Status of the 1.5 GeV Synchrotron Light Source DELTA and Related Accelerator Physics Activities

Transcription

1 Status of the 1.5 GeV Synchrotron Light Source and Related Accelerator Physics Activities 2006 RuPAC, September 10-14, Novosibirsk Thomas Weis for the machine and accelerator physics group Dortmund University Synchrotron Radiation Center

2 Content: Machine Status Insertion Devices Orbit Control EU-Cavity Beam Test Instability Investigation Machine Optics Frequent Injction Mode Summary Dortmund University Germany

3 BL12: Methods (II): Soft X-RaysX Photoemission Photoelectron Spectroscopy Fermi-Surface Mapping Universität Dortmund U250 FZ Jülich TGM 3 L=115,2 m E=1.5 GeV SAW

4 full energy 1.5 GeV ramped storage ring ~ 0.1 Hz rep. rate Full energy booster BoDo

5 3 GHz - klystron thermic electron gun 50 kev, 2 A single bunch mode few bunch mode Linear Injector 40 MW loss power (ohmic losses in copper) 4 µsec a few Hertz repetition rate output energy = MeV total length = 6.4 m (E = 12.5 MV/m) old SBTF-structure from DESY, Hamburg A. Jankowiak, T. Weis et al., Proc 2000 EPAC (2000) 636

6 g Single cell MHz RF-power 50 kw cw loss power cavity 30 kw energy transfer to beam 20 kw single RF-DORIS-type 500 MHz resonator

7 Maschine Parameters maximum beam energy circumference nominal beam current beam lifetime horizontal emittance coupling 1.5 GeV m 130 ma multi 1.5 GeV; 25 ma single 550 MeV > 8 h multi 1.5 GeV; > 20 min single 542 MeV 16 nm 1.5 GeV 3 %

8 Universität Dortmund Operation 2004/ weeks (3000 h) 2000 h user operation hours machine optimisation and machine physics Performance 2004/2005: Average availability during 20 user weeks 94/89 %. Max. beam current 120 ma. Average lifetime ~ 7hrs User operation 2004/2005 Availability [%] only minor vacuum openings Availability during user weeks User weeks 2005 Performance 2006: availability ~ 90% Max. beam current 130 ma. Average lifetime ~ 8-10 hrs

9 Insertion U55 permanent magnet undulator ACCEL Instruments SAW superconducting 5.3 T asymmetric multipole wiggler ACCEL Instruments U250 electromagnetic undulator in house fabrication, also acting as FEL undulator

10 photons/s/ma/mm 2 /mrad 2 /0.1%BW D. Schirmer et al., Proc EPAC (2004) 2296

11 Universität Dortmund D. Schirmer, Int. J. Mod. Phys. 2B (1993) 644 Superconducting 5.3 T asymmetric multipole Parameter Dipole Wiggler (sym. mode) Magnetic field [T] Critical current 5T and 4.2 K 471 Number of periods 10 5 Beam stay clear [mm] Horizontal opening angle θ ± 13 ± 25 of radiation [mrad] Critical energie ε C [kev] Critical wavelength λ C [Å] Power P [W/mrad] Vertical integrated photon ε C [photons/s/mrad/0.1%bw] Type of radiation (off-plane) Liquid He consumption Wiggler (asym. mode) elliptical polarised linear polarised high intensity great fraction of circular polarisation at high intensity ~ 12 liters/day with beam first superconducting multpole wiggler worldwide serving 3 hard-x-ray beamlines

12 Beamline BL 2 / dipole (ISAS) BL 5 / U250 (FZ Jülich) BL 8 / SAW 3 (U Wuppertal) BL 9 / SAW 2 (U Dortmund) BL 10 / SAW 1 (U NRW) Experiments X-ray fluorescence spectroscopy photoemission, spectroscopy material science, EXAFS, diffraction grazing incidence X-ray diffraction, SAXS, XSW, inelastic X-ray scattering EXAFS Photon energy white beam ev 2-30 kev 4-30 kev 4-30 kev Present status user operation user operation under commisioning operational end 2006 user operation Wiggler Beamlines under construction operational 2007 BL 11 / U55 (U Dortmund) BL 12 / dipole (U Dortmund) photoemission spectroscopy, photoelectron diffraction valence band spectroscopy, Fermi-surface mapping ev ev user operation under commissioning operational end 2006

13 Orbit Control and Stability slow (0.1 1 Hz) global orbit feedback system method: singular value decomposition based on a measured orbit response matrix M BPMs N correctors r r 1 2 r 3 r n = R ij M. Grewe et al., Proc EPAC (2004) 2568

14 Orbit Stability Universität Dortmund beam orbit deviation [mm] BPM 51 beam current BPM 29 beam current floating orbit location with high emphasis M. Grewe, thesis, Univ. Dortmund 2005

