rf commissioning in point 4 hardware commissioning: acs rf system - power systems acs cavities :...
TRANSCRIPT
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• Diagnostics and other Facilities
Summary/Conclusions
E. CiapalaOn behalf of the AB-RF Group
LHC MAC June 08 – RF commissioning in Point 4 1
2
ACS/ADT racks(driver amplifiers,PLC controls, fast interlocks)
Beam 1
Beam 2
8 Dedicated Pick-ups BPMC @ Q7L, Q7R, Q9L, Q9R
The RF Systems Underground at Point 4
APW Wideband Monitors3 left/3 right of IP4
Cavity feedback racks in Faraday cages
SC Cavity Cryomodules ( each with 4 single cell cavities)
16 Klystrons400MHz, 300kW
IP4
ADT Transverse Damper kickers- 4 modules left/4 right of
IP4+ space for 2 more modules
(upgrade)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 flowModification agreed with manufacturer:
• Dismantling in-situ in UX45, klystron in horizontal positionModification of all 16 klystrons & re-installation completed before start of
cavity testing November 2007.
A relatively straightforward operation
Overheating of collector
Klystrons in horizontal position in UX45 for modifications
Klystrons in normal vertical position in UX45
LHC MAC June 08 - RF Commissioning in Point 4
4
ACS Power Systems Commissioning
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
power converter
HV switch
mod 1 mod 2 mod 3 mod 4 thyratron 4uF
kly
circ
cav
kly
circ
cav
kly
circ
cav
kly
circ
cav
short circuit
Group of four Klystrons fed by one Power Converter.
Common crowbar, one tetrode modulator per klystron.Housed in Four HV Bunkers
Modulator
Crowbar
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
4.5 KRefrigerator
QUI
NRV
SC Cavities
Coupler cooling cct.
HP
MP
LP
WarmCompressor
Station
ColdBox
?
C (4.5 K; 3.0 bar)D (20 K; 1.3 bar)
Warm recovery line (≤300 K; ≤1.1 bar)
Safety System
Safety System
ACS Cavity Commissioning – Cryogenics for RF cavities
LHC MAC June 08 - RF Commissioning in Point 4
Cavityies He tanks & circuits are low pressure systems, <2 bar but fed from magnet QRL
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.
Courtesy S. Claudet
7
ACS Cavity Commissioning – Cool-down and first tests Sector 4-5
C8.B1
C7.B1
C6.B1
C5.B1
C4.B2
C3.B2
C2.B2
C1.B2
400.55
400.60
400.65
400.70
400.75
400.80
400.85
400.90
400.95
401.00
0%
100%
•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
0 10 20 30 40 50 60
10000
60000
110000
160000
210000
260000
LHC3 Q FACTOR 30.11.2007
CAV ACAV BCAV CCAV D
Coupler position in [mm]
Q f
acto
r
0 10 20 30 40 50 60
10000
60000
110000
160000
210000
260000
LHC2 Q FACTOR 30.11.2007
CAV ACAV BCAV CCAV DACS FREQ
Coupler position in [mm]
Q f
acto
r
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)
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 stability1-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-upLongitudinal damper: Damps the injection phase and momentum errors, batch by batch Acts on 400 MHz cavities. (Postponed)
Cavity Controllers installed in FC B for Sector 3-4 cavities
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
10LHC MAC June 08 - RF Commissioning in Point 4
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
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)
HT Cav phase Cav Pwr Gain Cntrl TP Phase Cntrl TP57.6 kV -166.3 deg 0.52 dBm 207 mV 93 mV55.7 kV -166.3 deg 0.52 dBm 201 mV 137 mV53.7 kV -166.3 deg 0.52 dBm 193.3 mV 189 mV51.8 kV -166.3 deg 0.52 dBm 186 mV 242 mV49.9 kV -166.3 deg 0.52 dBm 184 mV -300 mV to +300 mV47.9 kV -166.3 deg 0.52 dBm 187 mV -242 mV46 kV -166.3 deg 0.52 dBm 189 mV
Polar Loop compensates klystron gain and phase shifts with varying HV (without loop 8.4 degree RF per percent HV)
Cav8 B1 PSD of Phase noise Vcav-Ref RF f/b ON and Klystron Loop Open/Closed (~10 dB reduction @600 Hz)
Cav8 B1 PSD of Phase noise Vcav-Ref, RF f/b Open/Closed (~47 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
LHC MAC June 08 - RF Commissioning in Point 4
12
ACS RF Commissioning: Summary
Access system de-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..
