rf systems commissioning o. brunner ab/rf on behalf of the rf group (ltc – march ’08) many...

RF Systems Commissioning

O. Brunner AB/RF

on behalf of the RF group

(LTC – March ’08)

Many thanks to L. Arnaudon, Ph. Baudrenghien, W. Hofle, D. Valuch, J. Molendijk, A. Butterworth, F. Dubouchet, Ed. Ciapala, U. Wehrle, T. Bohl, P. Maesen, V. Rossi, M.E. Angoletta, E. Montesinos for their help

1obrunner, LTC March'08

Summary

400 MHz superconducting cavities (ACS)

RF dampers (ADT)

Pick ups & RF instrumentation

RF synchro & beam control


ACS – LHC accelerating system

100kV- 40A power converter

HV switch

mod 1 mod 2 mod 3 mod 4 thyratron 4uF capacitor

kly

circ

control systems:-interlocks-specialists applications-supervision

made up of: 4 4MW power converters 16 RF power stations (HV equipment, 330kW klystrons, circulators, RF loads, WG) 16 superconducting cavities (4 cryostats)

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kly

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cavities


Low level RF system

warm commissioning (WG short-circuited)1. High voltage commissioning: switch on tests (AB/PO) control interlocks operation: 10kV services cooling (air, water) control interlocks DCCTklystron (focus,...) crowbar (spark gap)

Still to be done (in March) test with all 4 power converters full power in parallel

test&calibrate TS/EL equipment optimize HV ripple (600Hz) test spare power converter test spare HV cables (surface to tunnel)


operation: 58kV klystrons current control crowbar (ext. trigger @ 62kV) klystron heaters set up DC power calibrations thermal power calibration RF switch ON RF calibrations

2. RF commissioning: RF interlocksRF calibrationklystron protectionRF pre-amplifierCirculator temperature control unit300 kW RF power testsklystron saturation curveKlystron freq responsegroup delay meas.

Status: done on 15/16 RF power stations To be finished in March

cold commissioning – status of sector 4-5 Access & RAMSES systems tested & validated

2 modules (sect 4-5) successfully cooled down in November

Cryogenics system Excellent cryogenic regulations (level&pressure) in the modules Several cryo control system communication problems ( He lost through modules safety valves) So far no direct impact of magnet quenches on RF cavities

Low RF power tests of 8 cavities done Mechanical Tuner range of 8 cavities measured&Q measurements performed

Parallel conditioning of eight cavities up to: 1MV/cavity with main coupler position1 (QL = 20’000) 2MV/cavity with main coupler position 2 (QL = 60’000)

Radiation measurements: Peak value: few mSv/h close to the cavities (8 cavities running in //)

Might get higher radiation above 2MV No radiation measured nor in UX45 nor outside the RF zone

five weeks of “conditioning”

(~1 ½ wk per cavity)

Main issues: frequent stops due to accesses in RF zone, UX45 (w/o film badges..)

logging system (Timber) not fully operational


Set up the Klystron drive limiter to prevent driving the klystron over the saturation limit during loop transients

Set up the Tuner Loop to keep the cavity on resonance

Set up the Klystron Polar Loop to compensate the variation of klystron power and phase shift (by e.g. caused by high voltage supply

ripple 600Hz).

Set up the RF feedback to keep the accelerating voltage at the desired value in the presence of transient beam loading later: 1 turn feedback

condition: cavities & main couplers must be fully conditioned successfully done on 3 cavities after training: 2-3 days of work/cavity

cold commissioning – low level RF set up

more results will be presented by Ph. Baudrenghien

Vcav Feedback Closed. 25 kHz span, 30 Hz BW

Phase Noise Vcav-Ref RF fdbk open ~4 dg pkpk, fdbk closed ~0.3 dg pkpk @1MV CW

Phase Noise Vcav-Ref RF all loops closed ~0.1 dg pkpk @1MV CW


Low Level RF hardware equipment - status

System Item HardwareReady - Installed

Firmware Drivers FESA App.SW

Expected ready forstartup

ACS Automatic conditioning system Yes

Cavity Controller RF Modulator/Klystron polar loop Yes

Cavity Controller Switch/protection module Yes

Cavity Controller RF feedback Yes

Cavity Controller Setpoint module Yes

Cavity Controller Clock generation Yes

Cavity Controller Clock distribution Yes

Cavity Controller Analogue demodulator Yes (Passive, no control)

Cavity Controller 1 turn feedback Yes

Cavity Controller Conditioning DDS Yes

Cavity Controller Tuner RF Front end Yes

Cavity Controller Tuner Control Yes

ACS High-level Logic & Interface to LSA Yes

Not yet startedIn progressCompleted


ACS system commissioning - status

cavities cold & ready for RF ~ mid-May

expected commissioning time: ~ 6-8 weeks

cavities cold & ready for RF ~ mid-June

expected commissioning time: ~ 4-5 weeks


Sector 4-5 Sector 3-4

ADT (dampers) system

Damper essential to avoid increase of transverse emittance

pick-up 1

Kickers

Real time digital signal processing

pick-up 2

• feedback: curing transverse coupled bunch instabilities (becomes important with increasing intensity)

