mqxa: decay and field harmonics
DESCRIPTION
FiDeL meeting, 30 March 2009. MQXA: DECAY AND FIELD HARMONICS. E. Todesco Magnets, Superconductors and Cryostats Group Technology Department, CERN. CONTENTS. Decay Field harmonics Allowed Not allowed. DECAY. Measurements: Rotating coil, 600 mm long, In one central position, - PowerPoint PPT PresentationTRANSCRIPT
E. Todesco
MQXA: DECAY AND FIELD HARMONICS
E. TodescoMagnets, Superconductors and Cryostats Group
Technology Department, CERN
FiDeL meeting, 30 March 2009
E. Todesco 30th March 2009 – Decay and harmonics in MQXA- 2
CONTENTS
Decay
Field harmonicsAllowedNot allowed
E. Todesco 30th March 2009 – Decay and harmonics in MQXA- 3
DECAY
Measurements:Rotating coil, 600 mm long, In one central position, Measurements taken every ~3.7 minutes for up to 6 hoursOne close to injection (390 A) and one at high field (7149 A, i.e. ~ 7.3 TeV)
E. Todesco 30th March 2009 – Decay and harmonics in MQXA- 4
TRANSFER FUNCTION DECAY
Decay from 1 to -4 units after 20 minutes, from 2 to -8 units after 200 minutesWe propose to neglect this effect in FiDeL
-10
-8
-6
-4
-2
0
2
4
6
0 25 50 75 100 125 150 175 200 225 250
db2
(uni
ts)
Time (minutes)
1918171615141312111098765432
E. Todesco 30th March 2009 – Decay and harmonics in MQXA- 5
B6 DECAY
Decay from 0.2 to 0.8 units after 20 minutes, from 0.4 to 1.3 units after 200 minutes
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
0 25 50 75 100 125 150 175 200 225 250
db6
(uni
ts)
Time (minutes)
1918171615141312111098765432
E. Todesco 30th March 2009 – Decay and harmonics in MQXA- 6
B6 decay
The double exp fit works well
Time constants of about 500 sMagnet t (s) d c err
2 480 0.71 0.82 0.0093 420 0.69 0.86 0.0104 900 0.68 0.48 0.0045 480 0.85 0.69 0.0106 300 0.55 0.88 0.0067 420 0.68 0.91 0.0098 420 0.65 0.98 0.0159 480 0.55 1.30 0.013
10 480 0.50 1.29 0.01511 420 0.53 1.20 0.01012 480 0.56 1.09 0.00813 360 0.37 1.11 0.01714 480 0.65 0.88 0.00715 480 0.71 0.66 0.00916 540 0.60 0.62 0.00717 540 0.60 0.90 0.01118 540 0.86 0.69 0.01019 480 0.69 0.87 0.010
E. Todesco 30th March 2009 – Decay and harmonics in MQXA- 7
Decay OTHER HARMONICS
Other multipolesAll other multipoles are neglectedThere is an unexplained systematic decay in a4
b 3 a 3 b 4 a 4 b 5 a 5 b 6 a 6 b 7 a 7 b 8 a 8 b 9 a 9 b 10
Ave -0.01 -0.02 -0.02 -0.57 0.02 0.00 0.58 0.01 0.00 0.00 0.00 0.00 0.00 0.00 -0.02
Stdev 0.40 0.32 0.09 0.53 0.13 0.11 0.13 0.03 0.01 0.01 0.01 0.01 0.00 0.00 0.00
Min -0.79 -0.74 -0.23 -1.61 -0.26 -0.24 0.26 -0.07 -0.02 -0.02 -0.02 -0.02 -0.01 -0.01 -0.03
Max 0.87 0.49 0.10 0.50 0.24 0.23 0.79 0.05 0.04 0.02 0.01 0.01 0.01 0.01 -0.01
Ave 0.12 -0.08 0.01 -0.66 0.01 0.00 0.88 0.01 0.01 -0.01 0.00 -0.01 0.00 0.00 -0.04
Stdev 0.64 0.44 0.15 0.81 0.20 0.20 0.23 0.04 0.02 0.03 0.01 0.02 0.01 0.01 0.01
Min -1.26 -0.85 -0.33 -1.85 -0.47 -0.34 0.45 -0.04 -0.02 -0.06 -0.02 -0.04 -0.02 -0.01 -0.05
Max 1.52 0.75 0.30 1.18 0.29 0.47 1.27 0.07 0.06 0.05 0.02 0.03 0.01 0.01 -0.02
Aft
er 2
0 m
inut
esA
fter
200
m
inut
es
E. Todesco 30th March 2009 – Decay and harmonics in MQXA- 8
CONTENTS
Decay
