LCLS-II 1.3 GHz CM Demagnetization & Active Cancellation - - PowerPoint PPT Presentation

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LCLS-II 1.3 GHz CM Demagnetization & Active Cancellation - - PowerPoint PPT Presentation

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LCLS-II 1.3 GHz CM Demagnetization & Active Cancellation Saravan K. Chandrasekaran Technical Review Meeting for BCR May 25, 2016 Outline Introduction Previous work Residual magnetic fields and Q 0 pCM test plan for

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LCLS-II 1.3 GHz CM Demagnetization & Active Cancellation

Saravan K. Chandrasekaran Technical Review Meeting for BCR May 25, 2016

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Outline

  • Introduction

– Previous work – Residual magnetic fields and Q0

  • pCM test plan for demagnetization & active cancellation

– Understanding till now, & what remains to be understood

  • Production demagnetization & active cancellation coil

– Proposed design of coils and connectorization – Cost summaries for different options – Need-by schedule

  • Operational modes

– Information for SLAC controls

5/25/2016 S.K. Chandrasekaran | LCLS-II CM Demag & Active Cancellation Tech. Review 2

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Outline

  • Introduction

– Previous work – Residual magnetic fields and Q0

  • pCM test plan for demagnetization & active cancellation

– Understanding till now, & what remains to be understood

  • Production demagnetization & active cancellation coil

– Proposed design of coils and connectorization – Cost summaries for different options – Need-by schedule

  • Operational modes

– Information for SLAC controls

5/25/2016 S.K. Chandrasekaran | LCLS-II CM Demag & Active Cancellation Tech. Review 3

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Magnetic scope, specifications & sources

  • First large CW project where magnetic shielding being analyzed

stringently, especially longitudinal component of magnetic field

– Bavg ↓ → Rs ↓ → Q0 ↑ → Pdiss↓ → $oper ↓

  • LCLS-II specification [1]:

– Bavg<5 mG to reach Q >2.7E10 at 2 K, 16 MV/m

  • Major magnetic field sources: vacuum vessel, components, earth

– Bvessel< 3 G [2] – Bcomponents~ 1 G – Bearth≈ 483 mG at SLAC [3] – B//,beamline≈ 150 mG

  • Most analyses done assuming SLAC tunnel magnetic fields

5/25/2016 S.K. Chandrasekaran | LCLS-II CM Demag & Active Cancellation Tech. Review 4

[1] “1.3 GHz Superconducting RF Cryomodule,” Functional Requirements Document, LCLSII-4.5-FR-0053. [2] A. Crawford, arXiv:1507.06582v1. [3] National Oceanic and Atmospheric Administration, 2014--2019 World Magnetic Model.

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Trapped Magnetic Flux & Q0

  • Smaller ambient magnetic fields beneficial

– For high Q & for low flux expelling material

  • Q0>3 x 1010 may be realized for trapped B<3 mG

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↓B  ↑ ↑Q0

  • M. Martinello et al., IPAC 2016
  • S. Posen et al., arXiv 2016
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Benefits of degaussing vessel [4,5]

  • Vessel must be degaussed

after final handling

– Fields in steel could be ~200 G when exposed to ~500 mG

  • Edge ~factor of 3 reduction
  • Central ~factor of 2 reduction

5/25/2016 S.K. Chandrasekaran | LCLS-II CM Demag & Active Cancellation Tech. Review 6

[4] A. Crawford, arXiv:1409.0828v1. [5] A. Crawford, arXiv:1503.04736v1.

  • Expt. With B// ≈50 mG
  • 400
  • 300
  • 200
  • 100

100 200 300 400 1 2 3 4 5 6 7 8 9 10 11 B [milligauss] Z [meters] Bz Pipe Before DeMag Bz Pipe After 600 A-Turns/m

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What Q to expect with & without demagnetization & compensation coils?

