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Patrice NOUVEL. Design of a dependable Interlock System for linear colliders. TE-MPE Technical Meeting. Summary. Introduction Context Problematic State of the art Requirements establishment Operational context F unctional requirements Performance requirements
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Patrice NOUVEL Design of a dependableInterlock Systemfor linearcolliders TE-MPE Technical Meeting
Summary • Introduction • Context • Problematic • State of the art • Requirements establishment • Operational context • Functional requirements • Performance requirements • Interfaces and constraints • Design proposal • Functional analysis • Implementation proposal • Design verification • Feasibility study • Hardware demonstrator • Conclusion and future works
Context - CLIC • CLIC (Compact Linear Collider): • 3 TeV Collisions • Two beams acceleration scheme • 2012: Conceptual Design Report (CDR) • Cooperation with ILC (International Linear Collider) • Future: • ILC : industrialization • CLIC : continue R&D based on CDR CLIC CDR Vol1 CLIC CDR Vol1
Context - CLIC • Power and energy: • Beams : • Main Beam : 280 GJ, 40 nm2 (x 10 000 pilot beam) • Drive Beam : 1.4 MJ, 1 mm2 (x 100 pilot beam) • Equipment : 580 MW site • Beam operation • 50 Hz (100 Hz) • Charge density ramp Need to protect the machine M. Jonker et al. MACHINE PROTECTION ISSUES AND SOLUTIONS FOR LINEAR ACCELERATOR COMPLEXES. LINAC12 Pilot beam (Cu) : Energydeposit < 60 J/g
CLIC and machine protection • Machine Protection [1] : • Risk reduction => impact and occurrence of unwanted event • Impact : protect => e.g. collimators • Occurrence : prevent => e.g. interlock systems • CLIC failures classifications and strategy : • Fast failures (< 1 µs) : e.g. deflected beam in RF cavity • Passive protection • Inter-cycle failures (2 ms – 20 ms) : e.g. power converter • Interlock system • Safe by design principle • Slow failures (>20 ms) : e.g. beam orbit drift • Interlock system [1] B.Todd et al. Machine protection of the Large Hadron Collider. 6th IET Conf, on System Safety - 2011
Interlock system • Principle : • Stop the beam operation and/or extract the beam based on the machine state • Initial requirements for the CLIC Interlock System: • Beam permit: VETO, PASS(binary information, unique and global) • Beam permit loop implementation • Post-pulse analysis: last pulse stability to estimate the next pulse stability • Hardware demonstrator
Thesisproblematic Design of a dependable interlock system for linear collider • Work Positioning: • How to answer the problematic: • Design: concepts -> pre-prototype • Integration dependability • Study post-pulse analysis and linear collider • Starting points: • CLIC project • Initial requirements • State of the art on Interlock Systems B. TODD, PhD thesis 2006. A Beam Interlock System for CERN High Energy Accelerator. P.NOUVEL, PhD thesis 2013 Design of a dependable interlock system for linear collider System Life cycle - IEEE 1220
State of the art • Protect the machine: permit • Reliability and availability • Modular architecture • Typical interfaces : • Data acquisition • Actuators • Control system • Timing system • Post mortem Cosylab: machine protection workshop 2012
Selected protection systems • LHC Interlock system • FPGA • Response time max: 100 µs • SIL 3 (100 y < MTBF < 1000 y) • 17 nodes, 140 interfaces • LHC Safe Machine Parameters • Threshold comparison • LCLS Interlock system • FPGA, gigabits link • Threshold comparison [1] [2] [3] [1] R. Schmidt et al. Protection of the CERN Large Hadron Collider – New Journal of Physics. 2006 [2] B.Todd. The Safe Machine Parameter – 2011 [3] S. Norum et al. The machine protection system for the LinacCoherentLigthSource. PAC. 2009
Methodology choice • Needs: • Establish a balanced specifications • Basic, transferable to non-experts • Iteration • Set up the project basis (from specifications to prototype). Deal with project uncertainties • Special focus on the dependability • Proposal: • IEEE 1220 : Standard for application and management of the system engineering process • Tailored version of IEC 61508 : Functional Safety of Electrical/Electronic/ Programmable Electronic Safety-related Systems
