Application of a Streak camera at PITZ D. Lipka, DESY Hamburg
Contents Operation Principle of a Streak camera, movie Measurement of Photo Injector laser bunch Measurement of electron bunch length Measurement of longitudinal phase space Summary 11/16/2018 D. Lipka, DESY Hamburg
Longitudinal Light Pulse Measurement Operation principle of a streak camera Movie M. Werner 11/16/2018 D. Lipka, DESY Hamburg
Longitudinal Light Pulse Measurement Operation principle of a streak camera T i me output Synchroscan streak camera: time resolution 2 ps 11/16/2018 D. Lipka, DESY Hamburg
Developed by Max Born Institute (MBI) at Berlin Photo Injector Laser Longitudinal laser distribution Gaussian distribution FWHM = (7 ± 1) ps, inhomogeneous space charge density Changed to Flat-Top FWHM ~ 20 ps, fall and rising time 5-7 ps, homogeneous space charge density Developed by Max Born Institute (MBI) at Berlin 11/16/2018 D. Lipka, DESY Hamburg
Photo Injector and Diagnostics until 2004 screens: YAG powder, aluminum foil beam shape [destructive] BPM: ‘antenna’ beam position [non-destructive] Faraday cup (isolated copper dump) beam charge [destructive] integrating current transformer (ICT) beam current [non-destructive] slits (beamlets) transverse phase space [destructive] dipole, magnetic deflection beam momentum [destructive] Cherenkov radiator, streak camera long. phase space [destructive] 11/16/2018 D. Lipka, DESY Hamburg
Bunch Length Measurement 11/16/2018 D. Lipka, DESY Hamburg
Bunch Length Measurement Bunch length in RMS 90 %: cut out the tails with < 10 % max. intensity Minimum bunch length @ 1 nC: FWHM = (21.0 ± 0.5stat ± 4.1syst) ps (6.3 ± 0.1stat ± 1.2syst) mm at same phase of 27o where the minimum momentum spread is obtained 11/16/2018 D. Lipka, DESY Hamburg
Longitudinal Phase Space: Measurement Method Measure momentum and longitudinal distribution simultaneously by using a Cherenkov radiator in the dispersive arm → correlation → complete longitudinal phase space Design setup: Optical transport from radiator to streak camera with mirrors and lenses, Light bunch is elongated due to dispersion in lenses transmission filter with 10 nm bandwidth used 11/16/2018 D. Lipka, DESY Hamburg
Longitudinal Phase Space Measurement: Results Optimum phase is f0 with highest energy gain Head of bunch on left hand side About 30 pC bunch charge opt. phase - 5o opt. phase opt. phase + 9o Bunch reaches iris of cavity before change of polarity Bunch reaches iris of cavity after change of polarity Thanks to Juliane Rönsch 11/16/2018 D. Lipka, DESY Hamburg
Longitudinal Phase Space Measurement: Results simulated measured Thanks to Juliane Rönsch 11/16/2018 D. Lipka, DESY Hamburg
Longitudinal Phase Space Measurement: Results simulated longitudinal phase space convoluted with resolution of streak camera measured longitudinal phase space simulated longitudinal phase space longitudinal distribution momentum distribution bunch charge: 1 nC flat-top longitudinal laser distribution phase with maximum beam energy Thanks to Juliane Rönsch 11/16/2018 D. Lipka, DESY Hamburg
Summary Streak camera widely used at PITZ Characterization of photo laser bunch length and structure Bunch length Longitudinal phase space Intensity of photons from electron bunch too low for single bunch measurements 11/16/2018 D. Lipka, DESY Hamburg