Field Quality Working Group - Stephane Sanfilippo AT-MTM

Dynamic effects on Quadrupoles

AT-MTM

S.Sanfilippo, N.Sammut, L.Bottura ,W.Venturini.

Field Quality Working Group - Stephane Sanfilippo AT-MTM

Coupling current effects

Dynamic effects on quadrupoles_1

dB/dt

resistive contact at cross-overs Rc

Advance in field b2 dB/dt and 1/Rc

Allowed and non allowed multipole errors brrn, arr

n. No measurements in quadrupoles magnets for the moment.

Field Quality Working Group - Stephane Sanfilippo AT-MTM

Decay

Dynamic effects on quadrupoles_2

non-uniform dB/dt

appears during constant current excitation.

associated with current redistribution in the superconducting cables.

result of a complex interaction:

current redistribution local field magnetization bore field

assume that the dynamics follows that of current diffusion:

cndecay n a 1 e

t t inj

1

1 a 1 e

t t inj

2

Powering history dependence92

1

Field Quality Working Group - Stephane Sanfilippo AT-MTM

Quantities measuredQuantities measured :Integrated and local TF and harmonics as a function of time and current.

System usedSystem used : : 6-m twin rotating coil. Repeatability : 0.3 units (b2), 0.02 units (b6).

Decay Measurement.Decay Measurement.

Measurements performed after the training of the MQ,MQY up to ultimate.

0

5000

10000

15000

-2000 0 2000 4000 6000

tim e from beginn ing of in jection (s)

dip

ole

cu

rre

nt

(A)

IIinjinj=763 A=763 A

dB/dB/dtdt=7 =7 mTmT/s/s

IIcollcoll=11870 A=11870 A

350 A350 A

ttinjinj= 1000 s= 1000 s

PrePre--cycle.cycle.

0

5000

10000

15000

-2000 0 2000 4000 6000

tim e from beginn ing of in jection (s)

dip

ole

cu

rre

nt

(A)

IIinjinj=763 A=763 A

dB/dB/dtdt=7 =7 mTmT/s/s

IIcollcoll=11870 A=11870 A

350 A350 A

ttinjinj= 1000 s= 1000 s

PrePre--cycle.cycle.

Simulated Machine Cycle for MQ: decay at injection.

I nominal

I injection

50 A

I nominal

Pre-cycle Inom (A) tnom (s) I min (A)

MQ 11850 1000s 50

MQY 3610 1000s 50

Measurement

Cycle.Iinjection (A) tinjection(s)

MQ 760 1000s

MQY 176 1000s

Statistics : 9 MQs and 6 MQYs.

Parameters.

quench

Field Quality Working Group - Stephane Sanfilippo AT-MTM

Decay results for MQsDecay results for MQs

TF (units) b6 (units)

Average -3 0.56

sigma 1.6 0.2

@760 A, 1000s

Field Quality Working Group - Stephane Sanfilippo AT-MTM

Decay results for MQs (multipoles)Decay results for MQs (multipoles)

@760 A, 1000s

Feeble systematic. Significant random.Feeble systematic. Significant random.

Field Quality Working Group - Stephane Sanfilippo AT-MTM

Decay modelling for bDecay modelling for b22, b, b66..MQ

cndecay n a 1 e

t t inj

1

1 a 1 e

t t inj

2

92

1

TF b6

n -3 0.56

a 0.35 0.1

1 138 30

-3.5

-3

-2.5

-2

-1.5

-1

-0.5

0

0 200 400 600 800 1000

time (s)

b2 (

unit

s)

average data

model

0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0 200 400 600 800 1000time (s)

b6

(un

its)

averagedatamodel

Field Quality Working Group - Stephane Sanfilippo AT-MTM

Decay results for MQYsDecay results for MQYs

TF (units) b6 (units)

Average -6.4 0.46

sigma 2 0.1

Field Quality Working Group - Stephane Sanfilippo AT-MTM

-0.6

-0.4

-0.2

0

0.2

0.4

0.6

0.8

b3 a3 b4 a4 b5 a5 b6 a6 b7 b10

Multipole order.

Mu

ltip

ole

var

iati

on

(u

nit

s @

17m

m)

Decay results for MQYs (multipoles)Decay results for MQYs (multipoles)

High value for a3 and a4 (systematic and random) enhanced by the behavior of SSS635!

@176 A, 1000s

Field Quality Working Group - Stephane Sanfilippo AT-MTM

Example of SSS635.Example of SSS635.

@176 A, 1000s

Skew sextupole_SSS_635 (MQY)

-10.00

-5.00

0.00

5.00

10.00

15.00

0 1000 2000 3000 4000

Current (A)

a3 (

units

@ 1

7 m

m) ap 1

ap 2

6 units at 176 A!

-2 units of decay.

Decay

Field Quality Working Group - Stephane Sanfilippo AT-MTM

Decay modelling for bDecay modelling for b22, b, b66MQY

-7

-6

-5

-4

-3

-2

-1

0

0 200 400 600 800 1000time (s)

b2

(un

its)

average data

model

0

0.1

0.2

0.3

0.4

0.5

0.6

0 200 400 600 800 1000time (s)

b6

(u

nit

s)

average data

model

cndecay n a 1 e

t t inj

1

1 a 1 e

t t inj

2

92

1

b2 b6

n -6.19 0.48

a 0.14 0.7

1 38 80

Field Quality Working Group - Stephane Sanfilippo AT-MTM

Decay results for TF of MQYs, MQM (block 4)Decay results for TF of MQYs, MQM (block 4)

TF (units)

Average -3

sigma 3

TF (units)

Average -4

sigma 1

Statistic on 3 MQMsStatistic on 6 MQYs

average

Still large random, smaller systematic than in SM18. Difficult to model (noise in the measurements).

Field Quality Working Group - Stephane Sanfilippo AT-MTM

Conclusions and issues.

Decay of MQY, MQM, MQ quadrupole types: Significant for b2 (-6 units,-4 units, -3 units), large random. For b6 between 0.4 units and 0.6 units . Strange behaviors in SM18 for non allowed multipoles (ex: SSS635).

Special measurements to be performed (2006, 2007). Effect of the ramp rate (14 units foreseen for b2 for Rc~15, R. Wolf). Influence of the pre-cycle on the decay (on spare magnets in 2007?).

flat-top current IFT

flat-top duration tFT

waiting time before injection tpre-injection

Injection duration.