Field harmonicsAllowedNot allowed
E. Todesco 30th March 2009 – Decay and harmonics in MQXA- 9
Field harmonics: ALLOWED
The MQXA are critical after the squeezeWe propose to set the model at high field exactly on the measured valuesGeometric set at value at 7 TeVA persistent component can recover the 1.1 unit difference at injection
For the allowed b6, b10
Small changes from 3.3 to 6.8 TeVNo need of different settings at 4-7 TeVb10 always negligible
b6 b10Ave -0.81 0.04Std 0.22 0.01Ave 0.38 -0.01Std 0.08 0.00Ave 0.33 -0.01Std 0.08 0.01Ave 0.33 -0.01Std 0.09 0.01Ave 1.13 -0.06
Std 0.24 0.01
392 A
3207 A (3.3 TeV)
6177 A (6.3 TeV)
6677 A (6.8 TeV)
6677 A - 392 A
E. Todesco 30th March 2009 – Decay and harmonics in MQXA- 10
Field harmonics: ALLOWED
Geometric:One per magnetSet at the value at 7 TeV
Persistent componentOne per family, to take into account of about -1 units at injection
pinjError of ~0.2 units at 2000-4000 A
b6 b102 0.520 -0.0043 0.462 -0.0024 0.457 -0.0035 0.486 -0.0036 0.441 -0.0057 0.378 -0.0058 0.396 -0.0159 0.347 -0.013
10 0.214 -0.01111 0.424 -0.01112 0.348 -0.01213 0.334 -0.01614 0.359 -0.01115 0.302 -0.00816 0.360 -0.00617 0.311 -0.00818 0.338 -0.01019 0.348 -0.007
-1.5
-1.0
-0.5
0.0
0.5
0 2000 4000 6000 8000
b6
(uni
ts)
Current (A)
Integral
Dcloop
Fit
E. Todesco 30th March 2009 – Decay and harmonics in MQXA- 11
Field harmonics: NOT ALLOWED
The MQXA are critical after the squeezeWe propose to set the geometric on the measured value at 7 TeV
For the not allowedSystematic b4 of about 1.3 units - relevant
Systematic a3 of 0.2 units – all the other systematic to zero
Offset at injection: all close to zero except a4, which has a systematic at injection of -1.3 unitsSpread at injection much larger than at high field – to be added in the MAD model as a random component
b3 b4 b5 b7 b8 b9 a3 a4 a5 a6 a7 a8 a9Ave -0.12 1.28 0.04 0.00 0.03 -0.01 0.35 -1.32 0.09 -0.01 -0.01 0.00 0.00Std 1.05 0.15 0.31 0.03 0.02 0.02 1.01 1.27 0.27 0.04 0.03 0.02 0.01Ave 0.01 1.24 0.00 0.00 0.02 0.00 0.21 -0.06 0.02 -0.03 0.00 0.00 0.00Std 0.28 0.11 0.04 0.01 0.00 0.00 0.35 0.26 0.04 0.02 0.01 0.01 0.00Ave 0.03 1.28 -0.01 0.00 0.02 0.00 0.21 -0.02 0.01 -0.03 0.00 0.00 0.00Std 0.30 0.11 0.04 0.01 0.00 0.01 0.36 0.27 0.04 0.02 0.01 0.01 0.00Ave 0.04 1.30 0.00 0.00 0.02 0.00 0.21 -0.02 0.01 -0.03 0.00 0.00 0.00Std 0.31 0.11 0.04 0.01 0.00 0.01 0.37 0.28 0.04 0.02 0.01 0.01 0.00Ave 0.17 0.02 -0.05 0.00 0.00 0.00 -0.14 1.30 -0.08 -0.02 0.01 0.00 0.00
Std 1.08 0.14 0.29 0.03 0.02 0.02 1.08 1.26 0.29 0.04 0.03 0.02 0.01
392 A
3207 A (3.3 TeV)
6177 A (6.3 TeV)
6677 A (6.8 TeV)
6677 A - 392 A
E. Todesco 30th March 2009 – Decay and harmonics in MQXA- 12
CONCLUSIONS
Geometric: set on values at collision (about 7 TeV), one component per magnet
Negligible difference from 5 to 7 TeV
Persistent: about -1 unit on b6, taken into account by a persistent component, the same for every magnetPersistent: about 0.06 units in b10, neglected
For MAD: additional spreads from collision to injection given
Decay: negligible effect on TF, b6, b10Fit for b6 has been computed as an excercise