Long Quadrupole Giorgio Ambrosio

BNL - FNAL - LBNL - SLAC

Long Quadrupole Giorgio Ambrosio

DOE review of LARP program Jun. 19-20, 2008

LBNL

OUTLINE:- The road to the LQ- LQ main features and plans- FY08 development and issues- Schedule and budget

Long Quadrupole – G. Ambrosio 2LARP annual DOE Review – LBNL, Jun. 19-20, 2008

Long Quadrupole

Main Features:• Aperture: 90 mm• magnet length: 3.6 m

Goal:• Gradient: 200+ T/m

Timeframe:• Performance and reproducibility by the end of 2009

– Testing 3 LQs


The road to the LQ


Plan for Length Scale-Up

LENGTH SCALE-UP CHALLENGE: No Nb3Sn accelerator magnet longer than 1m has ever been builtLARP plans to have a successful 4m long quadrupole by end of 09

FNAL Long Mirrors

LARP Long Quadrupoles

LARP LQ Design Study

LARP Long Racetracks 2006

2007

2008

2009

LARP TQs


Long Coils R&D - Results• 2nd Long Racetrack (4m coils): 96% of SSL

So we can successfully make long Nb3Sn coils!But the LR had flat coils without ceramic binder, and

coils were not heat treated in a closed cavity under pressure

• 2nd Long Mirror (4m coil): 87% SSL~ Accel. quality coil using RRP

114/128Performance improved by heating

the outer layer instability

• 1st Long Mirror (2m coil): ~ SSL~ Accelerator quality coil using PIT conductor

Cos-theta coil w wedges, end spacers

Front view of mirror magnet

98% SSL taking into account simulated

temperature increase


LR result: segmented shell


“Original” & Present plans

No 3rd generation

In FY08

In FY07-08,No ceramic binder

2N + 1R

We had delays, some parts were skipped, but we want to keep the 2009 LQ goal “it can be done, but not without pain!”


Mitigation factors• Significant effort for fabrication and inspection of

practice coils– Started before definition of latest details (holes for coil lifting,

pockets for trace wiring)• Saved time with some extra costs

• LQ coil reaction and impregnation at two labs (BNL, FNAL)– This is going to save time during LQ coils production – Providing risk mitigation (equipment failure)

• Cost of fixtures and tooling at two labs

• Continuous coil fabrication until successful inspection – Travelers continuously updated to be able to start production

right away


LQ main features*

*LQ Design Report available on LARP web site at:https://plone4.fnal.gov/P1/USLARP/MagnetRD/longquad/designreport/


Conductor

• Cable:– LQ cable design = TQ cable design – 27 strands, 0.7 mm diameter, – 10 mm wide cable, 1° keystone angle

• Strand: – OST-RRP 54/61 for LQ01

• Strand used in TQS02 and TQC02 coils and LR• Good performance at 4.5 K• Performance at 1.9 K under investigation

– Higher number of subelements (108/127) may be used in following LQs

• See schedule for options


Magnetic Design

Parameter Unit Collars Shell

N of layers - 2136

29.33N of turns -Coil area (Cu + nonCu) cm2

4.2 K temperature – Jc = 2400 A/mm2

Quench gradient T/m 221 233Quench current kA 13.3 13.4Peak field in the body at quench

T 11.5 11.9

Peak field in the end at quench

T 11.9 11.4

Inductance at quench mH/m 4.6 4.9Stored energy at quench kJ/m 406 439 1.9 K temperature – Jc = 2400

A/mm2

Quench gradient T/m 238 251Quench current kA 14.4 14.5Peak field in the body at quench

T 12.4 12.9

Peak field in the end at quench

T 12.9 12.4

Stored energy at quench kJ/m 472 512

2800 A/mm2

231 24414 13.912 12.5

12.5

443 4772800 A/mm2

249 26315.1 15.112.9 13.513.5516 557

Coil layout = TQs- 2 layers (NO splice)- iron closer to coils in

shell structure- Peak field in ends with

collar structure


Mechanical Design - I• LQ Magnet Structure Review

– Nov 28-29, 2007 at BNL• LQC = Long TQC - LQS based on TQS

YokeGap

Collar-YokePreloadShim

ControlSpacer

Skin

Collar

YokeCollaringKey

Inner poleOuter polepiece

Coil MidplaneShim


LQMS Review plan• Scale up issues:

