Status of ELETTRA. Operations. Photon Sources Developments Insertion Devices Free Electron Lasers

Transcription

1 Status of ELETTRA Operations Photon Sources Developments Insertion Devices Free Electron Lasers Accelerator Developments SC 3 rd Harmonic Cavity Feedback Systems Upgrade of the RF System New Full Energy Injector D. Bulfone

2 Operations Operating Parameters for Users Shifts Injection energy 0.9 GeV Final energy 2.0 GeV 2.4 GeV 320 ma 140 ma Starting current (τ = 27 hrs) (τ = 45 hrs) Components failure as percent of user downtime for 2003 Filling pattern multibunch, ~ 90 % contiguous Total Hours Total Users Hours Percentage User Hours at 2-2.4GeV User Uptime (excluding storms) User Uptime (including storms) User Uptime uptime %Total uptime %Total-storms/micro Beamlines 2% Miss-handling 6% Storms/biginterruptions 18% Total Other 4% Electricity 0% Water/Air Compr/Condiz 1% Power Supplies 3% 3HC 15% Instability 1% Linac (Other) 11% Vacuum Components 1% Instrumentation 8% Magnets/Pulsed Magnets 5% General inj/setup/delays 14% Radio Frequency 3% High Level Software 0% Controls 3% Control Access 0% Interlocks 1% Insertion Devices 2%

3 Insertion Device & Beamline Status ID type section Period Nper gap status (mm) (mm) EU10.0 PM/Elliptical operating U5.6 PM/Linear x operating U12.5 PM/Linear x operating EEW EM/Elliptical operating W14.0 HYB/Linear x operating U12.5 PM/Linear x operating U8.0 PM/Linear operating EU4.8 PM/Elliptical operating EU7.7 PM/Elliptical operating EU6.0 PM/Elliptical operating EU12.5 PM/Elliptical/QP operating FEU PM/Figure operating SCW SC/Linear Commissioning 23 ID segments installed (6 APPLE-2 type): all eleven long straights filled. PM = Permanent Magnet HYB = Hybrid EM = Electromagnetic SC = Superconducting QP = Quasi-Periodic - Beamlines : 16 in operation (12 ID, 4 BM) 3 in commissioning (1 ID, 2 BM) 6 under construction/development (1 short ID, 2 ID, 3 BM)

4 Figure-8 8 Undulator The second segment of the twin Figure 8 undulator has been installed in March 2003 to generate linearly polarized radiation in the 5-11 ev range for inelastic UV scattering experiments (IUVS beamline). Period 140 mm Number of periods 32 Minimum gap 19 mm Bx, By max T, 0.75 T Kx, Ky max. 3.4, 9.4 Total Power (400 ma) 2.5 kw Flux (photons/s/0.1%bw) x2 Low on-axis power density enables efficient pinhole power filtering Distribution of power min. gap pinhole Power within nominal beamline acceptance for Figure-8 undulator and vertical-field undulator (same fundamental photon energy, period length and N of periods)

5 Figure-8 8 Undulator - Magnetic Measurements & Commissioning: Negligible phase error (σ Φ <2º), negligible magnetic field multipole errors, field roll-off in agreement with expectations: nearly ideal behavior. Comparison between measured tune shift (dots) vs. gap and that predicted from the ideal magnetic field (2GeV) (black=horizontal plane, red=vertical) Residual closed orbit error (<50 µm 2GeV) compensated by correction coils

6 Superconducting Wiggler The Superconducting multipole Wiggler (SCW) is the photon source (10-25 kev) for the second Diffraction beamline. Factor of 3 (14) higher flux compared to the permanent magnet wiggler of the existing diffraction beamline at 12.5 kev (25 kev) Installed in November 2002 Vertical misalignment of 2 mm was due to an additional force of about 700 kg on the magnet vessel in the presence of an insulating vacuum. Good agreement between measured and theoretical vertical tune shift as a function of magnetic field at 2GeV. Horizontal tune shift at 3.5 T < LHe Consumption: With no electron beam: Period length 64 mm Peak field 3.5 T Total no. of poles 49 Pole sequence 1/4, -3/4, 1, -1 1, -3/4, 1/4 Internal aperture 81 mm (H) x 10.7 mm (V) Total power 18.3 kw (2 GeV, 400 ma) Detail design and manufacture by the Budker Institute of Nuclear Physics (BINP) B (T) LHe Consumption (l/h) 3.5 ( power mode) (persistent mode) (ramping field) Bo [T] DQy * Measured o Theoretical Anomalous LHe consumption with electron beam: 5 (1) l/h at 2.0 (2.4) GeV with 300 (140) ma Tapers and liner are being replaced during the present shut-down.

