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RF Commissioning in Point 4

RF Commissioning in Point 4 . Hardware Commissioning: ACS RF System - Power Systems ACS Cavities : Sector 4-5 ACS Cavities : Sector 3-4 ADT Power and Feedback Systems Commissioning Preparation for beam: RF Synchronization Beam Controls - ACS and ADT

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RF Commissioning in Point 4

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  1. RF Commissioning inPoint 4 • Hardware Commissioning: • ACS RF System - Power Systems • ACS Cavities : Sector 4-5 • ACS Cavities : Sector 3-4 • ADT Power and Feedback Systems Commissioning • Preparation for beam: • RF Synchronization • Beam Controls - ACS and ADT • Diagnostics and other Facilities • Summary/Conclusions E. Ciapala On behalf of the AB-RF Group LHC MAC June 08 – RF commissioningin Point 4

  2. The RF Systems Underground at Point 4 16 Klystrons 400MHz, 300kW ACS/ADT racks (driver amplifiers, PLC controls, fast interlocks) SC Cavity Cryomodules ( each with 4 single cell cavities) Cavity feedback racks in Faraday cages 8 Dedicated Pick-ups BPMC @ Q7L, Q7R, Q9L, Q9R Beam 1 Beam 2 ADT Transverse Damper kickers- 4 modulesleft/4 right of IP4 + space for 2 more modules (upgrade) APW Wideband Monitors 3 left/3 right of IP4 IP4 LHC MAC June 08 - RF Commissioning in Point 4

  3. ACS Power - Klystron Collector cooling modifications Klystron ‘boilers’ modified: • Bad water cooling of collector (SM18 klystron vacuum leak) • Hypervapotron mode • Requires homogenous water flow • Modification agreed with manufacturer: • Dismantling in-situ in UX45, klystron in horizontal position • Modification of all 16 klystrons & re-installation completed before start of cavity testing November 2007. • A relatively straightforward operation Overheating of collector Klystrons in normal vertical position in UX45 Klystrons in horizontal position in UX45 for modifications LHC MAC June 08 - RF Commissioning in Point 4

  4. power converter HV switch mod 1 mod 2 mod 3 mod 4 thyratron 4uF kly kly kly kly circ circ circ circ short circuit cav cav cav cav ACS Power Systems Commissioning Group of four Klystrons fed by one Power Converter. Common crowbar, one tetrode modulator per klystron. Housed in Four HV Bunkers Modulator Crowbar • High voltage commissioning – No RF: • Power convertor tests (AB/PO) • Controls, interlocks • Operation: 10kV • UX45 services, cooling (air, water) • DCCT • Klystron equipment, focus supplies • Crowbar operation (with spark gap) • Operation: 58kV • Klystron modulator control • crowbar (ext. trigger @ 62kV) • Klystron heaters current settings • Completed for all four systems HV Bunker LHC MAC June 08 - RF Commissioning n Point 4

  5. ACS Power Systems Commissioning - RF into Waveguide Short • 1) Preliminary • RF interlocks, Klystron protection (Wattchers) • RF calibration (Power Meters, directional Couplers) • RF pre-amplifier levels • Circulator temperature control unit set-up • 2) 300 kW RF power tests and calibration: • Check DC Power, Collector Power, RF Power, • 3) Measure klystron saturation curves and set up clamping RF LOGBOOK: \\cern.ch\dfs\Departments\AB\Groups\RF\Machines\LHC\LowLevel\Commissioning\CavController\CavSettingUp\B1\CAV2B1 LHC MAC June 08 - RF Commissioning in Point 4

  6. Warm Compressor Station 4.5 K Refrigerator Warm recovery line (≤300 K; ≤1.1 bar) MP HP LP Coupler cooling cct. ? Cold Box SC Cavities Safety System NRV D (20 K; 1.3 bar) C (4.5 K; 3.0 bar) QUI Safety System ACS Cavity Commissioning – Cryogenics for RF cavities Cavityies He tanks & circuits are low pressure systems, <2 bar but fed from magnet QRL Courtesy S. Claudet Concern:Overpressure in D-Line on multiple magnet quench (<20 bar estimated) Rely on:Process control, auto blocking outlet valve, non-return valve (NRV) in D-Line. Safety study:(SC, AT-CR & AB-RF ) Analysis of all risk situations (~10): EDMS 880723 => Recommendations => 1.5/1.8/2.1 release valves/rupture discs, procedures. Warm Recovery Line (WRL)installed to recuperate static losses when D-Line closed, to avoid release valves opening. Late decision. Extra outlet dome on module, cryo lines, heaters etc. LHC MAC June 08 - RF Commissioning in Point 4

