linac coherent light source (lcls) low level rf status

Ron Akre, Dayle Kotturi

Lehman Review [email protected], [email protected]

October 24-26, 2006

Linac Coherent Light Source (LCLS)

Low Level RF Status



October 24-26, 2006

Safety First and Second and Third…..to Infinity

Hazards in the LLRF systemRF 1kW at 120Hz at 5uS = 0.6 Watts average, 2 Watt average amps at 2856MHz, 60W average amps at 476MHz

Hazards – RF Burns / CataractsMitigation – Avoid contact with center conductor of energized connectors. All employees working with LLRF systems are required to have the proper training.

110VAC ConnectorHazards - Shock Mitigation - Don’t touch conductors when plugging into outlet.All chassis are inspected by UL trained inspector.



October 24-26, 2006

Status of Hardware for Injector Turn-onLinac Sector 0 RF Upgrade

All 3 RF Chassis completed and Installed (Master Oscillator, Master Amp, PEP phase ShifterControl Module ready for test – higher phase noise levels if not installed

Sector 20 RF distribution systemPhase and Amplitude Controllers (PAC) – 5 unitsPhase and Amplitude Detectors (PAD) – 2 unitsPhased Locked Oscillator – Use SPPS unit for Turn OnLO Generator – Complete - 75% tested – looks good so farMultiplier – 476MHz to 2856MHz – Complete4 distribution chassis – Complete 102MHz, 2056MHz, 2830.5MHzLaser Phase Lock – Needs testing – Only high risk itemDistribution Amplifiers – 10W, 2850MHz due Oct 25, 102MHz Amp being built

LLRF Control and Monitor System1 kW Solid State S-Band Amplifiers – 5 units – Design Complete, In FabPAD – 12 units – 6 required for turn on PAC – 6 unitsBunch Length Monitor Interface – Will use PAD to collect data

Beam Phase CavityWill use 2 channels of PAD ChassisPill box cavity with 2 probes and 4 tuners – 2805MHz 3 units Complete



October 24-26, 2006

Status of Software for Injector Turn-onPAD Software

OperationalPAC Software

OperationalLocal Feedback (in VME)

Data analysis shows simple feedback algorithm will work.Optimization of algorithm continues.Time measurement: measure time needed for data acq, for transfer to VME, for VME processing, for transfer to PAC.Time measurement: needed for multiple local loops. Eg. Measure scalability from 1 to N instances.

RF Gun Temperature FeedbackIn Design

Calibration and TestOperational

High Level ApplicationsIn progress (This means we are working on specifications.)

Storing of boot params, serial numbers, etc in flash or on the board for PAD and PAC



October 24-26, 2006

Status of Documentation + Reviews

LLRF Control Design SpecificationThis Engineering Specification Document was signed off by Project Office on 9/27/2006.

LLRF Final Design ReviewThis review was held on 9/19/2006.The scope of the review covered:

RF Distribution Reference System for Injector Commissioning RF System for Injector Commissioning

PAD PAC VME

The goals of the review were: Injector turn on is January 3, 2007. The designs of the prototype PADs and PACs have been built and tested. Fabrication is scheduled for October, 2006. Please review analysis of test data and the proposed design and comment on the proposed systems' ability to meet LCLS specifications. Review our test plans and suggest improvements



October 24-26, 2006

LCLS Layout

P. Emma



October 24-26, 2006

LCLS RF Jitter Tolerance BudgetLCLS RF Jitter Tolerance Budget

RMS tolerance budget for <12% rms peak-current jitter or

<0.1% rms final e− energy jitter. All tolerances are rms levels and the voltage and

phase tolerances per klystron for L2 and L3 are Nk larger,

assuming uncorrelated errors, where Nk is the number of

klystrons per linac.