  • At 2 K, 16 MV/m
  • RBCS = 4.5 nΩ, R0 = 1.5 nΩ
  • Rs = RBCS + R0 + (Flux trap. sens. x Bavg)

5/25/2016 S.K. Chandrasekaran | LCLS-II CM Demag & Active Cancellation Tech. Review 7

Scenario Flux trapping sensitivity (nΩ/mG) Demag. & Comp. coil? Bavg (mG) Rs (nΩ) Q (x1010)

  • Oper. cost

(M$) ($100/MW-h) [13] Realistic 0.5 [10,11] No 15 13.5 2 4.6 Yes 3 7.5 3.5 <3.4 Conservative (100% trapping) 1.2 [12] No 15 24 1.1 >>5.7 Yes 3 9.6 2.8 3.5

[10] D. Gonnella et al., J. Appl. Phys. 117, 023908, 2015. [11] A. Grassellino et al., SRF proceedings, MOP028, 2015. [12] M. Martinello et al., SRF proceedings, MOPB015, 2015. [13] J. Theilacker, personal communication with A. Grassellino, 2015.

  • Q=3.5x1010  higher gradient operation possible
  • Q=1.1x1010  current cryoplant capacity insufficient
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Outline

  • Introduction

– Previous work – Residual magnetic fields and Q0

  • pCM test plan for demagnetization & active cancellation

– Understanding till now, & what remains to be understood

  • Production demagnetization & active cancellation coil

– Proposed design of coils and connectorization – Cost summaries for different options – Need-by schedule

  • Operational modes

– Information for SLAC controls

5/25/2016 S.K. Chandrasekaran | LCLS-II CM Demag & Active Cancellation Tech. Review 8

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Overview

  • Overall goal:

– Prove the importance of demagnetization & active cancellation systems to the performance of the cryomodules

  • Testing in three phases

– Phase I: Vacuum vessel only

  • pCM assembly schedule must be unaffected

– Phase II: Coldmass as it transitions into cryomodule

  • pCM assembly schedule must be unaffected

– Phase III: Cryomodule at CMTS

  • Data for production readiness review is priority
  • Cooldowns for understanding other systems/overall pCM beyond the

scope of this topic

5/25/2016 S.K. Chandrasekaran | LCLS-II CM Demag & Active Cancellation Tech. Review 9

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Phase I: Vacuum vessel (VV) only

  • Goal: Obtain data for the effects of physical

movement & transport on the residual magnetic field of the VV 1. Measure the remnant field inside VV 

a. Beamline, top & bottom equator locations

2. Wind coils to VV  3. Demagnetize VV  4. Measure the remnant field inside VV  5. Pick up VV, move inside building using crane, rotate 360°, set down where it was before  6. (If time permits) Transport VV on an air-ride  equipped flatbed truck for ~10 miles inside FNAL 7. Measure the remnant field inside VV  8. (If time permits) Test tune active cancellation coils

5/25/2016 S.K. Chandrasekaran | LCLS-II CM Demag & Active Cancellation Tech. Review 10

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pCM Vacuum Vessel Demagnetization

  • Wires wound onto the outer surface of vessel
  • Used Powerpole connectors to test them for use in the ‘belt’

type system

  • FNAL electrical standards determined size of wire

– NFPA-70 = AWG 6; FNAL = AWG 4 – Strand count not taken into consideration due to low duty factor – HI-POT testing of insulation required at FNAL after each move

  • f vessel with coils, or installation of coils if removed

5/25/2016 S.K. Chandrasekaran | LCLS-II CM Demag & Active Cancellation Tech. Review 11

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Results: VV demagnetization (B magnitude)

5/25/2016 S.K. Chandrasekaran | LCLS-II CM Demag & Active Cancellation Tech. Review 12

Bavgat cavities >500 mG ↓ <50 mG & uniform

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Results: VV demagnetization (B longitudinal)

5/25/2016 S.K. Chandrasekaran | LCLS-II CM Demag & Active Cancellation Tech. Review 13

Bz at cavities >300 mG ↓ <50 mG & uniform

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Effect of crane handling

  • Handling

– Lifted demagnetized VV using crane, moved within building while slung from crane, rotated 360°, set back down

