contents 1 – introduction project summary recent activities

“Status of the PS B-train upgrade”Machine Studies Working Group, 20.06.2014 [email protected]

/28 MAGNETIC MEASUREMENT LABORATORY cern.ch/mm

Contents

1 – IntroductionProject summary Recent activities

2 – Current statusPrototype hardware and softwareOther test facilities

3 – Planned activitiesDevelopment and characterization of the prototype system

4 – Next stepsFurther accuracy improvementDeployment to other machines

Status of the PS B-train upgradeM Buzio, D Giloteaux, D Oberson (TE/MSC/MM)

mailto:[email protected]



Acknowledgment

• Thanks to S. Gilardoni (BE/ABP), R. Steerenberg and the whole PS operation team (BE/OP) for motivating the B-train upgrade project and supporting the necessary tests

• Thanks to F. Caspers (BE/RF) for his essential support towards FMR development

• Thanks to H. Damerau (BE/RF), J. L. Gomez Costa, Q. King (TE/EPC), P. Odier, L. Soby (BE/BI), J. Serrano (BE/CO) for their collaboration towards the definition of the new serial distribution link

• Thanks to A. Beaumont, D. Bodart, G. Golluccio, O. Dunkel, L. Gaborit, P. Galbraith, R. Beltron Mercadillo (TE/MSC) for their technical and scientific contribution to the project




Introduction




History recap

2000 Current Mark III electronics installed and maintained by P. Dreesen and his team (TE/EPC). This system uses pick-up coils in both F/D halves of U101, but peaking strip markers only in F

2006 TE/MSC/MM takes on responsibility for real-time magnetic measurement systems

2011 Mark IV B-train upgrade project green-lighted by IEFC

Hardware R&D2008 NMR marker @ 60 mT with passive ferrite gradient compensation2010 Omni-Yig polycrystalline FMR2011 Off-line diagnostic “spy” system2012 5x pick-up coil array for multipoles

Beam instability investigations2010 14 mm MRP oscillation after I8 on zero cycles linked to undetected F/D imbalance2011 Bdot noise linked to the initial lack of filters to GND for POPS2011 Instability at injection on the 2nd CNGS cycle only after low-energy cycles2012 Tune decay @ 26 GeV linked to 50 ms quadrupole eddy-current field decay 2014 Identification of the source of A3 in the bare machine (ongoing)




Functional specificationsWhy to build an upgraded system for the PS ? Improvements are needed along three axes:• Reliability

new markers as a long-term alternative for difficult-to-replace peaking strips reduction of down time due to timing conflicts

(synchronization between peaking strip window and current cycles; internal integrator recalibration)

more robust signal transmission remote diagnostics

• Operational flexibility sensors in both F/D halves to recover full information mitigate B-train errors due to the imbalance induced by specific operation sequences that today are best avoided

(e.g. F8 degaussing cycles, certain combinations of cycles) allow higher flat-bottoms and thus shorter cycles

(NB: the current very low 5 mT value is imposed by the peaking strips !) remote switching between OP and SPARE chains

• Precision and accuracy 5 µT resolution (currently limited by the repeaters)

more accurate integration, drift correction more flexibility in the calibration and in adapting to new operation modes




Mark IV B-train

Main design choices:

1. Modern electronics (integrator, marker trigger generator) based upon CERN-supported solutions (Industrial PICMG1.3 PC + SPEC PCIe carried card + FMC mezzanine)

2. Software compatible with accelerator control systems (CERN Scientific Linux + FESA)

3. Field markers based on commercially available components (FMR resonator / NMR probes)

4. Optical-fibre serial transmission of numerical measurement results(OpenHardware White Rabbit)

5. New timing-independent, streaming integration and drift/gain correction algorithms




N different marker levels up to 4 N corrections per cycleCorrections smeared over a certain t to avoid sudden jumps

ADC offset ( integrator drift) updated every time the same marker level is reached

Integrator gain error updated every time a different marker level is reached

𝐵=𝐵0+𝑎∫0

𝑡

(1+𝜀(𝑡 ))(𝑉 (𝑡 )−𝑉 0(𝑡)¿)𝑑𝑡 ¿

t1low time

B

t2low t1

hi t2hi

field markers

ܤ

ܤ ௪

New concept: continuous digital distribution of B(t) on a fast serial line to replace old pulse train• Output stream continuously updated with current B(t) values

no need for complex triggering and reset logic; no B0 initialization burst• Adaptive auto-calibration of gain and offset using field markers on flat-top and flat-bottom

fully transparent correction of measurement error

fast and robust transmission, no more timing conflictsbut: drift correction must be applied continuously on-the-fly

Streaming integration




Mark IV B-train

Staged roll-out proposal:

Mark IV.0 (prototype) – 2014/2015

Mark III in // to prototype electronics/firmware + 2× FMR markers

Mark IV.1 – 2015:

Mark III in // to pre-series electronics + new sensors (high field markers, advanced coil arrays)

Mark IV.2 – around LS2 ?

