Transcript PowerPoint
A Transverse Profile Imager for SwissFEL Rasmus Ischebeck A Transverse Profile Imager for SwissFEL > Profile measurement in FELs > Imaging scintillating crystals > Applications Rasmus Ischebeck 2 Transverse Profile Monitors Rasmus Ischebeck University of Illinois 3 Profile Measurement in FELs Rasmus Ischebeck 4 Coherent OTR Rasmus Ischebeck Joe Frisch 5 Coherent OTR Rasmus Ischebeck Joe Frisch 6 1-Dimensional Profile Monitor Rasmus Ischebeck Gian Luca Orlandi, Prajwal Mohanmurthy 8 x-y Correlations > Intrinsic correlation > Explicit x-y dependency introduced by RF deflector Rasmus Ischebeck 9 A Transverse Profile Imager for SwissFEL > Profile measurement in FELs > Imaging scintillating crystals > Applications Rasmus Ischebeck 10 2-Dimensional Profile Monitors > Optical transition radiation (OTR) > Scintillation Rasmus Ischebeck 11 Imaging Scintillators Rasmus Ischebeck 12 Electron Beam Profile Monitors Scintillators, OTR Screens & Wire Scanners Installed scintillators • Ce:YAG • 5 µm • 20 µm • 200 µm • Ce:LuAG • 200 µm Rasmus Ischebeck – Scintillators for SwissFEL 13 Electron Beam Profile Monitors Visual Light Optics • • • OTR screen / scintillator is at an angle of 45º to the optical axis For overview camera (1:5.3 demagnification) • Use Scheimpflug criterion to correct image plane orientation For 1:1 imaging • • Perspective control lens is not available commercially Only central part (~1…2 mm) of the screen can be imaged within depth of field Rasmus Ischebeck – Scintillators for SwissFEL 14 Design Considerations > Scheimpflug imaging principle Observation of the Scheimpflug imaging principle allows to image the entire screen without depthof-field issues. To avoid astigmatism, the lens is not tilted, but the detector is tilted. For a 1:1 imaging, we tilt the CMOS sensor by 15º. > Snell’s law of refraction The YAG / LuAG scintillators are observed at such an angle that Snell’s law of refraction is observed. As a consequence, we can image beams that are smaller than the thickness of the scintillator. Rasmus Ischebeck 15 Imaging Scintillating Crystals Rasmus Ischebeck 16 Imaging Scintillating Crystals Rasmus Ischebeck 17 Imaging Scintillating Crystals Rasmus Ischebeck 18 Imaging Scintillating Crystals Rasmus Ischebeck 19 Trigonometry… Rasmus Ischebeck 20 Observed Beam Size Rasmus Ischebeck 21 Ideal Observation Angle Rasmus Ischebeck 22 Measurement Principle > Combination of two monitors: > Scintillating crystal > Optical transition radiation Rasmus Ischebeck 23 Implementation (coherent) OTR to camera Rasmus Ischebeck 26 Screen Monitor Rasmus Ischebeck 27 A Transverse Profile Imager for SwissFEL > Profile measurement in FELs > Imaging scintillating crystals > Applications Rasmus Ischebeck 28 Quadrupole Scan Rasmus Ischebeck 29 Beam Transmitted Through Slit Rasmus Ischebeck 30 Slice Emittance Measurements > Slice emittance measurement of a 1.3 pC beam Measurement performed by Eduard Prat & Marta Divall 200 µm Rasmus Ischebeck 31 Slice Emittance Measurement Rasmus Ischebeck Eduard Prat 32 Slice Emittance Measurements > Core slice emittance as a function of charge Rasmus Ischebeck Measurements performed by Eduard Prat & Marta Divall 33 A Transverse Profile Imager for SwissFEL > A transverse profile imager that considers > Snell’s law of refraction in the scintillating crystal > The Scheimpflug imaging condition > Prototype installed at the SwissFEL Injector Test Facility > Resolution measured with this prototype: σ ≲ 10 µm, ε ≲ 30 nm > Sensitivity: Q ≲ 1 pC Next Plans > Prove immunity to coherent OTR > Start series production Rasmus Ischebeck 34 Thank You to… > Hansueli for the technical design > The AMI team for manufacturing the components > Markus for the assembly > Markus, Albert & the vacuum group for installation > Eduard the emittance measurement software, and for using the new profile monitor extensively for emittance measurements > Gian Luca, Marta, Simona, Carlo, Thomas & Eduard for the measurements presented in this talk > Vincent for help with optical design > Andrea for support with patenting the design, and with connections to industry > Helge for camera server software, and Babak for synchronized data acquisition > The entire Commissioning and Operations crew Rasmus Ischebeck 35 Rasmus Ischebeck