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Published bySaige Anderson Modified about 1 year ago

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The HiLumi LHC Design Study is included in the High Luminosity LHC project and is partly funded by the European Commission within the Framework Programme 7 Capacities Specific Programme, Grant Agreement Q4 in IR15 Operating cycle R. De Maria. Thanks to G. Arduini,, J-P. Burnet, M. Giovannozzi, S. Fartoukh, M. Fitterer, M. Korestelev, M. Solfaroli, H. Thiesen, E. Todesco.

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Maximum ramp/discharge rates define the squeeze and ramp down duration. Important quantity for the annual integrated luminosity. Reducing the duration will reduce the ideal fill duration and increase the integrated luminosity. Discharge rates of standalone 2-in-1 magnets like Q4 limits the minimum squeeze durations: largest current just after the ramp and reduces in a controlled way during the squeeze. Discharge rates of triplets limits the minimum pre-cycle durations: triplets run at the nearly maximum current through all the flat top and must be discharged not necessarily as controlled as the squeeze but enough to guarantee reproducibility of the cycle. In order to evaluate the impact of ramp rates: WP2 provides gradients, WP3 provides currents, inductance, QPS limitations, EPC group computes maximum ramp rates as function of the current by including in addition resistance, operating voltage and other PC limitations, OP compares the circuits and determines which circuit limits the minimum duration of the squeeze and the pre-cycle. 2 Ramp rate limitations

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Optics are defined by quadrupole gradients normalized by the energy. Injection optics needs to be compatible with: lower current limits at injection energy, nominal gradients at flat top (if we do not ramp&squeeze). Since the ratio between energy is 6.4% and 3% is given by low current limits injection optics are often not flexible enough. At low current magnets have also larger variance in the transfer function and multipole components: Lower current limit: input from EPC, Expected value and uncertainty of the absolute multipole components at low current. 3 Low current limitation

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Includes injection, squeeze and VDM optics for HLLHCV1.0, HLLHCV1.1. HLLHCV1.0 Q4 decay too fast depending on the scenarios (e.g. no ramp& squeeze, squeeze in IR15 to β*=1 m before ATS). Different strategies (e.g. slower Q4 decay and no ATS before β*= 1.2 m) are in preparation for HLLHCV Q4 (MQYY) cycle for HL-LHC Squeeze duration will benefit from a 2-quadrant power converter for Q4.

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Includes injection, squeeze and VDM optics for HLLHCV1.0, HLLHCV1.1. HLLHCV1.0 Q4 decay too fast depending on the scenarios (e.g. no ramp& squeeze, squeeze in IR15 to β*=1 m before ATS). Different strategies (e.g. slower Q4 decay and no ATS before β*= 1.2 m) are in preparation for HLLHCV Q4 (MQYY) cycle for HL-LHC Squeeze duration will benefit from a 2-quadrant power converter for Q4.

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6 Backup

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7 Squeeze HLLHCV1.0

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8 MB Triplet discharge: LHC Run I What limits triplet discharge? There seems room in the voltage.

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9 MB, Q4(slowest), triplet discharge run I Triplet limits pre-cycle duration, follow by the slowest Q4 (there is a large variation in those between circuits)

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