quench statistics

Quench statistics

Outline:

Reminder of the facts about natural quenches in the main dipole circuit in sectors 4-5 and 5-6

observed quench characteristics and propagation of quenches

quench behaviour in the tunnel vs. SM18 quench data

symmetric quench propagation phenomenon

What can be done to speed up the quench training in the machine

A. Siemko and E. Todesco

MAC 23 Meeting 13/o6/2008 A. Siemko

Quench Training, Retraining, Memory Effect,…

Reminder of the “jargon” used

Extract of Natural Training Quenches at 1.8K to Reach Ultimate Field of 9 Tesla

8.0

8.5

9.0

9.5

Quench Number

Mag

netic

Fie

ld a

t Que

nch

B [T

esla

]

QuenchRetraining

MemoryEffect


Quench Training in Sectors 4-5 and 5-6

0 5 10 15 20 25 309000

9500

10000

10500

11000

11500

12000

5.340

5.540

5.740

5.940

6.140

6.340

6.540

6.740

6.940S45S56

Quench number

Que

nch

curr

ent

[A]

Corr

espo

ndin

g en

ergy

[Te

V]


Training quench characteristics

Typical current decay curve

dI/dt+10A/s

-100 A/s


HYDRAULIC BEHAVIOUR DURING A QUENCH

18 bar

2 min.

3 h

Pressure build-up

Pressure discharge


Example of a training quench and quench propagation

Natural quench in A22R4 at 9859 A (magnet name 3176) 4 magnets quenched (3 after quench propagation) Sequence of events:

Magnet Cryogenic cell Local time t quench [s] I quench [kA] E [MJ]A22R4 21R4 16:50:34.947 0 9.859 4.957B22R4 21R4 16:51:24.679 49.732 6.011 1.843C22R4 21R4 16:52:07.532 92.589 3.829 0.748C21R4 19R4 16:52:41.798 126.855 2.644 0.357

Total 7.905


What can be expected from series tests in SM18 Powering to Nominal Field of 8.33 T

0

50

100

150

200

250

300

350

400

450

500

550

0 1 2 3 4 5 6 7 notreachedNumber of quenches to reach 8.33T

Num

ber o

f Cry

o-di

pole

s 01 02 03

Histogram of the number of quenches to reach 8.33 Tesla for 1252 LHC dipoles

during 1st powering 38 % of MB magnets has reached the nominal field without quench

42 % of MB magnets has required 1 quench to reached the nominal field


What can be expected from series tests in SM18

A. Siemko and P. Pugnat

Thermal Cycle performed on ~10 % of MB magnets

The number of quenches that can be expected in the tunnel can be estimated although the sample is not “entirely” random


What can be expected from series tests in SM18

Retraining data for magnets submitted to a TC in Sector 4-5

Magnet name

1st quench level before

TC (A)

TC

1st quench level after TC

(A)

Current difference

(A)1 1193 11332.9 12251.3 +918.42 1196 11270.9 12389 + 1118.13 2129 10659 11246 + 5874 2140 10859 12654 + 17955 2142 11200 12476 + 12766 2164 10850 11979 + 11297 2166 10332 11912 + 15808 3138 9870 12272 + 24029 3193 9536 11977 + 2441

10 3219 10660 10791 + 13111 3220 9870 11474 + 1604


Extrapolation method

• From thermally cycled magnet sample {TC} the reduction of the average number of quenches to reach I nominal (11850A) and I commissioning (12000A) is equal to ~ 82%

• Assuming the same reduction for other magnets {NoTC} Average number of Training Quenches

per sector can be calculated

Magnets tested virginMagnets tested after

thermal cycle

82% reduction of number of

quenches to go to nominal

1232

115 115

?


Extrapolation method

Additional hypotheses: No “problematic” MBs in the machine after series tests in SM18 No long time relaxation of the trained magnets No retraining for magnets submitted in SM18 to a thermal cycle No important detraining ? Estimation for detraining:

0.04 x 3 x 22 < 3 additional Quenches/Sector

Magnet 1st Q level

2nd Q level

N° of Q's to 8.33 T (11.85 kA)

N° of Q's to 8.4 T (12 kA)

N° of Q's to 9 T Bmax 1st run

Th. Cycle

1st Q level ATC

2nd Q level ATC

N° of Q's to 8.33 T ATC (11.85 kA)

N° of Q's to 8.4 T ATC (12

kA)TCAverage 7.70 8.22 1.82 2.26 3.62 8.90 8.44 8.66 0.33 0.46STDEV 0.66 0.46 1.35 1.57 2.33 0.14 0.35 0.27 0.78 0.73

# 113 108 115 115 42 115 100 84 113 110NoTCAverage 8.06 8.54 1 1 3 8.90STDEV 0.65 0.37 1 1 2 0.15

# 785.00 643.00 791 791 420 791.00?


Estimated number of quenches per sector

* calculations were based on a sample of 115 MBs submitted to a TC ** assuming two quenches per working day

