1. MQXF protection: work in progress and plans Vittorio Marinozzi 9/23/2013 1 QLASA calibration with HQ02 data

2. 2 MQXF protection seems hard to achieve MQXF hot spot temperature simulations are very close to the upper limit of 350 K How much are the simulations conservative? I’ve made several conservative approximations Trying to answer analyzing data from HQ02 tests

3. 3 1. High dI/dt effects Manual trip 13 kA No protection heaters 60 m Ω dumping resistance This is not only quench back: there should be 20 m Ω of coils resistance after 1 ms (the whole magnet quenched is about 5.5 m Ω). With dumping resistance, dI/dt effects are not negligible! In this case, MIITs estimations differ by 35%. Plan is to simulate a decay with a smaller resistance (10 mΩ) and see the impact on MIITs estimation. 120 kA/s

4. 4 2. Protection heaters Manual trip 13 kA Only OL heaters No dumping resistance We can check: Heaters delay time OL-IL propagation In the MQXF simulation we’ve used heaters delay time computed by Tiina’s code. Plan is to compare Tiina simulations with HQ02 data Problem: at 120 kA/s simulation is faster than experimental data! Are we overestimating the coil resistivity? 120 kA/s

5. 5 2. Protection heaters Another example Manual trip 11 kA Only OL heaters No dumping resistance Manual trip 11 kA Only OL heaters No dumping resistance

6. 6 2. Protection heaters Another example Spontaneous quench 14.4 kA Only OL heaters 60 m Ω dumping resistance (80 ms delay) Spontaneous quench 14.4 kA Only OL heaters 60 m Ω dumping resistance (80 ms delay)

7. 7 2. Proposals to improve protection study  Analysis of HQ02 manual trip with no protection heaters, and different dumping resistances: 1.Estimation of the dI/dt effects. 2.Comparison with 2D simulation of eddy currents in the yoke, collar, beam tube, etc….  Target: numerical estimation of these effects.  Analysis of HQ02 manual trip with no dumping resistance: 1.Use heaters delay time by Tiina’s program (used for MQXF). Target: check accuracy of the code, and estimate how much conservative the protection heaters simulation is. 2.Can we do resistive (or inductive) voltage measurements in order to check if resistance growth is well simulated, and the actual impact of dI/dt effects?