mqxab: decay and field harmonics
DESCRIPTION
FiDeL meeting, 26 th May 2009. MQXAB: DECAY AND FIELD HARMONICS. E. Todesco Magnets, Superconductors and Cryostats Group Technology Department, CERN. Ackowledgements : P. Schlabach , G. Velev. CONTENTS. Features and function in the machine, and available measurements for field harmonics - PowerPoint PPT PresentationTRANSCRIPT
E. Todesco
MQXAB: DECAY AND FIELD HARMONICS
E. TodescoMagnets, Superconductors and Cryostats Group
Technology Department, CERN
FiDeL meeting, 26th May 2009
Ackowledgements: P. Schlabach, G. Velev
E. Todesco 24th May 2009 – Decay and harmonics in MQXB - 2
CONTENTS
Features and function in the machine, and available measurements for field harmonics
Field harmonicsAllowedNot allowed
Decay
E. Todesco 24th May 2009 – Decay and harmonics in MQXB - 3
MQXB: FEATURES AND FUNCTION IN THE MACHINE
16 magnets making 8 Q2, on each side of the four interaction points
Design and manufacturingmade in the US
Two layer, four-blocks, graded coilFree-standing collars
Currents: Injection 716-776 A to give 13.2 – 14.3 T/mCollision 5 TeV: 8120 ACollision 7 TeV: 11380 A to give 205 T/m
Beam dynamics:Negligible at injection, critical at high field after squeeze
E. Todesco 24th May 2009 – Decay and harmonics in MQXB - 4
Field harmonics: AVAILABLE MEASUREMENTS
What do we have today ?
‘Integral’ measurements:For all magnets, for every cold massValues at 4 currents namely ~injection (669 A), 5460 A, ~collision at 7 TeV (11345 A), ultimate (11923 A). Injection (716-776A) higher than what measured (669 A): goodTo be checked:
PrecycleWaiting time before making the measurement
‘Dcloop’ measurements:More current values, only for transfer function
Other informations from papers
E. Todesco 24th May 2009 – Decay and harmonics in MQXB - 5
CONTENTS
Features and function in the machine, and available measurements for field harmonics
Field harmonicsAllowedNot allowed
Decay
E. Todesco 24th May 2009 – Decay and harmonics in MQXB - 6
Field harmonics: ALLOWED
The MQXB are critical after the squeezeWe propose to set the model at high field exactly on the measured valuesGeometric set at value at 7 TeV
For the allowed b6, b10
b6 at 7 TeV is smaller than 0.1 units – very well optimized ! Negligible changes from 3.3 to 7 TeV:no need of different settings at 4-7 TeVAt injection, -1.5 unit of b6 and a very small additional spread (0.2 units)
b10 always negligible
b6 b10
Ave -1.52 0.05
Stdev 0.61 0.02
Ave 0.06 0.01
Stdev 0.36 0.01
Ave 0.07 0.02
Stdev 0.36 0.01
Ave 0.07 0.02
Stdev 0.36 0.01
Ave -1.67 0.04
Stdev 0.19 0.01
669 A
5460 A
11347 A
11925 A
669 A - 11347 A
E. Todesco 24th May 2009 – Decay and harmonics in MQXB - 7
Field harmonics: ALLOWED
Geometric:One per magnetSet at the value at 7 TeV
First 3 cold masses had a lower value b6, then a correction has been done through shims [G. Velev et al., IEEE Trans. Appl. Supercon. 17 (2007) 1109]
DC magnetizationComputed on the data averaged over all magnets: one generic, to take into account of about -1.5 units
pqinjc
Cold mass b6 b10
1 -0.401 0.016
2 -0.309 0.019
3 -0.403 0.020
5 0.163 0.028
6 0.353 0.026
7 0.224 0.016
8 -0.012 0.044
9 0.218 0.020
10 0.372 0.029
11 0.398 0.031
12 0.181 0.023
13 0.309 0.019
15 0.427 0.018
16 0.220 -0.001
17 0.157 0.015
18 -0.231 -0.009
19 0.415 0.003
20 -0.859 0.030
Average 0.07 0.02
Stdev 0.36 0.01
E. Todesco 24th May 2009 – Decay and harmonics in MQXB - 8
Field harmonics: NOT ALLOWED
The MQXB are critical after the squeezeWe propose to set the geometric on the measured value at 7 TeV
