CLIC Klystron-based Design D. Schulte for the CLIC team D. Schulte, Klystron-based Design, January 2017

D. Schulte, Klystron-based Design, January 2017 Introduction Goals Develop conceptual design of the first energy stage Design of lattices Beam dynamics studies Design optimisation with other groups (e.g. module) Klystron-based alternative Develop concept for the principle of the energy upgrades Explore issues arising from upgrades and address important ones Experimental activities Contribution to experiments Evaluation of impact of experimental programme on design Explore opportunities of further experiments Explore upgrade options based on novel technologies Deliverables Lattice decks Specifications Layouts Reports Will not cover details of work Will evolve with results Mainly give idea of scope and get going on things Maybe wait with discussions until the end D. Schulte, Klystron-based Design, January 2017

Klystron-based First Stage Example RF unit design (I. Syratchev) With simple cost model find similar cost than drive beam-based design at 380GeV Much improved RF unit design More expensive at 3TeV 1076 units /beam The pulse compressor used for parameter determination in the Baseline Report has been still a previous version But used updated model D. Schulte, Klystron-based Design, January 2017

Optimisation Procedure Optimised cost systematically similar to drive beam-based design Boundaries respected Beamstrahlung level consistent with experimental request Risk for the structure is slightly less than for 3TeV machine but the same for all designs Beamdynamics constraints 50Hz operation Some increase of risk in damping rings mitigated by increased horizontal emittance Beam stability in main linac is constant (single and multi-bunch) BDS is at the limit for the energy Note: some effects are reduced, some are increased but not by large numbers D. Schulte, Klystron-based Design, January 2017

Klystron-based Design Cost Model Ph. Lebrun, G. Riddone, I. Syratchev Based on: Scaling of CE and infrastructure cost Analytic estimate of module cost Analytic cost of RF unit D. Schulte, Klystron-based Design, January 2017

Reminder: New Structure Choice D. Schulte, Klystron-based Design, January 2017

Reminder: Selected 380 GeV Beam Parameters 109 5.2 nb 352 frep Hz 50 ex/ey mm/nm 0.95/30 bx/by mm/mm 8.2/0.1 sx/sy nm/nm 149/2.9 sz mm 70 Ltotal 1034cm-2s-1 1.5 L0.01 0.9 ng dE % 6 The emittances are nominal values at the IP Draft values for emittances targets are Exit of damping ring ex < 700nm, ex < 5nm Exit of RTML ex < 850nm, ex < 10nm Exit of ML ex < 950nm, ex < 20nm A limited flexibility exists for the collision parameters O(10%) since the beam size is larger than the minimum that could be achieved Also the waist shift allows to gain a few percent D. Schulte, Klystron-based Design, January 2017

Remember: CLIC Energy Stages Ecms=380Gev, L=1.5x1034cm-2s-1, L0.01/L>0.6 For higgs and top production, specified by CLIC physics group Ecms=O(1.5TeV) Depends on LHC findings Ecms=3TeV, L0.01=2x1034cm-2s-1, L0.01/L>0.3 Klystron-based first energy stage has to be consistent with energy upgrade Bunch charge of > 4x109 > 312 bunches D. Schulte, Klystron-based Design, January 2017

Rational and Cases to be Explored Ideal would be to have the same structure design for the scenario with drive beam and with klystrons The first energy design should be consistent with an energy upgrade keeping the initial structures and adding other designs Reference is the drive beam-based design for 380GeV (DB244): use the same structure but with klystrons upgrade with other structures and power old structures with klystrons or new drive beam modules ideal solution if it works Exploration 1 (K244): find the best solution for a structure that can be used with drive beam or klystrons and is compatible with the upgrade could replace the reference case Exploration 2 (K): find the best structure for the use with klystrons ensure that is compatible with an energy upgrade if these structure are continued to be powered by klystrons N > 4x109 N > 312 Pulse length 244ns Any pulse length D. Schulte, Klystron-based Design, January 2017

Klystron-based Design Structure Choice Expect significant cost increase compared to optimised structure for klystron-based design D. Schulte, Klystron-based Design, January 2017

Klystron-based Design Structure Choice Slightly better cost for structure that is optimised for klystron-based design Very slight increase in cost for drive beam-based design D. Schulte, Klystron-based Design, January 2017

Klystron-based Design Structure Choice Significantly better cost for structure that is optimised for klystron-based design For the upgrade cannot use this design with drive beam D. Schulte, Klystron-based Design, January 2017

Selected 380 GeV Beam Parameters for K N 109 3.87 nb 485 frep Hz 50 ex/ey mm/nm 0.66/30 bx/by mm/mm 8.2/0.1 sx/sy nm/nm 120/2.9 sz mm -- Ltotal 1034cm-2s-1 1.5 L0.01 0.9 ng dE % The emittances are nominal values at the IP Draft values for emittances targets are Exit of damping ring ex < 500nm, ex < 5nm Exit of RTML ex < 600nm, ex < 10nm Exit of ML ex < 630nm, ex < 20nm A limited flexibility exists for the collision parameters O(10%) since the beam size is larger than the minimum that could be achieved Also the waist shift allows to gain a few percent D. Schulte, Klystron-based Design, January 2017

D. Schulte, Klystron-based Design, January 2017 Conclusion For the klystron-based design, significant cost saving could be expected from the scenario K compared to DB244 Proposed strategy is to refine the optimisation for this point and to explore two structures DB244 and K Igor’s changes in the pipeline issues with previous design different pulse compressors higher efficiency 12GHz klystrons … When can we base a design on these? in particular experimental verification schedule Cost model should be reviewed Power model will be needed Should review impact of different parameter sets on all systems How much change is required? Iterations might be required D. Schulte, Klystron-based Design, January 2017