• excitation: of transverse oscillations for beam measurements & other applications (e.g. tune meas)

• damping: of transverse injection oscillations

Amplification


ADT racks(driver amplifiers,PLC controls, fast interlocks)

ADT (4 modules)left of IP4+ space for 2 more modules (upgrade)

ADT (4 modules)right of IP4 + space for 2 more modules (upgrade)

Beam 1

Beam 2

SR4 (surface):Signal Processing electronics (VME crates)HV Power ConvertersPLC controls

8 Dedicated Pick-ups BPMC @ Q7L, Q7R, Q9L, Q9R

ADT system - layout


ADT (dampers) commissioning - status

end of power commissioning: March

System Item Hardware Firmware Drivers FESA App. SW Expected ready for startup

ADT Power PLC controls Yes

ADT Low level Transverse feedback Yes (on the critical path)

ADT Low level ADT radial position acquisition Yes (on the critical path)

ADT High-level logic & interface to LSA Yes


RF Beam Observation Status

APWL Pick-Ups 6 pick-ups in LHC tunnel (4 for RF Group, 2 for BI Group) all installed pick-up combiners not yet installed (soon)

Instrumentation instruments for RF Beam Observation all installed digital acquisition cards for RF Beam Observation, UX45 all installed digital acquisition cards for RF Beam Observation, SR4 not yet installed modules for peak detector (VME) under construction software for Mountain Range, low frequency signals (OASIS) under test software for bunch profile acquisition and analysis not yet implemented

System Item Hardware Firmware Drivers FESA App.SW Expected ready for startup

Beam Obs Signal distribution switching Yes

Beam Obs Detected signals (100MS/s) Yes, minimum functionality

Beam Obs Injection MR (8GS/s) Yes, minimum functionality

Beam Obs Bunch length measurement (8GS/s) Yes, minimum functionality


RF synchro & beam control

beam control loopsmodules

beam phase modules (rigid and precise, for final use)

vector sum

ACS cavitieswide band pick-up

(APW)beam

radial strip line pu(Q10)

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am

plit

ud

e

bu

nch

ph

ase

volt

ag

e s

een

by e

ach

bu

nch

beam

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ase

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voltage seen by bunch

ph

ase

pu

sig

nal

frequency program

f RF re

ference

radial loop(for initial commissioning when ramp is not very reproducible)

stable phase

radial position

fiber optic link toCCC, CMS, AB/BT...

bunch freq

Frev

to longitudinal damper

10MHz (GPS)tempo


Status:

Distribution of fast clocks to the experiments (Frev, 40 MHz) :Installation of Fiber Optic Transmitter and Receiver modules underway. Prototype link tested OK (S. baron, PH dept)

Distribution of Frev and kicker pulses to BI and BT: installation of TX/RX underway

Installation of the RF Synchro modules in SR4 to generate Frev and kicker pulses: starting end March

Link with the SPS: commissioning end March- begin April

Aim: all commissioned by mid April

RF synchro & beam controlSystem Item Hardware Firmware Drivers FESA App. SW Expected ready for

startup

All VME crates Crate Management Unit Needed - critical

RF Synchro Trigger unit Yes

RF Synchro Injection pulse generator Yes

RF Synchro Dual wideband switch Yes

RF Synchro Dual wideband demux Yes

RF Synchro 400 MHz phase shifter Yes, minimum functionality

RF Synchro Optical Tx analog Yes

RF Synchro Optical Rx analog Yes

RF Synchro Optical Tx digital Yes

RF Synchro Optical Rx digital Yes

RF Synchro Synchro Loop (Phase Synchro) Yes

Beam control Frequency Program DDS Yes

Beam control VCXO Yes, minimum functionality

Beam control Beam phase measurement Yes, minimum functionality

Beam control Beam position measurement Yes, minimum functionality

Beam control Low level loops DSP Yes

Beam control LL Loops Interface Yes

Beam control Beam parameters DSP No (Postponed 2009)

Beam control Longitudinal feedback No (Postponed 2009)


Conclusions 400 MHz superconducting cavities (ACS)

High RF power stations commissioning comes to an end 8 cavities & main couplers conditioned LL RF setting up successful so far

Objective: get all LL RF modules + related SW ready&tested for next cool down Should be ready for beam on time (if not suffering from too many accesses in RF zone)

RF dampers (ADT) Power commissioning almost finished Critical: LL RF modules + related SW

Pick ups & RF instrumentation Good shape

RF synchro & beam control Well advanced Some LL RF modules + SW on the critical path


rf systems commissioning o. brunner ab/rf on behalf of the rf group (ltc – march ’08) many...

Documents

rf commissioning

rf power stationsto

rf cavitieslow rf power

rf zone

rf loads

rf groupltc

rf calibrations2

rf feedbackto