  7. ACS Cavity Commissioning – Cool-down and first tests Sector 4-5 • Pressure test 2.1 bar done all modules (incl. Sector 3-4) Mid 2007 • Start cooling 2 modules (sector 4-5) on Nov 20th 2007 • Careful setting up of cryogenic processes and safety systems • 2 modules cold on Nov 22nd - 24 hours to stabilize • Low-Power tests, Generator connected to w/g transition piece, measure resonant frequency and Qext • Check of Tuning Range on 8 cavities Sector 4-5 • (frf = 400.790 MHz) Check of Qext on variable couplers LHC MAC June 08 - RF iCommissioning n Point 4

  8. ACS – Low Level RF systems – Cavity Controllers in UX45 Faraday Cages • Cavity Controller • One system per cavity (in 2 VME crates) • Located in two Faraday cages in the UX45 cavern • Control phase and amplitude of cavity voltage. • Take reference from AB-PO standard function generators interfaced via serial link into cavity contoller. • Minimize disturbances from • HT ripples from Power Converters: 1 % HT ripple -> 8.4 degrees @ 400.8 MHz • Transient Beam loading • Keep demanded klystron power reasonable and avoid saturation (300 kW max). • Largely digital implementation • Operates at the bunch rate (40 Msps) Cavity Controllers installed in FC B for Sector 3-4 cavities Modules/Functions: Tuner Loop: Keeps cavity at optimum tuning to minimize klystron power (Also ‘half detuning ‘ to keep the power flat across beam segments and gaps) RF Feedback Loop: Reduces the cavity impedance at the fundamental (by 20 linear for Q=20000, by 180 at Q = 180000). Precision of RF voltage, transient beam loading and longitudinal stability 1-T Feedback: Adds factor 10 reduction on the revolution frequency side-bands. (Transient beam loading + longitudinal stability) Klystron Polar Loop: Compensates for the klystron gain/phase changes. (HT drifts and ripples, 50 Hz components and multiple). Set Point: Voltage & Phase control, Interface to the function generator, can also customize the voltage reference for each bunch, phase and amplitude. Conditioning:Automatic conditioning system integrated. with local synthesizer. Also used for open loop set-up Longitudinal damper: Damps the injection phase and momentum errors, batch by batch Acts on 400 MHz cavities. (Postponed) LHC MAC June 08 - RF Commissioning in Point 4

  9. ACS Cavity Commissioning – Conditioning (Power Processing) • Processing simultaneously cavity and power coupler, fast gain loop acting on vacuum activity • Use same strategy as for initial conditioning in SM18 test stand: • Initial pulsing with slow rise-fall envelope, increasing voltage, increasing pulse width then DC, at all coupler positions. Keep low vacuum set limits throughout. Conditioning time as expected. Quickly reached 2 MV/cavity (Nominal 5.5 MV/m) in pulsed mode Then ~ 2weeks overall net time to get to CW operation at 300 kW • Process handled by local DDS in cavity controller, • Full remote control via network, • Run all cavities simultaneously => time saving • Radiation measurements: • Peak value: few mSv/h close to the cavities (8 cavities running) •  Might get higher radiation above 2MV… • No radiation measured nor in UX45 nor outside the RF zone LHC MAC June 08 - RF Commissioning in Point 4

  10. ACS Cavity Controller Commissioning in UX45 – Cavities Cold • Some time taken to set up signal levels and calibrate signal distribution system • Test results matched those in SM18 tests on a single cavity: • Tuner Loop:good stability, ~ 1 step correction per second (25 Hz) as expected • RF feedback: Loop delay as expected 600 – 650 ns, Closed Loop response as expected: 700 kHz 2-sided BW • Q ~ 600, R reduced from 2.7 Mohm (Q=60000) to 27 kohm Closed Loop, Cav 7 B1, Q=60000, O.L. gain ~ 100 • Overall open loop freq responses & Group delay LHC MAC June 08 - RF Commissioning in Point 4

