Libera and ELETTRA Marco Lonza, Giulio Gaio, Vincenzo Forchi’ Sincrotrone Trieste – ELETTRA

Booster Injector shut down of ELETTRA since October 2007 for the connection of the new Booster Injector to the storage ring users operations restarted the 3rd of March 2.5 GeV Booster allows for full-energy and top-up injection former injector based on a 1 GeV Linac will be available for the FERMI@Elettra Free Electron Laser FERMI@Elettra site Booster Old Linac Storage Ring

Booster Installation and Commissioning booster installation 26th April 2007 – 3rd August 2007 18.09.2007 Linac 100 MeV 14.10.2007: 0.8 GeV extraction 8.10.2007 – 10.12.2007 connection of the booster to the storage-ring 22.12.2007: 2.0 GeV extraction 21.02.2008: 2.0 GeV injection into Elettra Linac beam profile Booster Ring 100 MeV Booster Linac

Accumulated current in “frequent injection” mode Booster Status the booster is currently operating at 2.0 GeV 1 Hz (specified 2.5 GeV 3 Hz) limitation due to bending and quadrupoles power supplies (max current, repetition rate and ripple) power supplies refurbishing program: 2.4 GeV 3 Hz by beginning of April, reduced ripple by August 2008 present operation: full energy injection at 2.0 GeV, injection once a day on top of the stored current, max injection rate 0.4 mA/s (specified 1 mA/s) “frequent injection” mode successfully tested first top-up tests foreseen in the next run, top-up operation not before autumn 2008 Accumulated current in “frequent injection” mode

Libera at Elettra 107 Libera Electron purchased in 2006, 100 installed release 1.42 used up to end of March, 1.82 installed during last shutdown not decided yet whether to buy the 2.0 release or not not real need (at the monet) for new features such to justify the expense same considerations for Libera Brilliance behavior of Libera is good, apart from: steps in the position readings when changing attenuators frequency components at 70 Hz: to be investigated one Libera used for tune measurement in the Booster no Libera used for multi-bunch feedback systems (still using the old systems with DSPs)

Global Orbit Feedback Architecture 96 rohmboidal + 4 low-gap BPMs all equipped with Libera Electron 82 corrector magnets per plane 12 VME stations with Motorola 6100 CPU boards running Linux (Tango control system) and RTAI real-time extension (feedback processing) feedback stations acquire position data at 10 kHz from Libera Electron through Gigabit Ethernet links data shared in real-time through Reflective Memory fibre optics 10 kSample/s D/A converters generate the analog correction signals sent to the corrector power supplies Master Station connected to the reflective memory for feedback supervision and data acquisition Event system: 1 EVG, 12 EVR, Libera Clock Splitters and fibre optics to distribute MC, SC, PM and Trigger signals

Differential Analog Links to Corrector Power Supplies Global Orbit Feedback Architecture From N-1 GOF Station F.O. Links To N+1 GOF Station GOF Station CPU Reflective Memory DACs 7 Horizontal Differential Analog Links to Corrector Power Supplies 7 Vertical ±400 mA ±48/70 mrad H/V @2GeV Control System Network Corrector Setting DC Setting Ethernet Switch Gigabit Ethernet Links Control System Network Libera Libera Libera Libera Libera Libera Libera Libera BPM Buttons BPM Buttons BPM Buttons BPM Buttons BPM Buttons BPM Buttons BPM Buttons BPM Buttons

Control Algorithms PID dedicated to low frequency (0-150 Hz) noise components Harmonic Suppressors damp periodic noise components: 50, 100, 150, 200, 250 and 300 Hz 50 Hz and harmonics Feedback OFF Feedback ON Amplitude spectrum of the horizontal beam position

Fast Global Orbit Feedback operator Panel Milestones of the feedback project the existing RF BPM detectors have been replaced with Libera Electron: March 2006 - March 2007 installation of the feedback system: finished in February 2007 loop closed in March 2007 since beginning of September 2007 the feedback is routinely used during users shifts operations stopped in October 2007 and re-started in March 2008 still work to be done to: optimize PID and Harmonic suppressors optimize singular values use weights for BPMs (and correctors?) Fast Global Orbit Feedback operator Panel

