Fast Global Orbit Feedback for the Australian Synchrotron Eugene Tan Accelerator and Operations 13/12/20101 ACAS Workshop on Accelerator Feedback Systems - Eugene Tan

Contents Introduction Stability Requirements Fast orbit feedback (FOFB) system 13/12/20102 ACAS Workshop on Accelerator Feedback Systems - Eugene Tan

Australian Synchrotron 3 GeV, 3 rd Generation Light Source 13/12/20103 ACAS Workshop on Accelerator Feedback Systems - Eugene Tan 1.Electron gun/source 2.Linear Accelerator 3.Booster Synchrotron 4.Storage Ring (see picture below) 5.Beamline 6.Experimental Station

Australian Synchrotron Properties Broadband radiation source. 13/12/20104 ACAS Workshop on Accelerator Feedback Systems - Eugene Tan o.au/education/everyon e/radio-astronomy/

Australian Synchrotron Properties High photon flux and collimated Small sources sizes 13/12/20105 ACAS Workshop on Accelerator Feedback Systems - Eugene Tan Source of radiation at synchrotron light sources Bending MagnetWigglerUndulator Sensitive to Vertical Motion Sensitive to Horizontal and Vertical Motion

Contents Introduction Orbit Measurements And Corrections Fast orbit feedback (FOFB) system 13/12/20106 ACAS Workshop on Accelerator Feedback Systems - Eugene Tan

Stability Requirements Current definition: “position stable to 10% of beam size” (size = one sigma) Purpose is to minimise flux variation to < 1%. 13/12/20107 ACAS Workshop on Accelerator Feedback Systems - Eugene Tan Horizontal Size (um)Vertical Size (um) Dipole8758 Wiggler/Undulator32016

Orbit Measurements And Corrections Beam Position Monitors (BPMs) 13/12/20108 ACAS Workshop on Accelerator Feedback Systems - Eugene Tan

Orbit Measurements And Corrections 13/12/20109 ACAS Workshop on Accelerator Feedback Systems - Eugene Tan 98 BPMs Corrector Magnets generating transverse fields using additional windings on Sextupole magnets Libera BPM Electronics from Instrumentation Technologies

Orbit Measurements And Corrections Correctors in the lattice generates particular “patterns” in the closed orbit. Zeroth order perturbation. 13/12/ ACAS Workshop on Accelerator Feedback Systems - Eugene Tan Perturbation on the circular orbit relative to ideal. Corrector setting of 1 urad (61 mA or 0.3 mT or 3 Gauss)

Orbit Measurements And Corrections Measure a BPM-Corrector Response, 13/12/ ACAS Workshop on Accelerator Feedback Systems - Eugene Tan 98 BPMs 42 Horizontal Correctors 56 Horizontal Correctors

Orbit Measurements And Corrections Invert response to generate  Correctors to correct orbit As R is not necessarily square, pseudo-inverse, R’, is obtained using Singular Value Decomposition (SVD) method. 13/12/ ACAS Workshop on Accelerator Feedback Systems - Eugene Tan

Noise Sources Mechanical Vibrations EMC and Electrical Earthing Insertion Devices (wiggler, undulators) moving. Thermalisation of Dipole Magnet (very slow) 13/12/ ACAS Workshop on Accelerator Feedback Systems - Eugene Tan

Measuring Orbit Stability Libera streams unbuffered orbit postion data at 10 kHz. Observed noise at frequencies: – 3 freq. between Hz – 50 Hz – 64 Hz – 100 Hz These were also confirmed by PSD measurements. More work with to identify what is “real”. 13/12/ ACAS Workshop on Accelerator Feedback Systems - Eugene Tan

13/12/ ACAS Workshop on Accelerator Feedback Systems - Eugene Tan

Contents Introduction Orbit Measurements And Corrections Fast orbit feedback (FOFB) system 13/12/ ACAS Workshop on Accelerator Feedback Systems - Eugene Tan

Fast Orbit Feedback (FOFB) System Systems have generally been distributed due to the size of the network and computational requirements. Algorithms include: PID, Harmonic Suppression 13/12/ ACAS Workshop on Accelerator Feedback Systems - Eugene Tan BPM Computing /Feedback CorrectorsBeam GbE Network

Fast Orbit Feedback (FOFB) System Examples of distributed systems (Elettra): 13/12/ ACAS Workshop on Accelerator Feedback Systems - Eugene Tan Libera Corrector Sector n Linked using reflective memory to distribute position and operational data. Corrector Fast VME Based Processing