– TQC models didn’t exceed 200 T/m– Collaring long coils

– TQS structure needs modifications for long magnets

• Segmented shell– Improvements introduced based on

TQS test results

• Plan:– Procure in FY08 both shell and collar

long structures• Provides options & back up

– 1st LQ with shell-based structure• Best performance, shorter assembly,

easier to replace coils– 2nd LQ with collar-based structure

• Reusing LQ01 coils (done w TQs)– 3rd LQ with structure depending on

previous results

TQS LQS


Advantages of Proposed Plan• Larger probability of success within FY09 by

developing both structures– Providing back-up (LQC01 back-up for LQS01) and

options (several options after LQS01 tests)

• We are building a large and unique set of expertise and experimental data for the design of the structure for the LHC phase-II upgrade

• All 3 labs are strongly involved with this plan the best intellectual contribution from all experts very high level of internal scrutiny


LQMS Review close-out


LQMS Review close-out• “However, from our perspective”:

– Concerns about schedule, changes from TQS to LQS, stresses, coil alignment, end-load, TQ performances

• Addressed:– Shear stress addressed in dedicated technical note

• Available at: https://dms.uslarp.org/MagnetRD/longquad/shear_note_V4.doc– Schedule concerns addressed by 2 lab for R&I, LQ priority, contingency – LQS with iron pads at TQS; test of 1m LQS structure at LN, and of

whole LQS structure at 300 K with dummy coils– TQS02 tested (2 times) replacing limiting coils

• Replies/responses to all recommendations are in the back-up slides


Quench Protection

• Goal: – MIITs < 7.5 Temp ~ 380 K (adiabatic approx)

• Quench protection param. (4.5 K) – conservative hypothesis– Dump resistance: 60 m(extract ~1/3 of the energy; Vleads ~ 800 V)– 100% heater coverage ( heaters also on the inner layer)– Detection time: ~5 ms based on TQs with I > 80% ssl– Heater delay time: 12 ms based on TQs with I > 80% ssl


LQ plans and work in progress


Fabrication and test plans• Coils are being fabricated at FNAL and BNL

– 2 practice coils at FNAL, 1 at BNL– 4 coils by the end of FY08

• 3 at FNAL, 1 at BNL• Start spare coils in Q4

– 6 coils in FY09 (more using contingency)• 2 at FNAL, 4 at BNL

• Shell structure: design, procurement & test at LBNL– Ready by the end of FY08

• Test of 1m model at LN & whole structure at 300K with dummy coils– LQS01 mechanical assembly and pre-load at LBNL – LQS01 electrical assembly and prep for test at FNAL

• Collar structure: procurement at FNAL– Some parts held in contingency until Q4.

• All LQ models to be tested at FNAL– LQ01 test in Feb 2009


LQS design

• Shell: 4 segments, 0.8 m long• Yoke: 50 mm laminations with 3.3 m long tie rods• Pads: 50 mm laminations with 3.3 m long tie rods• Masters: 2 segments, 1.6 m long• Stainless steel axial rods w 24.5 mm diameter

• 20 mm shell• 4-split iron yoke• Iron masters with 2 bladders and 2

interference keys• Iron pads with holes for coil end

support and tie rods• Stainless steel sheet between coil and

pad laminations


Assembly - I• Coil-pad sub-assembly

– Pads bolted around the coil– Bolts “disappear” under

compression• Yoke-shell sub-assembly

– Gap keys keep yoke stacks apart and pre-tension the shell


Assembly - II• Assembly of 4 single shell-yoke

sub-assemblies• Connection of shell-yoke sub-

assemblies with tie rods• Insertion of coil-pad sub-

assembly


LQS status• All parts in house• Instrumentation of 0.8m section

in progress– 0.8m section will be fully assembled

with dummy coil and tested at LN

Coils: FNAL, BNLStructure: LBNLTest: FNAL


Long Nb3Sn coil challenges• Conductor:

– Need km-size strand piece length, and long cabling runs (250 m for 4m long quad coils)

• Insulation: – Need technique for long coils

• Reaction:– Need long oven– The displacements due to differential expansions scale

with length– Total friction force scales with length

• Impregnation:– Impregnation time increases with length

• Handling:– LARP set criteria for Max strain: -0.15%< <0.05%

LQ coil


LQ Coil Fabrication

• React&Impr fixture change:– From 2-in-1 used for TQ coils to

single coil fixtures for LQ• More symmetric coils (+)• New parts, new procedures (-)

– Symmetric plates (as in LR)

• Coil design:– LQ coils = TQ coils w minor modifications


LQ coil fabrication issues• Practice coil issues:

– Coil bowing after reaction (PC #2) Pre-heat treatment of all fixture parts Symmetric fixture (add top plate) Reduce friction (mica)

– Damaged lead (PC#2)• Due to coil bowing because of winding

tension Keep coil always under load Introduce gaps only for HT?

