LLRF Control System

Dayle Kotturi, Ron Akre

LLRF Workshop, CERN [email protected], [email protected]

October 10-13, 2005

LLRF Control System

Outline Token photograph

Scope

Requirements

Design Considerations

Evaluation

System drawings

How this fits into beam-based longitudinal feedback

Conclusions



October 10-13, 2005



October 10-13, 2005

Scope (1)The low level RF controls system consists of RF phase and amplitude controls at these locations:

Laser

Gun (Klystron 20-6)

L0-A, a.k.a. L0-1 (Klystron 20-7)

L0-B, a.k.a. L0-2 (Klystron 20-8)

L0 Transverse cavity (Klystron 20-5)

L1-S (Klystron 21-1)

L1-X (Klystron 21-2)

L2 - (Klystrons 24-1,24-2,24-3) to control avg phase/ampl of L2

L3 Transverse cavity (Klystron 24-8)

L3 - 2 sectors of klystrons, S29+S30



October 10-13, 2005

Scope (2)



October 10-13, 2005

Requirements (1)

Meet phase/amp noise levels defined as: 0.1% rms amplitude

100 fs rms in S-band (fill time = 850 ns)

125 fs rms in X-band (fill time = 100 ns)

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 (L2 has 28; L3 has 48)



October 10-13, 2005

Requirements (2)Achieve 120 Hz feedback to maintain phase/amp stabilityWhen beam is present, control will be done by beam-based longitudinal feedback (except for T-cavs); when beam is absent, control will be done by local phase and amplitude controller (PAC)Adhere to LCLS Controls Group standards: RTEMS, EPICS, Channel Access protocol

Ref: Why RTEMS? Study of open source real-time OS

Begin RF processing of high-powered structures May, 2006



October 10-13, 2005

Design considerations

Through end of January 2005, various solutions were evaluated, from 100% COTS modules to hybrids of in-house designed boards.

By May 2005, the options were narrowed down to two: an Off-the-shelf solution and an in-house solution.



October 10-13, 2005

Evaluation (1)The off-the-shelf solution is:

Expensive ($25K per instance * 10 instances)

Noisy. ADCs are up to 150’ from what they measure so analog noise levels and ground loop problems would need to be dealt with

The in-house solution is: Possibly longer to develop due to board design and fabrication time



October 10-13, 2005

Evaluation (2)

Characteristics of the COTS solution were seen as requiring more effort than those of the in-house solutionPotential offered by the lower cost of the in-house solution to replace 250 klystron controllers in the remainder of the LINAC is attractiveHardware people were available as of 22aug2005 to work on board design if µcontroller was decidedTurned to the EPICS community for ideas and chose a µcontroller



October 10-13, 2005

Evaluation (3)

Lower cost alternatives to the $15K VME chassis and IOC were discussed in the session on hardware at the EPICS Collaboration Meeting. April 27-29, 2005

Of the options presented, only the Coldfire uCdimm 5282 processor had the communication speed and power to meet our data requirements. Cost is $150 per processor plus the development of the board it sits on



October 10-13, 2005

Evaluation (4)By choosing the Arcturus Coldfire uCdimm 5282 processor, we are able to make use of the port of the operating system, RTEMS, which has already been done.

RTEMS is the standard for the real-time operating system chosen for LCLS by the Controls Group

EPICS, the standard for the control system software for LCLS runs on RTEMS

With these choices, the LLRF control system will be fully integrated into the rest of the LCLS EPICS control system and can speak to other devices and applications such as control panels, alarm handlers and data archivers, using Channel Access protocol, the standard communication protocol for this project.