RAMSES RP monitoring systems tested & validatedPeak 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 systemClose 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 modulesSo far no observation of magnet quenches on RF cavities
RF Summary Sector 4-5
5 weeks cold in 2007, then 7 weeks in 2008Low power tests on all 8 cavitiesConditioning to nominal field and full powerSet up of loops on three out of 8 cavities. Need ~ 2weeks to finish the other 5….
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)
RF Commissioning in Sector 3-4….Cryo instrumentation etc. starting nowLow power tests on all 8 cavities NEXT
WEEK…Conditioning to nominal field and full
powerSet up of loops on all 8 cavities.
LHC MAC June 08 - RF Commissioning in Point 4
Sector 3-4cavities cold & ready for RF ~ mid-Juneexpected commissioning time: ~ 6-8 weeks
Sector 4-5cavities cold & ready for RF ~ Julyexpected commissioning time: ~ 2-4 weeks
LHC MAC June 08 - RF Commissioning in Point 4 13
Sector 4-5 Sector 3-4
Hardware Commissioning Status
14
ADT Power Systems Commissioning
LHC MAC June 08 - RF Commissioning in Point 4
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.
15
ADT Power Installation/Commissioning - in Tunnel
LHC MAC June 08 - RF Commissioning in Point 4
•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)
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)
LSA operational applications and
setti ngs management
Expert applications LabVIEW/MATLAB
Front Ends PC/Linux/FESA
PLC supervision
Front Ends VME/LynxOS/FESA
RF Low-Level electronics
Front Ends cPCI/Linux/FESAAnalogue signals
acquisition
PLCs Schneider Unity
CMW Middleware
RF power and cavity equipment
Signal observation OASIS
ModbusTCP/IP
LHC MAC June 08 - RF Commissioning in Point 4 16
17
Remote control GUIs, based on Labview and AB/CO ‘Knobs’, operational and extensively used during commissioning.
ACS HV controls, klystron & cavity, Local conditioning DDS control
Web based ACS overall status
Labview applications
Software Applications
LHC MAC June 08 - RF Commissioning in Point 4
18
LLRF - RF Fast Timing and Synchronization
Synchronization of the SPS-LHC RF bunch into bucket transferGeneration of beam synchronous signals: 40 MHz bunch clocks, revolution frequencies, 40 MHz 7TeV reference
injection pulsesTransmission of timing & clocks to the users: BI, BT and Experiments, from SR4 via fibre linksFine-rephasing of the two rings before physics
Locking each ring on a low-noise fixed-frequency synthesizer.
System Comprises 5 VTUs, 3 generators, 30 Fibre optics Tx/Rx Pairs.
Recent Successful Dry-Run test with all users and OP group, including basic software.
DDS1 DDS2F RF Prog 1 F RF Prog 2
WB
sw
itch
WB
sw
itch
Inj. F rev
F injRing 1
Ring 2
Ring 1
Ring 2
Pha
se s
hifte
r
1/(7 h) divider
1/h Divider
RF IN
OUT
1/h DividerRF IN
OUT
SyncOUT
RF IN
Sync
Bucket nbr.
Shi
fted
F in
j to
SP
S
Del
aye
d F
c to
SP
S
SP
S e
xtr.
war
ning
Inj. Pulse generator
RF IN
OUT
Inje
ctio
n pu
lse
Injection VETO
Sync
Ring 1
Ring 2
Ring 2
Ring 1
Next
Shut
Open
Inj. Phase
WB Demux
Inj.
Rin
g 1
Inj.
Rin
g 2
Fiber optic links to AB/BT
Fiber optic links to/from SPS FC
Ring 2
Ring 1
F rev prog1
F rev prog2
Fiber optic links to UX45
VTU
DUAL FREQ PRGM
BUCKET SELECTOR
INJ PULSE GENE
VTUVTU
Programmable delay in the bucket selector selects the LHC bucket for transfer
Module generates pulses sent to the injection kickers
Divider adjusts the relative position of Beam 2 wrt Beam 1
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 Loop locks 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 Loop locks 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 Loop to keep the beam centered during acceleration ramp. Can use for commissioning in place of Synchro loop.
R1
Low-levelLoops
Processor
Radial PUFront-end
VCXO
Phase Discri
F RF Prog 1
Radial loop
Phase loop
Synchro loop
DDS1 DDS2
Sync
F1
,P1
F2
,P2
F1 F2
1/h divider
Master F rev
To Ring 1 Cavity Controllers (fibers)
Dual Frequency Program and
Rephasor FPGA
Function Gen. Function Gen.
F RF Prog 2
DUAL FREQUENCY
PRGM
Master F RF
Beam 1
Rad. PU
Beam/Vt phase
RF/Fprog phase
F out
Ra
d P
os.
