To determine to what extent environmental factors and anthropogenic disturbances dictate N dynamics in tropical forest soils, changes of concentrations of inorganic N in soil were investigated during ...a period of extreme climatic conditions caused by
El Niño and
La Niña. This allowed the determination of factors driving the N-dynamics in tropical soils more clearly than during normal seasonal cycles. Three N-limited pine forests in Central Java, Indonesia, were studied monthly for over a year. N-NH
4
+ and N-NO
3
− were abundant in the organic layers, and decreased with increasing depth. Regular litter removal from the forest floor and branch-cutting at two pine forest sites significantly reduced the N-NH
4
+ concentration in the organic and mineral layers, but had only a minor influence on N-NO
3
− concentration. The N-NH
4
+ and N-NO
3
− concentrations and pH showed a distinct seasonal variation with extremely large amplitude in all studied soil layers, this corresponded to variation in soil moisture content. Concentrations were low during the extreme dry period of
El Niño of 1997, and significantly increased during the subsequent long wet period of
La Niña. The largest changes occurred in the organic top layers and changes were more pronounced than during normal seasonal cycles. It is concluded that N-dynamics in litter and fragmentation layers were most influenced by seasonal precipitation and to a lesser degree by litter removal.
The future High Luminosity upgrade of the Large Hadron Collider (HL-LHC) at CERN will include the low-beta inner triplets (Q1, Q2a/b, Q3) for two LHC insertion regions. The Q1, Q3 components consist ...of eight 10 m-long LMQXFA cryo-assemblies fabricated by the HL-LHC Accelerator Upgrade Project. Each LMQXFA Cold mass contains two Nb3Sn magnets connected in series. A stainless-steel shell is welded around the two magnets before the insertion into the cryostat. There is a limit on how much coil preload increase induced by the shell welding is allowed. Distributed Rayleigh backscattering fiber optics sensors were used for the first time to obtain a strain map over a wide area of a Nb3Sn magnet cold mass shell. Data were collected during welding of the first LMQXFA cold mass and the results confirm that the increase of the coil pole azimuthal pre-stress after welding do not exceed requirements.
The design concept of the Electron Ion Collider (EIC), which is under construction at BNL, considers adding a 2nd Interaction Region (IR) and detector to the machine after completion of the present ...EIC project. Recent progress with development and fabrication of large-aperture high-field magnets based on the Nb3Sn technology for the HL-LHC makes this technology interesting for the 2nd EIC IR. This paper summarizes the results of feasibility studies of large-aperture high-field Nb3Sn dipoles and quadrupoles for the 2nd EIC IR.
The next generation high energy physics accelerators will require magnetic fields at ~20 T. HTS coils will be an essential component of future accelerator magnets and several efforts are currently ...dedicated on designing 20 T HTS- LTS hybrid magnets. Among the existing challenges, there is the lack of a robust quench detection system for hybrid magnet technology. Another big challenge is represented by the high number of training quenches required by Nb3Sn magnets to reach performance level. In this framework it is important to find a tool that allow local real-time monitoring of magnet strain and temperature. In this paper, we propose the use of fiber optics sensors for diagnostic and quench detection in future accelerator superconducting magnets. Discrete and distributed fiber optic sensors have demonstrated to be a promising tool. The goal is to instrument hundreds of accelerator superconducting magnets and to move beyond the proof-of-concept level. Significant developments are still needed. Here, we are going to present the most recent results and discuss the most urgent technical developments in order to make those sensors a robust and reliable diagnostic tool for accelerator superconducting magnets over the next 10 year. We foresee that discrete fiber sensors will be a stable diagnostic probe for superconducting magnets over the next 3 to 5 years. More R&D work will be necessary for distributed fibers. The most urgent needs are the increase of sample rate and sensitivity. Close collaboration with vendors will be necessary to improve mechanical properties and fabrication processes in order to produce hundreds of meters of fiber and instrument a large number of accelerator superconducting magnets. Those R&D efforts will last up to 10 years with a founding level that spans between 5-10 M$.
