LLRF FOR CHOPPERGrégoire HagmannPhilippe BaudrenghienBE/RF/FB

February 24th, 2013

LLRF Linac 4, G.Hagmann 2

Block Diagram

Chopping «pattern»

• Plates delay adjustment• Monitoring (Waveform & chopping time)• Interlocks

LLRF Linac 4, G.Hagmann 3

Location “CDU”

Rack AY01

LLRF Linac 4, G.Hagmann 4

Rack AY01• BIS cables arrivals• Need of space for

transition patch panel : 2U

• Need 1U Beam permit patch=>TE/MPE/EP

• Need 1U User permit parchWho? BE/RF or TE/MPE?

• Position for BIS patch-panels?DRAFT

Transition patch neededNo Burndy on VME board

LLRF Linac 4, G.Hagmann 5

Chopper Limitations• Max Chopper pulse length : 500us (programmable)• => need monitoring (start counter at “source on”)• => Drive off when “source off”• => Drive off when >500us (timeout) from “source on”• => What if timeout? Alarm? User Permit False? OP action?

<500us

LLRF Linac 4, G.Hagmann 6

Ring blankingDiscussion with A.Blas• Compatible with booster?

(Magnetic compensation in RF lowlevel…)• Reaction time for ring interlock?

LLRF Linac 4, G.Hagmann 7

Ring blankingDuring the Linac 4 pulse (window), Can one ring be inhibited?And does it need immediate action?If YES :→ “Dynamic” Ring blanking→ Need timing ring identification→ Need 1 chopping pattern table per ring→ Need accurate HW timing(s) for re-synchronization

If NO :Can 1 ring interlock be interpreted like a change in nb of turn of the ring?If YES:

→ High level software re-compute chopping pattern (new settings)→ Load of the new chopping pattern and played for next cycle/user

If NO:→ No change in chopping pattern table→ Need ppm information for which ring are “played” (Timing or with Software)

LLRF Linac 4, G.Hagmann 8

L4-Booster synchronizationBeam must be chopped during the 1us PSB ring change

References document : • Synchronization between Linac4 and the PS Booster

CERN-ATS-Note-2010-052

2 solutions :• Synchronization for every Ring

• “Dynamic” ring blanking feasible• Accurate synchronization signals => accuracy?• 1 “pattern” table for every ring• Table switching

• 1 single synchronization after “Source On” timing start• No “Dynamic” ring blanking (or more complex => to be studied)• 1 accurate synchronization signal• 1 “pattern” table for all rings• No distinction if 1 or more ring => “just” one chopping pattern

RF frequencies (L4 & booster) stability?

RF Linac4

HW timing

Tr << TRF

TRF ≈ 2.84ns

LLRF Linac 4, G.Hagmann 9

L4-Booster synchronization3 Proposals :

Re-synchronization for every ring (Meeting Dec 16th 2011)• 4 timings CTRV (next Ring identifier)

• 1 accurate HW timing at every ring start• Dynamic ring blanking feasible• Safer, consistency between Chopper and PSB

injection Distributor

• 1 timings CTRV (source on)• 1 accurate HW timing at the window start (linac 4 pulse)

• 1 pattern table for 4 rings• No Dynamic ring blanking• Need new setting (at the next cycle) for new pattern

• 4 accurate HW timings, 1 per ring (ring start)• Dynamic ring blanking feasible• HW More complex, More cabling

LLRF Linac 4, G.Hagmann 10

L4-Booster synchronizationexemple

• 4 timings CTRV (next Ring identifier)• 1 accurate HW timing at every ring start

• Dynamic ring blanking feasible• Safer, consistency between Chopper and PSB

injection Distributor

Ring 1 start

HW timing

Ring 2 start

Ring 3 start

Ring 4 start

LLRF Linac 4, G.Hagmann 11

CDU details

LLRF Linac 4, G.Hagmann 12

CDU details

Monitoring, Gating, etc.

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LLRF Linac 4, G.Hagmann 13

CDU details• VME board “RF” type• BIS input & output on LEMO

• EPG.0B.304.HLN (or similar)• XXX.1B.308.XXX

• RF Interlock• 1 interlock or 2 interlocks (1 per chopper) ?• From AY01• Optical, Multi-mode, ST • Same for cavity-controller PIMS, CCDTL…)

• TX pulses monitoring• Veto• Diagnostics

LLRF Linac 4, G.Hagmann 14

BIS «gating»BEAM INTERLOCK SPECIFICATIONS FOR LINAC4, TRANSFER LINES AND PS BOOSTER WITH LINAC4 (L4-CIB-ES-0001 rev.0.3) :

Þ Gating with timing from BE/CO (CTRV) ?Þ Fail safe?Þ Gating rather in the BIS than CDU ?Gating ON

BIS event Latched

Gating OFFChopper forced OFFBIS even unlatched

LLRF Linac 4, G.Hagmann 15

New special «BI» timing• Addition of a new «CTRV like» timing feasible• Not fail safe

• 2 solutions:• Implemented HW similar to the BIS signal

• => Fixed implementation• => Simple functionality• => “Robust”• => Timing always needed

• Through FPGA• => Flexible implementation• => Complex functionality possible

• Timing Hardware?

LLRF Linac 4, G.Hagmann 16

New special «BI» timing

Chopper ON Chopper OFF

Chopper ON (latched)

LLRF Linac 4, G.Hagmann 17

RF Interlock

HFBR-1414

« Phoenix contact » module open (example of a design)

« Phoenix contact » module closed

Power side (PLC) :

LowLevel side :• ST optical receiver on CDU board• By-pass input foreseen for “debug & tests”

LLRF Linac 4, G.Hagmann 18