15 Orbit Stability beam orbit deviation [mm] M. Grewe, thesis, Univ. Dortmund 2005 Universität Dortmund limited number of BPMs and correctors limited corrector strengths BPM beam 51 current (heat load) induced movement of beam current vacuum chambers and quadrupols ongoing program concerning machine surveillance and magnet repositioning and... beam current... decoupling of quadrupoles and vacuum chambers (BPMs) BPM 29 nevertheless: reference orbit is reproducible over months within +/- 250 µm horizontally and +/- 150 µm vertically

16 bunch train signal - 2 ns spacing Fast Beam and Instability Investigation filling pattern measurement bunch by bunch, turn by turn postmortem analysis of beam loss due to coupled bunch mode - CBM instabilities BPM set up real time longitudinal CBM instability detection

17 Bunch by Bunch Beam Analysis time [ns] sampling of BPM sum signal at 2 GS/s, bandwith 1 GHz oversampling technique using shift between RF frequency and sampling frequency

18 real time (~ 1 s delay) analysis of longitudinal coupled bunch CBM modes Oscillation Amplitude (degree) I > 95 ma I < 90 ma Coupled Bunch Mode No filling pattern + option to inject beam into specific buckets J. Kettler et al., Proc EPAC (2006) 1034

19 CBM DORIS type cavity E= 1.5 GeV T = C I= 87mA I th 75mA L 1 /L 4 Oscillation Amplitude (degree)?? L 16 I th 35mA Coupled Bunch Mode No

20 Full understanding of filling pattern induced mode spectra Oscillation Amplitude (degree) Spectrum measured with DORIS BLUE: measured GREEN: theoretical 144/192 buckets filled induced synchr. frequency spread Landau damping Coupled Bunch Mode No

21 CBM DORIS type cavity with damping antennas CBM 22 Oscillation Amplitude (degree) E= 1.5 GeV CBM 52 Coupled Bunch Mode No Threshold CBM 22 Threshold CBM 52 Oct. 18 th 2005

22 EU-Project: Design, Construction and Beam Test of a n.c. HOM-damped 500 MHz-Resonator for Synchrotron Radiation Sources Alu-model

23 The HOM-Damped EU-Cavity Single Trapped Mode Resonator Plunger Cavity design: F.Marhauser & E.Weihreter BESSY, Berlin RF window Waveguide cut-off between fundamental and first HOM frequency HOM energy is dissipated in external RF loads Nose cones Ridged waveguides

24 Residual Longitudinal Impedance Impedance Z [Ω] o = measured data Z < 5 kω complex time domain calculations for a very complex geometry full validation of calculations by beadpull measurements (o) effective damping also of transverse Z Frequency [MHz] F. Marhauser, E. Weihreter, Proc EPAC (2004) 979 Proc EPAC (2002) 2172

25 EU-Cavity 5/2004 9/2004 7/2005 8/2006

26 CBM Characterisation of EU-Cavity Spectrum measured with EU CBM 52 not induced by cavity, also seen with the DORIS-type cavity responsible Z ~ 9 kω Oscillation Amplitude (degree) Filling pattern: 144/192 buckets filled, Coupled Bunch Mode No reason still unknown: candidates: strip line kickers broken RF-contacts in bellows, valves resonant vacuum chambers and tapers

27 Summary EU-Cavity Beam Test Successful test with 1.5 GeV (I = 140mA) 542 MeV (I = 280 ma). No cavity induced instabilities have been found. Cavity was successful operated over more than one year in regular user shifts. Loss power capability of the prototype limited to kw due to non sufficient RF contact between HOM-dampers and body. thermal stress + micro vacuum leaks New HOM-damper design (BESSY) with invacuum ferrites avoiding RF-window and external HOM loads. ALBA (Barcelona Light Source) and the Metrology Ring (Berlin) will be equipped with EU-type cavities. The ESRF is planning to adept the philosophy of HOM-damping. E. Weihreter et al., Proc EPAC (2006) 1280 R. Heine et al., Proc EPAC (2006) 2856

28 O. Kopitetzki et al., Proc EPAC (2006) 1945 Modelling of the Machine Optics 2 independent measurements of optical β functions. tune scan method (local variation of quadrupole strengths and orbit response matrix analysis (ORM). comparable results but at different locations ORM-analysis provides sensitive information on phase beating a big step forward towards a better machine modelling.

29 Example: Horizontal Phase Beating Phase Advance Deviations between Model and Measurement modified model refined quadrupole strengths and magnet locations minimisation of Ψ

30 Frequent 125 ma +/ 5 % increased average beam current beam current and lifetime ~ 7 h constant lifetime time increased photon flux for users constant heat load on chambers and beam lines increased machine stability machine tests with shutters closed successful. discussions with users and approval authorities ongoing. G. Schmidt et al., Proc EPAC (2004) 2299

31 Acknowledgments EU-cavity collaboration colleagues from: BESSY, Daresbury CLRC, MaxLab, NTHU Financial support from university, EU, NRW, FZJ and BMBF machine and accelerator physics group Help from colleagues from ESRF, ALBA, SLS, Diamond... organisers of RuPAC