  11. ACS Cavity Controller Commissioning in UX45 – Cavities Cold • Klystron ‘Polar’ Loop: • Performance as expected from SM18 tests & Matlab simulations. Adjusted response of the Klystron Loop (~15 us) with the RF feedback loop ON (time response ~ 1 us) Cav8 B1 PSD of Phase noise Vcav-Ref, RF f/b Open/Closed (~47 dB reduction@600 Hz) Cav8 B1 PSD of Phase noise Vcav-Ref RF f/b ON and Klystron Loop Open/Closed (~10 dB reduction @600 Hz) • Only managed to completely set up 3 of the eight cavities before Sector 4-5 was warmed up, however progress made on procedures and software will allow faster completion of other cavities • Polar Loop compensates klystron gain and phase shifts with varying HV (without loop 8.4 degree RF per percent HV) LHC MAC June 08 - RF Commissioning in Point 4

  12. ACS RF Commissioning: Summary • RF Summary Sector 4-5 • 5 weeks cold in 2007, then 7 weeks in 2008 • Low power tests on all 8 cavities • Conditioning to nominal field and full power • Set up of loops on three out of 8 cavities. • Need ~ 2weeks to finish the other 5…. • Access systemde-bugged. Two systems: main tunnel system and upper UX45 system. • Some delays due to co-activities on equipment in RF zone. Handling of 18kV reset on door forcing, etc.. • RAMSESRP monitoring systems tested & validated • Peak value: few mSv/h close to the cavities (8 cavities conditioning simultaneously) Can expect higher radiation above 2MV, conditioning before installation (in SM18) was done to 3 MV (8 MV/m) • No radiation measured in UX45 nor outside the RF zone • Cryogenics system • Close collaboration with AT-ACR in setting up (important) • Availability and reliabilty good.. • Some initial cryo control issues, (He lost through safety valves instead of through WRL) • Excellent cryogenic regulations (level & pressure) in the modules • So far no observation of magnet quenches on RF cavities • RF Commissioning in Sector 3-4…. • Cryo instrumentation etc. starting now • Low power tests on all 8 cavities NEXT WEEK… • Conditioning to nominal field and full power • Set up of loops on all 8 cavities. • Power Tests since Sector 4-5 commissioning • Test with all 4 power converters simultaneously at full power • Optimize HV ripple on power converter (600Hz) • Test spare power converter • Test spare HV cables (surface to tunnel) LHC MAC June 08 - RF Commissioning in Point 4

  13. Hardware Commissioning Status Sector 3-4 Sector 4-5 • Sector 3-4 • cavities cold & ready for RF ~ mid-June • expected commissioning time: ~ 6-8 weeks • Sector 4-5 • cavities cold & ready for RF ~ July • expected commissioning time: ~ 2-4 weeks LHC MAC June 08 - RF Commissioning in Point 4

  14. ADT Power Systems Commissioning • 9 HV power converters • Eight installed in SR4, one in 867 tests stand (for tests and as spare) • One power converter (15kV, 14A dc) drives two power amplifiers, i.e. four tetrodes. • All tested up to required power (12kV - 2 x 7A) B867, before being installed in SR4 • All tested with DC operational settings (12kV - 2 x 2.5A) in SR4 for several weeks, and with RF applied on the amplifiers • 16 Power Amplifiers: • Tested in B867 tests stand at full DC anode voltage of 12kV, 7A of DC current per amplifier and with 0 dBm signal source. • Input circuit, amplitude and phase characteristics of all 16 amplifiers were stored in pictures and data files. • Tests showed similarity of the characteristics of amplifiers with tetrodes of the same type. LHC MAC June 08 - RF Commissioning in Point 4

  15. ADT Power Installation/Commissioning - in Tunnel • High voltage feeders to kickers (strip connectors) mounted to their supports in the tunnel. • All kickers were aligned, baked out to (200 degC), and connected to the vacuum chambers • Water cooling systems were tested (single amplifier and the whole system) • RF tests were made on individual amplifiers, then with all the amplifiers together • Problems : • 1 HV resistor broken (water leak), repaired and re-installed, no more fault • 2 HV capacitors burnt, repaired and re-installed. • 1 amplifier shown an over heat of the input socket (not confirmed with a second test in our tests area, pt100 fault?) • Still have to finish the RF heat run and the final measurements (planned by end-June) LHC MAC June 08 - RF Commissioning in Point 4