IEEE 1220 Methodology • Requirements establishment • Design proposal • Design proposal Adapted to the problematic System Engineering Process – Extract from IEEE 1220
Requirements establishment • Methodology: • Operational scenarios • System interfaces identification • Functional requirements • Performance requirements • Critical interfaces study • Comments: • Only main requirements specified System Engineering Process – Extractfrom IEEE 1220
Requirements establishment - synthesis • Main functional requirements (intent declaration) : • Critical: interlock the machine, post-pulse analysis • Non-critical : control, monitoring, test • Main performance requirements: • Response time: 2 ms to interlock the machine, 6 msto perform the post-pulse analysis • Dependability: • Critical interfaces: • Technology, local interfaces, architecture Requirements for one node regarding the redundancy • For more information: • MPE-TM (22.03.2012) • Dependability requirements and Design compliance for Interlock Systems. 2013 SYSTOL conference
Design proposal • Functional analysis: • System behavior • Functional decomposition • Functional architecture • Implementation proposal • Sub-functions • System • Modules System Engineering Process – Extractfrom IEEE 1220
Functional analysis: decomposition • Sub-functions definition • Individual data analysis • Global analysis • Beam permit system • Control function • Operational scenarios • Time, data and control flow • Requirements assignments • Failure modes and effects • Safety and monitoring function • Functional risk reduction
Implementation : sub-functions • Beam permit system => Beam permit loop • Individual Data Analysis => Threshold comparison • Global analysis => Summarizers
Implementation: system • Implementation : • Beam permit loop for each linac • Front end used as slave node (beam permit loop) • Concentrators modules dedicated to post-pulse analysis • Master module delivering the final beam permit to actuators • 3 types of modules
Implementation: modules Common part (control, monitoring, test)
Design verification • Concepts feasibility study: • Beam permit system, beam permit loop • Post-pulse analysis • Hardware demonstrator: • Ability of the design to reach the requirements • Basis for prototype System Engineering Process – Extractfrom IEEE 1220
Feasibility: context • CLIC Test Facility: CTF3 • Feasibility study: • Drive Beam generation • 2-beams acceleration • Protection system existing: • Interlock • Valve monitoring (software) • Vacuum monitoring (software) • Repetitive beam losses in CLEX (software) • Beam mostly harmless (~ 700 J, ~ 1 mm²) 140 m
Feasibility: experiment • Objectives: • Apply post-pulse analysis • Enhance beam operation • Statement: • Recurrent vacuum leak (1.5% unavailability) • Hypothesis: • Repetitive beam losses • Automatic beam operation • Proposal: • Automatic process to restart the beam with safety considerations
Feasibility: JAVA application • Technical description: • Machine interlocked • Checking klystrons • Sending probe beams • Post-pulse analysis : BPM, radiation monitors • Based on threshold comparison • Logging: application and post-pulse analysis
Feasibility: results and discussion • Threshold management: • Initial definition (location, operating condition) • Dynamic (operating condition) • Need of machine parameters: • Suggestion: integrate safe machine parameters • Post-pulse analysis: • Based on fast equipment (120 s) • Computation (integration, averaging, extremum)
Hardware demonstrator • Technology choice [1] : • VHDL Blocks: • Current ideal implementation: FPGA • VHDL blocks for sub-functions (transferable) • VHDL blocks for test bench (GTP, control, monitoring) • Design to reach the requirements: • Response time: minimize the critical path • Dependability: functional specifications, simulation (unit testing, system integration, code coverage), hardware test [1] B. TODD, PhDthesis 2006. A Beam Interlock System for CERN High Energy Accelerator.
