J. Kerby

Status of the LHC inner triplet quadrupole program at Fermilab

Fermilab, in collaboration with LBNL and BNL, is developing a quadrupole for installation in the interaction region inner triplets of the LHC. This magnet is required to have an operating gradient of 215 T/m across a 70 mm coil bore, and operates in superfluid helium at 1.9 K. A 2 m magnet program addressing mechanical, magnetic, quench protection, and thermal issues associated with the design was completed earlier this year, and production of the first full length, cryostatted prototype magnet is underway. This paper summarizes the conclusions of the 2 m program, and the design and status of the first full-length prototype magnet.

Field quality in Fermilab-built models of quadrupole magnets for the LHC interaction region

Superconducting quadrupole magnets for the interaction regions of the Large Hadron Collider are being developed by the US-LHC Accelerator Project. These 70 mm bore quadrupole magnets are intended to operate in superfluid helium at 1.9 K with a nominal field gradient of 215 T/m. A series of 2 m model magnets has been built and cold tested at Fermilab to optimize their design and construction and to study the performance of the magnets. Field measurements of the 8 model magnets and comparisons with the required field quality are reported in this paper.

Construction experience with MQXB quadrupole magnets built at Fermilab for the LHC interaction regions

Fermilab is building eighteen full length cold masses for the LHC Interaction Region inner triplets. One prototype and several production assemblies have been completed. This paper summarizes the construction details. Topics include coil fabrication, ground insulation, collaring, instrumentation, electrical testing, and final assembly. In-process measurements are presented and explained. Problems encountered during construction and their solutions are discussed.

Superconducting Splittable Quadrupole Magnet for Linear Accelerators

A new superconducting quadrupole magnet for linear accelerators was fabricated at Fermilab. The magnet is designed to work inside a cryomodule in the space between SCRF cavities. SCRF cavities must be installed inside a very clean room adding issues to the magnet design, and fabrication. The designed magnet has a splittable along the vertical plane configuration and could be installed outside of the clean room around the beam pipe previously connected to neighboring cavities. For more convenient assembly and replacement a “superferric” magnet configuration with four racetrack type coils was chosen. The magnet does not have a helium vessel and is conductively cooled from the cryomodule LHe supply pipe and a helium gas return pipe. The quadrupole generates 36 T integrated magnetic field gradient, has 600 mm effective length, and the peak gradient is 54 T/m. In this paper the quadrupole magnetic, mechanical, and thermal designs are presented, along with the magnet fabrication overview and first test results.

Design, development and test of 2 m quadrupole model magnets for the LHC inner triplet

Fermilab and LBNL are in the midst of a model magnet program to develop and prove the design of quadrupoles for use in the LHC Interaction Region inner triplets. These magnets have a nominal gradient of 205 T/m in a 70 mm bore, and operate in superfluid helium at 1.9 K. The R&D program addresses magnetic, mechanical, thermal design and quench protection issues. This paper describes design, fabrication experience and test results from the first 2 m models.

Field quality in Fermilab-built models of high gradient quadrupole magnets for the LHC interaction regions

Superconducting quadrupole magnets for the interaction regions of the Large Hadron Collider are being developed by the US-LHC Accelerator Project. These 70 mm bore quadrupole magnets are intended to operate in superfluid helium at 1.9 K with a nominal field gradient of 215 T/m. A series of 2 m model magnets are being built and tested at Fermilab to optimize design and construction parameters. Measurements of the field quality of the model magnets tested to date and comparisons with the required field quality are reported in this paper.

Thermal studies of a high gradient quadrupole magnet cooled with pressurized, stagnant superfluid

A 2-m long superconducting model of an LHC Interaction Region quadrupole magnet was wound with stabrite coated cable. The resulting low interstrand resistance and high AC losses presented the opportunity to measure magnet quench performance in superfluid as a function of helium temperature and heat deposition in the coil. Our motivation was to duplicate the high radiation heat loads predicted for the inner triplet quadrupoles at LHC and study the coil cooling conditions in the magnet. At the Magnet Test Facility in Fermilabs Technical Division, the magnet quench performance was tested as a function of bulk helium temperature and current ramp rate near the planned high luminosity interaction region field gradient of 205 T/m. AC loss measurements provided a correlation between current ramp rate and heat deposition in the coil. Analysis indicates that the results are consistent with there being little participation of superfluid helium in the small channels inside the inner layer in the heat removal from the coil. However magnet performance will be limited by the outer coil pole turn in LHC at a current level well above the operating current.

Magnetic Field Measurements of LHC Inner Triplet Quadrupoles Fabricated at Fermilab

Fermilab, as part of the US-LHC Accelerator Project, is producing superconducting low-beta quadrupole magnets for the large hadron collider (LHC). These 5.5 m long magnets are designed to operate in superfluid helium at 1.9 K with a nominal gradient of 205 T/m in the 70 mm bore. Two quadrupoles separated by a dipole orbit corrector in a single cryogenic assembly comprise the Q2 optical elements of the final focus triplets in the LHC interaction regions. The field quality of the quadrupoles is measured at room temperature during construction of the cold masses as well as during cold testing of the cryogenic assembly. We summarize data from the series measurements of the magnets and discuss various topics of interest.

Test results of LHC interaction regions quadrupoles produced by Fermilab

The US-LHC Accelerator Project is responsible for the production of the Q2 optical elements of the final focus triplets in the LHC interaction regions. As part of this program Fermilab is in the process of manufacturing and testing cryostat assemblies (LQXB) containing two identical quadrupoles (MQXB) with a dipole corrector between them. The 5.5 m long Fermilab designed MQXB have a 70 mm aperture and operate in superfluid helium at 1.9 K with a peak field gradient of 215 T/m. This paper summarizes the test results of several production MQXB quadrupoles with emphasis on quench performance and alignment studies. Quench localization studies using quench antenna signals are also presented.

Test results from the LQXB quadrupole production program at Fermilab for the LHC interaction regions

As part of the US-LHC Accelerator Project, Fermilab is producing fully cryostated assemblies that will be installed as the Q1, Q2 and Q3 optical elements for the LHC Inner Triplets. The main quadrupole magnets in the Q1 (LQXA) and Q3 (LQXC) assemblies are MQXA elements designed and fabricated by KEK and Toshiba, while those in the Q2 (LQXB) assemblies are MQXB quadrupoles designed and fabricated by Fermilab. The cryostat assemblies for all magnets are designed by Fermilab, and final assembly of the optical elements occurs at Fermilab. This paper describes the production test results for the second LQXB cryostat assembly.