Sector name # of magnets submitted to TC

Expected number of

quenches below 11.85 kA*

Expected number of

quenches below 12 kA*

Estimated operation time

(working days)**

1-2 8 22 ± 5 24 ± 5 12 ± 2.5 2-3 16 23 ± 5 27 ± 5 13.5 ± 2.5

3-4 14 21 ± 5 26 ± 5 13 ± 2.5

4-5 11 22 ± 6 26 ± 5 13 ± 2.5

5-6 2 21 ± 6 26 ± 6 13 ± 3

6-7 10 20 ± 6 23 ± 5 11.5 ± 2.5

7-8 38 14 ± 5 18 ± 5 9 ± 2.5

8-1 16 19 ± 5 22 ± 5 11 ± 2.5


MONTECARLO ANALYSIS

Aim: critically review the quench data taken at SM18 to see if they partially justify the 5-6 results

Montecarlo analysis with pessimistic hypotheses, more than what used the previous method

A method based on extrapolation:

We take the first virgin quench of all magnets of 5-6 (available for all magnets)

We sum the correlation between 1st quench after thermal cycle and 1st virgin quench measured in 136 magnets, split per firm We take the correlations that are available, i.e. that ones of poorly

quenching magnets (pessimistic hypothesis) This correlation is affected by a random part that must be taken into

account one needs a MonteCarlo

The method gives only the first quench for each magnet Up to now, all 5-6 quenches were in different magnets


MONTECARLO ANALYSIS

MonteCarlo results versus sector 5-6 HC data Qualitatively is fine: a lot of Noell, a few Ansaldo, no

Alstom Now, after 27 Noell quenches, we are below of around

400-600 A

8

9

10

11

12

0 20 40 60 80First quench number

Cur

rent

(kA

)

AlstomAnsaldoNoellAnsaldo HCNoell HC

5-6: Montecarlo vs hardware commissioning


MOTECARLO ANALYSIS

Noell magnets lost some memory, but not completely

8

9

10

11

12

0 20 40 60 80First quench number

Cur

rent

(kA

)

Noell MonteCarloNoell HCNoell virgin

5-6


TRAINING EFFECT MEASURED IN SM18

In general magnets gain current from 1st virgin quench to 1st quench after thermal cycle The gain the larger when the virgin quench is lower

Noell shows some anomalous behavior It is the only manufacturer that has some magnets

with a detraining loss

-2

-1

0

1

2

3

4

8 9 10 11 12 13 141st virgin quench (kA)

1st q

uenc

h at

c - 1

st v

irgin

que

nch

(kA

)

AlstomAnsaldoNoell


TRAINING IN SM18 VS. TRAINING IN SECTOR 5-6

… the detraining loss looks worse in the sector 5-6 data

-2

-1

0

1

2

3

4

8 9 10 11 12 13 141st virgin quench (kA)

1st q

uenc

h at

c - 1

st v

irgin

que

nch

(kA

)

NoellNoell HC


Phenomenon of Symmetric Quenches

In sector 5-6 five symmetric quenches were observed after quench propagation caused by a thermo-hydraulic wave One quench (in B16.R5 at ~7.4 kA) has developed the high “MIITs” and

resulting high hot spot temperature

There is a weakness in the magnet protection.


ANALYSIS AND FUTURE STRATEGY

Development of “tools” to speed-up training is undergoing

Overshooting with current to have more training quenches at the same time Requires development of dedicated electronics to prevent diodes

overheating and to control maximum number of quenching magnets Forced quench training

Tried on 4th June (3 quenches at the same time) and on 5th June (4 quenches) but not conclusion yet


Conclusions

During the high current quenches in MB magnets of RB45 and RB56 circuits:

all individual systems (PC, PIC, QPS, EE and CRYO) performed as designed

typical quench propagation time from magnet to magnet was observed to be in the rage of 40-60 seconds – slightly slower as compare to the initial estimates (better).

Statistical analysis of the quench data taken at SM18 do not explain the quench behavoiur of dipoles in sectors 4-5 and 5-6

Much more pronounced than expected detraining effect was observed in a lot of Noell magnets.

Critical review the production data of the magnets can help to understand the quench behaviour observed in sector 5-6


Conclusions

There is a weakness in the magnet protection in case of symmetric quenches

Remedy is under study

Much more pronounced than expected detraining effect was observed in a lot of Noell magnets.

