US LHC Accelerator Research Program bnl fnal lbnl

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US LHC Accelerator Research Program bnl - fnal- lbnl - slac Next Steps –

US LHC Accelerator Research Program bnl - fnal- lbnl - slac Next Steps – Construction of TQC 02 R. Bossert LARP Internal Review November 29 – December 1 2006 TQ Internal Review – Nov. 29 -Dec. 1, 2006 TQC Next Steps

Introduction TQC 01 successfully reached the “first magnet” design goal of 200 T/m. However,

Introduction TQC 01 successfully reached the “first magnet” design goal of 200 T/m. However, there were several issues that limited the performance. They will be corrected in TQC 02 TQC 01 used MJR strand, and TQC 02 will incorporate RRP strand. Several structural changes will be made to TQC 02, based on TQC 01 construction experience, analysis, observations and measurements made during disassembly. TQC 02 coils will be completed soon, and magnet assembly will begin. TQ Internal Review – Nov. 29 -Dec. 1, 2006 TQC Next Steps 2

TQC 01 Performance issues There are two major issues concerning the performance of TQC

TQC 01 Performance issues There are two major issues concerning the performance of TQC 01. Low plateau at 4. 5 K and to a lesser degree 1. 9 K, with all straight section training quenches in the area of the inner coil where the outer pole pieces are “non-glued”. 2. Mid-plane outer coil quenches near the lead end, ultimately limiting the magnet performance. There is indication of permanent cable degradation in this area. TQ Internal Review – Nov. 29 -Dec. 1, 2006 TQC Next Steps 3

Reasons for Low Plateau A. Low azimuthal preload in the straight section, for the

Reasons for Low Plateau A. Low azimuthal preload in the straight section, for the reasons listed below: • A deliberate attempt during construction to stay near the low end of the “acceptable preload window”, due to fears of over-compression causing cable degradation. • Use of the traditional 40 GPa linear Modulus of Elasticity for the coils. • Epoxy instead of the intended G-10 was used to fill the inner pole slot, resulting in lower preload than predicted by the model. B. Outer pole pieces in much of the straight section were not bonded to the coil, allowing motion by the pole block and increased bending of the coil in this area. C. Low collar-to-yoke preload ratio, also increasing bending in the collared area. TQ Internal Review – Nov. 29 -Dec. 1, 2006 TQC Next Steps 4

Collared Coil Modifications Straight section modifications to improve training behavior: A. Increase collaring preload

Collared Coil Modifications Straight section modifications to improve training behavior: A. Increase collaring preload from 70 MPa, increasing the collaring-to-yoking distribution of preload. B. Increase contact area of yoke upon collars, allowing radial support over a greater azimuthal area. This should also result in a rounder final coil shape. C. Use FEA, skin and control spacer gauges as the “primary” method of measuring preload. Use knowledge gained from TQC 01 experience to more accurately read azimuthal coil gauges during construction. This knowledge includes attempts to calibrate gauges retroactively on the TQC 01 coils and using information from similar gauges placed on TQS 01 b. TQ Internal Review – Nov. 29 -Dec. 1, 2006 TQC Next Steps 5

Collared Coil Modifications D. Also improve other instrumentation (better temperature and magnetic field compensation

Collared Coil Modifications D. Also improve other instrumentation (better temperature and magnetic field compensation and calibration, as well as possible instrumentation on bronze inner pole. ) E. Continue to use full-round collars in body and leave bronze pieces in, but attempt to retroactively glue them into the coils. F. Change the material within the pole slot from epoxy to G-10. G. Remove inner coil trace. TQ Internal Review – Nov. 29 -Dec. 1, 2006 TQC Next Steps 6

Straight Section Modifications H. Use an available 12 mm bolt-on skin for TQC 02

Straight Section Modifications H. Use an available 12 mm bolt-on skin for TQC 02 instead of the welded skin. Load is applied with a hydraulic press, then bolts are tightened while load is still applied. • This will allow us to control the application of preload during construction in a much more accurate and uniform way. • It will also allow changes in the shim system if it is deemed necessary during the construction of the magnet, an option which was not available on TQC 01. TQ Internal Review – Nov. 29 -Dec. 1, 2006 TQC Next Steps 7

Reasons for Cable Degradation at Mid-plane A. Bending due to the application of local

Reasons for Cable Degradation at Mid-plane A. Bending due to the application of local pressure at the mid-planes, as in the body but applied at the end area. This pressure is more extreme at the ends because the metal end parts do not compress or bend as do the coils. It was also higher at the ends in TQC 01 because stainless steel yoke packs were used, which result in higher stresses after cooldown. B. An asymmetrical application of force at the mid-planes. Apparently due to minor asymmetries in the application of force during the yoking process, more force was applied along the axis at which the leads of coil 9 and 13 are located. C. Mid-plane leads appear to be slightly “raised” above the surface of the outer perimeter of the outer coil, as demonstrated by Fuji film imprints before assembly of TQC 01. D. The degradation may become more severe at high current, when the coil pushes against the end plate and/or outer collar surface. This increase in degradation at 12000 amps was enough to cause this area to limit the magnet performance at this level. TQ Internal Review – Nov. 29 -Dec. 1, 2006 TQC Next Steps 8

Modifications to Eliminate Cable Lead Degradation A. Provide radial support at the ends over

Modifications to Eliminate Cable Lead Degradation A. Provide radial support at the ends over a larger azimuthal area, as is being done in the body. B. Relieve the azimuthal size of the end saddles. This can not be done on TQC 02, because the coils are already made. An equivalent effect can be achieved by reducing the mid -plane and radial shims in this area. TQ Internal Review – Nov. 29 -Dec. 1, 2006 TQC Next Steps 9

Modifications to Eliminate Cable Lead Degradation C. Use iron yoke laminations over the entire

Modifications to Eliminate Cable Lead Degradation C. Use iron yoke laminations over the entire magnet length. D. The. 75 mm thick collaring shoe can be relieved at the splice area by. 3 mm. E. Apply strain gauges to the bronze end saddles to monitor the stress in the peak stress area during assembly, and adjust if stresses start becoming dangerously high. Also add more voltage taps in critical areas. TQ Internal Review – Nov. 29 -Dec. 1, 2006 TQC Next Steps 10

TQC 02 Assembly Status 2 of the TQC 02 coils are complete and have

TQC 02 Assembly Status 2 of the TQC 02 coils are complete and have been shipped to Fermilab. The remaining two coils are impregnated and will be shipped in early December. All other parts are ready except: • Instrumentation still needs to be applied to coils. • Outer pole pieces still need to be removed and bonded to coils. • Collar packs are stacked, but welding still needs to be completed. • Yoke packs still need to be stacked. • End plates need to be modified to use with bolt-on skins. All this work will be completed by mid-December, and assembly can begin. TQ Internal Review – Nov. 29 -Dec. 1, 2006 TQC Next Steps 11