Fiber Optic TX
BEAM CONTROL
LOOPS MODULE
Radial steering with radial loop
Coarse F1
LF switch
Phase Discri
7 TeV synthesizer
Phase shifter
180 deg hybrid
a b
BEAM POS
MODULE
FPGA
AD
C
SYNCHROMODULE
Ib RF Summing Network
Vt
Phase PU
AD
C
CORDIC (+ AGC?)
Bunch/RF phase
CORDIC (+ AGC?)
Vt/RF phase
Phase Difference
and Averaging
BEAM PHASE
MODULE
AD
C
Cavities
Analog I/Q demod
Analog I/Q demod
Master FrfMaster Frf
AD
C
AD
C
Delay adjust
Function Gen.
fsync
fphase
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
The VCXO generates the RF sent to the Cavity Controllers
This synthesizer replaces the frequency program during physics
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.
LHC MAC June 08 - RF Commissioning in Point 4
20LHC MAC June 08 - RF Commissioning in Point 4
Q9
ADC
FPGA
...
...
SERDES
...
...
Q7
ADC
SERDES
SERDES
SERDES
SERDES
FPGA
Xilinx Altera
Q
I
fc = 40 MHz
fc = 40 MHz
ADC
ADCQ
I
fc = 40 MHz
fc = 40 MHz
DAC
ADC
FPGA
SERDES
ADC
SERDES
SERDES
SERDES
SERDES
FPGA
Xilinx Altera
Q
I
fc = 40 MHz
fc = 40 MHz
ADC
ADCQ
I
fc = 40 MHz
fc = 40 MHz
DAC
ΔxQ7
ΔxQ7
ΔxQ9
ΔxQ9
Δx
Δx
400.8 MHz
180º
180º
Coaxial Transmission LinesAndrew HELIAX
7/8" Dielectric Foam
length ~ 650mlength ~ 450m
Macom H-92-2000 MHz
Comb Filter400.8 MHz
Beam position VME moduleProduces normalized beam position digitally at 40 MHzSeries hardware completedFirmware developmentf
Signal processing VME moduleDSPU (“Damper Loop”)Produces vector sum of two PU signalsProvides notch filter at n * Frev, individual tof compensation for each module, loop gain adjust (via op DAC)Based on ACS 1T-FB moduleProto tested, series hardware being assembles, then firmwareSEC
commission in A3
commission in A4
ADT Signal Processing Systems (SR4 Surface)
400MHz BP filters
Gbit SerDes link
21
OptionalNot applicable
System Item Hard-ware
Firm-ware
Drivers FESA Expert App.SW
Comments
Cavity Controller RF Modulator/Klystron polar loopCavity Controller Switch/protection moduleCavity Controller RF feedbackCavity Controller Setpoint moduleCavity Controller Clock generationCavity Controller Clock distributionCavity Controller Analogue demodulatorCavity Controller 1 turn feedback Not essential for startupCavity Controller Conditioning DDSCavity Controller Tuner RF Front endCavity Controller Tuner ControlADT Low level Transverse feedback Minimum functionalityADT Low level ADT radial position acquisition Minimum functionalityAll Crate management module Needed as soon as possibleRF Synchro Trigger unitRF Synchro Injection pulse generatorRF Synchro Dual wideband switchRF Synchro Dual wideband demuxRF Synchro 400 MHz phase shifter Minimum functionalityRF Synchro Optical Tx analog Passive (no control)RF Synchro Optical Rx analog Passive (no control)RF Synchro Optical Tx digital Passive (no control)RF Synchro Optical Rx digital Passive (no control)RF Synchro Synchro Loop (Phase Synchro) Identical to SPS moduleBeam control Frequency Program DDS Similar to conditioning DDSBeam control VCXOBeam control Beam phase measurementBeam control Beam position measurementBeam control Low level loops DSPBeam control LL Loops InterfaceBeam control Beam parameters DSP Postponed 2009Beam control Longitudinal feedback Postponed 2009ACS/ADT Interlock timestamping Not essentialACS Power PLC controlsACS High-level logic & interface to LSAADT Power PLC controlsADT Signal distribution switching RabbitADT High-level logic & interface to LSAACS Automatic conditioning systemBeam Obs Signal distribution switching RabbitBeam Obs Peak detector Minimum functionalityBeam Obs Detected signals (100MS/s) Minimum functionalityBeam Obs Injection MR (8GS/s) Minimum functionalityBeam Obs Bunch length measurement (8GS/s) Minimum functionalitySPS Rephasing Test MD June 2008SPS Ions acceleration Postponed 2009
Not yet startedIn progressCompleted
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!