Drop Mark III, production electronics + integral coils




Current Status




Mark IV.0 – Prototype electronics in U101

2× AnaPico 20 GHz signal generators for F,D FMR (local frequency setting only)

Front End industrial PC

Switching chassis - simulated/measured B-train (based on POPS being on/off)- OP/SPARE B-train (HW signal from CCC)

B-train chassis including: 8-page multi-function display,analog and digital I/O, RF amplifier, power supplies

New high quality PFW/I8 DCCT outCourtesy O. Michels

OP

syst

emSP

ARE

syst

em

SPEC FMC 2-ch. integrator card- “classic” integration reset at c0 + weighted sum of F/D integrals- basic offset correction- software-configured ADC/preampli calibration with internal voltage reference, automatically due during zero cycles (NB yearly offline calibration still necessary)

SPEC FMC 2-ch. marker card- trigger generation with high-Q FMR- trigger generation with NMR all functionality

quoted tested Commercial White Rabbit switch




White Rabbit distribution• All cabling + spares in place • Broadcast mode with two switches tested @ 250 kHz (50 design target, 300 theoretical max.)

first test results: 5.6 µs latency seen by POPS receiver • P.C. broadcast internally measured current 1 kHz, 1% on-the-fly B(I) simulation for:

- timing-independent marker trigger enable- telegram-independent cycle recognition- internal diagnostics and alarms- simulated B-train in case of measured B-train failure (?)

Tx testsOK

lab testsOK

planned:same as POPS

In operationImplemented now Large headroom for expansion




peaking strips

fluxloops

peaking strips

fluxloops

FMR LO FMR LO

prototypeharmonic

array

Mark IV.0 (currently installed) – Sensor configuration

Mark IIIB-train

Mark IVB-train

Aim:

• characterise hardware components, firmware algorithms and WR communications• obtain same functionality as Mark III (integrator reset @ c0) with maintainable electronics/markers• verify the advantages of a second 60 mT marker in F half

B-UP

B-DOWN

001011011011100




Recap: NMR vs. FMR markers

100 T

FMR

Sensor output during a field ramp in “marker mode” (fixed frequency excitation)

10 T

NMR

Marker NMR

•absolute reference (metrological standard)•commercially available instrument

•Requires B compensation• limited ramp rate: 20 to 50 mT/s•B43 mT

FMRsingle-crystal

•works up to several T/s•simple direct acquisition of the resonance•commercially available sensor• larger dynamic range for a given sensor (current unit: 60-300 mT)

•B60 mT •broader resonance peak •needs complex calibration• temperature-dependent (must be optimized for a target field)




Metrological characterization of FMR field marker

Calibration of a factory-optimized Noryl-case resonator in a reference dipole vs. NMR:• DC reproducibility: 0.04 G over the range 550 to 1200 G• Ramp reproducibility: 0.1 G @ 600 G, 2.4 T/s• Temperature dependence: 0.04 G/C (2C in U101 close to tolerance !)• Roll angle dependence: 0.04 G/mrad @ 600 G; non-linearity vs. B disappears at certain angles

very difficult to use in teslameter mode; strict mechanical tolerance in marker mode• Resonance spread due to B: still very good Q1000 at B/B=4.6 m-1 (as in U101)

ramp-rate dependence reproducibility non. linearity error vs. B, roll angle

nominal horizontal mounting




Spy system

• System ready to resume (after disk clean-up)• New high-quality F8 + PFW current readout from DCCT

(courtesy of O. Michels) still to be cabled and tested

• Based on National Instruments hardware: PXIe chassis, RT controller, 2 6366 DAQ cards (82 MHz parallel 16-bit channels + 3210MHz digital I/O channels)