October 10-13, 2005

I and Q Demo-dulator

CPU

FIFOs

DAC

slow

Temperature monitors

EVR

VME Crate at S20

CPU

Laser and RF ref

L0-AL0-B

L1-SL1-X

T Cav

gun

Controls gigabit ethernet (interface to MCC)

Eth recvr

Private ethernet8 kBytes at 120 HzPAD

ADC

FPGADAC

1 trigger for 4

channels of 1k

samples

Private ethernet4 kBytes at 120 Hz

In-house modules sharing VME crate for timing triggers47

6 MHz

RF R

eferen

ce cl

ock d

istrib

uted t

o all 3

0 sec

tors i

n the

Lina

c and

beyo

nd

RF Reference/4 = 119 MHzstabilized to 50 fs jitter

RF Reference*6 = 2856 MHzstabilized to 50 fs jitter

Coldfire CPU

running RTEMS

and EPICS

Coldfire CPU

running RTEMS

and EPICS

Global longitudinal beam-based

feedback VME crate

PAC

RF Phase and Amplitude correction at 120 Hz for:laser, gun, L0-A, L0-B, L1-S, L1-X, T cav

10' accelerator

IQ Modulator gives phase

and amplitude control

1 kW 1 kW

Solid State Sub Booster

Klystron

SLED cavity

60 MW

HPRF240 MW

60 MW

1 kW

All except laser RF

100 mW

119 MHz Laser

Oscillator

Amps

GunNB: For the gun, SLED

cavity is shorted out

119 MHz120 Hz

UV

photodiode

photodiode

1 trigger to travel up to ½ sector

away

Beam-based longitudinal

fast feedback gigabit

ethernet

DAC

slow

VME Crate for longitudinal,

beam-based feedback

System Drawings (1)



October 10-13, 2005

I and Q Demo-dulator

CPU

FIFOs

DAC

slow

Thermocouple system

EVR

VME Crate at S24

CPU

Controls gigabit ethernet (interface to MCC)

Eth recvr


PAD

ADC

FPGADAC

1 trigger for 4

channels of 1k

samples


In-house modules sharing VME crate for timing triggers47

6 MHz

RF

Refer

ence

cloc

k dist

ribute

d to a

ll 30 s

ector

s in t

he Li

nac a

nd be

yond

RF Reference/4 = 119 MHzstabilized to 50 fs jitter

RF Reference*6 = 2856 MHzstabilized to 50 fs jitter

Coldfire CPU

running RTEMS

and EPICS

Coldfire CPU

running RTEMS

and EPICS

L2: in sector 24, there are 3 stations to adjust in order to accurately control phase and amplitude for long, beam-based

fast feedback

PAC

Sector 25 T Cav (L24-8)

RF Phase and Amplitude correction at 120 Hz for:L2, S25 Tcav and L3

10' accelerator

IQ Modulator gives phase

and amplitude control

1 kW 1 kW

Solid State Sub Booster

Klystron

SLED cavity

60 MW

HPRF240 MW

60 MW

1 kW

100 mW

NB: For the gun, SLED cavity is shorted out

1 trigger to travel up to ½ sector

away

Beam-based longitudinal

fast feedback gigabit

ethernet.Setting only

L24-1

L24-3L24-2

S30

S29

DAC

slow


beam-based feedback

System Drawings (2)



October 10-13, 2005

Eth recvr

EVR

VME Crate at S20

CPU

CPU

Eth recvr

EVR

VME Crate at S24

CPU

PACGun

PADPADPAD

PAC

RF Dist’n

Laser

PACL0-B

PADPAD

PACL1-S

PADPAD

PACL0-Tcav

PADPAD

PACL0-A

PADPAD

PAC

PAD

PAD

PACL1-X

PADPADPAD

PAC

L24-1

PAC

L24-2

PAC

L24-3

PAC

Tcav L24-8

PAC

S29

Overview of RF Phase and Amplitude correction at 120 Hz for LCLS LINAC

PAC

S30

PACPAC

PAC

PAC

PAD

PADPAD


beam-based feedback

Total number of Coldfire processors: 37Total number of PACs: 18Total number of PADs: 19

Total number of VME crates: 3

System Drawings (3)



October 10-13, 2005

How this fits into global feedback (Gun)

TOROID

BUNCH CHARGE

BEAM PHASE CAVITY

GUN RF FEEDBACK

InputsGUN-CELL1-PHAS/AMPLGUN-CELL2-PHAS/AMPL

ActuatorsGUN RF ACTUATORS

2856MHz R ef

GUN RF ACTUATORS

LCLS RF Oscilla tor

LINAC MDL Ref.

