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Synchrotron Radiation Sources Past, Present and Future

Synchrotron Radiation Sources Past, Present and Future. By Vic Suller. Contents The Origins of Synchrotron Radiation Synchrotron Radiation Characteristics Storage Rings as Sources Insertion Devices The Future with 4 th Generation Sources.

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Synchrotron Radiation Sources Past, Present and Future

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  1. Synchrotron Radiation Sources Past, Present and Future By Vic Suller Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

  2. Contents • The Origins of Synchrotron Radiation • Synchrotron Radiation Characteristics • Storage Rings as Sources • Insertion Devices • The Future with 4th Generation Sources Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

  3. Crab Nebula - the first Synchrotron source observed?? Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

  4. CAMD in Baton Rouge, LA Center for Advanced Microstructures and Devices Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

  5. Accelerator Synchrotron Radiation Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

  6. Discovery of Electron JJ Thompson October 1897 Accelerated Charge Radiation Lienard July 1898 Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

  7. ELECTROMAGNETIC RADIATION Field lines from a stationary charge Field lines from an accelerated charge Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

  8. z Spatial distribution of radiation from a charge accelerated along the z axis x y Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

  9. Principle of Betatron Acceleration Cross section of a Betatron Coil Steel Vacuum chamber Acceleration by Induction - The Betatron Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

  10. Prediction of Energy loss by radiation in an accelerator Iwanenko & Pomeranchuk June 1944 Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

  11. GEC(USA) electron accelerators 1946 Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

  12. First attempt to Detect Synchrotron Radiation John Blewett 1947 – used a microwave receiver expecting Harmonics of the orbit frequency (100 MHz) - nothing found! First correct theory of Synchrotron Radiation Julian Schwinger 1947 – showed the importance of relativistic effects Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

  13. Light from the GE Synchrotron 1947 Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

  14. Betatron - CERAMIC Synchrotron - GLASS Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

  15. Relativistic effects in Synchrotron Radiation • Contraction of the orbit in the electron frame • Result:- Orbit frequency increases by factor g • Relativistic Doppler shift from the electron frame to the lab • Result:- Frequency further increases by factor 2g • Relativistic forward focusing of the emission • Result:- Frequency further increases by factor 2pg Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

  16. Electron frame Lab frame q f velocity b acceleration acceleration Relativistic focusing of Synchrotron Radiation Transformation between frames:- tan q = g-1 sin f (1+b cos f )-1 If f = 900 then q = g-1 Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

  17. Relativistic effects in Synchrotron Radiation (cont) The effect of 3 relativistic processes upshifts the orbit frequency by ~g3 For example 2 GeV electrons in a 100m orbit orbit frequency 3 MHz g = 3914 g3 =6.0 1010 100m Þ 1.7 nm (0.7 keV) For protons to radiate equivalently in a 100m orbit Energy = 3.7 TeV and magnetic field = 10 kT Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

  18. Synchrotron Radiation Features • Continuum source from IR to X-rays • Source in a clean UHV environment • High Intensity and Brightness • 4. Highly Polarized • 5. Stable & controllable pulsed characteristics …highly attractive for research applications!!! Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

  19. Synchrotron Radiation Features The synchrotron radiation spectrum is described with reference to a characteristic(often called 'critical') wavelength lc, or photon energy ec where B is the bending magnetic field. Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

  20. Synchrotron Radiation Spectral Flux Intensity When the radiation at a given wavelength is integrated over all angles of vertical emission the resultant Spectral Flux Intensity is given by photons/sec/mr/0.1% bandwidth is a numerical factor which essentially governs the shape of the spectrum. Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

  21. Synchrotron Radiation Spectra Examples of spectra produced by electron storage rings:- Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

  22. APS CAMD NSLS-VUV Typical Synchrotron Radiation Spectra Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

  23. Typical Synchrotron Radiation Spectra 2 APS CAMD VUV Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

  24. 1st Generation Synchrotron Radiation Sources Originally built for some other purpose (1965 – 1975) Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