• Acquisition of all sensors and B-train signals • Introduced in 2010 to track the magnetic state in F/D halves • Used to check the consistency of sensor and B-train signals,

timing and currents• Testbed for the design of new sensors and acquisition

algorithmsCurrents: Imain, IF8L, 8 × IPFW

Flux coils: 3 × F + 3 × DPeaking strips: 3 × F + 3 × D

Peaking strip currents: 3 × F + 3 × DNMR/FMR marker

Distributed Bdot: 2 × channelDistributed B-trains: 2 × channel (up + down)

Cycle/Supercycle timing signals

analog signals

digital signals




B-train test bench

• Test bench equipped with a dipole magnet ramping up to 10 T/s, FGC2 power supply• New RP zone in I8 being set-up, expected in operation this summer• Aim:

- calibration of FMR markers vs. a combination of NMR marker + flux loop (mini B-train)- stand-alone test bed for B-train electronics/algorithms- stand-alone test bed for FGC3 control algorithms and NMR readout software (with TE/EPC)

• Upcoming test campaigns:- calibration of single-crystal FMR markers (one installed, 4 additional units in stock)- characterization of upcoming high-field and polycrystalline FMR markers

Test dipole

NMR probe

FMR resonator

scanning supportnetwork analyzer NI PXI ADC

NMR teslameter

frequency synthesizer




Planned activities




What’s next

1. Finalization and debugging of the firmware/VHDL/Linux device drivers• Communication with CCC via FESA: develop the classes discussed with OP team• Integrator: VHDL timing registers to check and control + DMA transfer data• Local FMR frequency control • Dynamic (smoothed) adjustment of the integrator offset/gain upon reception of marker triggers • Etc. etc. …

2. Component-level tests• Drift error statistics vs. machine cycles, ambient conditions definition of marker levels,

frequency of correction etc ..• White Rabbit communication to/from all users

3. Offline system-level tests• Mark IV = Mark III using same sensors (coils + 1x peaking strip in F)• Mark IV ≥ Mark III using augmented sensors (coils + 2x peaking strips in F/D)• Mark IV ≥ Mark III using new sensors (coils + 2x FMR in F/D)

compare repeatability of FMR vs. P.S./beam as a function of cycling, ramp rate, temperature …

4. Online system-level tests• run the machine with the Mark IV system




Recap: magnetic length

• In the “hard edge” model, the magnetic length is used to express integrated strength as a function of central field

• LmLiron core (the = holds for permanent magnet arrays)• as used by many codes (e.g. MAD), the choice of Lm is

largely arbitrary as long as the correct integral results• typically, in short magnets saturation affects the ends

more than the center Lm(I) drops at high field

0.990

0.995

1.000

1.005

1.010

1.015

1.020

0 50 100 150 200 250

I [A]

BdLB0

Tran

sfer

func

tion

norm

alize

d @

130

A

saturation

𝓁𝑚(𝐼 )= 1𝐵0(𝐼 )

∫−∞

∞

𝐵 ( 𝐼 ,𝑠) 𝑑𝑠

B0

815

816

817

818

819

820

821

822

823

0 50 100 150 200 250Lm

[mm

]

I [A]

High field - saturation

Low field - linear range




B-train calibration

∫𝑜𝑛𝑒𝑚𝑎𝑔𝑛𝑒𝑡

𝐵 (𝑡 , 𝑠 )𝑑𝑠=𝓁𝑚 ( 𝐼 (𝑡 ) )𝐵 (𝑡𝑜 ,𝑠𝑚 )+𝓁𝑐 ( 𝐼 (𝑡 ) )∫𝑡 𝑜

𝑡

𝐵 (𝜏 ,𝑠𝑐 )𝑑𝜏

• Mark III: calibration depends upon the position of coils and peaking strips and is built-in in the coil surface areas and peaking strip excitation currents – the results is rigidly fixed (NB: the installed flux loop take practically a point-like measurement)

• Mark IV: flexible system takes into account explicitly the relationship between local and integral field values vs. current (also cycling, ramp rate …)

• Calibration coefficients λm, λc for all markers and coils can be computed/measured in U17/obtained from comparison vs. beam energy

∮𝑎𝑙𝑙𝑟𝑖𝑛𝑔

❑

𝐵 (𝑡 ,𝑠 ) 𝑑𝑠=100 ⟨𝓁 ⟩[𝜆𝑚 ( 𝐼 (𝑡 ) )𝐵 (𝑡𝑜 , 𝑠𝑚 )+𝜆𝑐 ( 𝐼 (𝑡 ) )∫𝑡 𝑜

𝑡

𝐵 (𝜏 ,𝑠𝑐)𝑑𝜏 ]marker position coil position

average field measured by the B-train

average magnetic lengthof one unit

“implicit” user factor




High-field marker

• Recent tests for MedAustron B-train evidence clearly that the magnetic length is much more history-dependent at low than high field increased precision by marking at the flat-top for drift correction

• To be evaluated: trade-off with larger integrator drift during ramp-up • To be evaluated: trade-off with smaller dynamic range for gain correction (mid-level marker is best ?)