7 Infra-Red Beamline Development of a new type of bending magnet exit port for the Infra-Red beamline (install. early 2004). Source aperture angle of H x V = 70 x 25 mrad 2 (allow both edge and main magnet infrared radiation) Vacuum valve Vacuum chamber halves Beam shutter Photon absorber Beam shutter Displacement of vacuum valve to handle increased horizontal opening angle. Beam shutter with horizontal motion for valve protection. Modified photon absorber covering a vertical aperture of 25 mrad. New Al bending magnet chamber with tapered aperture of radiation slot in the region of the rhomboidal chamber

8 EUFELE Storage Ring FEL The ELETTRA Storage Ring FEL provides intense, monochromatic Sincrotrone Trieste Italy ( λ/λ ~ 10-4 CEA-LURE France ) and tunable radiation in the wavelength range between CLRC-Daresbury Lab. 190 and 350 nm. CNRS-LURE France ENEA-Frascati Italy The project is financed by a contract with the European Community Fraunhofer Institute, Jena (EUFELE, now at month 24/36) and includes a number of partners. Laser Zentrum Hannover - Goal: The goal of the EUFELE project is to build a FEL user facility, implementing all the developments necessary to perform selected experiments that will demonstrate the suitability of this radiation source for practical applications. - Source Intensity Stability: Improve the electron beam stability (use of local orbit feedback and long. multi-bunch feedback recently started) Induce a Q-switching regime by modulating the storage ring RF - Periodic giant pulses (~50 times peak intensity than standard regime) Q-switched regime Standard regime England Germany Germany

9 EUFELE Storage Ring FEL - Mirrors: Oxide-based (SiO 2, Al 2 O 3 ) multilayer mirrors have been successfully used so far. However, high absorption of these materials in the VUV limits the central wavelength to about 190 nm. Systematic study to exposure to synchrotron radiation different fluoride-based (MgF 2, LaF 3, AlF 3 ) mirrors. Work in progress lasing at the lowest possible energy (700 MeV) trying to avoid the rapid loss of reflectivity of the mirrors. - FEL Diagnostics: Dedicated in-vacuum beamline, including remotely adjustable mirror, fluorescent screen and diaphragm, has been constructed. It deflects the laser beam, outcoupled from the upstream cavity mirror, to a high performance spectrometer providing a resolution of the order of Experimental Station: Experimental station for spin polarization measurements (study of the dynamics of magnetization reversal at the ps timescale) has been moved from LURE to ELETTRA.

10 11th ESLS Workshop - Single-Pass Free Electron Laser User Facility: Facility Undulator Building Experimental User Hall Present Linac Building Linac Tunnel (Extension) 1 GeV Linac Brightness of ELETTRA Photon Sources 1 Linac Æ 3 FELs: nm (1 GeV Linac) nm (1 GeV Linac) nm (3 GeV Linac) D. Bulfone Status of ELETTRA

11 Superconducting 3 rd Harmonic Cavity - Milestones: January 03: First cool-down of the cavity January-June 03: commissioning and repair of some system malfunctions (e.g. upgrade of the cold tuning system) July 03: routine operation during Users shifts at 2 GeV. - The Twofold Effect of 3HC: 1. Bunch lengthening of more than a factor of 3 2. Landau damping of longitudinal instabilities. - Voltage Feedback: V cell [ kv ] = The cavity voltage is kept constant along the beam current decay by acting on the cells tuning motors. 2 GeV, Vcell = 310 kv f 320mA = +60 khz f 230mA = +52 khz 2.4 GeV, Vcell = 150 kv f 140mA = +51 khz f 130mA = +43 khz - Ongoing Maintenance: f 3HC I beam [ ma ] [ khz ] 3 f [khz ] RF Ongoing replacement of the vacuum valve between 3HC and the SCW.

12 Digital Transverse Multi-Bunch Feedbacks Baseband Y Signal Digital Correction Y Signal (0 250 MHz) Processing (0 250 MHz) RF Front-End A/D DSP D/A RF Amplifier Wideband Y & X Signals Hybrid Network BPM Kicker - Horizontal TMBF: Following installation of the first vertical TMBF system in November 01, second TMBF acting on the horizontal plane put into operation in April Restore Harmonic Sextupoles strength, which was temporarily increased to remove horizontal instabilities, with gain in lifetime. Operation of the TMBF systems has been reliable. init, run, standby procedures fully automated. Betatron Tune measurement by exciting three selected bunches with antidamping/damping transients, while keeping TMBF on all other bunches.