  25. 2nd Generation Synchrotron Radiation Sources Dedicated, purpose designed (1975 – 1985) Some examples:- Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

  26. Synchrotron Radiation Brightness Notice that Brightness, as here defined, is often referred to as Brilliance, with an accompanying incorrect use of the term brightness for the Spectral Flux Density. It is best to avoid confusion by using the well established radiometric definitions as given here. Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

  27. Note that source Brightness as defined is anisotropic, the value depends on the source density distribution and on the observation angle. It is often more convenient to use, as a figure of merit, an average brightness which for dipole sources is defined Average Spectral Brightness = is the vertically integrated flux, 2.36sx is the fwhm of the horizontal electron beam size, 2.36sz is the fwhm of the vertical electron beam size, and 2.36sg/ is the fwhm of the photon emission angle in the vertical plane. The latter is a combination of the electron beam vertical divergence and the photon emission angle thus Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

  28. Radiation Dispersion Betatron oscillation Radiation loss Initial momentum RF restores Final momentum Radiation excitation and damping of oscillations Radiation excitation Radiation damping Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

  29. The equilibrium of the excitation and the damping of the betatron oscillations determines the emittance of the stored beam with the result: • The emittance is determined by the behaviour of the dispersion - and the horizontal betatron function within the bending magnets. The emittance is given by the lattice of the machine. Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

  30. Minimum emittance of Chasman-Green lattice Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

  31. Theoretical Minimum Emittance lattice Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

  32. 3rd Generation Synchrotron Radiation Sources Dedicated, high brightness, designed to include Insertion Device Sources (1985 – 2005?) Some examples:- Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

  33. Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

  34. APS at Argonne National Laboratory Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

  35. Trends in 3rd Generation Light Source Performance Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

  36. DOUBLE BEND LATTICE FUNCTIONS Length (m) Proposed South East Advanced Light Source (1) Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

  37. Proposed South East Advanced Light Source (2) Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

  38. Wiggler or Wavelength Shifter • Placed in a straight section • Net deflection zero • High magnetic field 5-10T • Large horizontal fan ~200 mr Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

  39. CAMD Wiggler • Central pole 7 Tesla • End poles 1.5 Tesla • Made by Budker Institute Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

  40. SRS Daresbury 6 Tesla Wiggler Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

  41. Multi Pole Wiggler • Multiple alternating poles • High magnetic field 2-5T • Small horizontal fan ~20 mr • Superposition of source points Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

  42. SRS Daresbury 2.4 Tesla Permanent Magnet MPW Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

  43. Undulator • Multiple alternating poles • Period lu = 10s of mm • Beam deflection < 1/g • Interference makes line spectrum • Very high brightness Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

  44. Undulator magnetic field electron bc lu Undulator electromagnetic wave bc stationary electron 1/g . lu Undulator approximate theory In the laboratory frame the electron travels towards the undulator magnetic field at relativistic velocity. • In the electron frame the undulator appears as an EM-wave relativistically contracted to 1/g . lu. • There is then a relativistic Doppler shift 1/2gback to the laboratory frame. • Thus the undulator produces monochromatic radiation of Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

  45. Undulator correct theory It is essential to account for the transverse motion of the electron in the undulator. Introduce the deflection parameterk Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

  46. photon A electron B Undulator constructive interference As an electron moves from A to B the photon moves ahead. A photon emitted at point A will constructively interfere with one emitted at point B if it gains by a whole number of wavelengths:- n = 1,3,5,… Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

  47. Undulator Spectrum (calculated) Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

  48. ESRF Undulator Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

  49. In vacuum Undulators – for small gap / period SRC Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

  50. SRC Wisconsin 6 EM Undulator Synchrotron Radiation Storage Rings Vic Suller: CAMD Louisiana & SRS Daresbury

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