synchrotron final presentation
TRANSCRIPT
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Wiggler
Wiggler is an Insertion device in a Synchrotron
It is a series of magnet which is designed periodically to deflect a beam of charged particles in side a storage ring of Synchrotron
These deflections creates a change in acceleration which produces emission of broad synchrotron radiation tangent to the curve
Wiggler has a broader spectrum of radiation then an undulator
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Advanced Light Source (ALS)
Located in Berkeley, California
Original Building is situated in East Bay Hills overlooking San Francisco Bay was completed in 1942
It was designed by Arthur Brown, Jr.
It is of the biggest sources ofUltraviolet and Soft X – ray light
ALS serves about 2,000 researchers("users") every year from academic,industrial, and government laboratories worldwide
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ALS Quick Facts
210 ALS Staff
600 Referred publication per year
$57.5M Average operating budget per year
5300 Average number of operating hours per year
39+ Beam test facility i.e. number ofbeamlines
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About Paper
About Wigglers which are used in ALS
Two 3.4 m long wigglers are being designed and constructed
One is a 19 period planar wiggler with 16 cm period length known as W16.0 Wiggler, designed to provide photons up to 12.4 KeV for Protein Crystallography
Other is a 14 period 20 cm period length elliptical wiggler, commonly known as EW20.0 Elliptical Wiggler, designed toprovide circularly polarized photons in the range of 50 eV to 10 KeV for Magnetic Circular Dichroism Spectroscopy
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Principal parameters of WigglersParameter (Units) W16.0 EW20.0
Vertical Magnetic Gap (cm) 1.4 1.4
Horizontal Magnetic Gap (cm) 7.2
Peak Vertical Field (T) 2.0 2.0
Peak Horizontal Field (T) 0.095
Maximum Horizontal Peak Frequency (HZ)
1.0
Period Length (cm) 16.0 20.0
Number of Periods 19 14 Vertical, 14.5 Horizontal
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W16.0 WigglerMechanical Configuration:W16.0 includes a Magnetic structure, Support/drive, Control and a Vacuum System
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W16.0 WigglerMagnetic Structure:
Variable gap, hybrid – permanent magnet magnetic structure design and construction are different from those ALS Undulators
Basic building block of magnetic structure is half – period pole assembly
Unit consist of a Aluminum keeper and a pole this is in pinned
25 Kg half – period pole assemblies are individually mounted on two backing beams
Pole Surfaces are aligned to within 25 microns with respect to each other on each backing beam
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W16.0 WigglerSupport/drive System:
Provides framework for holding the Magnetic Structures and drive system the open and close Vertical Magnetic Structure Gap
Similar to ALS Undulator but shorter 3.5 m in Length and 1.5 m in Width
Gap motion is achieved by Stepper Motor with Transrol roller screws attached
Control and Vacuum System:
A compumotor system identical to ALS Undulators
Vacuum system in also similar but they are 3.8m in Length
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EW20.0 Elliptical WigglerMechanical Configuration:EW 20.0 includes a Horizontal and Vertical Magnetic structure, Support Structure and a Vacuum Chamber
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EW20.0 Elliptical WigglerVertical Magnetic Field Structure:
This consist of a periodic structure with 14 periods
To achieve 2.0 T peak poles are tapered in both transverse and longitudinal directions near the pole tip
Entrance and Exit vertical magnetic structures are configured, so that the central electron beam in on axis for all beam values
Except for period length and pole configuration, design and construction of EW20.0 vertical magnet is very similar to W16.0 Wiggler
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EW20.0 Elliptical Wiggler
Horizontal Magnetic Field Structure:
Period length is same like Vertical Magnetic Structure but longitudinally phase shifted ¼ period relative to the vertical magnetic structure
Magnetic field distribution includes 14 ½ periods and ends are modified to achieve normalized structure, same as vertical field
Horizontal core structures are laminated from 0.64 mm thick M – 36 electrical steel
Powered by Water cooled electrical coils
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EW20.0 Elliptical WigglerVacuum Chamber:
It is a welded stainless steel assembly that includes a beam chamber, 18 pump out tubes pump tubes
Beam Chamber aperture, with internal dimension of 1.0 cm by 6.1 cm is adequate for dynamic aperture requirements
Vertical gap of 1.4 cm and Horizontal magnetic gap of 7.2 cm are achievable with this beam aperture
With ALS operation at 1.9 GeV and 400 mA, maximum chamber temperature rise is 40 Centigrade
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References1) E. Hoyer, et al., “Undulators at the ALS, 5th International Conf. on Syn Rad. Inst”
2) “U10.0 Undulators Conceptual Design Report”, LBL PUB – 5390 (June 1994)
3) “W16.0 Wiggler Conceptual Design Report”, LBL PUB – 5288 (Feb 1991)
4) “EW20.0 Elliptical Wiggler Conceptual Design Report”, LBL PUB – 5400 (March 1995)
5) “Optimization Design Study for an Elliptical Wiggler at ALS”, LBL PUB – 35510 (Feb 1995)
6) http://en.wikipedia.org
7) http://www.als.lbl.gov