P. Emma

Lowest Noise Floor Requirement 0.5deg X-Band = 125fSStructure Fill time = 100nSNoise floor = -111dBc/Hz @ 11GHz 10MHz BW-134dBc/Hz @ 476MHz

X-bandX-band XX--

0.500.50



October 24-26, 2006

Slow Drift Tolerance LimitsSlow Drift Tolerance Limits

Gun-Laser TimingGun-Laser Timing 2.4*2.4* deg-Sdeg-S

Bunch ChargeBunch Charge 3.23.2 %%

Gun RF PhaseGun RF Phase 2.32.3 deg-Sdeg-S

Gun Relative VoltageGun Relative Voltage 0.60.6 %%

L0,1,X,2,3 RF Phase (approx.)L0,1,X,2,3 RF Phase (approx.) 55 deg-Sdeg-S

L0,1,X,2,3 RF Voltage (approx.)L0,1,X,2,3 RF Voltage (approx.) 55 %%

(Top 4 rows for (Top 4 rows for // < 5%, bottom 4 limited by feedback dynamic range) < 5%, bottom 4 limited by feedback dynamic range)

* for synchronization, this tolerance might be set to * for synchronization, this tolerance might be set to 1 ps (without arrival-time measurement)1 ps (without arrival-time measurement)

(Tolerances are peak values, not rms)(Tolerances are peak values, not rms) P. Emma, J, WuP. Emma, J, Wu



October 24-26, 2006

Linac Sector 0 RF Upgrade

PEP PHASE SHIFT ON MAIN DRIVE LINE MDL RF with TIMING Pulse – Sync to DR

Master Oscillator is located 1.3 miles

from LCLS Injector

1.3 Miles to LCLS Injector

LCLS must be compatible with the existing linac operation including PEP timing shifts

Measurements on January 20, 2006at Sector 21show 30fS rms jitter in a bandwidth from 10Hz to 10MHz

MASTERAMPLIFIERS

IQPAUPEP ControlCamac Module

MAIN LINAC (SECTOR 0) RF/TIMING SYSTEM

1

476MHz MASTEROSCILLATOR

PEP PHASE SHIFTER+-720 Degrees in 0.5mS

SLC COUNTDOWNCHASSIS 476MHzDivide to 8.5MHz

Master TriggerGenerator MTGSyncs Fiducial to8.5MHz Damping Ringand 360Hz Power Line

8.5MHz

360Hz LineSync.

476MHz

360Hz

Fiducial GeneratorSyncronized to:360Hz Power Line8.5MHz Damping Ring476MHz RF Distribution

SumFiducialto RF



October 24-26, 2006

RF Distribution Lab vs. MDL Measurements

John Byrd LBNL

LCLS Reference System Lab Measurements

20fS rms Jitter 10Hz to 10MHz

Existing Linac MDL Sector 0

126fS rms Jitter 10Hz to 10MHz

If PEP IQPAU Chassis is not commissioned we may not meet LCLS specifications



October 24-26, 2006

Sector 20 RF Distribution

LO and 102MHz resync by adjusting 2856MHz PAC while monitoring S21 2856MHz

Laser resync with laser PAC while monitoring difference in 119MHz laser and FIDO out

MDL from Sector 0

RF CONTROLSPAC

380-208-22476MHz to 2856MHzMULTIPLIER

2830.5MHz LO Gen

RF MONITORPAD

119MHz Phase

119MHz

RF HUT Coupler476MHz Ref. 80uW

LASERReference

4x 476MHz13dBm OUT

ExistingTIMING SYSTEMFIDO Output

LCLS 476MHz PLL120HzTRBR

+13dBm in

Track/HoldTRBR

2856MHz16 Way Distribution20dBm each

GunL0AL0BL0TCAVL1SL1X

+17dBm out

2856MHz10 Watt Amplifier

102MHz16 Way Dist22dBm each

476MHzLASER LOCKReference

119MHz0dBm OUT

LO Phase Monitor

102MHz5Watt Amplifier

RF MONITOR PAD

RF CONTROLSPAC

GunL0AL0BL0TCAVL1SL1XLINACEXPERIMENTS

Sample and Hold PLLwith DAC offset adjustand Error Monitor

RF CONTROLSPAC

2830.5MHz10 Watt Amplifier

380-208-22476MHz to 2856MHzMULTIPLIER

2830.5MHz LO16 Way Distribution20dBm each

2856MHz in

IQ Modulator to adjust2830.5MHz to 2856MHz Phase

Divide 112 to 25.5MHzSSB Mix to 2830.5MHz4X to 102MHz

25.5MHz out

102MHz out 2830.5MHz out

RF CONTROLSPAC

GunL0AL0BL0TCAVL1SL1X

+13dBm in

LO Phase Monitor

LO Phase Monitor

RF CONTROLSPAC

RF MONITORPAD

+17dBm out

RF MONITOR PAD

FSJ4-50 0.8dB/30ft

2856MHz from Sector 21

LCLS LLRF 476MHz Linac Ref.

