops, and a fixed volume 8 K blowdown system to remove heat and maintain temperature stability of the toroidal field (TF) magnets during and immediately following fusion pulses. CRYO 4.5 K equivalent peak cooling power is 17 kW for the cryoplant and 2.9 MW for the blowdown system during a 10-second fusion pulse. Primary cryoplant mechanical equipment includes screw compressors, turbo-expanders, heat exchangers, and circulation pumps, while the blowdown system consists of a series of warm and cold helium storage tanks operating at independent temperatures and pressures, with make-up compressors to reset the blowdown system between pulses. CRYO also includes a distribution valve box and multiple vacuum-jacketed (VJ) process lines ranging in nominal diameter from 20 to 600 mm. This paper investigates the various sub-elements which in combination represent SPARC CRYO, and attempts to address some of the technical challenges identified by the team.
Operation of the cryogenic plant at NSLS-II. Problems and Solutions.
Authors: Bozeat B. , Gash W. , Oliva J. , Rose J. , Sikora R. , Sitnikov A. 
Published: July 2024

Abstract
The cryogenic plant operating 10+ years at the National Synchrotron Light Source II (NSLS-II) at Brookhaven National Laboratory (BNL) and supplying the liquid Helium for three superconducting Radio Frequency cavities. The objective is the continuous liquid Helium supply without interrupting operation. This paper outlines our experience in troubleshooting of various failures of the cryogenic plant and main considerations regarding the selection of the equipment and components.
LCLS-II Linear Accelerator Cool-Down And Pump-Down
Authors: Ravindranath V , Apte A , Fauve E. , Pflueckhahn D. , Rama B. , Shrishrimal S. , Vyawahare S. , Bhattacharya R , Creel J , Norton R , Mieral A 
Published: July 2024

Abstract
SLAC National Accelerator Laboratory has upgraded to LCLS-II, featuring a 4 GeV superconducting linear accelerator composed of 37 cryomodules and two large helium refrigeration systems with a cooling capacity of 4 kW at 2.0 K. LCLS-II linear accelerator was successfully cooled from ambient temperature to 4.5 K and then to its final operating temperature of 2.0 K (31 mbar). In this paper, we describe the cool-down strategy, provide details of the 2.0 K pump-down results, and discuss the challenges faced during commissioning.
Influences of distributed J-T effect on the performance of mixed-refrigerant Joule-Thomson refrigeration cycle
Authors: Sun Y W , Wang H C , Gong M Q , Dong X Q 
Published: July 2024

Abstract
In a mixed-refrigerant Joule-Thomson (MRJT) cycle, the working fluid usually produces a throttling effect in the expansion element. However, the high-pressure flow in the recuperator could also generate a throttling effect due to the narrow channels, i.e., the distributed Joule-Thomson effect (DJTE). Previously published studies indicated that the cooling performance of cryocoolers would be improved by DJTE accompanying the heat recovery process. However, most of the current research on this phenomenon is focused on the heat transfer characteristics of the cryocooler itself, with a lack of research on the effect of DJTE on the cycle performance in much detail.
Therefore, a detailed investigation of the influence pattern of DJTE on the cycle performance is carried out by combining with the exergy analysis. The simulation is conducted under three quintessential conditions of the recuperator. The results indicate that it is possible to manipulate the DJTE to maintain satisfactory cycle performance under specific conditions. In addition, at a constant minimum temperature difference in the recuperator, the maximum achievable DJTE is closely related to the isothermal throttling effect of the mixed refrigerant. The conclusions of this paper clarify the effect and the application value of DJTE on the cycle efficiency, which provide a reference for determining reasonable operating conditions and ensuring the cycle efficiency in practical applications.
Thermodynamic and exergetic evaluation of CO2 liquefaction for ship transport
Authors: Zheng Pingyang , Zhang Zhentao , Yue Yunkai , Yang Junling , Li Xiaoqiong , Hao Jiahao , Zheng Maowen 
Published: July 2024

Abstract
CO2 liquefaction is significant to ensure CO2 transport safety and improve efficiency. Aiming at the temperature and pressure required for ship transport, this paper examines four liquefaction schemes including the compression refrigeration system, the Linde Hampson system, the precooled Linde Hampson system and the Claude system. The thermodynamic and exergetic ananlysis models are established primarily and total power consumption, liquefaction efficiency as well as exergy efficiency of the four systems are calculated and compared. The precooled Linde Hampson system shows the best performance with the three indicators of 391.74 kJ/kg, 97.97 % and 55.86 %, respectively. Additionally, exergy destruction among the system components are analyzed for Linde Hampson system and precooled Linde Hampson system. The maximum exergy destruction stem is from compressors. Another thing to note is that the proportion of the total exergy destruction with Joule-Thomson (J-T) valves are 19.38 % and 2.63 %, respectively. Furthermore, the replacement of the J-T valve by a liquid expander allowed for 9.35 % and 0.94 % electric power saving for the two systems, respectively. The pressure drop before and after the J-T valve directly determines the effect of this change. The research results could provide some vital reference for choosing proper CO2 liquefaction methods and reducing energy consumption during the process.
Spallation neutron source purifier replacement project for the central helium liquefier
Authors: DeGraff B , Harrell P , Howell M , Maurisak M , Wilson C 
Published: July 2024

Abstract
The Spallation Neutron Source (SNS) at Oak Ridge National Laboratory (ORNL) operates the Central Helium Liquefier (CHL) to provide 2K helium refrigeration to the superconducting radio frequency (SCRF) cavities in the linear accelerator (LINAC). To maintain the purity of the helium, the CHL operates a LN2 cooled, dual-bed purifier. This purifier was purchased as a refurbished unit during the construction of SNS about 20 years ago. The current operational issues with the existing purifier will be discussed. The procurement, fabrication status and commissioning plans for this new purifier will also be discussed.
Design of Muon Campus full flow purifier for varying operational conditions and horizontal shipping
Authors: Subedi J. , Tope T. , Hansen B. , Jia Y. , Makara J. , Tillman J. , Tang Z. 
Published: July 2024

Abstract
Constant ingress of impurities in Muon Campus g-2 experiment at Fermilab has resulted in reduction of efficiency of cryogenic expanders and occasional undesired downtime to flush the impurities. Due to insufficiency of current 0.06 kg/s mobile purifier, a full flow purifier is designed to be used in Muon Campus which purifies 0.24 kg/s of Helium throughput of 4 compressors through charcoal bed at 80 K and returns ambient Helium back to the system. The purifier is designed to be operated near liquid Nitrogen temperature during cold operations and up to 400 K during regeneration. Both warm and cold operational range of the purifier has required use of appropriate clearances in design due to expansion and contraction. The vessel of around 5.5 m height which is designed to be operated vertically is to be shipped horizontally. The asymmetrical position of heavy stainless steel heat exchanger in the purifier support frame and 5g vertical load design consideration for shipping has required use of shipping supports and heat exchanger rotational stops to comply with design requirements. FEA of purifier system is performed in cold, warm and shipping cases to verify that the purifier satisfies the design requirements.