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Diamond Light Source Status and Future Challanges R. Bartolini Diamond Light Source Ltd and John Adams Institute University of Oxford DL-RAL Joint Accelerator Workshop 20 January 2009

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Summary 1) Introduction to Diamond 2) Status of the 3 GeV Storage Ring Orbit correction; Optics control; IDs; Orbit stability; 3) Latest developments and future challenges Top-Up operation; Further ID installation; Customised optics; Ultra short radiation pulse generation; DL-RAL Joint Accelerator Workshop 20 January 2009

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235 m 100 MeV Linac 3 GeV Booster C = 158.4 m 3 GeV Storage Ring C = 561.6 m Experimental Hall and Beamlines 235 m office building peripheral labs. and offices future long beamlines technical plant Diamond Layout

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Milestones and key facts First LINAC beam (100 MeV) First turn in booster First turn in Storage ring Beamline commissioning start First users 300 mA January 2009: 13 IDs operational 2007: 3120 h operation (uptime for users 92.4%) 2008: 4080 h operation (uptime for users 94.9%) 2009: 4656 h operation 31 st August 2005 21 st December 2005 3 rd May 2006 23 rd October 2006 29 th January 2007 15 th September 2007 DL-RAL Joint Accelerator Workshop 20 January 2009

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Diamond storage ring main parameters non-zero dispersion lattice Energy3 GeV Circumference561.6 m No. cells24 Symmetry6 Straight sections6 x 8m, 18 x 5m Insertion devices4 x 8m, 18 x 5m Beam current300 mA (500 mA) Emittance (h, v)2.7, 0.03 nm rad Lifetime> 10 h Min. ID gap7 mm (5 mm) Beam size (h, v)123, 6.4 m Beam divergence (h, v)24, 4.2 rad (at centre of 5 m ID) 48 Dipoles; 240 Quadrupoles; 168 Sextupoles (+ H / V orbit correctors + Skew Quadrupoles ); 3 SC RF cavities; 168 BPMs

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Diamond Storage Ring DL-RAL Joint Accelerator Workshop 20 January 2009

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The beam orbit is corrected to the BPMs zeros by means of a set of 168 dipole corrector magnets: the BPMs can achieve sub- m precision; the orbit rms is corrected to below 1 m rms: Storage Ring Closed Orbit < 1 m (first achieved 22th October 2006)

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Correction of linear optics with LOCO (Linear Optics from Closed Orbit) LOCO: fits quadrupoles to reproduce the theoretical closed orbit response matrix circles = model crosses = measured Modified version of LOCO with constraints on gradient variations (see ICFA newsletter, Dec’07) - beating reduced to 0.4% rms Quadrupole variation reduced to 2% Results compatible with mag. meas.

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Emittance 2.78 (2.75) nm Energy spread 1.1e-3 (1.0e-3) Emittance coupling 0.5% Emittance and energy spread measured using two X-ray pinholes cameras Measured emittance very close to the theoretical values confirms the optics Emittance coupling is now routinely corrected to 0.1% with LOCO Closest tune approach 0, rms Dy 1 mm

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13 Insertion Devices operational 7 IDS in Phase I and first ID of Phase II were installed and commissioned in early 2007 BeamlineIDType I02U23In-vacuum I03U21In-vacuum I04U23In-vacuum I06HU64APPLE-II I15SCW3.5 T Superconducting Multipole Wiggler I16U27In-vacuum I18U27In-vacuum I22U25In-vacuum I07U23In-vacuum I11U22In-vacuum I19U22In-vacuum I24U21In-vacuum I04.130.8 mmShort ex-vacuum 10 in-vacuum undulators 1 variable polarization APPLE-II device 1 3.5T superconducting wiggler 1 short ex-vacuum

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Beam stability should be better than 10% of the beam size and divergence For Diamond nominal optics (at the centre of the short straight sections) but IR beamlines will have tighter requirements for 3rd generation light sources this implies sub- m stability Strategies and studies to achieve sub- m stability identification of sources of orbit movement passive damping measures orbit feedback systems Orbit stability requirements at Diamond

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Ground vibrations to beam vibrations Amplification factor girders to beam: H 31 (theory 35); V 12 (theory 8); 1-100 Hz HorizontalVertical Long Straight Standard Straight Long Straight Standard Straight Position (μm) Target17.812.31.260.64 Measured3.95 (2.2%)2.53 (2.1%)0.70 (5.5%)0.37 (5.8%) Angle (μrad) Target1.652.420.220.42 measured0.38 (2.3%)0.53 (2.2%)0.14 (6.3%)0.26 (6.2%)

