Potential nitrification and factors controlling nitrifying activity in tropical pine forest and agricultural soils in Central Java, Indonesia were studied. Soils from three different pine forest ...sites and a fertilized coffee plantation were sampled monthly during the dry and wet period of 1997–1998. Both organic material (litterL, and fragmented litterF) and mineral soil (M) up to 15 cm depth showed a high potential N-NO
3
– production. In the growth-medium used, the production of NO
3
– increased exponentially and was substantially higher than the net NO
3
– production in laboratory soil incubation experiments. Nitrifying populations assessed using the most-probable-number method were highly abundant in all soil layers, without significant differences between layers. However, net NO
3
– production in the L and F layers was significantly higher than that found in the M layers. High seasonal and temporal variations were observed for net NO
3
– production and nitrifying populations. This was most likely explained by soil moisture content, N-NH
4
+ content and soil pH. Denitrification might also be one of the major factors causing the high temporal nitrification variation due to high potential NO
3
– reduction and the fact that denitrifying populations were abundant in these soils. The fertilized coffee plantation soil showed nitrifying populations, potential nitrification and nitrifying activity that were significantly higher than that of the three pine forest soils, whereas litter removal activities at one site in a pine forest substantially reduced NO
3
– production. It is concluded that tropical pine forests and fertilized agricultural soils in Indonesia have a high potential for carrying out nitrification, which is due to a high abundance of nitrifying populations. Soil moisture content, pH and N-NH
4
+ availability are the major factors controlling nitrifying activity in the soil.
The U.S. LHC Accelerator Research Program (LARP) and CERN are combining efforts for the HiLumi-LHC upgrade to design and fabricate 150-mm-aperture interaction region quadrupoles with a nominal ...gradient of 130 T/m using Nb 3 Sn. To successfully produce the necessary long MQXF triplets, the HiLumi-LHC collaboration is systematically reducing risk and design modification by heavily relying upon the experience gained from the successful 120-mm-aperture LARP HQ program. First-generation MQXF short (MQXFS) coils were predominately a scaling up of the HQ quadrupole design, allowing comparable cable expansion during Nb 3 Sn formation heat treatment and increased insulation fraction for electrical robustness. A total of 13 first-generation MQXFS coils were fabricated between LARP and CERN. Systematic differences in coil size, coil alignment symmetry, and coil length contraction during heat treatment are observed and likely due to slight variances in tooling and insulation/cable systems. Analysis of coil cross sections indicate that field-shaping wedges and adjacent coil turns are systematically displaced from the nominal location and the cable is expanding less than nominally designed. A second-generation MQXF coil design seeks to correct the expansion and displacement discrepancies by increasing insulation and adding adjustable shims at the coil pole and midplanes to correct allowed magnetic field harmonics.
The new FNAL g-2 experiment is based on the muon storage ring previously used at BNL. The 1.45-T dipole magnetic field in the storage ring is required to have very high (1 ppm) homogeneity. The muon ...beam injected into the ring must be transported through the magnet yoke and the main superconducting coil cryostat with minimal distortions. The old inflector magnet shielded the main dipole fringe field inside the muon transport beam pipe with an outer NbTi superconducting screen and did not disturb the field in the area of the circulating beam. Nevertheless, this magnet had coils with closed ends, in which a large fraction of muon beam particles were lost The new magnet is also self-shielded, but the magnet ends are open for beam transport, and it has a larger aperture for beam transport. All of these modifications are very critical for the success of the FNAL g-2 experiment. This paper describes the magnet conceptual design, including the choice of superconductor, and the optimization of the coil geometry.
As part of the Large Hadron Collider Luminosity upgrade (HiLumi-LHC) program, the US LARP collaboration and CERN are working together to design and build a 150 mm aperture quadrupole magnet that aims ...at providing a nominal gradient of 140 T/m. The resulting conductor peak field of more than 12 T requires the use of Nb 3 Sn superconducting coils. In this paper the coil design for the quadrupole short model (SQXF) is described, focusing in particular on the optimization of the end-parts. We first describe the magnetic optimization aiming at reducing the peak field enhancement in the ends and minimizing the integrated multipole content. Then we focus on the analysis and tests performed to determine the most suitable shapes of end turns and spacers, minimizing the mechanical stress on the cables. We conclude with a detailed description of the baseline end design for the first series of the short model coils.
The U.S. LHC Accelerator Research Program (LARP) and CERN are combining efforts for the HiLumi-LHC upgrade to design and fabricate 150-mm-aperture interaction region quadrupoles with a nominal ...gradient of 130 T/m using Nb sub(3)Sn. To successfully produce the necessary long MQXF triplets, the HiLumi-LHC collaboration is systematically reducing risk and design modification by heavily relying upon the experience gained from the successful 120-mm-aperture LARP HQ program. First-generation MQXF short (MQXFS) coils were predominately a scaling up of the HQ quadrupole design, allowing comparable cable expansion during Nb sub(3)Sn formation heat treatment and increased insulation fraction for electrical robustness. A total of 13 first-generation MQXFS coils were fabricated between LARP and CERN. Systematic differences in coil size, coil alignment symmetry, and coil length contraction during heat treatment are observed and likely due to slight variances in tooling and insulation/cable systems. Analysis of coil cross sections indicate that field-shaping wedges and adjacent coil turns are systematically displaced from the nominal location and the cable is expanding less than nominally designed. A second-generation MQXF coil design seeks to correct the expansion and displacement discrepancies by increasing insulation and adding adjustable shims at the coil pole and midplanes to correct allowed magnetic field harmonics.
