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Storage ring optics characterization – the basics

Storage ring optics characterization – the basics. Beam Diagnostics DCCT Strip lines BPMs Scrapers Synchrotron light monitors Loss monitors Measuring tunes, b , h, chromaticity, a?. Photon factory DCCT. T. Honda et al., EPAC98. LOW FREQUENCY COMPONENT ISOLATED BY .010” GAP.

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Storage ring optics characterization – the basics

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  1. Storage ring optics characterization – the basics • Beam Diagnostics • DCCT • Strip lines • BPMs • Scrapers • Synchrotron light monitors • Loss monitors • Measuring tunes, b, h, chromaticity, a? Beam-based Diagnostics, USPAS, June 23-27, 2003, J. Safranek

  2. Photon factory DCCT T. Honda et al., EPAC98 Beam-based Diagnostics, USPAS, June 23-27, 2003, J. Safranek

  3. LOW FREQUENCY COMPONENT ISOLATED BY .010” GAP INSULATED BY CERAMIC BUSHINGS .010 GAP BEAM DIRECTION SENSOR ISOLATED ON ONE END CERAMIC BREAK PREVENTS CURRENT FROM FLOWING THROUGH BELLOWS SPEAR3 DCCT TOROID image current TOROID Beam-based Diagnostics, USPAS, June 23-27, 2003, J. Safranek

  4. Bergoz PCT DCCT (or PCT) circuit 7 kHz 14 kHz Nonlinear ferrite core beam J.A. Hinkson, LBNL The DC bias current is adjusted to remove the 2nd harmonic (14 kHz) response of toroid. The beam current is proportional to the DC bias current. Ferrite core Xsection Simplified circuit, K. Unser, 1992 Beam-based Diagnostics, USPAS, June 23-27, 2003, J. Safranek

  5. Beam position monitors Electron BPM buttons sample electric fields; striplines couple to electric and magnetic fields. Examples of photon BPMs: Copper fluorescence bpm: Split ion chamber: Tungsten blade monitor: Beam-based Diagnostics, USPAS, June 23-27, 2003, J. Safranek

  6. Loss monitors Bergoz Kuske measurements made with scintillator and photo multiplier. Kuske et al., PAC01. Beam-based Diagnostics, USPAS, June 23-27, 2003, J. Safranek

  7. Beam size measurements: Scrapers Synchrotron light monitors Beam-based Diagnostics, USPAS, June 23-27, 2003, J. Safranek

  8. Beam frequencies Importance, global measure of optics. First measurements made of ring. Instabilities Beam frequencies If you have a single bunch with charge q in a storage ring with a revolution time T0, the signal on an oscilloscope looks like where I’m assuming a zero-length bunch. A spectrum analyzer would see the Fourier transform of this, w0 T0 Time Frequency Beam-based Diagnostics, USPAS, June 23-27, 2003, J. Safranek

  9. frequency (1/sl) For SPEAR3, c/sl = 67 GHz. Beam-based Diagnostics, USPAS, June 23-27, 2003, J. Safranek

  10. fb f0 Frequency Betatron tune Integer and ½ integer ambiguities Beam-based Diagnostics, USPAS, June 23-27, 2003, J. Safranek

  11. Synchrotron tune Beam-based Diagnostics, USPAS, June 23-27, 2003, J. Safranek

  12. Measured spectra HLS tune meas., Sun et al. PAC01 Multibunch spectra, instabilities, Sebek, Friday. Courtesy J. Byrd Beam-based Diagnostics, USPAS, June 23-27, 2003, J. Safranek

  13. More on spectrum Turn by turn measurements, FFT, NAFF, betatron phase (Tuesday) Nonlinear dynamics (tune vs. amplitude; tune vs. closed orbit; Thursday) Impedance measurements (Friday) Beta function measurements Chromaticity Beam-based Diagnostics, USPAS, June 23-27, 2003, J. Safranek

  14. Beta function measurement • Dnu=betaKL/4pi • Measurement issues • Keep orbit constant • Hysteresis • Saturation • Sometimes cannot vary individual quadrupoles Beam-based Diagnostics, USPAS, June 23-27, 2003, J. Safranek

  15. SPEAR b-function correction before after Courtesy Heinz-Dieter Nuhn Beam-based Diagnostics, USPAS, June 23-27, 2003, J. Safranek

  16. Other b measurements Fit response matrix Mij = sqrt(…), Y. Chung et al., PAC’93 Derive from betatron phase measurements (Tuesday lecture) Beam size measurement Minty and Spence, PAC’95 Beam-based Diagnostics, USPAS, June 23-27, 2003, J. Safranek

  17. Dispersion Dispersion is the change in closed orbit with a change in electron energy. The energy can be changed by shifting the rf frequency. (a = momentum compaction) So the dispersion can be measured by measuring the change in closed orbit with rf frequency. Beam-based Diagnostics, USPAS, June 23-27, 2003, J. Safranek

  18. Dispersion X-Ray Ring h indicates large Kx errors Dispersion distortion can come from quadrupole or dipole errors. Vertical dispersion gives a measure of vertical bending errors or skew gradient errors in a storage ring. PEPII hx andhy measurement Uli Wienands Beam-based Diagnostics, USPAS, June 23-27, 2003, J. Safranek

  19. Chromaticity Beam-based Diagnostics, USPAS, June 23-27, 2003, J. Safranek

  20. Momentum compaction Beam-based Diagnostics, USPAS, June 23-27, 2003, J. Safranek

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