4 x +13dBm out

380-208-38476MHz Amp30dB Gain 19dBm

102MHz16 Way Dist22dBm each

+7dBm out

+16dBm out+13dBm out

LASER DiodeMeasurement

Phase Noise and Timing

2856MHz and 119MHz

LASER DiodeOutput

LO Phase MonitorRF MONITOR PAD

RF MONITOR PADLO Phase Monitor



October 24-26, 2006

Lab Test SetupReference, PAC, PADThe LCLS RF system duplicated in the lab and used for testing of PADs and PACs.

At least two of each frequency generation chassis is built to measure phase noise levels.

Most components will have development chassis which can be used as a spare.

There is only one Dayle, spare is not in the budget.



October 24-26, 2006

LCLS New Reference System Lab Measurements

2856MHz : 22fSrms 10Hz to 10MHz 2830.5MHz : 22fSrms 10Hz to 10MHz

25.5MHz : 152fSrms 10Hz to 1MHz 102MHz : 281fSrms 10Hz to 10MHz

Lab Tests Show Reference System Noise Levels Meet All LCLS Requirements

2856MHz = 70fSrms

2830.5MHz = 70fSrms

25.5MHz = 2pSrms

102MHz = 2pSrms

John Byrd - LBNL



October 24-26, 2006

RF Cable Routing

RFHUT

All cables are routed from devices in temperature stabilized area to the centrally located, temperature stabilized, RF Hut in the linac gallery.

Picture taken from Carl Rago’s Talk

Cables run down through penetration 20-17 which is enclosed by the RF Hut



October 24-26, 2006

RF System Cables / Specifications

LCLS Specifications:Laser, RF Gun – 2.3pSL0A, L0B, L1S, L1X, L2, L3 – 5pS

Laser

RF Gun

L0A

Phase Cavity

L0B

L1S

L1X

L2 Ref

Laser

RF Gun

L0A

Phase Cavity

L0B

L1S

L1X

L2 Ref

Laser

RF Gun

L0A

Phase Cavity

L0B

L1S

L1X

L2 Ref

1

Number of cables per deviceReference cables are8ft and can drift +-50fS

1

2

4

2

2

2

5

RF HUT

+-240fS

+-310fS

+-370fS

+-290fS

+-500fS

+-160fS

+-140fS

+-240fS

Cable Drift Based onTemperature variationsand temp co of 5ppm/degCPADs

Reference2830.5MHzLO

Most Devicesare in Tunnel

LinacSector 0 RF

MDL

L2 - 4 SectorsSpecifications70fS rms jitter+-5pS drift

L3 - 6 SectorsSpecifications150fS rms jitter+-5pS drift

L0, L1 - 5 KlystronsSpecifications100fS rms jitter+-2.3pS drift



October 24-26, 2006

SLAC Linac RF – New ControlThe new control system will tie in to the IPA Chassis with 800W of drive power available. The RF Reference will be from the new RF reference system.

Solid State Sub-Booster PAC

I and Q will be controlled by the PAC chassis, running 16bit DACs at 102MHz. Waveforms to the DACs will be set in an FPGA through a microcontroller running EPICS on RTEMS.

Existing System

Klystron

Accelerator

SubBooster

MDL 476MHz

Next Sector

6 X2856MHz

Sub Drive Line

High PowerPhase ShifterAttenuator

SLED

Phase &AmplitudeDetector

ExistingPhaseReferenceLine

200MW-45dB

3kW

1mW1W

20mW

To NextKlystron

I

RF LO

Q

1

2

3

4

IPA



October 24-26, 2006

Linac Station 21-1 Tests



October 24-26, 2006

Linac 21-1 Test Set-up

Linac Ref Amp

MDL

6x Multiplier 2830.5MHzGenerator

PAC

102MHz 2830.5MHz

PADCLK LO

CLK OUT

CLK

SSSB

ExistingIPA

5045 KLYSTRON

RF

IN1

RF

OU

T2

KlystronForward RF

Accelerator x3

SLED

New Equipment AddedFor Tests

Power Coupled out from 476MHz MDL drives a 476MHz Amplifier which feeds a 6X Multiplier from 476MHz to 2856MHz.

