Highlights of Prototype SC Magnet Tests (LCLSII- 4.5-EN-0612) and Proposed Production Magnet Test Plan (LCLSII-4.5-EN-611-R0) and XFEL Magnet Test Results Talk by Chris Adolphsen SLAC LCLS-II Tests and Reports by V. Kashikhin, M. Tartaglia, J. DiMarco, A. Makarov, V. Bocean, N. Andreev FNAL

LCLS-II Split, SC Quad/Corrector (‘One Size’ for all CMs) 3.7 um Filaments ‘Dunk’ Test Setup (for 4.5 K LHe bath)

10 quads between 0.5 and 1 A All quads < 6 A Max Current LCLS-II CM Quad Magnet Need to limit the current range at low field to avoid large hysteresis

“Physical” Standardization – F.J. Decker, SLAC-PUB- 5483, 1991 Coil Heaters can also be used to zero the persistent currents

Does this depend on the starting condition and does the dipole strength affect the results ? Nominal Cal = 0.125

XFEL Current Range XFEL CM Quad Magnet

LCLS-II Dipole Transfer Curve Example Hysteresis even larger (persistent current effect ?), but less critical

Example of Harmonic Measurement

Proposed LCLS-II Test Program Coils, half and full assembly when warm: – Coil resistance, inductance, ‘ring down’, 1 kV highpot and polarity tests Do one of the following based on cost 1.Dunk in LN and measure coil resistances and voltage drops for I = 0.4 A 2.Dunk in LHe – do above and quench tests up to 30 A (< 1 A/s ramp) in individual and all windings 3.Dunk in LHe – do above and use R= 10 mm rotating coil at I = 0.4, 1.0, 2.0, 4.0, 10.0, 15.0, 20.0 A to measure integrated field and harmonics (to a6,b6) for each coil set

XFEL Magnet and Test Program

XFEL Test Results (1) “The harmonic tests at 2 K were focused on precise multipoles measurement at 3 fixed currents and hysteresis measurements …. The magnets were powered from -50 A to 50 A with a different ramp rates. Several fast ramping current pre-cycles were necessary to predefine the persistent current effects in the superconducting wire.”

XFEL Test Results (2) “For such a small batch of magnets the available superconducting wires were limited and the selected wire is not optimal for this application [37 um filaments ?]. Furthermore due to the nested arrangement of magnets, crosstalk between the coils appears especially at low currents… in the first section of the accelerator where the beam energy is low the magnets operate only at a few percent level of the maximal design current (50 A) and hence suffer from persistent current contributions. ” and

Summary Main features of magnet design meet specs (cooldown to 2K, no quenches, field strength, harmonic content, alignment reproducibility). Need standardized, reproducible and reasonably fast way to calibrate integrated field that can be used to set the field level during operation at LCLS-II to the 1% level. – Probably need to measure each quad cold with rotating coil Should verify that cross talk between dipole and quadrupole operation within acceptable limits. Should review misalignment build-up (field to exterior CM reference points).