1. Application of a Streak camera at PITZ
D. Lipka, DESY Hamburg

2. 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

3. Longitudinal Light Pulse Measurement
Operation principle of a streak camera
Movie
M. Werner
11/16/2018
D. Lipka, DESY Hamburg

4. 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

5. 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

6. 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

7. Bunch Length Measurement
11/16/2018
D. Lipka, DESY Hamburg

8. Bunch Length Measurement
Bunch length in RMS 90 %:
cut out the tails with < 10 % max.
intensity
Minimum bunch 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

9. 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

10. 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

11. Longitudinal Phase Space Measurement: Results
simulated
measured
Thanks to Juliane Rönsch
11/16/2018
D. Lipka, DESY Hamburg

12. 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

13. 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