Critical review the production data of the magnets can help to understand the quench behaviour observed in sector 5-6

“Tools” to speed-up training of magnets in the machine are under development


Additional information (quench data)Sector # Date Time Magnet Cold mass Magnet ID

Quench current [A]

Delta_Iq [A] Field [T]

Energy [TeV]

S45 1 1/24/2008 16h57 C27L5 LBALA.27L5 HCLBAL_000-IN003180 9789 1036 6.909 5.808S45 2 1/25/2008 16h50 A22R4 LBALA.22R4 HCLBAL_000-IN003176 9859 -1941 6.958 5.849S45 3 1/31/2008 13h44 A27R4 LBBLA.27R4 HCLBBL_000-IN003191 10274 -893 7.243 6.089

S56 1a 4/28/2008 09h59 A28L6 LBBRC.28L6 HCLBBR_000-IN003362 10004 -145 7.054 5.930S56 1b 4/28/2008 09h59 B29R5 LBARA.29R5 HCLBAR_000-IN002245 10004 -217 7.054 5.930S56 2 4/28/2008 17h08 A29L6 LBARB.29L6 HCLBAR_000-IN003370 10227 -1902 7.209 6.060S56 3 4/29/2008 16h42 A23L6 LBARB.23L6 HCLBAR_000-IN003372 10358 894 7.300 6.136S56 4 4/30/2008 09h02 A15R5 LBBRA.15R5 HCLBBR_000-IN003188 10545 -1762 7.430 6.246S56 5 5/6/2008 18h12 C32R5 LBARB.32R5 HCLBAR_000-IN003368 10652 115 7.503 6.308S56 6a 5/7/2008 17h53 A10L6 LBBRM.10L6 HCLBBR_000-IN003246 10715 -1736 7.547 6.344S56 6b 5/7/2008 17h53 C16L6 LBBRA.16L6 HCLBBR_000-IN003387 10715 -1482 7.547 6.344S56 7 5/9/2008 15h13 A21R5 LBBRA.21R5 HCLBBR_000-IN003358 10751 -1732 7.572 6.365S56 8 5/15/2008 19h43 B8R5 LBBRF.8R5 HCLBBR_000-IN003337 10793 338 7.601 6.389S56 9 5/16/2008 17h22 A20L6 LBBRC.20L6 HCLBBR_000-IN003357 10835 -1657 7.630 6.414S56 10 5/19/2008 12h34 B17R5 LBARA.17R5 HCLBAR_000-IN003352 10883 -1606 7.663 6.441S56 11 5/19/2008 19h19 C15R5 LBBRC.15R5 HCLBBR_000-IN003338 10910 -1270 7.682 6.457S56 12 5/20/2008 07h35 C15R5 LBBRC.15R5 HCLBBR_000-IN003338 10720 -1460 7.551 6.347S56 13 5/20/2008 18h07 A12R5 LBARA.12R5 HCLBAR_000-IN003367 10918 1315 7.687 6.462S56 14 5/21/2008 18h17 A19L6 LBARB.19L6 HCLBAR_000-IN003376 10944 -1699 7.705 6.477S56 15a 5/23/2008 07h44 B9L6 LBARE.9L6 HCLBAR_000-IN003330 10977 -1710 7.728 6.496S56 15b 5/23/2008 07h44 B33R5 LBARA.33R5 HCLBAR_000-IN003375 10977 -1477 7.728 6.496S56 16 5/23/2008 17h48 B29L6 LBBRA.29L6 HCLBBR_000-IN003336 10986 471 7.734 6.501S56 17 5/26/2008 07h41 A19R5 LBBRA.19R5 HCLBBR_000-IN002265 10997 640 7.742 6.508S56 18 5/26/2008 16h54 A18L6 LBBRC.18L6 HCLBBR_000-IN003364 11019 -1738 7.757 6.520S56 19 5/27/2008 10h48 C30R5 LBARB.30R5 HCLBAR_000-IN003320 11040 191 7.771 6.533S56 20 5/27/2008 17h40 A11L6 LBBRB.11L6 HCLBBR_000-IN003215 11067 -713 7.790 6.548S56 21 5/28/2008 07h35 B14L6 LBARA.14L6 HCLBAR_000-IN003349 11075 849 7.796 6.553S56 22 5/28/2008 19h08 B24L6 LBARA.24L6 HCLBAR_000-IN003343 11090 832 7.806 6.562S56 23 5/29/2008 07h30 B19R5 LBARA.19R5 HCLBAR_000-IN003327 11102 1167 7.814 6.568S56 24 5/29/2008 18h39 A25R5 LBBRA.25R5 HCLBBR_000-IN003381 11119 722 7.826 6.578S56 25 6/4/2008 08h55 C17L6 LBARA.17L6 HCLBAR_000-IN003329 11124 380 7.829 6.581S56 26 6/5/2008 08h16 B32R5 LBBRA.32R5 HCLBBR_000-IN003315 11153 -201 7.849 6.598S56 27 6/6/2008 14h38 A16R5 LBARA.16R5 HCLBAR_000-IN003204 11173 -423 7.863 6.610

quench statistics

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