MQY-30 Test Result Report H. Bajas, M. Bajko, V. Desbiolles, O. Dunkel, J. Feuvrier, L. Fiscarelli, C. Giloux, G. Kirby, F. Pincot, E. Ravaioli, F. Rougemont, P. Viret, G. Willering.

Main Goals of the Test Magnet Memory test at 4.2 K to nominal current (3900 A) Training at 1.9 K to target current (4950 A) Unbalanced Magnetic Measurements CLIQ protection study

Electrical scheme Facility/Magnet Allows to separately power each aperture or both aperture in series. Integration of two current leads at the middle of each apertures for CLIQ discharge.

All potentials respond Continuity assured Electrical tests All potentials respond Continuity assured Resistivity in accordance with OFH Copper (3%). Estimate of the cable length per aperture: =(2*((3.64*52)+(3.64*22)))*4 = 2155 mm

Hot Spot Temperature Estimate (adiabatic) Miits (300 K) < 3 MA2.s

Current, voltage and dump resistor IMAX = 5 kA Rdump = 160 mW UMAX = 800 V LMag = 74 mH or 148 mH tmag = Lmag / Rdump = 462 ms (or 925 ms) HV passed at 1 kV Cryostat Safe might not be safe pressure wise… Pressure monitoring and provoked quenches at intermediate current Energy values Estored = 0.5 * Lmag * IMAX 2 = 0.5*148*5^2 = 1.85 MJ Eextracted = 0.20 * Estored = 370 kJ Edeposited = 1480 kJ Quench threshold, validation time & extraction switch inertia vth= 10 mV Dt = 1.5 + 10 + 3 = 14.5 ms Quench detection on: -differential and direct signals - connections MIITs & Hot Spot Temperature Miits = (Dt+0.5 tmag ). IMAX 2 = (14.5+0.5*925)*5^2=12 MA2.s Magnet burnt Should relies on the magnet resistance growth. Careful check of the MIITs.

Quench Heater powering

Quench Heater powering Need of re-wiring the circuit so assure redundancy on single coil test . … powered in series, it yields: R1 = 15.2 (15.8) W R2 = 15.5 (14.9) W

Quench Heater signal survey Voltage Current Resistance Time constant Joule Energy Temperature Quench Heater OK Wrong reading (900V) …Gain issue…

1.9 K Endurance test performed for one hour From April the 7th to the 17th Three days of magnetic measurements Shaft stop rotating during cooldown (Apt. 1) or powering (Apt. 2) Cryogenics time: btw. 1 & 7 hours CLIQ box issue: (stop test CLIQ) Apt. 2 Apt. 1 Apt. 1 & 2 1.9 K 4.2 K

Example of quench (natural quench, 2 apertures) Current and MIITs Current and derivative

Example of quench (natural quench, 2 apertures) Differential signal (protection) Direction voltage

Computation of the inductive and resistive voltage and equivalent resistance. Voltage derivation Resistance derivation Voltage to ground < 800 V Resistance of the magnet (1.1 W) much higher than 160 mW dump resistor

1.3 MJ dissipated in the bath during the magnet resistance growth (358 kJ dissipated by the dump). Energetic approach 20% / 80%

How we came to it Apt. 2 Apt. 1 Apt. 1 & 2

Energetic approach

Extrapolation of the dissipated energy as function of the current HQ magnet

Pressure rise in the cryostat during the highest energy quenches. Opening of the safety valve at 2.3 bar (to balloon). No accumulation of the pressure in the cryostat thanks to large enough outlet and pressure valve gas release.

Inductance measurement

From resistance to resistivity to mean average temperature (copper as thermometer)…

Interesting resonant signal (direct) system At QH firing (t ~ -20 ms) At current extraction (t ~4 ms)

Quench Heater vs. CLIQ energy CLIQ induces more heating of the coils than the quench heaters do. Consequently Faster extraction

Conclusive remarks Magnet successfully tested. Performance measured up to 4940 A @1.9 K (3900 @4.2 K). Energy, MIITS and Pressure controlled by provoked quenches at increasing current. Quench Heater and CLIQ efficiencies compared up to 3 kA. Unbalanced magnetic measurements limited to stuck shaft, need to improve assembly Long Station Test facility qualified up to 1.3 MJ dissipated in the bath.

… Or adiabatic condition

Inductance fit

Energy: Quench Heater vs. CLIQ

Thermal cycle