LHC MAC June 08 - RF Commissioning in Point 4
Attenuator hardware
PU construction
Installed in tunnel
Triggering acquisition @ 8 Gs/sPeak detection 250Ms/s
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
LHC MAC June 08 - RF Commissioning in Point 4 24
Additional slides
LHC MAC June 08 - RF Commissioning at Point 4 25
A1, First Turn Pilot: Inject pilot and center first turn with RF OFFAdjust front end gains to see PU signals, Label bucketsPrepare injection frequency and bunch timing, injection timing, beam dump,
experiment clocks, cavity initial phasing
Beam Commissioning – ACS 400 MHz RF system
A2 Capture and Circulating Pilot at Injection energy.Commission phase loop and synchro loop. RF ON/OFfCaptureCheck cavity phasingAdjust relative positions of the 2 rings for collisions in IPs (cogging)
A3 to A11, Increasing Intensity to Collision on Flat TopPrecise measurements of lifetime, longitudinal profile Set up radial loopSet up multi-bunch injection, Commission the Filling Pattern maskSet up multi-batch injection, Commission the changing filling pattern mask, & update
in phase loopRamping, with function generators and software facilities, fine tuning of rampOptimization of the RF voltage on the flat topRephasing 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 in Point 4 26
A4, [450 GeV] Commissioning Damper Loop Measure de-coherence time with damper offMeasure open loop transfer function (mainly at ~low frequency)Make necessary adjustments (gain, phase, delay), Close damper loopScan gain, phase, delay and measure damping time and stability limitsMeasure beam lifetime as function of damper gainScan injection kicker pulse by moving bunch.
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] - passiveCommissioning RF front-end (beam position module) of damper and check optics:Verify RF signals from RFLLCommission analog front-endCommission digitization and frev tagging of bunchCheck phase advance Q7->Q9->damper (both beams and planes) Verify beta functions.
A6, A7 RampCheck abort gap cleaning, test parameters & methodsCheck 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
27LHC MAC June 08 - RF Commissioning in Point 4
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 ps rms white noise just compensates synchrotron radiation damping. We measure 2.4 10-2 ps rms 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 % rms emittance 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 simulations1 ps rms white noise now gives 0.1 % loss after 1 hour.
(Further improvement with Klystron Polar Loop)
RF Noise – additional slide from previous MAC
28LHC MAC June 08 - RF Commissioning in Point 4
Class/ Case
Risk Situation Heat load Mass flow
Pressure reached (bar)
Derogation
1a) Static losses D line blocked, no wrl
150 W 17 g/s 1.8 with SVs (4x2mm dia. needed)
Tank cold - 1.8 bar max
1b-1) D line overpressure, non-return valve failure (open) 5 magnet quench
2 Kg/s 1.8 with SVs
(4x23mm. needed
Exceptional - 1.8 bar max.
1b-2) D line overpressure, non-return valve failure (open) 25 magnet quench
10 Kg/s 2.1 with RDs
(4x36mm needed)
Exceptional - 2.1 bar max.
1b-3) D Line overpressure warm, non-return 5% leakage 25 magnet quench 20 bar
10 kg/s 2.1 with RDs
(4x34 mm needed)
Exceptional – 2.1 bar max
1c-1) C line blocked open (cold) 350 g/s 1.8 with SVs (4x10mm needed)
Tank cold – 1.8 bar max
1c-2) C line blocked open (warm) - 2 x 1.5 bar SVs per module
80 g/s 1.5 with special SVs (2x24mm needed)
1.5 bar max - Safe.
1d) Insulation vacuum break 11.4 kW 1.27 Kg/s
1.8 with SVs (4x18mm needed)
Exceptional - 1.8 bar max Opening of cryostat discs (P<1.5 bar)
1e) Sustained RF quench 150 kW 2.9 Kg/s
2.1 with RDs (4x48mm needed)
Exceptional & worst case - 2.1 bar max.
1f) Beam vacuum break (50 mm aperture – 350g/s air indrawn)
147 kW 2.8 Kg/s
2.1 with RDs (4x48mm needed)
Exceptional - 2.1 bar max.
2a) Beam vacuum break (100 mm aperture)
480 kW (HL limited
by tank surface area)
9.2 Kg/s
12 bar (Pressure due to
50 mm piping)
Exceptional & exceeds press test, even with opening of RDs. Risk of rupture He tank & opening of cryostat discs (P<1.5 bar).
Risk Analysis for SC Cavity He Tanks