Libera Tango Device Server Embedded Tango Device Server (by Nicolas Leclercq - SOLEIL) running in the SBC on top of the Generic Server (still not possible without it: thread problems?) the Tango server is a “in house” modified version of the one developed for the 1.40 release but does not implement the new functionalities the Tango server for the 1.82 is being developed by Nicolas need for a closer coordination and collaboration between Tango/Libera users with respect to the development and maintenance of the Libera Tango Server Giulio Gaio and Claudio Scafuri will take over from Vincenzo Forchi’ (resigning) the Libera Tango Server deployment at ELETTRA Tango Device “inside” or “outside” Libera? What about Soleil, ESRF, ALBA, ...? The behavior of the Tango Server seems different! Tango Server needs debugging directly in the SBC

Closed Loop Performance Integrated amplitude spectrum of the beam position noise measured by a BPM with feedback off and on

Closed Loop Performance Average BPM rms in the 0-5 Hz and 0-200 Hz frequency range with feedback off/on

Closed Loop Performance Average beam position rms using 10 Hz data of all the BPMs. The feedback is switched on at 270 mA

“Out of the Loop” Performance Horizontal beam position measured by a low-gap BPM not included in the loop with feedback off/on Feedback OFF Feedback ON

“Out of the Loop” Performance Photon beam position measured by exit slits on the GasPhase beam line. The orbit is perturbed by continuous ID gap changes Feedback ON Feedback OFF

Operational Aspects after a new injection and energy ramping an orbit correction program restores to required values the position and angle of the electron beam in the insertion devices and bending magnets the feedback is eventually activated taking the corrected reference orbit as the set point for the loop: the AGC is switched off to avoid “steps” in the position reading only the fast feedback operates to correct the orbit, no slow feedback working in parallel correction algorithm: SVD with singular values reduction (48 s.v.) a considerable part of the measured orbit drift is not due to real orbit distortions but to the movement of the BPMs driven by thermal drifts the situation has considerably improved with full energy injection: expected further improvement when a more frequent injection or top-up will be performed

Control Room Panels Expert Panels Operator Panel

Open Issues and Perspectives the feedback system is flexible, reliable and easy to use further studies needed to optimize the respose matrix inversion (SVD) modal analysis of orbit distorsion optimization of singular value reduction the global feedback minimizes the rms of the whole orbit, ID source points disadvantaged with respect to dedicated local correction weighting of BPMs to privilege the correction at the IDs with respect to global one rhomboidal BPMs are not adjacent to IDs, there are 2 correctors in between Low-Gap BPMs with position measurement (better resolution and stability) already installed in straight section 2 and 7 necessity and feasibility of the installation of other Low-Gap BPMs to be evaluated availability of integrated photon BPMs is extremely useful, both as complementary diagnostics and for a possible employment in-the-loop ongoing activity to integrate a picoammeter current detector with fast digital interface into the global feedback By Instrumentation Group By Instrumentation and Detectors Laboratory

Real-time performance Libera latency: 300 ms Gigabit Ethernet transmission time: 10 ms Ethernet switch latency: 1 ms Reflective Memory Latency (BPMs and correctors data): 25 ms matrix multiplication and 14 control channels (LP Filter + PID + 10 HS): 21 ms DAC settings: 10 ms all real-time tasks executed in 60-80 ms CPU Load (G4 PowerPC @ 1.3 GHz) feedback processing under RTAI: 60-70 % 8 TANGO servers (25 devices), control system interface, FFT of 10000 samples 20 times per second with transmission to the client: 20%

Diagnostic Features Diagnostic capabilities for machine physics studies, investigation of beam noise sources, searching of malfunctioning machine components Data recording: Each local station stores: 8 seconds of 10kHz data (BPMs and correctors); 5 days of 1Hz data; Master station stores: 5 seconds of 10kHz synchronous data of all BPMs and correctors Post Mortem Analysis: buffers stop automatically under given conditions on BPM signals allowing beam dump detection Arbitrary Waveform generation: driven by the master station, used to measure the corrector magnets transfer function Horizontal Plane BPM number Frequency (Hz)