Status of the CLIC DR wiggler design and production at BINP

Status of the CLIC DR wiggler
design and production at BINP
A.Bragin, E.Levichev, P.Vobly and
S.Zaitsev
Budker Institute of Nuclear Physics, Novosibirsk
April 25, 2008


Outline

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•
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Wiggler parameter selection
Magnetic and mechanical design
Quench protection system
Wiggler production status
Wiggler production schedule


CLIC DR emittance requirements
PM emittance

CLIC DR normalized emittance 
as a function of the wiggler period
and the field amplitude
(by M.Korostelev, IBS included)

PM

SC (NbTi)

Period length

cm

10

5

Aperture (beam)

mm

12

12

Peak field

T

1.7

2.5

W. length

m

2

2

Temperature

K

Room

4.2 K

SC emittance


Wiggler parameters selection I
For a sine-like wiggler model:

w

 0


8I
  32/ 5
 min 3Lw

  x 2w 



3
 10 I 5 

2/5

hw min


I5 
 10 3

Lw  w 2w 


1/ 5

 I5 
 
2 
 Lw  w  w 

Emittance minimization requires a shorter period length and, at
the same time, a higher magnetic field amplitude.

This is a contradictory requirement!

1/ 5

Wiggler parameters selection II
The field amplitude depends on the wiggler gap and period length as:

Bw ~ exp  g /  w 

Gap  field amplitude and period  emittance
The gap usually is defined by external conditions (SR passing)


PM technology vs. SC technology

4-m-long PM damping wiggler for
the PETRA III project
Facility

Year

Bm(T)

SC wiggler for the Diamond LS
g(mm
)

L (mm)

Ay(mm)

50

500

12-14


(m
m)

SC
CLIC DR
(short)

200
8

2.5

20
SC

CLS (Canada)

200
5

2.0

13.5

34

1120

9.5

DLS (UK)

200
6

3.5

16.4

60

1544

10

CLS-2
(Canada)

200
7

4.0

14

48

1000

9.5


Main principles

 Short period and high field amplitude
 Simple technology and easy production
 Easy in tuning
 Reliable (all coils are wound by a single wire 
min of contacts)
 Magnetic forces are directed in the iron yoke 
no fixing mechanical band is needed
 Special quench protection system is proposed


Schematic view and main parameters

SC coils
Iron beam-yoke

Period length
Vertical pole gap
Beam aperture
Peak field
Prototype length
Stored energy

5.0 cm
2 cm
1.2-1.4 cm
2.5 T
50 cm
57 kJ


Magnetic design I
Magnetic flux

Air – blue
Iron – green
Coil - red

Half period

y

z
End part


0

Magnetic design II
Field amplitude in the wiggler parts (3D)

BINP Mermaid Magnetic code

Units at the plots – kG and cm

Longitudinal cross

Transverse cross/coil

Transverse cross/between coils

3-4 T

7T
5-6 T


1

Magnetic design III
Field distribution (3D)
Longitudinal in central pole

Transverse

dB/B = ±3.5x10-4
at X = ±1 cm

Longitudinal in the end part


2

Mechanical design I
General view

Regular coil
Iron yoke

End coils to compensate the first
and the second integral

Corrector coils with
individual PS


3

Mechanical design II
Yoke regular part


4

Mechanical design III
Magnetic forces in the
regular coil

SC wire contacts

Iron yoke

End coils to compensate the first

and the second integral

Corrector coils with
individual PS


5

Superconductor
For many years Bochvar Institute in Moscow produces special NbTi SC wire for
BINP with the following parameters:
Single wire length (0.5 m)
– ~2.0
km
SC packing factor
– 67.5
%
Critical current
for 7 Т – 700 А
for 8 Т – 450 А
Wire diameter
– 0.9 mm
SC strand thickness
– 30 um

In our case the current
density in the SC wire is
1250 A/mm2

Critical current

curve


6

Quench protection system I

A comparator measures the voltage difference between upper and low
coils, which appears in case of quench. If the difference appears, the
heater (stainless steel strip mounded along all the coils) heats the
coils by the capacitor pulse discharge, providing uniform distribution
of the stored energy along the wiggler.


7

Quench protection system II

Voltage distribution
diagrams with and
without the quench
protection system


8

Magnetic measurements


Testing

cryostat

700 A PS 

 Hall probe array (5 probes
placed horizontally with 10 mm
distance)


9

Status
 Wiggler development and design is completed
 The wiggler manufacturing drawings passed the
technological department
 Parts of the spooling device are manufactured and its
assembling will start in near future
 We have all materials including SC wire
 We have the testing cryostat, power supplies for the
main coil (700 A) and for the correction coils (2 PSs 10 A)
 We have all necessary equipment for magnetic
measurement
 The quench protection system is under development now


0

Schedule

17.03.07 – 01.10.07: the wiggler design and starting

the production of the coiler unit to test the winding
technology
01.10.07 – 01.03.08: finalizing of the winding
technology and starting of production of the wiggler
prototype
15.11.07 – Status report including: magnetic field
calculation, winding technology description, drawings of the
wiggler prototype and winding tooling, description of the
quench protection system

01.03.08 – 01.06.08: yoke and tooling production
01.06.08 – 15.07.08: coils production
15.07.08 – 01.08.08: wiggler installation in the
cryostat
01.08.08 – 01.10.08: wiggler test and magnetic


1

Conclusion
 The short prototype of the SC wiggler for the CLIC
DR is under production at BINP
 Main parameters of the wiggler are: Bmax = 2.5 T
with the period length of 50 mm and the pole gap
of 20 mm
 Such a gap allows to have the vertical beam
aperture around 12-14 mm
 The vertical beam aperture is defined by SR
beams passing and wake fields, which may heat
the vacuum chamber walls