Courtesy G. Golluccio




High-field FMR

• High field marker is beneficial for accurate drift correction, essential for gain correction• Current units are limited about 9 GHz @ 28 GHz/T 0.3 T • Range of peak field of interest: 1.26 T (PS) to 2.02 T (SPS) 34 to 57 GHz !! • Single-crystal units in the 20-30 GHz range being manufactured by OmniYig• … rather expensive test equipment to be procured …

Network Analyzer for characterization and calibration

Programmable Frequency Synthesizer + RF amplifiers for operation in marker (fixed-frequency) mode




Field harmonics in bare magnet @ injection

• First-time high-precision harmonic measurements vs. I(t)(B1-B15, A1-A15, magnetic axis, field direction)

• Tests to be carried out on U17 in bldg. 150 with a 34 × 750 mm quadrupole-compensated rotating coil

• Locally available power supply has acceptable stability up to about 600 A (1500 G)

• Caveat: reconstructing a meaningful integral inside a curved magnet requires very accurate position measurements and mathematics still under development …

Stepwise measurements centred in all blocks in sequence




Further developments




peaking strips

fluxloops

peaking strips

fluxloops

FMR LO FMR LO

rectangularharmonic

array

Mark IV.1 – Sensor configuration

Mark IIIB-train

Mark IVB-train

NMR NMR

FMR HI FMR HIrectangularharmonic

array

Aim:• enable faster/magnetically more stable operation with 60 mT flat-bottom cycles (Mark IV only)• improve accuracy:

- streaming integration i.e. continuous drift correction for true machine timing independence- high field FMR markers for relative gain calibration- NMR markers for absolute gain calibration- new rectangular harmonic PCB coil array for well-conditioned field harmonic integration- more sensors to capture eddy current effects/saturation in the end regions ( additional, independent integration channels)

B-UP

B-DOWN

001011011011100




FMR LO

Mark IV.2 – Sensor configuration

Mark IVB-train

NMR NMRFMR HI FMR HI

10 × rectangularharmonic arrays

FMR HI FMR HI

Ideal final configuration:• drop all legacy sensors and electronics• free pole gap to fit in integral coils + multiple markers in the linear/saturated regions

for best possible integral accuracy

FMR LOFMR LO FMR LO

001011011011100




CERN-wide deployment plan

• Approved/budgeted: PS, PSB, ELENA• In all cases: existing systems to be tested in parallel with new one• All necessary resources (esp. manpower) not allocated yet

Machine Ref.

Magnet Marker Users Demands Project

approved

LEIR 2 × MB in the ring

pre-set RF Only in case of new project

No

PSB 1 × MB NMR RF, PC

diagnostics Operational

after LS2 (2019) Yes

PS U101 peaking

strips RF, PC

diagnostics Operational

asap Yes

SPS 1×MBA 1×MBB

NMR (not in use)

RF Re-introduction of NMR

marker (some PPM after LHC) No

AD 1 × MB

in the ring NMR

(not in use) -

Useful for occasional recalibration

No

ELENA 1 × MB NMR RF, PC Operational

01/2016 Yes




Conclusions

• Getting closer to initial goal i.e. future-proof alternative to existing B-train • Lots of potential for improving dramatically accuracy and extending the benefits to other machine• Work more difficult than anticipated, lack of manpower• To be circulated for approval/published:

- detailed list of signals to be exchanged with CCC via FESA (or Oasys)- detailed test time requirements (in the shadow of operation / MD time)- functional and engineering specifications

• Electronics and technical design details + test results will be presented later in the year


contents 1 – introduction project summary recent activities

Documents

btrain errors

ps btrain upgradem buzio

ps operation team beop

peaking strip markers

peaking stripsreduction

acknowledgment thanks

peaking strip window

machines status