  16. Controls and Software • Front-end hardware: • PLCs for equipment control • VME Crates for LLRF systems and feedbacks • All front-end software based on FESA • Applications software: • LSA (Control room) • Applications for RF experts and system commissioning • Signal diagnostics accessible via OASIS: • Fast digitizers in Compact PCI crates • Embedded acquisition buffers in digital LLRF hardware • Slow Controls • PLC, FESA classes, specialist applications for power systems, Developed & tested • ACS & ADT slow control systems installed in UX45, tested and fully commissioned locally. • Remote control GUIs, based on Labview and AB/CO ‘Knobs’, operational and extensively used during commissioning. • LLRF controls (Cavity Controller, Beam Control, RF synchro) • Drivers for 30 different VME modules, based on rigorously defined memory map and functionality (streamlined design environment built up) • Cavity Controller and Synchro front-end software operational; ‘Expert’ GUIs available • Beam Control front-end software implementation in progress • Interface with operational software • Parameter model and settings management defined in LSA; implementation in progress by AB/OP • Full remote control of cavity systems via LSA to be tested after Sector 3-4 commissioning (end June) LHC MAC June 08 - RF Commissioning in Point 4

  17. Software Applications Remote control GUIs, based on Labview and AB/CO ‘Knobs’, operational and extensively used during commissioning. Web based ACS overall status ACS HV controls, klystron & cavity, Local conditioning DDS control Labview applications LHC MAC June 08 - RF Commissioning in Point 4

  18. LLRF - RF Fast Timing and Synchronization • Synchronizationof the SPS-LHC RF bunch into bucket transfer • Generationof beam synchronous signals: 40 MHz bunch clocks, revolution frequencies, 40 MHz 7TeV reference injection pulses • Transmissionof timing & clocks to the users: BI, BT and Experiments, from SR4 via fibre links • Fine-rephasingof the two rings before physics • Locking each ring on a low-noise fixed-frequency synthesizer. • System Comprises5 VTUs, 3 generators, 30 Fibre optics Tx/Rx Pairs. • Recent Successful Dry-Run test with all users and OP group,including basic software. Programmable delay in the bucket selector selects the LHC bucket for transfer Divider adjusts the relative position of Beam 2 wrt Beam 1 Module generates pulses sent to the injection kickers LHC MAC June 08 - RF Commissioning in Point 4

  19. ACS (RF System) Beam Control Systems • One system per ring, located on the surface (SR4) • Generates Master RF @ 400.8 MHz (VCXO output), phase is adjusted continuously. Update at 11 kHz revolution frequency • Three loops for each beam: • Phase Looplocks the Cavity-Sum voltage (8 cav/beam) onto the Beam PU signal in order to minimize the RF phase noise. The loop is switched ON at first injection. • Synchro Looplocks the VCXO output on a Frequency-Program DDS. The DDS output frequency is the injection frequency during filling and follows the B field during acceleration. The loop is ON before injection and remains ON all the time in normal operation (until re-phasing before physics when the DDS is replaced by a Synthesizer) • Radial Loopto keep the beam centered during acceleration ramp. Can use for commissioning in place of Synchro loop. Injection frequency, injection phase and stable phase will be adjusted by observing these two signals A function sets the RF frequency on the injection plateau and through the ramp • Critical Modules: Status - • Beam Phase - in final development • Dual frequency program – firmware testing • Beam Position – firmware testing • System Test - • with VCXO, Beam Control loops, Synchro modules undergoing measurements in Lab. This synthesizer replaces the frequency program during physics The VCXO generates the RF sent to the Cavity Controllers LHC MAC June 08 - RF Commissioning in Point 4

  20. ADT Signal Processing Systems (SR4 Surface) commission in A3 400MHz BP filters commission in A4 GbitSerDes link Signal processing VME module DSPU (“Damper Loop”) Produces vector sum of two PU signals Provides notch filter at n * Frev, individual tof compensation for each module, loop gain adjust (via op DAC) Based on ACS 1T-FB module Proto tested, series hardware being assembles, then firmware SEC Beam position VME module Produces normalized beam position digitally at 40 MHz Series hardware completed Firmware development f LHC MAC June 08 - RF Commissioning in Point 4

  21. LLRF Systems – Electronics Modules and Software Development Status LHC MAC June 08 - RF Commissioning in Point 4

  22. APWs and Diagnostics • Two Wideband Longitudinal Monitors per beam • One per beam to surface SR4, beam control system • One to local racks on cryo side of RUX45 tunnel - observation • Multiplexers and CPCi acquisition crates in place in UX45. • ‘Mountain range’ display & bunch length/profile measurements Software development in progress : • Essential diagnostics for beam commissioning! • Installed in tunnel • Triggering acquisition @ 8 Gs/s • Peak detection 250Ms/s • Attenuator hardware PU construction LHC MAC June 08 - RF Commissioning in Point 4