Fast Orbit Feedback (FOFB) System Examples of distributed systems (Soleil): 13/12/ ACAS Workshop on Accelerator Feedback Systems - Eugene Tan Libera (FB on int. FPGA) Libera Libera (FB on int. FPGA) Fast Corrector Control System. Slow feedback system that account for the fast correctors. Control System. Slow feedback system that account for the fast correctors. Sector n Connection to adjacent sectors’ Fast FB BPMs

FOFB at the ASLS Possibility of a centralised topography: 13/12/ ACAS Workshop on Accelerator Feedback Systems - Eugene Tan Processor Sector 1’s Liberas Sector 1’s Correctors Sector 2’s Liberas Sector 2’s Correctors Sector 3’s Liberas Sector 3’s Correctors Sector 4’s Liberas Sector ’s Correctors

FOFB at the ASLS Simple topology Goals: – Reuse existing GbE switches and/or network infrastructure – Reuse existing corrector power supplies 13/12/ ACAS Workshop on Accelerator Feedback Systems - Eugene Tan BPM Computing /Feedback CorrectorsBeam GbE Network

FOFB at the ASLS 13/12/ ACAS Workshop on Accelerator Feedback Systems - Eugene Tan GbE Switch Liberas Sector n GbE over copper (separate VLAN) 10 kHz data packet rate Corrector Sector n GbE based DAC GbE over copper (separate VLAN) Single Central Processor, PC based computer, Intel or PowerPC GbE Switch Fiber Differential Analogue

FOFB Sub-systems: BPM 13/12/ ACAS Workshop on Accelerator Feedback Systems - Eugene Tan GbE Switch Liberas Sector n GbE over copper (separate VLAN) 10 kHz data packet rate Corrector Sector n GbE based DAC GbE over copper (separate VLAN) Single Central Processor, PC based computer, Intel or PowerPC GbE Switch Fiber Differential Analogue Instrumentation Technologies’ GbE (RIO) Gathers 10 kHz data into a single large UDP data packet in all Liberas in group. Complete within 20 us. Any one Libera can be used to transmit. Test of throughput and latency over GbE network needs to be tested.

FOFB Sub-systems: Network 13/12/ ACAS Workshop on Accelerator Feedback Systems - Eugene Tan GbE Switch Liberas Sector n GbE over copper (separate VLAN) 10 kHz data packet rate Corrector Sector n GbE based DAC GbE over copper (separate VLAN) Single Central Processor, PC based computer, Intel or PowerPC GbE Switch Fiber Differential Analogue Network architecture: design and optimise network path through current infrastructure. test latency given expected throughput from all Liberas. test for collision rate. Local switch – 10 kHz = 10 Mbits/s; Central switch 140 Mbits/s.

FOFB Sub-systems: Processor 13/12/ ACAS Workshop on Accelerator Feedback Systems - Eugene Tan GbE Switch Liberas Sector n GbE over copper (separate VLAN) 10 kHz data packet rate Corrector Sector n GbE based DAC GbE over copper (separate VLAN) Single Central Processor, PC based computer, Intel or PowerPC GbE Switch Fiber Differential Analogue Central processor: realtime processing jitter ~20 us use of multi-core processors maybe. Algorithms: PID + harmonic suppressor (Elettra)

13/12/ ACAS Workshop on Accelerator Feedback Systems - Eugene Tan GbE Switch Liberas Sector n GbE over copper (separate VLAN) 10 kHz data packet rate Corrector Sector n GbE based DAC GbE over copper (separate VLAN) Single Central Processor, PC based computer, Intel or PowerPC GbE Switch Fiber Differential Analogue Corrector power supply: Use current system in analogue mode. Currently limited to ~60 Hz Latency and jitter tests required. Thorough study required ASAP In-house design of GbE based DAC or commercial products (e.g. CompactRIO by NI). Latency and jitter tests. FOFB Sub-systems: Correctors

Resolution/noise floor of measurements: < 1um. Required resolution and stability correctors: 2 mA 2 mA/120 A = 17×10 -6 (~16 bits plus sign). So a 18bit DAC up to 10 kHz. 13/12/ ACAS Workshop on Accelerator Feedback Systems - Eugene Tan Freq. (Hz) Amp. (um)Approx. Current (mA)Magnet and PSU – 2 mH 120 A ± 10 V 160 – 330 A/s

Acknowledgements Marco Lonza, Giulio Gaio and Stefano Cleva (Elettra) Nicolas Hubert (Soleil) Instrumentation Technologies support Greg LeBlanc, Brian Jensen, Elsa van Garderen, Nick Hobbs and Tim Buttler. 13/12/ ACAS Workshop on Accelerator Feedback Systems - Eugene Tan