LARP CM15 Magnet Testing Working Group SLAC, November 2 nd 2010

Outline Test requirements for the long HQ (consider two cases, 3.3 m coil length - same as LQ - and 4 m coil length): possible facilities and required upgrades. Large diameter probes for field quality measurements: probe fabrication, anti-cryostat/header modifications, possibility to perform measurements in LHe Magnet protection from shorts/ground faults Electrical QA: status, analysis, etc. Quench Detection AOB

Test requirements for the long HQ: possible facilities and required upgrades Facilities (FNAL, BNL and CERN) 3.3-m long HQ coils  Fermilab: No upgrades are required for testing from 4.5K to 2.5K. Lambda plate is necessary for 1.9K test. New warm bore is required for magnetic measurements  BNL: PS  CERN: Test facility will be ready by March-April 2011 Cryostat working at K range 20 kA power supply Commissioning of DAQ and control systems

Test requirements for the long HQ: possible facilities and required upgrades (cont’d) 4-m long HQ coils  BNL  CERN : Test facility will be ready by March-April 2011 Possible Upgrades Fermilab:  “Lambda plate” for 30kA top plate  New warm finger with 90-mm outer and 70-mm inner diameter (estimated cost ~ 20k$, 5-6 months from order placement) BNL: CERN:

Large diameter probes for field quality measurements What is a reference radius for magnetic measurements?  CERN asking for 95-mm of free bore diameter ? Define magnetic zone length  Non-connection end, straight part, layer jump, connection end Large diameter probes  Fermilab: Currently using probes have a reference diameter of 46 mm New PC board based probes with various reference radius and length are fabricated (low cost). Fabrication of new tangential coils will be much more expensive and time consuming  BNL:

Large diameter probes for field quality measurements (cont’d) Large diameter probes  CERN Anti-cryostat/Header modifications  Fermilab Need new warm bore Maximum outer/inner diameter is 90-mm/70-mm Need to build new header, lambda plate and warm bore if more than 90-mm reference diameter is required Test in LHe

Magnet protection from shorts/ground faults Fermilab Symmetric coil (and heater) grounding  The maximum coil to ground voltage reduced by factor of 2  Ground current through the fault was significantly reduced (from 40 A to about 3 A)

Magnet protection from shorts/ground faults (cont’d) Fermilab: Active coil ground fault detection  Isolated 5 V voltage source connected in series with the ground resistor  Voltage drop develop across the ground resistor (100-Ohm) in case of coil to ground short  “Always armed”  Should not depend on power supply voltage and magnet inductance  Is equally sensitive to ground fault at different locations

Magnet protection from shorts/ground faults (cont’d) Fermilab  Plan to implement an active heater ground fault system too  Ready to share experience BNL:  Plans for the ground fault detection CERN:

Electrical QA: status, analysis, etc. Pulse test  Test procedure  Maximum voltage for the test Initial and after test Hipots  Fermilab performs Hipot at 1.9K too after first few quenches.

Quench Detection Fermilab  FPGA based quench management system was implemented in addition to the existed VME based system  Difference of the Half-coil signals are mainly used for quench detection  Current dependent thresholds implemented for the Half-coil signal modules both in VME and FPGA based systems  Whole-coil signal also triggers quench BNL CERN

What else ? Documentation: Fermilab  Magnet description