5/25/2016 S.K. Chandrasekaran | LCLS-II CM Demag & Active Cancellation Tech. Review 14

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Effect of transport

  • Transport

– Set demagnetized VV on air-ride equipped, lowboy, flatbed truck – Drove within Fermilab for 10 miles, max. speed 30 mph

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Results: Effect of crane handling & transport

5/25/2016 S.K. Chandrasekaran | LCLS-II CM Demag & Active Cancellation Tech. Review 16

  • No change in magnetic field distribution within VV after

handling and transport experiments

  • Demagnetization may not be required after each move for

each CM

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Phase II: Coldmass as it transitions into CM

  • Goal: Obtain data with and without vessel

1. Measure magnetic field at cavities when coldmass attached to Big Bertha, before VV is slid on 

a. Fluxgates in longitudinal direction outside cavities’ helium vessel, & azimuthal direction inside cavities’ helium vessels

2. Re-measure magnetic field at cavities after VV slid on, and CM is formed

5/25/2016 S.K. Chandrasekaran | LCLS-II CM Demag & Active Cancellation Tech. Review 17

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Phase III: Cryomodule at CMTS

  • Goal: Prove effectiveness & need for demagnetized VV (dVV) & active

cancellation (AC) 1. Install CM at CMTS 2. Before cooldown, tune AC coils to obtain minimal longitudinal mag. field

a. Compare fields without & with AC – prove effective

3. Demagnetize VV/CM if deemed necessary 4. Cooldown (#1) with dVV, AC ON, fast cooldown (FCD)

a. Determine Q0 of cavities at nominal gradient b. Provide data for production readiness review, best case scenario

5. Cooldown (#2) with dVV, AC ON, slow cooldown (SCD)

a. Determine Q0 of cavities at nominal gradient b. Baseline for SCD, with best case magnetic fields

5/25/2016 S.K. Chandrasekaran | LCLS-II CM Demag & Active Cancellation Tech. Review 18

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Phase III: Cryomodule at CMTS

6. Warm-up, cooldown (#3) with dVV, AC OFF, FCD

a. Determine Q0 of cavities at nominal gradient b. Isolate contribution of un-cancelled longitudinal magnetic fields

7. Simulate non-ideal VV (non-dVV) 8. Warm-up, cooldown (#4) with non-dVV, AC OFF, FCD

a. Determine Q0 of cavities at nominal gradient b. Isolate contribution of VV demagnetization

9. Warm-up, cooldown (#5) with non-dVV, AC OFF, SCD

a. Determine Q0 of cavities at nominal gradient b. SCD with worst-case magnetic fields (at CMTS)

  • 10. Warm-up, non-dVV, AC ON

a. Determine if non-dVV longitudinal field can be cancelled b. Transverse field still remains

5/25/2016 S.K. Chandrasekaran | LCLS-II CM Demag & Active Cancellation Tech. Review 19

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pCM understanding

  • Proven:

– LCLS-II 1.3 GHz VV has varying magnetic fields (>500 mG) in as-received state – VV can be successfully demagnetized – Demagnetization after each move may not be needed

  • Yet to be proven:

– Beneficial effects of demagnetization on Q0  pCM tests – Beneficial effects of active cancellation on Q0  pCM tests – No detrimental effects on other components within CM

  • First measurements by A. Crawford in 2014 indicate no effects
  • Tuner motor, piezo, instrumentation being checked again

5/25/2016 S.K. Chandrasekaran | LCLS-II CM Demag & Active Cancellation Tech. Review 20

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Outline

  • Introduction

– Previous work – Residual magnetic fields and Q0

  • pCM test plan for demagnetization & active cancellation

– Understanding till now, & what remains to be understood

  • Production demagnetization & active cancellation coil

– Proposed design of coils and connectorization – Cost summaries for different options – Need-by schedule

  • Operational modes

– Information for SLAC controls

5/25/2016 S.K. Chandrasekaran | LCLS-II CM Demag & Active Cancellation Tech. Review 21

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Production demagnetization & active cancellation coils

