Summary of test results of MQXFS1 the first short model 150 mm - - PowerPoint PPT Presentation

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Summary of test results of MQXFS1 the first short model 150 mm - - PowerPoint PPT Presentation

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Summary of test results of MQXFS1 the first short model 150 mm aperture Nb 3 Sn quadrupole for the High-Luminosity LHC upgrade Stoyan Stoynev (on behalf of HL-LHC AUP collaboration) MT25 Conference, Amsterdam, Nederlands 30 August 2017

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Stoyan Stoynev (on behalf of HL-LHC AUP collaboration) MT25 Conference, Amsterdam, Nederlands 30 August 2017

Summary of test results of MQXFS1 – the first short model 150 mm aperture Nb3Sn quadrupole for the High-Luminosity LHC upgrade

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SLIDE 2
  • MQXFS1 is the first 150 mm diameter,

1.5 m long Nb3Sn quadrupole from LARP/HiLumi

– Coils fabricated by CERN (#103 and #104) and LARP (#3 and #5)

  • Three test cycles performed

– MQXFS1a in Feb/May 2016 – MQXFS1b in Sep/Dec 2016

  • Increased azimuthal pre-stress (35%)

– MQXFS1c in May/July 2017

  • Increased axial pre-stress (65%)
  • Main goals

– Training and performance characteristics – Magnetic measurements (see Suzana’s talk) – Magnet protection studies (see Emmanuele’s talk)

Introduction

30-Aug-17 2

MQXFS1 and VMTF at FNAL

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SLIDE 3
  • Coils made of Nb3Sn strand

– RRP 108/127 (#3 and #5) – RRP 132/169 (#103 and #104)

SSL at 1.9 K: 21.5 kA (coil #103)

30-Aug-17 3

Cable properties and SSL estimates

Short- sample Current Field Gradient Current Field Gradient Nom. Current Nom. Gradient

  • Nom. Field

% Iss 4.3 K 4.3 K 4.3 K 1.9 K 1.9 K 1.9 K 1.9 K 1.9 K 1.9 K 1.9 K kA T T/m kA T T/m kA T/m T % Coil 103 19.550 13.383 155.164 21.50 14.599 169.083 16.47 132.667 11.425 77 Coil 104 19.775 13.525 156.783 21.78 14.769 171.026 16.47 132.667 11.425 76 Coil 3 20.118 13.740 159.245 22.28 15.080 174.573 16.47 132.667 11.425 74 Coil 5 19.725 13.493 156.424 21.85 14.813 171.526 16.47 132.667 11.425 75 Magnet 19.550 13.383 155.164 21.50 14.599 169.083 16.47 132.667 11.425 77

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SLIDE 4
  • Voltage taps on the IL and OL
  • CERN and LARP strain

gauge systems with gauges

– On coils, shell, rods – Azimuthal/longitudinal sensitivity

  • Adjustable quench antenna

(QA)

  • Magnet is protected with

IL/OL heaters

30-Aug-17 4

Instrumentation

Voltage taps schematics QA picture and initial positions

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SLIDE 5
  • ”CERN” and “LARP” SG

systems used in parallel

– Different (AC/DC) sources – Different configurations – Different DAQ and sampling frequency

  • Results consistent and also in

agreement with Finite Element Analysis (FEA) calculations

  • Coil pre-stress levels verified

with the SG and coil-unloading “shifted” to higher current after the first test cycle

30-Aug-17 5

Strain gauges monitoring

More on mechanical analysis in Giorgio’s talk ~15 kA ~17 kA

Coil 5, azimuthal strain

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  • Fairly fast training in the first test cycle
  • Slower in the next cycles with multiple detraining quenches

– All in coil 3, lead end – Between wedge and end-part (see dedicated poster presentation)

30-Aug-17 6

Quench training

In all tests the ultimate current (8% field above LHC

  • perational field) reached

Reached 95.8% of SSL@4.9K and 88.4% of SSL@1.9K Good training memory; partial loss of memory after axial pre-stress increase

Training in the three test cycles

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SLIDE 7
  • Reordering the training sequences in terms of coils
  • “CERN” coils and the mirror-magnet coil show similar training
  • “LARP” coils training fast initially but curve flattening fast

– Training obstructed by a “weak spot”

  • Likely same location in coils 3 and 5
  • See analysis in Thomas’ poster presentation

30-Aug-17 7

Quench training in coils

Quench current normalized to SSL per coil

4.5 K

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SLIDE 8
  • Very weak quench current

dependence on the ramp rate

  • High ramp-rate dependence

consistent in all test cycles

  • Cable degradation of ~5-6%

– At 4.5K - consistent between test cycles within 1 %

  • Behavior consistent with a magnet still training

– ~ same absolute quench current at 1.9 K and 4.5 K

30-Aug-17 8

Ramp rate dependence and temperature margin

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SLIDE 9
  • Only in the first test cycle training was rich in locations
  • Later many detraining quenches in coil 3
  • Quenches up-to 300 A/s similar to training quenches
  • At higher ramp rate all quenches in coil 5

– outer layer, mid-plane region

  • At higher temperature quenches in coil 5

– one exception in the first test cycle – all in inner layer, likely around first wedge like in coil 3 (@1.9K)

30-Aug-17 9

Quench locations

White marks: positions of QA sensors that helped in the location analysis In yellow: Likely region of most quenches in coil 3 (and 5)

See the dedicated poster presentation

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SLIDE 10
  • RRR measured per segment

and averaged per coil

  • Negative correlation observed

vs the first quench current

  • Underlying reasons not

understood (investigation on going)

30-Aug-17 10

RRR and training

First quench current vs RRR (per coil) RRR in coil segments

“(m)” – mirror magnet test

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SLIDE 11
  • Splice resistance measurements in all test cycles

– Consistent results

  • Different soldiering techniques used

in “LARP” and “CERN” splices – coils (03,05) vs (103,104)

  • CERN splices 2-3 times less resistive (as expected)
  • All splices good : R < 1 nΩ (acceptable level)

30-Aug-17 11

Splice resistance measurements

coil Splice R [nΩ] 03 A 0.34 03 B 0.30 05 B 0.29 103 A 0.15 104 A 0.10 Uncertainty: 0.06 nΩ

A = IL B = OL

Instrumental offsets not relevant in the context

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SLIDE 12
  • The first 150-mm dimeter Nb3Sn magnet demonstrated

strong performance

  • It reached 95.8% of SSL@4.5 K and 88.4% of SSL@1.9 K

– 15% above LHC operational current at 1.9 K – target currents reached in all test cycles

  • Behavior at high ramp rate and temperature did not change

with higher pre-stress levels or over time with testing

  • Multiple detraining quenches were observed after pre-stress

increase – mostly same coil, same location

– no real training plateau reached

Summary

30-Aug-17 12

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SLIDE 13
  • Very good training memory

– no sizable loss after azimuthal pre-stress increase – confirmed observations from MQXFS1 with thermal cycle test

  • Axial pre-stress (after azimuthal pre-stress) increase lead to

partial loss of training memory

– Possibly related to “un-loading” of the coil during the procedure

  • RRR coil values were observed to be negatively correlated

with the first quench currents in the coils

  • Splice resistances were measured to be very small

Summary

30-Aug-17 13

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SLIDE 14

30-Aug-17 14

Back up

  • Holding current tests performed successfully

– 8 hours at operational current and later at 17760 A – 2 hours at ultimate current (17890 A)

Cool-down

Start: 17 September 2016

Warm-up

End: 13 December 2016

MQXFS1b

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SLIDE 15

30-Aug-17 15

Back up