Demonstrator: modules Layout Blocks VHDL – Master Module
Demonstrator: hardware used • « SPEC » board: • SFP gigabit connector • Open hardware intiative • PCIe connector • FMC connector • Serial port • FPGA : Xilinx Spartan 6 • Gigabits link (IP) • Enough slices available • FMC (FPGA Mezzanine Carrier) : • Connectivity (Xilinx) • Debug (Xilinx) • Control software: LabVIEW
Demonstrator: test bench CLIC Interlock system pre-prototype Emulating the CLIC acquisition infrastructure
Measurement procedure • Response time: • Definition of the chain of event (CLIC) • Measures (intern, extern), extrapolations, estimations • Dependability : • Accelerated test: demand (acc factor x4000) and temperature (acc factor x8) • Limit : emulation 109 h > 3 years
Results and discussion • Response time – Interlock the machine: • 320 µs vs. 2 ms • 1.58 ms left for the acquisition infrastructure (and transmission) • Response time – post-pulse analysis : • 125 µs vs. 6 ms • Left time available for more advanced computation • Dependability: Measurement results Requirements node
Verification - Synthesis • Suggestions: • Integration Safe Machine Parameters • Implementation of mechanism to manage dynamically thresholds • Requirements produced: • Acquisition : 1.58 ms • Advanced computation : requirement at ~5 ms • Improvements: • Gigabits link • Dedicated thermic test (board limit) • Radiation (SEU) test to consider • Next step: • Prototype in a operational environment
General conclusion • Design of an Interlock System [1] • Requirements establishment • Design proposal • Design verification • Dependability • Requirements definition • Verification • Application to linear colliders • Increased knowledge of the post-pulse analysis • Deliverables • Design proposal and its implementation • Pre-prototype [1] P. Nouvel, B. Puccio, H. Tap, M. Jonker. Design process of the interlock system for the Compact Linear Collider. Poster presented at International Particle Accelerator Conference, 2013
Future works proposed • Short term: • Rigorous specification • JAVA application at CTF3 • Thermic test • Long term : • Conception methodology (model simulation, model based design) • Prototype integration : PCIe, remote monitoring/control. • Design translation to other accelerators (ILC, ESS) – capitalization • SMP integration study • Complementary research trails: • Definition of stability criteria for the post-pulse analysis • Interaction between the Interlock system and the beam operation sequencer • Extension to CLIC injectors (damping ring)
Thanks for your attention Questions ?
Annexe - Implémentation FPGA: maitre • FPGA : Spartan 6 • Horloge : 125 MHz • Utilisation : • Registers: 2200 ~ 4% • LUTs: 27 300 ~ 8 % (1% mémoire, 7% logique) • Slices: 942 ~ 13 % • MUXCY (carry path and carry multiplexer): 692 ~ 5% • LUT flip-flop pairs (fullyused): 1284 • IOB: 15 ~ 5% • Dual Port RAM 8kB: 1 ~ 1% • Dual Clock buffer: 2 ~ 6% • Global clock buffer: 5 ~ 31 % • DSP slices: 1 ~ 1% • GTP: 2 = 100 % • PLL : 2 = 50 %
Annexe - definition • IEEE 1233: • prototype: An experimental model, either functional or nonfunctional, of the system or part of the system. A prototype is used to get feedback from users for improving and specifying a complex human interface, for feasibility studies, or for identifying requirements.
Annexe – le cycle en V From« Functional Virtual Prototyping” Design Flow and VHDL-AMS . Y.HERVE, P.DESGREYS
Annexe – Model Based Design • Identification/modélisation du système • Analyse du contrôleur et synthèse • Simulation • Software in the loop • Hardware in the loop • Déploiement
Annexe - Machine protection [1] B.Todd et All. Machine protection of the Large Hadron collider. 6th IET Conf, on System Safety - 2011
Interface identification • Critical: • Acquisition and control infrastructure • Target systems (actuators) • Non-critical: • Technical Network • Human-system interface • Timing system • Data management system (configuration, logging data)
Functional requirements Requirements Use Exemples - Interlock the machine - Critical equipment failure - Low beam stability - Post-pulse analysis - Next pulse instability - Control function - Ability to trigger manually an interlock - Monitoring function - Knowledge of the component state of the system (maintainability) - Provide evidence of the interlocking signal - Test function - Trigger an interlock on given channel
Performance requirements • Response times: • Interlock the machine : less than 2 ms(requirements) • Post-pulse analysis : 6 ms
Performance requirements • Dependability: use of a tailored version of the IEC 61508 M. Kwiatkowski – PhD thesis 2013 : Methods for the Application of Programmable Logic Devices in Electronic Protection Systems for High Energy Particle Accelerators From M. Kwiatkowski – PhDthesis