MICE Spectrometer Solenoids Step IV running

MICE Spectrometer Solenoids Remember: Both magnets met the full specification at the vendor and were fully mapped. Cryogenic operation was very good. Both magnets had significant cooling headroom (SS2 more than SS1) SS2 (in upstream position of the beam line – SSU) has reached full operating current at RAL, but full training (soak, solenoid mode) has not been completed. Cryogenic headroom ~ 50% (3W) Vacuum excellent SS1 (in downstream position – SSD) had a M1 lead failure during training. Cryogenic headroom ~<25% (~1W) Vacuum excellent, but some issues if power feedthrough gets cold What is the path forward for Step IV? MICE CM March 31, 2016 RAL Alan Bross

Reminder: Basic design 5 2-stage CCs 1 single-stage CC 5 Coils Max current ~300A High inductance 10-40H M1 M2 E1 C E2 M1 in SSD Is DEAD MICE CM March 31, 2016 RAL Alan Bross

MICE CM March 31, 2016 RAL Alan Bross Power delivery system 2 Vacuum feedthroughs bring power into vacuum space One for ECE, one for M1 and M2 Copper leads to HTS IL/A = 3.6 X 106 A/m HTS: HTS-110 500A (M1, M2, C) and 250A E1 and E2 LTS: Vacuum feedthrough: Proprietary Wang design based on SSC superconductor Inside He space: Cu stabilized conductor MICE CM March 31, 2016 RAL Alan Bross

On 9/13/15 @1800 BST, SSD became Self-aware SS magnet protection and powering scheme after the September 13th, 2015 incident has been re-visited and, during the investigation process, it was realized that there are several problems in the protection and powering scheme that need to be addressed. Although there is no solution that will provide a perfect protection scheme, the existing one has been significantly improved upon. The improved protection scheme follows. MICE CM March 31, 2016 RAL Alan Bross

MICE CM March 31, 2016 RAL Alan Bross E-C-E Power system II MICE CM March 31, 2016 RAL Alan Bross

MICE CM March 31, 2016 RAL Alan Bross M1, M2 Power System II MICE CM March 31, 2016 RAL Alan Bross

External Dump Pack Resistors Centre Coil Resistor Trim Coil Resistor Match Coil Resistor MICE CM March 31, 2016 RAL Alan Bross

MICE CM March 31, 2016 RAL Alan Bross Operation During powering of the magnet circuits all the switches are closed. Several different scenarios can occur and the following actions will be taken: If magnet quench or ground fault on a circuit is detected: For all three circuits (M1, M2, E-C-E) the two main switches (primary and redundant) open – all together 6 switches open. If HTS or LTS quench occur: the External Dump Pack (EDP) switch of the circuit that experienced the lead quench opens. For E-C-E resistors located near magnet; M1 & M2 in RR2 In order to decrease the detection voltage threshold significantly the protection and monitoring scheme has changed: MICE CM March 31, 2016 RAL Alan Bross

MICE CM March 31, 2016 RAL Alan Bross Operation II A DCCT (direct-current current transformer) based current readout system was added to precisely measure the magnet current values and provide dI/dt signals for QPS: The “old” QPS still provides a quench trigger signal if any coil, HTS or LTS leads show resistive voltages. The protection scheme has changed: A dI/dt based protection (using the DCCT system) scheme with mutual coil balancing is used for SSD M2 and SSD E-C-E and for SSU M1 and SSU M2 circuits that monitors the magnet coil voltages; SSU E-C-E Half-Half coil based protection circuit threshold value was significantly lowered (by lowering the noise level of the circuit); An additional new protection layer (secondary) was added to the HTS and LTS protection scheme. It will produce a separate trigger for each circuit (M1, M2 or E-C-E) if HTS or LTS lead quench occur in that circuit. This trigger will be used to open the EDP for the circuit that detected HTS or LTS lead quench MICE CM March 31, 2016 RAL Alan Bross

MICE CM March 31, 2016 RAL Alan Bross Operations III NO additional individual “training” of either SSU or SSD is planed Obviously, we have not “trained” the channel: SSU-FC-SSD. Additional quenches must be assumed This presents the greatest risk to SSD because of potential damage to the power feedthrough for M1/M2 on SSD (vacuum to He space) Initial SSD operations limited to E-C-E MICE CM March 31, 2016 RAL Alan Bross

Fundamental issue with SSD M2 of SSD looks fine, but given that we do not know in detail the condition of this feedthrough, running first with M2 off is envisioned. However, any quench in SSD (from E-C-E) will produce a pressure pulse Has been checked once and feedthrough held (still vac tight). Next time…???? MICE CM March 31, 2016 RAL Alan Bross

MICE CM March 31, 2016 RAL Alan Bross Conclusions SSU is in good shape Magnetically Cryogenically Vacuum SSD not so much. M1 is not retrievable Cryogenic headroom OK, but worse Vacuum is fine The new PS/QD/QPS system will have a significant upgrade and will protect these magnets as well as possible (limited by the magnets intrinsic design). MICE CM March 31, 2016 RAL Alan Bross

MICE CM March 31, 2016 RAL Alan Bross Conclusions Installations of components, re-configuration of the QPS modules and finalization of the DCCT system input to the QD system is ongoing. Final install and initial commissioning is scheduled to begin on April 27th. A second round of work in May will be needed to full commission the SS PS/QD/QPS systems for full magnet operations. SSs ready in June for Step IV operations MICE CM March 31, 2016 RAL Alan Bross