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Significant reduction of the rms beam motion up to 100 Hz; Higher frequencies performance limited mainly by the correctors power supply bandwidth Global fast orbit feedback at Diamond 1-100 Hz Standard Straight H Standard Straight V Position (μm) Target12.30.64 No FOFB2.53 (2.1%)0.37 (5.8%) FOFB On0.86 (0.7%)0.15 (2.3%) Angle (μrad) Target2.420.42 No FOFB0.53 (2.2%)0.26 (6.2%) FOFB On0.16 (0.7%)0.09 (2.1%)

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Summary of Current Machine Status TargetAchieved Energy3 GeV3 GeV Beam current300 mA 300 mAMachine Development 250 mAUser Mode Emittance - horizontal 2.7 nm rad2.7 nm rad - vertical 27 pm rad4-50 pm rad~ 27 pm in User Mode Lifetime at 300 mA> 10 h~ 18 h Min. ID gap7 mm 5-7 mmUser Mode, dep. on ID Stability< 10% 2.3% (H), 6.3% (V)No feedback of beam size0.7% (H), 2.3% (V)Feedback, 1-100 Hz & divergence DL-RAL Joint Accelerator Workshop 20 January 2009

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Higher average brightness Higher average current Constant flux on sample Improved stability Constant heat load Beam current dependence of BPMs Flexible operation Lifetime less important Smaller ID gaps Lower coupling Top-Up motivation BPMs block stability without Top-Up 10 m with Top-Up < 1 m Crucial for long term sub- m stability Top-Up operation consists in the continuous (very frequent) injection to keep the stored current constant to prevent the natural beam current decay

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User-Mode Operations “Standard” operation: 250 mA maximum, 2 injections/day DL-RAL Joint Accelerator Workshop 20 January 2009

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Top-Up operation First operation with external users, 3 days, Oct. 28-30 th No top-up failures, no beam trips due specifically to top-up Now Top-Up is the regular user operation mode DL-RAL Joint Accelerator Workshop 20 January 2009

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Future Insertion Devices BeamlinedateType I12Mar 09 4.2 T Superconducting Multipole Wiggler; contract with BINP; Beamline extending outside diamond buliding I20Jun 09 2 x hybrid wigglers 2T, W83, construction in-house; I07End 09 Cryogenic Permanent Magnet Undulator (U17.7) contract with Danfysik. Will substitute the in-vacuum U23 device installed as a temporary measure. I102010 Two APPLE II devices with 10 Hz polarization switching using 5- kicker scheme; engineering implications under study 2 girder changes I132010 Two In-vacuum undulators with “double mini-beta” optics proposed; beam dynamics and engineering implications under study. 1 or 2 girder changes Beamline extending outside diamond buliding I092011 Helical undulator + in-vac. CPMU, with “double mini-beta” optics proposed; beam dynamics implications under study. 1 or 2 girder changes

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A long straight sections is divided into two by a triplet of quadrupoles to achieve double mini beta in V and a virtual focus in H for coherence applications Pos. ‘A’ Customised optics in long straight sections

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I13 beamline DL-RAL Joint Accelerator Workshop 20 January 2009

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Low – alpha optics Higher Harmonic Cavities RF voltage modulation Femto–slicing 1) shorten the e- bunch2) chirp the e-bunch + slit or optical compression 3) Laser induced local energy-density modulation e – bunch Crab Cavities Synchro-betatron kicks There are three main approaches to generate short radiation pulses in storage rings Ultra-short radiation pulses in a storage ring

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Low alpha optics If high current effects are negligible the bunch length is = 1.7 10 –4 ; V = 3.3 MV; = 9.6 10 –4 z = 2.8 mm (9.4 ps) z depends on the magnetic lattice (quadrupole magnets) via We can modify the electron optics to reduce (low_alpha_optics) 10 –6 z 0.3 mm (1 ps)

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f s =340Hz f s = 340Hz => α 1 = 3.4×10 -6, σ L = 1.5ps f s = 260Hz => α 1 = 1.7×10 -6, σ L = 0.98ps f s =260Hz Machine tests with 1 ps lattice ε = 34 nm.rad; κ = 0.03% Q x = 21.137; Q y = 12.397

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Future Work Continue optics optimisation maintain nominal optics, lifetime characterisation, injection efficiency; characterisation of the non-linear optics (pinger magnet installed by end of 2007) Continue ID commissioning (Phase II and Phase III ID installation till 2014) optics compensation vs gap, DA effect, lifetime vs gap, frequency map vs gap ID request operation at 5 mm gap High current operation (300 mA) and TMBF impedance database; characterization of the instabilities (multi-bunch, single bunch) Maintain/Improve Top-up, FOFB performance Low alpha optics for users Thanks to R. Fielder, E. Longhi, I. Martin, B. Singh, J. Rowland and staff from Diagnostics, Controls, Operations, IDs, RF, … DL-RAL Joint Accelerator Workshop 20 January 2009

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