Status of Hall B Superconducting Magnets for the CLAS12 Detector at JLAB

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The torus magnet for the CLAS12 spectrometer is a 3.6 T superconducting magnet being designed and built as part of the Jefferson Lab 12 GeV Upgrade. The magnet consists of six coil case assemblies mounted to a cold central hub. The coil case assembly consists of an aluminum case and cover enclosing an epoxy vacuum impregnated coil pack. The coil pack consists of a 117 turn double-pancake winding wrapped with 2 layers of 0.635 mm thick copper cooling sheets. The coil case assembly is cooled by supercritical helium at 4.6 K. This report details the structural analysis of the coil case assembly and the assessment of the coil pack stresses. For the normal operation of the torus magnet, the coil case assembly was analyzed for cool down to 4.6 K and the Lorentz forces at normal operating current. In addition to the normal operating configuration, the coil case assembly was analyzed for Lorentz forces arising from coil misalignment and current imbalances. The allowable stress criteria for the magnet followed the approach of the ASME codes. Primary stresses were limited to the lesser of 2/3 times the yield strength or 1/3 times the ultimate tensile strength. Primary plus secondary stresses were limited to 3 times the primary stress allowable. The analysis was performed using ANSYS Maxwell to calculate the magneto-static loads and ANSYS Mechanical to calculate the stresses.

Section: Introductionmentioning

confidence: 93%

Electromagnetic and Mechanical Analysis of the Coil Structure for the CLAS12 Torus for 12 GeV Upgrade

Ghoshal

Pastor

Kashy

et al. 2015

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“…he 12GeV upgrade of the CEBAF accelerator includes upgrades to the accelerator and the experimental halls. The changes for the experimental Hall B include upgrades to the physics detectors and two new superconducting magnets [1][2][3][4][5][6]. One of those is a solenoid magnet that is currently being designed and fabricated by industry.…”

Section: Introductionmentioning

confidence: 99%

Design and Manufacture of the Conduction Cooled Torus Coils for The Jefferson Laboratory 12-GeV Upgrade

Wiseman

Elementi

Elouadhiri

et al. 2015

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The design of the 12 GeV Torus required the construction of six superconducting coils with a unique geometry required for the experimental needs of Jefferson Labs Hall B. Each of these coils consists of 234 turns of copper stabilized superconducting cable conduction cooled by 4.6 K helium gas. The finished coils are each roughly 2 X 4 X 0.05 meters and supported in an aluminum coil case. Because of its geometry new tooling and manufacturing methods had to be developed for each stage of construction. The tooling was designed and developed while producing a practice coil at Fermi National Laboratory. This paper describes the tooling and manufacturing techniques required to produce the six production coils and two spare coils required by the project. Project status and future plans are also presented.

Torus CLAS12-Superconducting Magnet Quench Analysis

Kashikhin

Elouadhiri

Ghoshal

et al. 2014

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The JLAB TORUS magnet system consists of six superconducting trapezoidal racetrack-type coils assembled in a toroidal configuration. These coils are wound with SSC-36an NbTi superconductor and have the superconductor peak field of 3.6 T. The first coil manufacturing based on the JLAB design began at FNAL. The large magnet system dimensions (8 m diameter and 14 MJ of stored energy) dictate the need for careful quench protection. Each coil is placed in an aluminum case mounted inside a cryostat and cooled by 4.6K supercritical Helium gas flowing through a copper tube attached to the coil ID. The large coil dimensions and small cryostat thickness drove the design to challenging technical solutions, suggesting that Lorentz and Eddy current forces during quench and various failure scenarios are analyzed. The report covers the magnet system quench analysis using the OPERA3d TM Quench code.