– Damaged leads (PC #3)• Due to shims overlapping Continuous shims Connect saddle to pole tip

– Inner pole shorter after HT (PC #3)• Still under investigation Introduce gaps only for HT?


Coil Instrumentation

Will use Kapton “Traces” as in TQs• Voltage taps: 13 IL + 7 OL• Protection heaters: on both layers

– Two traces (1.7 m each) per layer– Large ss strip with narrow heating areas

• Successfully tested on Long Racetrack – “Bubbles” may reduce heater efficiency

• Option: test at 4.5, 2.5 K and 1.9K (at the end)

• Strain gauges: 4 IL + 1 OL– Wires on trace for outer layer strain gauge– Gauges on the inner layer will be instrumented

with wires


Magnet tests

• Preparation for test– Adaptive QP threshold– Symmetric grounding– Handling and support of LQS at VMTF

• Handling fixture ~modified for pivoting

• Test all LQ magnets– Test at 4.5K and 2.5K (1.9K at the end)– Magnetic measurement, ramp rate

dependence, RRR…• Magnetic measurement only ½ length

– Thermal cycles to check “training memory”

0500

100015002000250030003500400045005000

0 2000 4000 6000 8000 10000 12000

Current (A)

|Vol

tage

Spi

ke| (

mV)

White = After FilterAll other Colors = Before Filter

Pivoting LRS01 in prep. for test at BNL


QA Plan:QA for LQ coil production:

• Travelers:– Each lab is responsible for its own travelers,

• Travelers will be distribute to the 3 labs– Fabrication steps (HT cycle, impregnation, insulation) and

measurement plan are the same

• Discrepancy Reporting:– Assures efficient reporting and recording of all discrepancies– All LQ task leaders will receive all DRs– New feature for LARP

• Documents on LARP web site (plone)– Easily available to the whole collaboration– Address: https://plone4.fnal.gov/P1/USLARP/MagnetRD/longquad/


“Projectized” task

• LARP is a collaboration with a program• LQ project-like features:

– Plan: Task sheets with milestones, budget for each milestones, and commitment (technical, not financial) by task leaders and supporting labs to do the job

– Budget: LQ had priority in the FY08 plans, and in the use of magnet contingency;

• No core-programs support

– QA: developed and implementing LQ QA plan


FY08 Budget

FY08 LQ budget (k$) after all contingency was allocated:

• Budget at FY08 start: $3.4M• After mid-year contingency allocation: $4.0M• After June contingency allocation: $4.2M

– including $413k for LRS02

BNL FNAL LBNL TOTAL BNL FNAL LBNL TOTALLong Quadrupole Ambrosio 4202 2794

LRLRS02 Assembly & Test Ferracin 302 111 413 278 115 393

LQCoil & Collar Fab. (FNAL) Nobrega 1722 1722 1195 1195Coil Fab. (BNL) Schmalzle 986 986 508 508Shell Fab. Ferracin 900 900 613 613Instrum. & Quench Prot. Felice 20 20 141 181 9 76 85

FY08 fund. allocation Expenses & Comm. May 31, 2008


Budget and spending profile• LQ budget and expenses (w commitments) in $k

We have similar plots for each task,For FNAL also with labor and M&S breakdown

0.0

500.0

1000.0

1500.0

2000.0

2500.0

3000.0

3500.0

4000.0

4500.0

Oct-07

Nov-07

Dec-0

7

Jan-0

8

Feb-

08

Mar-08

Apr-08

May-08

Jun-0

8Ju

l-08

Aug-08

Sep-08

FY08 budget:Linear profile among milestones

FY08 budget:Spending just before milestones

FY08 actual expenses

Budget after contingency distrib.


