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DTL & CCDTL (& PIMS?) EMQs

Th. Zickler

CERN

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Outlook

History

Requirements and constraints

Proposed quadrupole layout

Magnet field characteristics

Power requirements

Dynamic behaviour

Eddy currents

Conclusions and next steps

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History

Baseline:

A common quad type for entire Linac (DTL, CCDTL, SCL)

Beginning 2007:

2 Quad types combined with steerer (DTL, CCDTL & PIMS) due to restricted space

End 2008:

One common quad type for entire Linac (DTL, CCDTL, PIMS) and separate steerers

Summer 2009:

Review: further space restrictions require new solutions; management proposal to replace CCDTL intertank EMQs with PMQs

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Design Requirements and Constraints

General common requirements:

Operation modes:

– Linac4 operation: 1 Hz, 400 µs stable flat top

– Low Power SPL operation: 2 Hz, 1000 µs stable flat top

Power converter:

– Fast pulsed power converters (200 A / 1000 V)

– Maximum flat top duration: 2 ms

– Eddy currents? Flat top stability (1000 ppm)

Restricted space:

– allows only air cooling (natural convection)

– Limited current densities (< 2 A/mm2)

Field quality:

– Field homogeneity inside GFR: < 5*10-3

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Design Requirements and Constraints

DTL specific requirements:

2 quadrupoles

Restricted space:

– in particular intertank DTL 1-2

– Overall length: < 106 mm

– Width: no severe restrictions

Pick-up inside magnet:

– Aperture radius: 20 mm 27 mm

Magnetic field requirements:

– Max. integrated field gradient: 2.2 T

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Design Requirements and Constraints

CCDTL specific requirements:

14 + 7 quadrupoles

Restricted space:

– in particular intertank

– Overall length: < 198 mm (?)

– Overall radius: < 112 (140) mm

Aperture:

– Radius: 20 mm

Magnetic field requirements:

– Max. integrated field gradient: 1.8 T

No CCDTL prototype drawing available

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Design Requirements and Constraints

PIMS specific requirements:

12 quadrupoles

Restricted space:

– Similar to DTL

– Overall length: < 106 mm (?)

– Width: no severe restrictions

Aperture:

– Radius: 20 mm

Magnetic field requirements:

– Max. integrated field gradient: 1.7 T

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Design Requirements and Constraints

Summary (‘smallest common denominator’):

35 quadrupoles

Restricted space:

– Overall length: < 106 mm

– Overall radius: < 112 (140) mm

Aperture:

– Radius: 27 mm

Magnetic field requirements:

– Max. integrated field gradient: 2.2 T

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Proposed Quadrupole Layout

Aperture radius 27.0 mm

Integrated gradient 2.21 Tm/m

Nominal gradient 22.4 T/m

Iron length 80 mm

Magnetic length 99 mm

Total length 105 mm

Magnet width 222 mm

Magnet mass 21 kg

Air cooling

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Magnetic Field Quality

-5.0E-03

-3.0E-03

-1.0E-03

1.0E-03

3.0E-03

5.0E-03

-25.0 -15.0 -5.0 5.0 15.0 25.0

dB

y/d

x w

rt G

0

x [mm]

Gradient homogeneity along the x-axis Good field radius: 18 mm

2D field quality (gradient):

+5*10-3 / -7*10-3

-1.0E-02

-8.0E-03

-6.0E-03

-4.0E-03

-2.0E-03

-1.0E-16

2.0E-03

4.0E-03

6.0E-03

8.0E-03

1.0E-02

0.0 10.0 20.0 30.0 40.0 50.0 60.0 70.0 80.0 90.0

d|B

|/d

r w

rt G

0 [%

]

angle [degree]

Gradient homogeneity along the GFR boundary

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Magnetic Field Quality

Magnetic Field Quality

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3D Design

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Power Requirements

Nominal current (@ 2.2 Tm/m) 90 A

Nominal RMS current 5.4 A

Maximum current 100 A

Maximum RMS current 6.1 A

Magnet resistance @ 20°C 430 mΩ

Magnet inductance 14.8 mH

Maximum total voltage 2800 V

RMS power consumption 16.4 W

Maximum temperature increase 20°C

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0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2 2.2 2.4 2.6 2.8 3

max

. cu

rren

t

Time [ms]

SPL LP Cycle (2 Hz)

LINAC4 Cycle (1 Hz)

Dynamic Behavior

-10%

-8%

-6%

-4%

-2%

0%

2%

4%

6%

8%

10%

-0.1

0.0

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6

Erro

r [%

]

Fiel

d [T

]

Time [ms]

Measured Field [T] Scaled current [T] Error [%]

Linac4

Ramp time: 500 µs

dI/dt: 180 kA/s

Stable flat top: 400 µs

Low Power SPL

Ramp time: 200 µs

dI/dt: 450 kA/s

Stable flat top: 1000 µs

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Eddy Currents

Ramp time: 500 µs

Material: 316 LN

Wall thickness: 2 mm

Eddy currents in vacuum chamber and pick-up

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Eddy Currents

Time constant: < 50 µs

Stable (< 10-3) after 100 µs

No significant heating

-1.5E-02

-1.0E-02

-5.0E-03

3.0E-17

5.0E-03

1.0E-02

1.5E-02

-25.0 -20.0 -15.0 -10.0 -5.0 0.0 5.0 10.0 15.0 20.0 25.0

dB

y/d

x w

rt G

0

x [mm]

Gradient homogeneity along the x-axis

DTL.V0 (dc)

DTL.V0 (0.0 ms)

DTL.V0 (0.001 ms))

DTL.V0 (0.01 ms))

DTL.V0 (0.1 ms))

GFR

-0.10

-0.08

-0.06

-0.04

-0.02

0.00

0 1 10 100 1000

field

lag

time [µs]

Field lag after ramp end

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Conclusions and Next Steps

Solution found: one design for all Linac parts

Proposed design fullfills the requirements and constraints, in particular the required dimensional limitations

No problems from eddy currents in vacuum chamber and PU expected

Total flat top of 2 ms required for field stability

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Conclusions and Next Steps

Clarification needed:

– Available space (DTL, CCDTL, PIMS)

– Confirmation of aperture size

– Pick-up design

– Power converter: inductance, ramp rate, voltage....?

– Interference with other equipment

Next steps:

– Layout integration

– Pole optimization

– 3D calculations to study end field effects (shims)

– Possible field distortions