1. 1 Quench study Yury Ivanyushenkov, Elwyn Baynham, Tom Bradshaw, Amanda Brummitt, Steve Carr, Andrew Lintern, James Rochford STFC Technology RAL HeLiCal Group Meeting, RAL, 17 May 2007

2. 2 Scope -Prototype V quenches -Prototype VI quenches HeLiCal Group Meeting, RAL, 17 May 2007

3. 3 Prototypes Matrix IIIIIIIVVVI Former material Al Iron Prototype VI is re-wound and re- impregnated Prototype V Length, mm300 500 Pitch, mm14 12 11.5 Groove shape rectangulartrapezoidal rectangular Winding bore, mm 666.35 Vac bore, mm 4444.5 (St Steel tube) 5.23* (Cu tube) Winding8-wire ribbon, 8 layers 9-wire ribbon, 8 layers 7-wire ribbon, 8 layers 7-wire ribbon, 8 layers 7-wire ribbon, 8 layers Sc wireCu:Sc 1.35:1 Cu:Sc 0.9:1 StatusCompleted and tested Completed, tested and sectioned Completed and tested HeLiCal Group Meeting, RAL, 17 May 2007

4. 4 Prototype V quench study Undulator was left to warm up to 170K Undulator was left to warm up to 200K HeLiCal Group Meeting, RAL, 17 May 2007

5. 5 Prototype V summary -Prototype V has shown “training” -> likely due to imperfection in the resin -A possibility of improving impregnation process has been indicated -Prototype VI = Re-wound Prototype V, impregnated with improved method HeLiCal Group Meeting, RAL, 17 May 2007

6. 6 Prototype VI quenches HeLiCal Group Meeting, RAL, 17 May 2007

7. 7 Summary -Prototype VI has shown no ( or very little) “training” -> likely due to improved method of impregnation HeLiCal Group Meeting, RAL, 17 May 2007

8. 8 Undulator field at 2 K HeLiCal Group Meeting, RAL, 17 May 2007

9. 9 NbTi critical surface HeLiCal Group Meeting, RAL, 17 May 2007

10. 10 Undulator field at 2 K Max field on axis at I op = I c 4.2 K: ≈ 1.0 T 2 K : ≈ 1.2 T HeLiCal Group Meeting, RAL, 17 May 2007

11. 11 Conclusions (preliminary) -Lowering undulator working temperature from 4 K to 2K gives about 20% gain in the field on axis (period is 11.5 mm, magnetic bore is 6.35 mm, Fe former) HeLiCal Group Meeting, RAL, 17 May 2007