Stability Requirements for Superconducting Wiggler Beamlines
Zhong Zhong
NSLSII SCW Design
Magnet Peak Field B0 : 6 T 3.5 TPeriod Length λ: 6 cm 6 cmNumber of Main Poles (N) : 29 29number of end poles 4 4Wiggler Length (L): 0.87 m 0.87 mCritical Energy EC (0.665BE2): 36 keV 21 keVDeflection Parameter ( K=0.93B0λ ): 33.6 19.5Radiated Power at 500mA (3.9B02LI ): 61 kW 21 kWFan size (2K/): 11.4 milli-radians 6.7 milli-radiansAmpli. e- oscillation (X0= λw K/(γπ)) 0.11 mm 0.063 mmhoriz. beam chamber aperture (mm) ? ? vert. beam chamber aperture (mm) 10 10 magnetic (iron) gap (mm) 15 15 Table I: specifications of the 6 T wiggler and the alternative 3.5 T wiggler
Facility Manufacturer Field(T) Period (cm) # full-field polesNSLS X17 Oxford 6 17.4 5BESSY II Novosibirsk 7 14.8 13CLS Novosibirsk 4.2 4.8 25ELETTRANovosibirsk 3.6 6.4 45MAX lab ? 3.5 6.1 47Table II. A partial list of working super-conducting wigglers similar in specifications
NSLSII SCW Performance
1012
1013
1014
1015
1016
Flu
x [p
hoto
ns/s
ec/0
.1%
bw
/mra
d]
10 eV 100 eV 1keV 10keV 100keV
Photon Energy
Wigglers
VUVhcrit
NSLS-II DW100-1.8T,B=1.8T, 100mm,L=7m, K=16.8
NSLS-II, 25m-radius bend,B=0.4T, Ec=2.39keV
Bending magnets
NSLS-II DW100-1.8T,B=1.8T, 100mm,L=2m, K=16.8
NSLS-I 6.88m-radius bend,B=1.36T, Ec=7.09keV
NSLS-II SCW,B=3.5T, 60mm,L=1m, K=19.6
NSLS-II SCW,B=6T, 60mm,L=1m, K=33.6
Flux of the NSLS-II superconducting wiggler, compared with that of NSLS-II bending magnets, damping wigglers, and an alternative superconducting wiggler (W60 in NSLS-II CD0 proposal) with 3.5 T peak field.
Center Hutches
Side Hutches
2-D focusing sagittally bent Laue monochromator
Sagittal focusing tunable Laue
monochromator
Vertical focusing mirror
Beamline Optics & Instrumentation:
• 2 fixed-wavelength side stations and
• 2 center stations, white beam or focused monochromatic beam, or both
• 6-circle Huber diffractometer with bent Laue analyzer for high-resolution diffraction experiments.
NSLSII SCW Beamlines
NSLSII SCW Experimental Programs
• Angular dispersive x-ray diffraction (ADXD)• Large volume press• Diamond Anvil cell• Diffuse scattering• Powder diffraction
• Energy-dispersive x-ray diffraction (EDXD)• Large volume press• Diamond Anvil cell• Strain mapping
• Imaging and radiation therapy research• Diffraction Enhanced Imaging• Microbeam Radiation Therapy
ADXD, large samples
• large volume press, diffuse scattering, powder diffraction, sample size ~ 1 mm.• x-rays are focused by a sagittal focusing Laue monochromator at a magnification of approximately unity. • A position stability of 10% of sample size results in a source-position stability of approximately 100 µm horizontally and vertically. • Vertical angular stability: 10 µrad
• A wavelength stability of 10-4 • Si 111 monochromator at a Bragg angle of approximately 0.1 rad
First crytalSecond Crystal
Sagittal bending enables
sagittal-focusing Anticlastic bending
Allows meridional focusing
Lattice strain increases
integrated reflectivity by
1-2 orders of magnitude
compared to perfect crystal
EDXD
• Strain mapping, deformation experiments, diamond anvil cell, large volume press• Most challenging for orbit stability: use the peak position as a figure-of-merit. • Angle of the incident beam is defined by a fixed slit and the source • Diffraction angle (2) typically being 0.1 rad. • To obtain 10 micro-strains (10-5 d/d) accuracy, the incident angle as defined by the slit and source should be maintained to within 10-6 rad. •The source and beam-defining slit being 50 meters apart, the vertical source position should have a stability of 5010-6 meters, or 50 µm.
ADXD, small samples
• Diamond anvil cell, sample size: a few microns • Source position stability of 100 µm horizontally and vertically.
• K-B mirrors (at a magnification of approximately 100:1) are used to focus the x-rays. • A position stability of 1 µm at the sample
•Vertical angular stability: 10 µrad• A wavelength stability of 10-4 • Si 111 monochromator at a Bragg angle of approximately 0.1 rad
Imaging and radiation therapy•DEI and micro-CT, micro-beam radiation therapy (MRT)•The distance between the subject and detector is typically 1 meter, and a resolution of ~1 µm is typically desirable.•50 meters source-to-subject distance, •The source position should be stable to within 50 µm horizontally and vertically.
Synchrotron Beam
Double Crystal
Monochromator
Object
Detector
ObjectAnalyzer Synchrotron DEI Setup
Synchrotron RadiographyDetector
Summary: superconducting wiggler
• The source position should be stable within 50 µm horizontally and vertically• Source vertical angle should be stable within about 10 µrad.• There is no requirement on source horizontal angle due to the large horizontal divergence afforded by a superconducting wiggler.
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