brookhaven - fermilab - berkeley US LHC ACCELERATOR PROJECT LHC IR Quad Heaters

brookhaven - fermilab - berkeley US LHC ACCELERATOR PROJECT Michael Lamm2 Schematic of LHC Inner Triplet 4 IP x (2 Triplets/IP)=8 Circuits -Q1 and Q3 made by KEK, Q2 made by Fermilab. Q1 and Q3 opposite polarity of Q2. -“ FNAL” Q2 consists of two 5.5m magnets bussed in series and contained in a single cryostat -Series of 8 model magnets + one full scale prototype.

brookhaven - fermilab - berkeley US LHC ACCELERATOR PROJECT Michael Lamm3 Quench Protection Test on Model Magnets Magnet Protection Requirements: -Peak Temperature <400K -Peak Voltage to Ground <1000 V Heater Parameters: -Heater Insulation -Heater Width -Resistance Distribution -Heater Location Protection Parameters -Quench detection threshold mV -Strip heaters provide primary protection NO EXTERNAL ENERGY EXTRACTION -Redundancy two circuits (H1&H3, H2&H4) -Simulate CERN Heater Circuit: 7 mF, 900 V voltage, RC~100mS, Peak Power >20 W/cm2

brookhaven - fermilab - berkeley US LHC ACCELERATOR PROJECT Michael Lamm4 MQXB Quench protection program

brookhaven - fermilab - berkeley US LHC ACCELERATOR PROJECT Michael Lamm5 Two design Parameters: Heater Location and Distributed Resistance Inter Layer Vs. Outer Layer -Outer layer heaters are easier to install -Inter layer heaters might be more effective Longitudinal Resistance Distribution -Power supply specs are fixed, so..what is more important: larger area coverage or higher peak power? Outer Layer Inter Layer

brookhaven - fermilab - berkeley US LHC ACCELERATOR PROJECT Michael Lamm6 Using Quench Integral to Study Two Heater Parameters Outer heaters just as effective as inner Quench detection times significant part of quench integral Longitudinal resistance distribution works Inner vs.Outer Heaters Longitudinal Resistance Distribution

brookhaven - fermilab - berkeley US LHC ACCELERATOR PROJECT Michael Lamm7 Peak Temperature (use spot heaters that simulate spontaneous quenches) Most pessimistic quench location tested with spot heater. Spot heater quenches in pole turn

brookhaven - fermilab - berkeley US LHC ACCELERATOR PROJECT Michael Lamm8 Voltage to Ground For 1.9 M model, voltage to ground is low, less than 30 Volts at peak operating field gradient... The eight coils that make up a HGQ magnet are bussed in series, with inner to outer pole turn splice. Voltage to ground is largely due to resistive-inductive (im)balance between inner and outer coils imbalanced heater geometry

brookhaven - fermilab - berkeley US LHC ACCELERATOR PROJECT Michael Lamm9 Protection Conclusions Heaters -Heaters adequately protection magnet from excessive peak temperatures and peak voltage to ground -Outer layer heaters are just as effective as interlayer heater. Outer layer heaters chosen for ease of installation -Reducing insulation doesn’t seem to have much effect (or small compared to other variables -Increasing peak power is more important than longitudinal resistance: use HGQ08 style heater Bus Work -Parameterize temperature and velocity -Single layer stabilizer is adequate. Opt for 1 layer of copper