Coil parts & Instrumentation issues for LQ/HQ coils tested at Fermilab HQ/LHQ coil parts task force

HQM01 Test Results Preliminary

Coil parts & Instrumentation issues for LQ/HQ coils tested at Fermilab

HQ/LHQ coil parts task force

IntroductionCollect all issues related to HQ/LQ coil parts and instrumentation found at Fermilab before, during or after the test

Issues found before the test to be verified with the Lab fabricated or instrumented the coil

Keep updating the information on issues for old or forthcoming tests

Start summarizing findings

LQ/HQ coils tested at FermilabLQS01aStrip heater damage, delamination on the inner coil surfaceLQS01bStrip heater damageLQS02Mixed up voltage tap wiringHQM01 (coil 12)Coil to IL pole piece shortHQM02 (coil 13)Coil to IL pole piece shortOL heater to coil shortHQM03 (coil 14) in preparation to electrical checkoutCoil to OL splice block shortWires not potted into the LE outer layer splice blockLQS01aStrip heater in coil 7 (PH07A01) was lost during the test Heater was connected in parallel with other heaters, HFU decay profile slightly changed but was not noticed during the testMonitoring of HFU discharge was implemented after this test

PH07A01 heater was repaired after the testExposed area was filled with Stycast and 5-mil Kapton on top of it and cured with pressure. Damaged area of the heater was replaced with a 10-cm long copper wireThe same heater was lost again in LQS01b

LQS01aDelamination of coils inner diameterLarge bubbles underneath the large sections of the heaters

Rod SG are vulnerable to cool downSector D rod SG was lost during the initial cool-downAdditional sensor on each rod could help

HQM02 coil parts & instrumentation issues Pre-test electrical check-out: short found between the coil and the IL LE pole pieceShort location in A10B10 segment, close to B10Inner and outer layer pole pieces at LE are in contact Small axial gap between the LE and RE pole pieces

Inner layerOuter layerHQM02 coil parts & instrumentation issues Both strip heaters on the outer layer developed short to coil after 3rd quench at 4.6 K Significant increase of the quench current from ~14 kA to ~15.7 kAStrip heaters isolated and removed from the magnet protection

Was is safe to continue testing ?Symmetric grounding of both the magnet and strip heaters, as well as 10 mOhm dump resistor should reduce the maximum voltage drop across the coilSeveral manual trips and heater provoked quenches performed to analyze noise in signals Strain gauge data, especially from the bullets, were investigatedQuench current was gradually increased up to 14 kA before quench training was continued

HQM02 coil parts & instrumentation issues When exactly the short developed ?Active ground fault protection system tripped only after the quench HFU discharge plot for quench #3 indicated that short developed after the quench was detected (t=0)

OL heatersIL heaters

HQM02 coil parts & instrumentation issues When exactly the short developed ?HFU discharge profile compared to a reference plot

Quench # 3Quench # 2When exactly the short developed ?Ground fault current in quenches #3 and #18, both at ~ 15.7 kA

HQM02 coil parts & instrumentation issues

Quench # 3Quench # 18HQM02 coil parts & instrumentation issuesOL RE

HQM02 coil parts & instrumentation issues

2-mil Kapton ground wrap3 layers of 5-mil Kapton insulationHQM02 coil parts & instrumentation issues11/30/2011HQM02 inspection results

OL RE spacer-to-end shoe (IL or OL):openOL RE spacer-to-IL RE spacer: openIL RE end shoe-to-OL RE end shoe:openOL RE spacer-to-OL coil:48.99 OhmOL RE spacer-to-IL coil:49.12 OhmOL RE spacer-to-strip heater (NT):54.8 OhmOL RE spacer-to-strip heater (T):3.37 Ohm

Heater to coil short developed during the quench Did the spacer-to-coil short develop after the heater failure ?

HQ02HQ04HQ13HQ1426.8 mm22.6 mm10.6 mm18.8 mmHQM02 coil parts & instrumentation issuesOL LE before the test

OL LE after the testHQM03 coil parts & instrumentation issuesPreliminary electrical check-out: short found between the coil and the OL LE splice blockShort is located close to B2, could be B2 voltage tap wire pinched between the splice block

B2 vtap wireShort locationHQM03 coil parts & instrumentation issuesDifferent technology of splice wiring is used at Fermilab

SS foil in KaptonHQM03 coil parts & instrumentation issues

Wires not potted into the LE OL splice block

Need to repair (Stycast ?)