  23. Conclusions – Remaining Commissioning and Beam Preparation • Hardware Commissioning - Status and Remaining work • ADT and ACS power systems fully set up, with all required facilities in place. • Heat run of damper power systems to be done. • Sector 4-5 cavities conditioned to nominal voltage and power. Cavity controller loops set up on 3 cavities. 5 cavities still to complete, as soon as sector is cold • Sector 3-4 cavites; He tests (starting now) Low Power measurements, Conditioning and cavity controller set-up as soon as possible • Check of function generators and software to complete (“vertical slice”) • Preparation for Beam • RF synchro in place – clocks and timing now going to all users • ACS Beam control systems in advanced state but some items critical. • ADT electronics in test. • Software for beam control also critical, but basic functionality will be available for this run • Procedures for beam commissioning well defined. • Longitudinal Diagnostics in good shape to commission and study first beams…. LHC MAC June 08 - RF Commissioning in Point 4

  24. Additional slides LHC MAC June 08 - RF Commissioning in Point 4

  25. Beam Commissioning – ACS 400 MHz RF system A1, First Turn Pilot: Inject pilot and center first turn with RF OFF Adjust front end gains to see PU signals, Label buckets Prepare injection frequency and bunch timing, injection timing, beam dump, experiment clocks, cavity initial phasing • A2 Capture and Circulating Pilot at Injection energy. • Commission phase loop and synchro loop. RF ON/OFf • Capture • Check cavity phasing • Adjust relative positions of the 2 rings for collisions in IPs (cogging) A3 to A11, Increasing Intensity to Collision on Flat Top Precise measurements of lifetime, longitudinal profile Set up radial loop Set up multi-bunch injection, Commission the Filling Patternmask Set up multi-batch injection, Commission the changing filling pattern mask, & update in phase loop Ramping, with function generators and software facilities, fine tuning of ramp Optimization of the RF voltage on the flat top Rephasing each ring to the 7 TeV Synthesizer (see diagram slide 15) Fine adjustment of collision point (OP and EXP) LHC MAC June 08 - RF Commissioning at Point 4

  26. Beam Commissioning – ADT Transverse systems Phase A1 and A2 First turn and circulating beam (1 to 156 bunches Single batch) Observation of beam at damper pick-ups Q7, Q9 and delay equalization: Verification of signal levels (sum signals, calibrate using orbit system) Delay equalization of damper pick-up signals from Q7 and Q9 (in SR4) Kick calibration:-Excite transverse oscillations (phase A2) in order to check available damper kick strength A3, [450 GeV commissioning] - passive Commissioning RF front-end (beam position module) of damper and check optics: Verify RF signals from RFLL Commission analog front-end Commission digitization and frev tagging of bunch Check phase advance Q7->Q9->damper (both beams and planes) Verify beta functions. A4, [450 GeV] Commissioning Damper Loop Measure de-coherence time with damper off Measure open loop transfer function (mainly at ~low frequency) Make necessary adjustments (gain, phase, delay), Close damper loop Scan gain, phase, delay and measure damping time and stability limits Measure beam lifetime as function of damper gain Scan injection kicker pulse by moving bunch. A6, A7 Ramp Check abort gap cleaning, test parameters & methods Check machine protection, BLM triggering fors low intensity bunch and the damper in anti-damping. At 7 TeV, Again : Measure open loop transfer function.Make necessary adjustments (gain, phase, delay), Close loop Measure open and closed loop transfer functions LHC MAC June 08 - RF Commissioning in Point 4

  27. RF Noise – additional slide from previous MAC • RF feedback alone • Coast at 7 TeV/c with 16 MV, 2.5 eVs (fs0=23 Hz). • Blow-up rate below the 24 h synchrotron radiation damping time. • 1 psrms white noise just compensates synchrotron radiation damping. • We measure 2.4 10-2psrms from DC to frev=11250 Hz. • Crossing the 50 Hz line during ramp: • During ~ 1 min, 50 Hz falls inside fs band. Dangerous • 0.2 % rmsemittance increase • If amplitude of 50 Hz line is increased by 10 linear, we get 27 % emittance increase with bunch centre reduced in population • Circulating beam at 450 GeV/c with 8 MV, 0.7 eVs (fs0=63 Hz). • 50 Hz line multiples do not hit the populated synchrotron frequency band • -> no significant effect observed in simulations • 1 psrms white noise now gives 0.1 % loss after 1 hour. • (Further improvement with Klystron Polar Loop) LHC MAC June 08 - RF Commissioning in Point 4

  28. Risk Analysis for SC Cavity He Tanks LHC MAC June 08 - RF Commissioning in Point 4

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