13 Multi-Bunch Instabilities and Lifetime Summary of milestones in beam stability and lifetime associated to the operation of the Multi-Bunch Feedback systems and the 3HC. Stable Beam Multibunch Instabilities Lifetime [hours] Longitudinal Vertical Horizontal Single mode, constant amplitude Absent Damped by 3HC (90% contiguous filling) Damped by 3HC (90% contiguous filling) Damped by 3HC (90% contiguous filling) Absent Absent Damped by Ver. TMBF Damped by Ver. TMBF Damped by high Harmonic Sext. setting Damped by high Harmonic Sext. setting / 26 (Nov. 2001) 11.7 (Feb. 2003) / Damped by Ver. TMBF Damped by Hor. TMBF 27 (Aug. 2003) / Damped by Ver. TMBF Damped by Hor. TMBF / 45 (Sept. 2003) old user mode Comparison of twenty hours of operation at 2 GeV (left, starting current 320mA) and at 2.4 GeV (right, starting current 140mA) between the old user mode (blue) and the present one (red). 90 ma 2 GeV 2.4 GeV 180 ma 65 ma 90 ma

14 Digital Longitudinal Multi-Bunch Feedback RF Front-End Hybrid Network BPM Wideband I Signals A/D Digital Processing DSP D/A 3*RF Modulator RF Amplifier Kicker Same digital processing electronics as the transverse systems. Different software. Different back-end hardware. Even with the put into operation of 3HC, the LMBF is needed: Amplitude (a.u.) Phase (deg) Downsampled Fractional Tune Nominal Working Point Nominal Working Point Downsampled Fractional Tune Transfer function of the 4th order IIR (Infinite Impulse Response) filter, down sampling factor n = 10. Down-sampling is done by software. - As a back-up solution for longitudinal instabilities in case of 3HC malfunction. - To support operation with filling modes different from the present 90% contiguous one (partial filling + high current single bunch recently requested by the users), where the 3HC may become less effective. - To D. damp Bulfonelongitudinal instabilities of the 4-bunches beam used by storage ring FEL. Status of ELETTRA

15 Digital Longitudinal Multi-Bunch Feedback - System Commissioning: Following the cessation in the production of the commercial ADC and DAC boards, the digital processing electronics of one of the TMBF systems is used for the commissioning of the LMBF. [New family of ADC/DAC boards developed (P. Pollet, SLS). Tests of final prototype going on] Optimization of the back-end to minimize cross talk between adjacent bunches. Single bunch kicker pulse Amplitude of the synchrotron tune spectrum component of a number of bunches when selectively exciting only bunch #145. By activating the LMBF from the beginning of the injection process, 280 ma of a longitudinally stable beam at 0.9 GeV have been accumulated. Focussing on ramping (from 0.9 to 2 GeV). Issues: a) track synchrotron frequency change (from 15 to 10 khz, 3HC parked) by loading different filters b) track synchronous phase change (about 8º) by varying the firing time of the kicker pulse and the phase D. of Bulfone the RF front-end demodulator. Status of ELETTRA

16 Upgrade of the RF System - Goals: Provide RF systems with the necessary operating margin, when all IDs are operational (with a slight improve also in lifetime) Re-use the existing 60 kw system for the New Injector Booster The first phase of the project consists of a) replacing one of the existing 60 kw RF plants with a new 150 kw one, b) installing a new ELETTRA type cavity with improved cooling system and power feed-through (see ANKA, SLS), c) installing new low-level control electronics. - Activities and Status: New cavity has just been installed during the November 03 shut-down. The 150 kw power amplifier will be made by combining two 80 kw cw IOTs with a switchless combiner. Amplifier: ready to order. RF in Splitter ϕ Single transmitter Combiner RF out Circulator, waveguides and loads: ready to start call for tender. Single transmitter Completion foreseen by the end of beginning of 2005.

17 NEG-coated Al Vacuum ID Chamber (Sec. 9) Installed in March Internal gap 14 mm. Confirmed very good vacuum conditioning results measured on the previously installed chamber Dynamic pressure reached mbar/ma after about 40 Ah. Dynamic Pressure vs. Int. Current RUN 82: misure di radiazione da bresstrahlung sez RUN 81 RUN u.a integrated current (Ah)

18 NEG-coated Al Vacuum ID Chamber (Sec. 7) Installed in June Internal gap 14 mm. New Beam Position Monitor dedicated to Multi-Bunch Feedback systems Low-gap Beam Position Relocated horizontal & Monitors (Orbit( Feedback Project) vertical scrapers (see later contribution)

19 New Full Energy Injector - Pre-injector Linac: The 100 MeV pre-injector linac for the Booster will use two 50 MeV accelerating sections donated by CERN. The in house construction of the modulator for the klystron of the pre-injector has been completed. Tests are in progress. - Injection/Extraction Pulsed Magnets: The septum magnets for Booster injection and extraction and the upgraded septum magnet for injection in the SR will be delivered in February Installation of the upgraded septum in the SR is scheduled for the 2004 summer shutdown.

20 New Full Energy Injector The design of the fast kicker magnets, based on in-vacuum ferrite magnets, has progressed and a prototype will be constructed in 2004 to test with the kicker high voltage pulsed power supply. - Booster Magnets: Specifications for the Bending and Quadrupole magnets have been reviewed and are now available in their final version together with those of the Steerer magnets. The design of the Sextupole magnets is presently being reviewed. - Booster RF Plant: The 5-cell Doris type RF cavity has been delivered end of May 2003 and has undergone measurements and high power RF tests in the laboratory.