JACoW IPAC2024 (2024) THYN1 The Large Hadron Collider will soon undergo an upgrade to increase its
luminosity by a factor of ~10 1. A crucial part of this upgrade will be
replacement of the NbTi ...focusing magnets with Nb3Sn magnets that achieve a ~50%
increase in the field strength. This will be the first ever large-scale
implementation of Nb3Sn magnets in a particle accelerator. The High-Luminosity
LHC Upgrade, HL-LHC is a CERN project with a world-wide collaboration. It is
under construction and utilizes Nb3Sn Magnets (named MQXF) as key ingredients
to increase tenfold the integrated luminosity delivered to the CMS and ATLAS
experiments in the next decade.
The HL-LHC AUP is the US effort to contribute approximately 50% of the
low-beta focusing magnets and crab cavities for the HL-LHC.
This paper will present the program to fabricate the Nb3Sn superconducting
magnets. We are reporting the status of the HL-LHC AUP project present the
results from horizontal tests of the first fully assembled cryo-assembly.
Future colliders will operate at increasingly high magnetic fields pushing limits of electromagnetic and mechanical stress on the conductor 1. Understanding factors affecting superconducting (SC) ...magnet performance in challenging conditions of high mechanical stress and cryogenic temperatures is only possible with the use of advanced magnet diagnostics. Diagnostics provide a unique observation window into mechanical and electromagnetic processes associated with magnet operation, and give essential feedback to magnet design, simulations and material research activities. Development of novel diagnostic capabilities is therefore an integral part of next-generation magnet development. In this paper, we summarize diagnostics development needs from a prospective of the US Magnet Development Program (MDP), and define main research directions that could shape this field in the near future.
In this White Paper for the Snowmass 2021 Process, we propose the establishment of a magnet Leading-Edge technology And Feasibility-directed Program (LEAF Program) to achieve readiness for a future ...collider decision on the timescale of the next decade. The LEAF Program would rely on, and be synergetic with, generic R&D efforts presently covered - in the US - by the Magnet Development Program (MDP), the Conductor Procurement and R&D (CPRD) Program and other activities in the Office of HEP supported by Early Career Awards (ECA) or Lab Directed R&D (LDRD) funds. Where possible, ties to synergetic efforts in other Offices of DOE or NSF are highlighted and suggested as wider Collaborative efforts on the National scale. International efforts are also mentioned as potential partners in the LEAF Program. We envision the LEAF Program to concentrate on demonstrating the feasibility of magnets for muon colliders as well as next generation high energy hadron colliders, pursuing, where necessary and warranted by the nature of the application, the transition from R&D models to long models/prototypes. The LEAF Program will naturally drive accelerator-quality and experiment-interface design considerations. LEAF will also concentrate, where necessary, on cost reduction and/or industrialization steps.
By the end of October 2022, the US HL-LHC Accelerator Upgrade Project (AUP) had completed fabrication of ten MQXFA magnets and tested eight of them. The MQXFA magnets are the low beta quadrupole ...magnets to be used in the Q1 and Q3 Inner Triplet elements of the High Luminosity LHC. This AUP effort is shared by BNL, Fermilab, and LBNL, with strand verification tests at NHMFL. An important step of the AUP QA plan is the testing of MQXFA magnets in a vertical cryostat at BNL. The acceptance criteria that could be tested at BNL were all met by the first four production magnets (MQXFA03-MQXFA06). Subsequently, two magnets (MQXFA07 and MQXFA08) did not meet some criteria and were disassembled. Lessons learned during the disassembly of MQXFA07 caused a revision to the assembly specifications that were used for MQXFA10 and subsequent magnets. In this paper, we present a summary of: 1) the fabrication and test data of all the MQXFA magnets; 2) the analysis of MQXFA07/A08 test results with characterization of the limiting mechanism; 3) the outcome of the investigation, including the lessons learned during MQXFA07 disassembly; and 4) the finite element analysis correlating observations with test performance.
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