For the not allowedSmall systematic b4 of about 0.1 units – could be relevantAll the other systematic are very close to zero !Spread at injection is the same as at high field – this is strange: in general the spread at high field is smaller than at injection
Slight difference with data presented in [G. Velev et al., IEEE Trans. Appl. Supercon. 17
(2007) 1109], where one has a systematic a4 of about 0.2 unitsb 3 b 4 b 5 b 7 b 8 b 9 a 3 a 4 a 5 a 6 a 7 a 8 a 9
Ave -0.06 0.10 0.06 0.03 -0.02 0.00 -0.07 -0.16 -0.01 -0.01 -0.01 -0.03 0.00
Stdev 0.66 0.14 0.12 0.04 0.01 0.01 1.12 0.58 0.19 0.08 0.04 0.03 0.01
Ave 0.05 0.10 0.07 0.01 0.00 0.00 0.09 -0.10 0.02 -0.04 -0.01 -0.01 0.00
Stdev 0.61 0.14 0.11 0.03 0.01 0.01 1.00 0.51 0.17 0.10 0.04 0.03 0.01
Ave 0.06 0.12 0.09 0.01 -0.01 -0.01 0.08 -0.08 0.02 -0.08 0.00 -0.01 0.01
Stdev 0.61 0.14 0.13 0.04 0.01 0.01 0.99 0.52 0.18 0.19 0.04 0.03 0.01
Ave 0.09 0.12 0.09 0.01 -0.01 -0.01 0.08 -0.08 0.02 -0.07 -0.01 -0.02 0.00
Stdev 0.64 0.14 0.13 0.03 0.01 0.01 1.00 0.52 0.18 0.20 0.04 0.03 0.01
Ave -0.13 -0.02 -0.03 0.02 -0.01 0.01 -0.15 -0.08 -0.03 0.06 -0.01 -0.02 0.00
Stdev 0.25 0.05 0.09 0.02 0.01 0.01 0.37 0.16 0.07 0.18 0.01 0.03 0.01
669 A
5460 A
11347 A
669 A - 11347 A
11925 A
Average and stdev of ‘Integral’ data Average and stdev of ‘Integral’ data as presented by G: Velev et al in IEEE Trans. Appl. Supercon. 17 (2007) 1109
E. Todesco 24th May 2009 – Decay and harmonics in MQXB - 9
CONTENTS
Features and function in the machine, and available measurements for field harmonics
Field harmonicsAllowedNot allowed
Decay
E. Todesco 24th May 2009 – Decay and harmonics in MQXB - 10
DECAY
Measurements:We have no data, and we base our analysis on the results reported by G. Velev et al.In FNAL they used a two-parameter log fit
We used the listed parameters in Velev paper to reconstruct dataAverage b6 decay after 1200 s is 1.7 units with a 0.4 units spread
No info on the TF from that paper
E. Todesco 24th May 2009 – Decay and harmonics in MQXB - 11
DECAY
FiDeL fitWe use a double exponential fitThe fit error is negligible (0.02 units)The parameters d and have a very small spread (the exp fit looks pretty solid!)
We propose to neglect this component
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
0 200 400 600 800 1000 1200
b6 (u
nits
)Measurement (log fit)
FiDeL fit
Cold mass b6,1 ts c d Db6 at 1200 s
1 0.50 13.3 1.41 0.40 55 1.342 0.35 8.9 1.75 0.44 50 1.683 0.50 12.9 2.40 0.42 60 2.255 0.30 9.8 1.48 0.42 50 1.426 0.50 13.9 2.32 0.40 55 2.208 0.26 8.1 1.33 0.44 50 1.289 0.34 9.5 1.69 0.42 50 1.62
10 0.35 9.8 1.72 0.42 50 1.6511 0.33 8.7 1.66 0.44 50 1.5912 0.55 15.3 2.55 0.40 60 2.3813 0.35 9.3 1.75 0.42 50 1.6817 0.54 15.6 2.49 0.40 60 2.3219 0.23 7.6 1.20 0.44 50 1.15
Ave 0.39 11.0 1.83 0.42 53 1.7Stdev 0.11 2.8 0.46 0.02 4 0.4
Exponential fit parametersLog fit parameters
E. Todesco 24th May 2009 – Decay and harmonics in MQXB - 12
CONCLUSIONS
Geometric: set on values at collision (about 7 TeV), one component per magnet
b6 very well optimized (shimming from the fourth magnet to correct 0.5 units, final average within 0.1 units)Negligible difference from 5 to 7 TeVSmall systematic b4 (0.1 units)
Small systematic a4 (0.2 units) present in Velev papers, but not in our data – to be checked with FNAL colleagues
Persistent: about -1.5 unit on b6, taken into account by a persistent component, the same for every magnet
Decay: about 1.7 units on b6
Fit for b6 has been computed as an excercise, but we propose to neglect it in FiDeL
Anyway, it would be good to recover warm measurements, Dcloop, and decay