Task 6: Short Period Nb 3 Sn Superconducting Helical Undulator Jim Clarke/George Ellwood 28/11/2012

Contents Goals Status Testing Schedule 2

3 NbTi Helical Undulator Final Parameters: 215A Beam tube ID: 4.7 mm Winding ID: 6.35 mm Field on axis: 0.86 T Margin with this conductor: 30%

(Revised) Goals To create two identical undulators with Nb 3 Sn 300mm long and direct comparison with previous NbTi undulators The same period, diameter, winding groove etc as NbTi 4

Supercon – final wire choice 5 Field on axis 1.2T 40%> NbTi Operating current 720A Peak field on conductor 3.5T

Supercon Test Results from CERN 6 Operating current 720A required Wire will quench at <4T Not ideal but we will gain useful experience by winding an undulator with this wire So, we will wind two 300mm helical undulators and measure their performance in terms of quench, stability, and peak field

Alumina Coating 7 50µm Alumina plasma sprayed coating. This has been electrically tested to over 1000V without breaking down.

Heat treatment and vacuum impregnation tooling 8

1 st Milestone Undulator 9 Now fully fabricated, wound, impregnated and heat treated – ready for tests

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Testing No suitable test cryostat at RAL LASA Milan (Giovanni Volpini) have kindly offered to carry out the tests of both undulators Thanks to Amalia/CERN and Frank/KIT for also trying to fit us in! 15

4.3mm diameter bore Arepoc Hall probe mounted on a carbon fibre rod Maximum diameter 4mm

Good interaction with LASA Drawings developed Interfaces all being considered 17

Schedule Undulator 1 ready for test now Undulator 2 ready for test by end December Both undulators should be tested at LASA by mid Feb Test one after the other ~3 days each Simple peak B field check with Hall probe and magnet performance as function of current 18

Summary We are still on target to achieve our goals by the end of M48 We have completed the first undulator, fully impregnated and heat treated Second undulator to follow shortly Tests will be carried out at LASA Milan 19

Acknowledgements Many thanks to our colleagues at LASA, CERN, KIT and others within HFM without whom we would not have been able to achieve our goals 20