MQM and MQY Static models

Walter Venturini Delsolaro FIDEL meeting, 18 June 2009

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Outline

• New I_MIN_OP, Pre cycling prescription for MQM and MQY circuits

• New component, new I_LOW

• Statistics on model errors

Present situation, TF=const for I< I_Low

MQM setting error at injection

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Present situation, TF=const for I< I_Low

MQY setting error at injection

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Imin=100A from data

New I_MIN_OP

• I_MIN_OP for MQY magnets was 80 A, for MQM 120A.

• ECR launched to bring it to 100A for the MQM type

• This will allow precycling to 100A in all cases

• Precycles at 100A were used in B4 for most series measurements and for more detailed measurements in 2009.

• Precycles : ramp to I_FT at dIdt_pre, dwell at I_FT for T_FT, than ramp down at dIdt_pre to I_MIN OP (pre_injection plateau)

Engineering Change Request – Class I I

Change of minimum operational currents for various LHC IPQ circuits

Brief description of the proposed change(s) :

For the power converters of type RPHGA and RPHGB powering MQM type magnets, it is proposed to set the parameter I_MIN_OP to 100 A, with relaxed tolerances below 120 A. The change will make possible to reproduce in the LHC the pre cycles adopted during standard magnetic measurements, upon which the FIDEL model is based. The setting error resulting from not being able to do so was evaluated by BE-ABP to generate a sizable additional beta beat at injection.

Equipment concerned :

LHC power converters

Drawings concerned :

Documents concerned :

LHC Functional Layout DB LSA Database

LHC Equipment Catalogue LHC-MPP-HCP-0010

PE in charge of the item :

V Montabonnet, M. Zerlauth?

PE in charge of parent item in PBS :

Decision of the Project Engineer : Rejected.

Accepted by Project Engineer, no impact on other items. Actions identified by Project Engineer

Accepted by Project Engineer, but impact on other items. Comments from other Project Engineers required Final decision & actions by Project Management

Decision of the PLO for Class I changes : Not requested.

Rejected.

Accepted by the Project Leader Office. Actions identified by Project Leader Office

Date of Approval : Date of Approval :

Actions to be undertaken :

Date of Completion : Visa of QA Officer :

Note : when approved, an Engineering Change Request becomes an Engineering Change Order/ Notification.

New static model for MQM

• New component (penetration):

• New range for MQM: 100 A 5390 A 350A.

• Above old I_LOW (265 A) the old model coincides with the new within 1-2 units

)()( IExpAITFp

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Current (A)

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Model all components

data

average error 0.78standard deviation 1.95

max error 4.69Min error -3.83

Statistics on 15 MQM apertures (same REFPARM)

Fit Error Units

average all 0.47average stdev 1.96MAX STDEV 2.75average MAX 3.51average MIN -2.92MAX MAX 5.60MIN MIN -7.71

New static model for MQY

• New component (penetration):

• New range for MQY: 100 A 5390 A 400A.

• Above old I_LOW (176 A) the old model coincides with the new within 1-2 units

)()( IExpAITFp

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average error 0.45standard deviation 1.45

Max error 3.68Min error -2.08

Statistics on 14 MQY apertures (same REFPARM)

Fit Error unitsaverage ALL -0.35average stdev 1.91max Stdev 3.58

average MAX 3.72

average MIN -3.23

MAX MAX 9.66

MIN MIN -8.83

Summary

• The new penetration component A Exp(- α I) allows to have a single static model valid over the whole operational range.

• With respect to the previous situation we correct a systematic error at injection in the order of 10-40 units depending on the magnet: each magnet gets a correction in the right direction

• A=f(α, I_MIN_OP) ? Very likely. But:

– Consistent data at different I_MIN_OP exists only for 1 MQM and 1 MQY

– The correlation is not relevant in operation as long as I_MIN_OP is fixed

• My proposal is to add two parameters A and α to the REFPARM file, and adapt the LSA implementation accordingly