Slide 1

L. Wang

Work with T.O. Raubenheimer, J. WuLCLS-II Accelerator Physics meeting Jan 15th, 2013

Intensive MOGA Optimizations of LCLSII configurationsLCLS-II Accel. Phys. , L. Wang, SLACMany thanks to J Wu for useful discussion and help on the Litrack set-up, thanks F. Zhou for his help on IMPACT simulation data, M. Woodley and Y. Nosochkov for providing the R56 data.1ProblemLayout

Gun to L0, using IMPACT (thanks to F. Zhou)Particle Tracking start from L0 to beginning of the Undulator using LiTrackNominal R56 @BC1= 46 mm (thanks M. Woodley, Y. Nosochkov) Nominal R56 @BC2= 29 mmNominal R56 @Bypass Dogleg= -0.115 mmNominal R56 @HBEND= -0.383/0.479mm (HXR/SXR)Wake field is included

BC24.5 GeVBSY10/13.5 GeVTCAV3 BC1250/335 MeVL1SwirescannerL1X4 wire-scannersL2-linacL3-linacDL1135 MeVL0gunLCLS-II Accel. Phys. , L. Wang, SLACAll surface material are SS (except Undulator)WakeLCLS-II Accel. Phys. , L. Wang, SLACRegionLength (m)radius (m)Pipe shapewakecommentsL014.9S-bandL128.8S-bandL2313.8S-bandL3532.7S-bandLX0.6X-bandBypass extract550.01circularRW,SSBypass extract9770.025circularRW,SSBSY1920.01circularRW,SSLTU5100.02circularRW,SSHXR undulator1150.005flatRW, AlMOGA(Multi-Objective Genetic Algorithm)Variables:Phase and Voltage of L1,LX,L2,L3R56@BC1R56@BC2 Objectives & constrainsEnergy spreadJitters(RF Voltage and phase jitter, Charge jitter, Laser timing jitter) Energy at BC1(250MeV/335MeV)Energy at BC2(4.5GeV) Energy at the beginning of undulator (13.5GeV/10GeV)Peak current at the beginning of undulator (3kA/4kA)second order curvature

Optimization MethodLCLS-II Accel. Phys. , L. Wang, SLAC4Objectives

The energy spread is normalized by 0.03%LCLS-II Accel. Phys. , L. Wang, SLACFor instance (I/I)0=12%, (E/E)0=0.1%, ()0=100fs

Various JittersSimplified Jitter model in MOGAL1 Phase: [-30, -10]LX phase: [-162, -156]L2 phase: [-36, -31]L3 phase : [-10,0] (based on study at 250pC)LCLS-II Accel. Phys. , L. Wang, SLACThe range of RF phaseA larger range may be need for more studies!Converge slow; larger RF power6LCLS-II Accel. Phys. , L. Wang, SLACBenchmarked with design report

Only About 10 variables, but with many constrainsThe bunch profile (also the peak current) is not easy to be satisfied. Many efforts have been taken to make the optimization converge fast and well.Wake field and residual R56 after L3Wake field couples with bunch profile and add energy chirp in the phase space, therefore it can change the bunch profile/peak current ;the non-zero R56 also rotate the phase space, which causes the variation of the bunch profile/peak current after L3.CPULCLS-II Accel. Phys. , L. Wang, SLACComplexity250pC HXR250pC SXR150pC HXR40pC HXR20pC HXR20pC SXRLCLS-II Accel. Phys. , L. Wang, SLACresultsMOGA optimization of 250pC HXR(BC1@335MeV)LCLS-II Accel. Phys. , L. Wang, SLAC

Converge after 100 generations

Objectives @250pC HXRThe slope in z-profile shows the dI/dz near bunch center. ( thanks J. Wu) It doesn't mean anything for Gaussian shape bunch

20pC150pCLCLS-II Accel. Phys. , L. Wang, SLACHTTotal JittersParameters @250pC HXR---Solutions

Small jitter zoneRed zoneSmall energy spread zoneGreen ZoneLCLS-II Accel. Phys. , L. Wang, SLACLarge range with LX phase