The traditional fabrication process used for Formula Omitted accelerator magnets involves reaction of the coils at high temperature and impregnation with epoxy to restore the electrical and ...mechanical properties of the insulation. The traditional epoxy offers adequate structural and electrical properties, but has low radiation strength, limiting the lifetime of magnets operating in severe radiation environments. This paper presents the results of a study in which the traditional epoxy was replaced with Matrimid 5292 as a coil impregnation material. Test stacks of cable were fabricated and impregnated with epoxy and Matrimid. Electrical, structural and thermal properties were measured and compared. A 90-mm-bore, 1-meter-long Formula Omitted quadrupole coil made of RRP 54/61 strand was fabricated, reacted, impregnated with Matrimid, and tested in a single coil test structure (quadrupole magnetic mirror). Test results are compared with the results for similar coils impregnated with epoxy.
The traditional fabrication process used for Nb 3 Sn accelerator magnets involves reaction of the coils at high temperature and impregnation with epoxy to restore the electrical and mechanical ...properties of the insulation. The traditional epoxy offers adequate structural and electrical properties, but has low radiation strength, limiting the lifetime of magnets operating in severe radiation environments. This paper presents the results of a study in which the traditional epoxy was replaced with Matrimid 5292 as a coil impregnation material. Test stacks of cable were fabricated and impregnated with epoxy and Matrimid. Electrical, structural and thermal properties were measured and compared. A 90-mm-bore, 1-meter-long Nb 3 Sn quadrupole coil made of RRP 54/61 strand was fabricated, reacted, impregnated with Matrimid, and tested in a single coil test structure (quadrupole magnetic mirror). Test results are compared with the results for similar coils impregnated with epoxy.
The High Luminosity (HiLumi) Large Hadron Collider (LHC) project has, as the main objective, to increase the LHC peak luminosity by a factor five and the integrated luminosity by a factor ten. This ...goal will be achieved mainly with a new interaction region layout, which will allow a stronger focusing of the colliding beams. The target will be to reduce the beam size in the interaction points by a factor of two, which requires doubling the aperture of the low- $\beta$ (or inner triplet) quadrupole magnets. The use of Nb sub(3)Sn superconducting material and, as a result, the possibility of operating at magnetic field levels in the windings higher than 11 T will limit the increase in length of these quadrupoles, called MQXF, to acceptable levels. After the initial design phase, where the key parameters were chosen and the magnet's conceptual design finalized, the MQXF project, a joint effort between the U.S. LHC Accelerator Research Program and the Conseil Europeen pour la Recherche Nucleaire (CERN), has now entered the construction and test phase of the short models. Concurrently, the preparation for the development of the full-length prototypes has been initiated. This paper will provide an overview of the project status, describing and reporting on the performance of the superconducting material, the lessons learnt during the fabrication of superconducting coils and support structure, and the fine tuning of the magnet design in view of the start of the prototyping phase.
Helical solenoids have been proposed as an option for a Helical Cooling Channel for muons in a proposed Muon Collider. Helical solenoids can provide the required three main field components: ...solenoidal, helical dipole, and a helical gradient. In general terms, the last two are a function of many geometric parameters: coil aperture, coil radial and longitudinal dimensions, helix period and orbit radius. In this paper, we present design studies of a Helical Solenoid, addressing the geometric tunability limits and auxiliary correction system.
The High Luminosity (HiLumi) Large Hadron Collider (LHC) project has, as the main objective, to increase the LHC peak luminosity by a factor five and the integrated luminosity by a factor ten. This ...goal will be achieved mainly with a new interaction region layout, which will allow a stronger focusing of the colliding beams. The target will be to reduce the beam size in the interaction points by a factor of two, which requires doubling the aperture of the low-β (or inner triplet) quadrupole magnets. The use of Nb 3 Sn superconducting material and, as a result, the possibility of operating at magnetic field levels in the windings higher than 11 T will limit the increase in length of these quadrupoles, called MQXF, to acceptable levels. After the initial design phase, where the key parameters were chosen and the magnet's conceptual design finalized, the MQXF project, a joint effort between the U.S. LHC Accelerator Research Program and the Conseil Europeén pour la Recherche Nucleaíre (CERN), has now entered the construction and test phase of the short models. Concurrently, the preparation for the development of the full-length prototypes has been initiated. This paper will provide an overview of the project status, describing and reporting on the performance of the superconducting material, the lessons learnt during the fabrication of superconducting coils and support structure, and the fine tuning of the magnet design in view of the start of the prototyping phase.
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