Schedule

Options: - LQC01 with S01 coils, LQS02 with new coils (FY09 budget: $2.3M) - coils with new conductor for LQ03 (FY09 contingency)

Test cables extracted from coil 3


Conclusions• The Long Racetrack has successfully opened the

way for the use of coils and structures for long Nb3Sn accelerator magnets

• The Long Quadrupole FY08 work is completing the development of coils and structures for this goal adding accelerator quality features

• The Long Quadrupole FY09 plan aims at testing 3 LQs by the end of CY2009 exploring the use of shell and collar structures, providing: larger probability of success unique data and expertise for LHC-IR upgrades and for any future use of Nb3Sn magnets for HEP appl.

BNL - FNAL - LBNL - SLAC

Extra


LQMSR concerns I1. The structure plan and decisions are perhaps a bit late for the stated goal of a

demonstration in 2009- and you have to do better with respect to schedule that the program has done previously.

Yes, there have been delays in the whole program. Therefore the LQ plan has features to reduce their impact, and the impact of other possible causes of delays: coils will be reacted and impregnated at two labs (BNL and FNAL), two long structures are under procurement, we are planning to reuse some LQ coils in different structures

2. The 4m shell design and process have numerous changes over what was demonstrated in the TQ program, raising the potential for unknown risks, and has challenging assembly operations. This should be carefully reconsidered.

The changes should lead to performance improvement and help during the assembly of the long structure. Two tests of the LQS structure are planned with dummy coils: a test at LN of a 1m model, and a test at room temperature of the whole structure with Fuji films. Having both structures available provides further options and backup.


LQMSR concerns II3. The impregnated coil development to date has eliminated the positive coil-

collar registration, an essential feature of most successful collared accelerator magnet campaigns, and this appears to complicate the absolute alignment scale up to longer lengths, and potentially raise the conductor strain in ways that affect the ultimate gradient performance.

Other parts of the program (such as the HQ) are looking at coil alignment. This is not among the first LQ goals, although it can be tested by introducing keys in the collar structure (possibly after successful test of the LQC without keys, and of a TQC with keys). Alignment features were removed from the collar structure in order to allow more uniform stress distribution among the coils.


LQMSR concerns III4. The collared design performance results appear marginal both mechanically

and in magnetic gradient. Have you really been careful enough with the coil strain state management conditions including low tech handling and tooling issues?

See note by R. Bossert (TQC task leader).

5. The shell design places emphasis on axial restraint (all load), while the collared design does not (30% of axial load seen at the ends). The test results even qualitatively do not resolve this issue, raising doubt about its importance, and emphasis, and thus how this engineering issue really scales scales to 4 m, and why there are so many changes in LQ01.

Because of the importance of selecting the better of the two azimuthal coil support options (collar/shell), we have not changed the axial support levels associated with the collar/shell designs. The LQ structures aim at reproducing the pre-loading conditions of the best TQ models for each structure. Most changes of the LQS structures aims at easy assembly (masters), same load (SS rods) and lower pre-stress in the outer layer.


LQMSR concerns IV6. The anomalous results at 4.5K and 1.9K beg interpretation- at a minimum,

this should include strand strain degradation studies coupled with analysis conductor sub-models that characterize peak strains in cable strands, and possibly retesting TQS02 with new coils to replace those suspected of being inferior.

TQS02 has been tested with new coils showing some improvement at 4.5K, and no improvement at 1.9K. The understanding of these quench performance is among the main goals of the LARP magnet R&D (strand and cable tests, TQ models with new conductor, HQ).

7. We are concerned that all this may beat on the already narrow performance margins observed in the just completed 1m tests

We agree. For this reason the results of upcoming conductor and magnet tests will be taken into account by the LQ R&D (possible use of different conductor, and modifications coil fabrication, magnet assembly and pre-loading procedures).


Impact of skipped/delayed parts

• 3rd TQ generation – LQMS (LQ short models) – No test of LQS cross-section in TQ magnets– No test of TQC with alignment features– No test of 1m single-coil reaction fixture– Test of 127 sb conductor planned in FY09

• 2nd LR using coils reacted in closed cavity using ceramic binder– No test of reaction of long coils in a closed cavity using the

ceramic binder ( accelerator quality coils)• The LM compensated only partially because used Al-bronze poles w gaps

• LQ practice coils – No feedback about fixtures and procedures before 2008

Long Quadrupole Giorgio Ambrosio

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