Two Dimensional SR-Interferometer at PETRA III. Artem Novokshonov DESY, Tomsk Polytechnic University

Transcription

1 Two Dimensional SR-Interferometer at PETRA III Artem Novokshonov DESY, Tomsk Polytechnic University

2 First Part: Two Dimensional Interferometer at Petra III

3 Interferometer principal Schematic of the Interferometer Mirror Source point Mirror in Vacuum SR Mirror Slits Lens 500 nm Bandpass Filter Magnificating Lens Polarizer CCD Camera 14.2 m 0.88 m Slits

4 Previous interferometer Setup in optical hutch Optical beamline (bunch length diagnostics) magnification lens Glan- Thomson polariser double slit lens bandpass filter & CCD visible light beampipe mirror boxes synchrotron light from bending magnet NL 50 alignment mirror vertical design emittance confirmed o 30 m beam transport via relay optical system Gero Kube, DESY / MDI DEELS 2014 ESRF,

5 Previous interferometer USR studies o confirmation of 3 GeV hor. emittance Drawbacks o beamline with relay optics additional uncertainties (lenses) o setup blocks Streak camera system dismount interferometer for bunch length measurement o space for only one interferometer modify setup for measurement in other transverse plane beamline originally not designed for interferometric measurements status

6 First interferograms First interferograms from the new one interferometer Horizontal interferogram Vertical interferogram Two dimensional interferogram

7 New interferometer schematic Whole system view Extraction tube and mirror Schematic of Synchrotron radiation extraction Mirror Mirror Tube Optical line Tube SR

8 New interferometer schematic Optical line Slits SR CCD camera First Lens F = 510 mm σ - polarizer Bandpass filters nm FW = 10 nm Magnifying Lens

9 Matlab interface

10 First part of measurements First part of measurements was made in Emittance and beam size measured with the new interferometer Vertical Horizontal Beam size 20 μm 180 μm Emittance 32 pm rad 1.2 nm rad Designed sizes Vertical Horizontal Beam size 9 μm 180 μm Emittance 10 pm rad 1.2 nm rad The main problem is vibrations of interferogram! The causes of the vibrations: Vibrations of the optical line (table) Instability of the beam in this area Because of these vibrations a smaller exposure time should be used

11 First part of measurements Smaller exposure time leads to low intensity of pictures 5 superposed interferograms with 150 μs exposure time To use number of pictures with small exposure time shift them relative to each other and superpose 1 interferogram with 750 μs exposure time

12 First part of measurements

13 First part of measurements Dependencies of vertical emittance on an exposure time with one shot 500 nm bandpass filter Vertical emittance dependency on an exposure time with one shot ( ) Vertical emittance dependency on an exposure time with one shot ( )

14 First part of measurements Dependencies of vertical standard deviation on an number of shots with constant exposure time 500 nm bandpass filter Vertical emittance dependency on a number of shots Standard deviation dependency on a number of shots

15 First part of measurements Dependency of emittance on exposure time with 5 shots

16 Second part of measurements Second part of measurements was made in Emittance and beam size measured with the new interferometer Vertical Horizontal Beam size 15.5 μm 180 μm Emittance 20 pm rad 1.2 nm rad

17 Second part of measurements 1 shot with different exposure time 10 shots with different Exposure Time

18 Second part of measurements

19 Second Part: Virtual Lab Modelling

20 Virtual Lab Modelling Virtual Lab Fusion (VL) is an optical design software made by Light Trans company. Using VL one can simulate his own optical system with optical elements from the simplest (ideal lens, ideal mirrors, slits etc) up to structures made himself. Advantages of VL for SR interferometer modelling: o o User can define any slits constructions Parameter run can be performed Disadvantages: o VL is not performed for synchrotron field calculations Points to observe using VL: o o Different kinds of slits (pinhole and rectangular) Beam size determination mistake caused by shifting or rotating of slits

21 Virtual Lab Modelling Vertical comparison of VL results with results of SRW At a first stage, VL results of interferometer modelling had to be compared with results of already existing code. For this case a Synchrotron Radiation Workshop (SRW) software was chosen. Stages of the comparison: Synchrotron radiation field was calculated by SRW This field was propagated via double slit optical system in VL and SRW Beam sizes were determined from both programs VL results SRW results Real size σ hor 170 μm 169 μm 169 μm σ vrt 10 μm 9.4 μm 9.75 μm

22 Virtual Lab Modelling Two dimensional VL interferogram (rectangular slits) σ VL = 9. 4 μm σ real = μm Parameters of the slits: σ VL = 169 μm σ real = 169 μm Horizontal distance between slits 6 mm Vertical distance between slits 11 mm Half of horizontal slits width 0.5 mm Half of vertical slits width 0.5 mm

23 Virtual Lab Modelling Two dimensional VL interferogram (pinholes) σ VL = μm σ real = μm σ VL = μm σ real = 169 μm Parameters of the slits: Horizontal distance between pinholes 5 mm Vertical distance between pinholes 11 mm Radius of the pinhole 1 mm

24 Virtual Lab Modelling Slits rotating. Horizontal size determination Let us consider that our slits are rotated at some angle to the not tilted position. In this case there must be some mistake of beam size determination. Non rotated interferogram α 3 degree rotated interferogram

25 Virtual Lab Modelling Slits rotating. Vertical size determination Not rotated vertical interferogram 3 degree rotated interferogram

26 Further plans The cause of the vibrations and instability should be investigated Experiments about attenuation technique can be provided to make vertical size determination easier, more stable and precise Improvement of two dimensional fit Investigation of coupling can be done by rotating of slits Improvements of all modelling which was done in Virtual Lab Computer modelling using Oscelot python library

27 Thank you for your attention!