  • Due to the need for demagnetization after each move not

being present, proposal is to separate the two systems

  • Demagnetization to use AWG 4 cables

– Connectorized belt-type system – 1-set per Lab, 1-spare for both – Install at QC, remove – Install at CMTS, remove – Installation at SLAC not accounted for in estimates

  • Active cancellation to use AWG 22 or larger cables

– Connectorized belt-type system or wound around the vessel – To be left on CM permanently

5/25/2016 S.K. Chandrasekaran | LCLS-II CM Demag & Active Cancellation Tech. Review 22

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Demagnetization coils

  • Main body (5-turn) coils

– Powerpole connectors mounted to backing plate – Backing plate doubles as fastening & locking mechanism – All connectors along a line on vessel outside (bottom or side)

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Powerpole Backing plate

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Demagnetization coils

  • End (100-turn) coils – same concept as main coils

– Each layer is a separate ‘belt’ – 10 layers X 10 turns coils: 10 ‘belts’ of 10 turns (inc. lengths) – 20 layers X 5 turns coils: 20 ‘belts’ of 5 turns (inc. lengths) – Connector locations to be offset by 60°

5/25/2016 S.K. Chandrasekaran | LCLS-II CM Demag & Active Cancellation Tech. Review 24

Upstream end 10 X 10 Downstream end 20 X 5

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Active cancellation coils

  • AWG 22 or 18 (FNAL electrical safety and stranding)
  • Ribbon cable a possibility

– FNAL safety not big on using ribbon cable for constant current conduction

  • Can be connectorized using similar hardware as

demagnetization system

5/25/2016 S.K. Chandrasekaran | LCLS-II CM Demag & Active Cancellation Tech. Review 25

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Cost summaries

System Includes Cost ($) Demagnetization 1-set FNAL, 1-set JLAB, 1-set spare, labor for 2 install & removal 357,296 Active cancellation Only CM internal components purchased now; external wires etc. in operations (use demag wires in CMTS) 358,113 Active cancellation Full system installed during production 746,167

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$715,409 $1,103,463 Option #1 Option #2

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Need by dates

  • Fluxgates:

– Lead time ~12 weeks – CM2 at WS2 to be started ~October 21 – Fluxgates for CM2 to be ordered by mid-June

  • Cables:

– 90 C insulation wire lead time ~2 weeks – 105 C insulation wire lead time ~8 weeks – VV to be arriving soon…

5/25/2016 S.K. Chandrasekaran | LCLS-II CM Demag & Active Cancellation Tech. Review 27

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Outline

  • Introduction

– Previous work – Residual magnetic fields and Q0

  • pCM test plan for demagnetization & active cancellation

– Understanding till now, & what remains to be understood

  • Production demagnetization & active cancellation coil

– Proposed design of coils and connectorization – Cost summaries for different options – Need-by schedule

  • Operational modes

– Information for SLAC controls

5/25/2016 S.K. Chandrasekaran | LCLS-II CM Demag & Active Cancellation Tech. Review 28

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Signal list (active cancellation)

  • Active cancellation

– 5 Fluxgates per CM (4-wires per fluxgate)

  • Extension wires must be low resistance

– 3-active cancellation circuits per CM (2-wires per circuit)

  • Extension wires must be low resistance
  • Demagnetization

– Power supply controlled through 1-USB – 3-phase, 208 V, 30 A; L21-30R receptacle

5/25/2016 S.K. Chandrasekaran | LCLS-II CM Demag & Active Cancellation Tech. Review 29

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Operational modes

  • Commissioning:

– FGs read & coils tuned during commissioning – FGs read during cool downs – Tuning temperature to be determined from pCM tests

  • Algorithm to use FG data to tune coils

– Demagnetize if unable to cancel magnetic fields

  • Normal Operations:

– After current tuned, coils ALWAYS ON

  • To prevent flux trapping in the event of cavity quench

– FGs monitored all the time (multiplexing OK) – Data reviewed and coils adjusted during shutdowns – Demagnetize if unable to cancel magnetic fields

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Thank you!!!

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