PHAS

GUN RF REF.

LASER RF R EF.

PHAS AMPL

PHASEERROR

ActuatorL0, L1 to L2, L3Phase

AMPL

GUN-CELL2

GUN-CELL1

KLYSTRONAMPLIFIER / SLC CONTROL

LASER OSC

Reference

LASER OSC. PHASE

WATER TEMP

RF GUN

LASER PHASE ACTUATOR

LASER POWERACTUATOR

OUT

2856MHzRF REF.

LASER

GUN

L0A

L0B

L1-X

L1-S

GUN TUNE FEEDBACK

InputsGUN-FOR-PHASGUN-CELL1-PHASGUN-CELL2-PHAS

ActuatorsWATER TEMP

GUN-FOR

LASER OSCILLATOR PHASEand LASER POWERFEEDBACK

InputsLASER OSC. PHASEBUNCH CHARGEGUN-CELL1-AMPL/PHASGUN-CELL2-AMPL/PHASLASER PHASE & AMPLITUDEGUN RF ACTUATORSBEAM PHASE CAVITY

ActuatorsLASER POWERLASER PHASE ACTUATOR

PHASE ERROR BetweenL0, L1 and L 2, L3

LASER PHASE & AMPLITUDE?

LASER AMPLIFIER



October 10-13, 2005

How this fits into global feedback (L0)

L0B LOAD FOR

PHAS

L0B RF REF.

AMPL

L0B RF ACTUATORS

L0B

L0B THREET HERMOCOUPLEINPUTS

L0B-FOR


L0A RF ACTUATORS


L0A R F REF.

L0A

L0 BUNCH ENERGYFEEDBACK

Inputs4 DL1BPMs: BPM10,11,12,13Laser phase, power

Matrixed Information DL1 Energy

Status inputs Flags for what is broken

ActuatorsL0 AMPLITUDE

L0A RF PHAS/AMPL0B RF PHAS/AMP

DL1 BPM 13X Position




L0B RF Feedback

InputsL0B-FOR PHAS/AMPLL0B-LOAD FOR PHAS/AMPL3-THERMOCOUPLES

ActuatorsL0B RF PHAS/AMPL

L0A-FOR

L0A LOAD FOR

L0A T HREETHERMOCOUPLE INPUTS

L0A R F Feedback

InputsL0A-FOR PHAS/AMPLL0A-LOAD FOR PHAS/AMPL3-THERMOCOUPLES

ActuatorsL0A R F PHAS/AMPL

AMPLPHAS



October 10-13, 2005


L1D THREET HERMOCOUPLEINPUTS

L1X-FOR

L1X T HREE THERMOCOUPLEINPUTS

PHAS AMPL

L1 RF ACTUATORS

L1 RF REF.

L1 BUNCH ENERGY/LENGTHFEEDBACK

Inputs4 DL1BPMs: BPM10,11,12,133 BC1BPMs: BPMA12,BPMS11,

BPMM12Toroid atBC1: IMBC1OBLM atBC1: BLM11 Laser phase, power

Matrixed Information DL1 EnergyBC1 Energy and Bunch Length


ActuatorsL1 RF PHASL1 RF AMPL

L1C THREET HERMOCOUPLEINPUTSL1B THREET HERMOCOUPLEINPUTS

L1X R F Feedback

InputsL1X-FOR PHAS/AMPLL1X-LOAD FOR PHAS/AMPL3-THERMOCOUPLES

ActuatorsL1X R F PHAS/AMPL



L1X RF ACTUATORS

AMPLPHAS

L1X R F REF.