The 2856MHz out drives both the LO generator and the PAC.

The 2830.5MHz LO and 102MHz CLK Generator supplies the LO and CLK to the PAD. A CLK output of the PAD drives the PAC CLK.

The PAC output drives the SSSB.

The SSSB drives the existing IPA chassis

The klystron output coupler is used to measure phase and amplitude with the new PAD.



October 24-26, 2006

Linac 21-1 Test ResultsTests were done in the gallery with no temperature regulation on cables. Average RMS value of 2 second sliding average is 0.068 degrees.

Exponential Smoothing Yields the Following Results. Lowest noise is with a time constant of about 2 points.



October 24-26, 2006

LLRF Commissioning – no high power RF, no beamLow Level Lab Tests and Calibration PACs and PADs

Set at Operational TemperaturePAC Tests and Calibration – SSB Modulator : Set offsets and gainPAD Tests

ADC Board – SNR Cross Talk – Sine Wave histogramChassis – Two Tone or Single Tone - SNR, Noise Floor, IP3

Installation of PACs and PADs – Other systems required to be completeLLRF Racks - installedWater SystemTrigger systemAC Rack power

Test RF Cables - Measure Attenuation and Phase StabilityInstallation of Solid State Sub-Boosters (SSSB)Installation of RF VME Crate

Installation of network switchesGet devices booting from afsnfs2Test VME connectivity to PAD by sending I and Q avgs.Connection of PADs, PACs, and VME IOCs to network

Initial Set-up of PAC triggersAlign 119MHz trig to 102MHZ clocks for PACs and PADs

PAD CalibrationsEnter channel calibration factors (APCs, Power Scale Factors – coupler ratios…)

PAC CalibrationCalibration with spectrum analyzerCalibration with PAD channel

Phase Noise Measurements102MHz Clock : 2830.5MHz LO : 2856MHz RF : Laser Lock to RF



October 24-26, 2006

LLRF Commissioning - high power RF, no beam

Timing System setupLine up PAC and PAD triggers to existing modulator triggersAdjust PAC waveforms for 6 Klystron stationsAdjust PAD window length and offset to fit waveform

Commission local Feedback loopsGun TuneGun PhaseGun AmplitudeL0A PhaseL0A AmplitudeL0B PhaseL0B AmplitudeTcav PhaseTcav AmplitudeL1S PhaseL1S AmplitudeL1X PhaseL1X Amplitude

Test Standby Timing and BCS functions



October 24-26, 2006

LLRF Commissioning - high power RF, with beamTiming System setup

Adjust PAC and PAD triggers to align waveforms to beam time119MHz PAD/PAC triggers must move in increments of 14 ticks to keep all phases aligned (~117.6nS).PAD window must move in increments of four 102MHz cycles to keep phase reading the same. (~39.2nS). Increments of 9.8nS will cause 90 degree phase shifts in readings.

Commission local Feedback loopsGun Phase - Phase to beam (Rotate phase to get max beam energy)Gun Amplitude - Check Cal (RF power to maximum energy gain)L0A Phase - Phase to beamL0A Amplitude - Check CalL0B Phase - Phase to beamL0B Amplitude - Check CalTcav Phase - Phase to BeamTcav Amplitude - Check CalL1S Phase - Phase to BeamL1S Amplitude - Check CalL1X Phase - Phase to BeamL1X Amplitude - Check Cal



October 24-26, 2006

High Level ApplicationsGeneric

Correlation plotsCalibration of power levels using beam energy

Distribution SystemRotate Phase 360 degreesMonitor Phase Errors in DividersCorrect Divider Phase Errors

PACCalibration Mode OperationGenerate and Load WaveformsPanels for Phase and Amplitude Adjustment

PAD TestingCrosstalk, SNR, Noise FloorSine Wave HistogramPanels for Phase and Amplitude Monitoring

Local Feedback Control Panels



October 24-26, 2006

END of TALK

linac coherent light source (lcls) low level rf status

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