LCLS
Optical Diagnostics Design
Design Review March 3, 2004
Jim Bailey, ANL, Mechanical Engineer
A Work in Progress
1
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UNDULATOR SYSTEMS REVIEW MARCH 3-4, 2004
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Scanning Wire --- Existing Technology
Literature Survey:
Initial Search Produced 45 Publications Related to Scanning Wires
Reduced to 9 Relevant Publication Considering:
Mechanical Engineering Design
Small Beam Micron Size (Electron)
Date
Brief Review:
SLAC Papers
“A High Resolution Wire Scanner for Micron-Size…..
C. Fields, et al, 1989.
Mechanical Design of Wire Assembly
“Wire Scanner for Beam Size and…….at the SLC”
M.C. Ross, et al, 1991.
Mechanical Design of Wire Assembly
“Wire Breakage in SLC Wire Profile Monitors”
C. Fields, et al, 1998.
Theory for Wire Failure and Solutions
“Analysis of a Novel Diffractive Scanning …….”
R. Tatchyn, 1998.
Design Concept for Scanning Wire in LCLS
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Scanning Wire --- Existing Technology Continued
Other Papers
“ Wire Scanners for Small Emittance Beam……… in ATF”
H. Hayano, KEK, Japan, 1999.
Mechanical Design of Wire Assembly and Positioners
“A Method for Measuring Vibrations in Wire Scanner..”
Naoka IIDA, et al, KEKB, Japan, 1998.
Mechanical Design of Wire Assembly and Positioners
“A Wire Scanning Type … …. for an Undulator Radiation”
Xiaowei Zhang, et al, Japan, 1994.
Mechanical Design and Thermal Analysis of Wire Assembly
“Performance of Wire Scanner… .. Racetrack Microtron”
R.I. Cutler, et al, NBS-Los Alamos, 1987.
Mechanical Design of Wire Assembly
“Vibrating Wire Scanner for Beam Profile Monitoring”
S.G. Arutunian, et al, Yerevan Physics Inst., 1999.
Thermal Analysis of Wire
Other Sources:
Contacts at SLAC (E. Bong), APS, IPNS, SNS.
Commercially Available Devices.
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Scanning Wire – Design Considerations
Positioner Requirements:
Spacial Accuracy- (Beam Size, Sigma 25 Micron)
Absolute -- 25 Micron
Resolution – 1-5 Micron Linear
Stroke -- 6mm fine travel, 100 mm course travel (typical)
Speed and Acceleration – TBD (rep rate, detection scheme)
Environment –
Vacuum 1E-9 Torr, Ambient Temp.
Radiation – TBD
Limited Space
Wire/Foil Assembly:
Wire/Foil Properties Diameter/Thickness -- 25 Microns
Material -- Tungsten w/ Gold Plate, Graphite, Beryllium, Diamond
Configurations -- Round, Rectangular, Plate Edge
Wire/Foil Design Issues Mounting -Vibration -Heating -- Max. Allowable Material Temp.,
Thermal Expansion and Cyclic Stress Radiation Damage
X-Ray option-4
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Feature: near normal reflection improves depth of field
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OTR – Design Considerations
Imaging Requirements:
Field of View -- 6mm X 6mm Minimum
Image Resolution --10 Microns rms (min. 5 Micron/Pixel)
Camera -- Chip Size 1,200 X 1,200 Minimum (2MP)
W/ Shielding (Lead or Tungsten)
Optics (Light Transport) -- Screen Size Compatible w/ Camera CCD
Spacial Resolution < = 10 Micron
Upstream Filter -- Reduce Ambient Light (Background)
Thin Foil Reduce Scattering
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OTR -- Design Consideration
Geometry:
Model—
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Engineering/Physics Analyses
Radiation Issues -- Scattering from Wire/Foil
Beam Scattering – Input to Thermal Analysis
Thermal Analysis for Wire/Foil:
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Engineering/Physics Analyses Continued
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Conclusion
• Wire Scanner and OTR imager are the main diagnostics for the
electron and X-Ray beam profiles in the LCLS Undulator.
• Conceptual design of the Wire-Scanner has been established,
including X-Ray option. Component selection and initial quotation
have started.
• OTR Imager is at conceptual stage.
• Preliminary thermal & geometry models for the above have been
developed.
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