L1B-FOR

L1C LOAD FORL1C

L1XL1X LOAD FOR

L1S R F Feedback

InputsL1B-FOR PHAS/AMPLL1B-LOAD FOR PHAS/AMPLL1C-LOAD FOR PHAS/AMPLL1D-LOAD FOR PHAS/AMPLL1B 3 THERMOCOUPLESL1C 3 THERMOCOUPLESL1D 3 THERMOCOUPLES

ActuatorsL1 RF PHAS/AMPL

L1D LOAD FOR

BC1 BPMM12X Position

BC1 BPMS11X Position

BC1 BPMA12X Position

L1D

BC1BUNCHLENGTHL1B LOAD FOR

L1B



October 10-13, 2005


L2 24-1

L2 24-1 RF ACTUATORS

PRL RF

PHAS AMPL


L2 24-2 RF ACTUATORS

L2 24-2


AMPLPHAS

PRL RF

L2 BUNCH ENERGY/LENGTHFEEDBACK


BPMM123 BC2BPMs: BPM24401,

BPM24701,BPMS21Toroid atBC1: IMBC1OToroid atBC2: IMBC2OBLM atBC1: BLM11 BLM atBC2: BLM21Laser phase, power

Matrixed Information DL1 EnergyBC1 Energy and Bunch Length BC2 Energy and Bunch Length


ActuatorsL2 PHASE AND AMPLITUDE

L2 24-1 R FPHAS ACTUATORL2 24-2 R FPHAS ACTUATOR

BC2 BPM24401X Position

BC2 BPM24701X Position

BC2 BPMS21X Position

BC2 BUNCHLENGTH



October 10-13, 2005


DL2 BPMDL3X Position

PRL RF

L3 BUNCH ENERGYFEEDBACK


BPMM123 BC2BPMs: BPM24401,

BPM24701,BPMS212 DL2BPMs: BPMDL1,BPMDL3Toroid atBC1: IMBC1OToroid atBC2: IMBC2OBLM atBC1: BLM11 BLM atBC2: BLM21Laser phase, power

Matrixed Information DL1 EnergyBC1 Energy and Bunch Length BC2 Energy and Bunch LengthDL2 Energy


ActuatorsL3 AMPLITUDE

SECTOR 29PHAS ACTUATORSECTOR 30PHAS ACTUATOR

DL2 BPMDL1X Position

8 KLYSTRONAMPLIFIER / SLC CONTROL

SECTOR 29 PHASE ACTUATOR

PRL RF

8 KLYSTRONAMPLIFIER / SLC CONTROL

SECTOR 30SECTOR 29

SECTOR 30PHASE ACTUATOR



October 10-13, 2005

How this fits into global feedback

*These 10 sectors*8 klystron values are available from the SCP, but may be impossible to read @ 120 Hz. We could provide the corrected values @120 Hz.

L3 RF phase*L3 RF amplitude*

L2 RF phase*L2 RF amplitude*

BC-2 energyBC-2 bunch length

LIST OF AVAILABLE PARAMETERSupdated at 120 Hz unless specified otherwise

Laser phaseLaser powerGun RF phaseGun RF amplitudeGun chargeBeam phaseL0A RF phaseL0A RF amplitudeL0B RF phaseL0B RF amplitudeDL1 energyL1 RF phaseL1 RF amplitudeL1-X RF phaseL1-X RF amplitudeBC-1 energyBC-1 bunch length

DL2 energy



October 10-13, 2005

ConclusionsThis solution:

corrects the phase and amplitude of the RF at 120 Hzwhen there is beam, this system will integrate with the beam-based longitudinal feedback by accepting the latter’s RF phase and amplitude corrections and passing them on meets the spec for speed and noise avoids signal noise and ground loop problems meets LCLS control system requirements and standards running EPICS on RTEMS provides a low cost path for future upgrade in the rest of the LINAC when the rest of the klystron control is replaced

Documents

LLRF Control System