1 / 16

Introduction to the LCLS Undulators Heinz-Dieter Nuhn, SLAC / LCLS October 14, 2004

Introduction to the LCLS Undulators Heinz-Dieter Nuhn, SLAC / LCLS October 14, 2004. Undulator Overview Requirement Documents Undulator Fields and Tapering Cradle Components and Motion MMF Physics Requirements. Far Hall. Undulator. Near Hall. Linac Coherent Light Source.

adrina
Download Presentation

Introduction to the LCLS Undulators Heinz-Dieter Nuhn, SLAC / LCLS October 14, 2004

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript


  1. Introduction to the LCLS UndulatorsHeinz-Dieter Nuhn, SLAC / LCLSOctober 14, 2004 • Undulator Overview • Requirement Documents • Undulator Fields and Tapering • Cradle Components and Motion • MMF Physics Requirements

  2. Far Hall Undulator Near Hall Linac Coherent Light Source

  3. Undulator Segment Prototype

  4. Undulator Requirement Documents Index URL:http://www-ssrl.slac.stanford.edu/lcls/requirements.html

  5. Summary of Nominal Undulator Parameters Undulator Type planar hybrid Magnet Material NdFeB Wiggle Plane horizontal Gap 6.8 mm Period Length 30.0± 0.05 mm Effective On-Axis Field 1.249 T Standard Effective K 3.49290 ± 0.015% Range of Effective Undulator Parameter K 3.5000 - 3.4929 (3.4804) Accumulated Segment Phase Error Tolerance 10 degrees(at any point along segment) Module Length 3.40 m Number of Modules 33 Undulator Magnet Length 112.2 m Standard Break Lengths 48.2 - 48.2 - 94.9 cm Nominal Total Device Length 130.954 m Quadrupole Magnet Technology EMQ Nominal Quadrupole Magnet Length 7 cm Integrated Quadrupole Gradient 3.0 T

  6. Micro Tapering V: K values • The following list contains the nominal K values for the 33 undulator segments for the 6.8 mm gap height: To compensate energy loss from spontaneous radiation This amount of tapering requires only a negligible adjustment for break lengths. After achieving goal performance, tapering beyond saturation point is desirable. (up to 0.56% total)

  7. Undulator Pole Canting Suggested by J. Pflueger, DESY • Canting comes from wedged spacers • 4.5 mrad cant angle • Gap can be adjusted by lateral displacement of wedges • 1 mm shift means 4.5 microns in gap, or 8.2 Gauss • Beff adjusted to desired value Source: Liz Moog

  8. Canting the poles helps in many ways • Facilitates final setting of Beff • Remote control of position allows run-time adjustment • Allows compensating for temperature effect on field strength: ±1.0°C temperature error would require ±1.2 mm lateral shift of undulator Source Liz Moog

  9. Effective B field vs. x See I. Vasserman’s Talk for Prototype Measurements Measured slope of 6.6 Gauss/mm agrees with calculations(~ 5.7 Gauss/mm for 3 mrad cant) Field variation allowance between segments is DB/B = 1.5x10-4, or DB = 2 Gauss, which translates to Dx = 0.3 mm ( or 1 micron in gap) Source Liz Moog

  10. Using Undulator Roll-Away and K Adjustment Function Neutral; K=3.4965; Dx=+0.0 mm First; K=3.5000; Dx=-1.5 mm PowerTp; K=3.4804; Dx=+7.0 mm Last; K=3.4929; Dx=+1.5 mm RollAway; K=0.0000; Dx=+100 mm

  11. Cradle Components • Cradle Components include • Undulator strongback arrangement mounted on horizontal slides • Vacuum chamber support • BPM • Quadrupole • WPM sensors • HLS sensors • (diagnostics chamber) • The undulator strongback arrangement (segment) is mountable on and removable from the cradle with the vacuum chamber in place and without compromising the alignment of the vacuum chamber. • Undulator strongback can be taken off the cradle for magnetic measurements • Complete cradle assembly will be aligned on Coordinate Measurement Machine (CMM).

  12. Motions of the Cradle and of Cradle Components • Remotely Controlled Motion: • Cradle: x, y, roll • x, y motion of cradle ends are coupled • roll motion capability is to be used to keep roll constant • Undulator: x • Horizontal slide stages move undulator strongback independent of cradle and vacuum chamber • Manual Adjustment: • Cradle Movers to fixed support girder (AMP) • Quadrupole and BPM position to cradle.

  13. MMF Physics Requirements • Earth Magnetic Field Compensation • Establish environmental magnet field in MMF to be equal to the environmental field at target location in undulator hall to better than 0.01 T. • MMF Temperature • Average ambient MMF temperature needs be 20.0 ± 0.1 oC to match the ambient undulator hall temperature of 20.0 ± 0.2 oC. • Magnetic Undulator Shimming to • Reduce phase error below 10 degrees at 0.15 nm. • Reduce 1st Field Integral below ±40×10-6 Tm • Reduce 2nd Field Integral below ±50×10-6 Tm2 • Definition of Standard Undulator Axis (SUSA) so that • SUSA is Parallel to Undulator Center Line • Effective K along SUSA is 3.4965 ± 0.0005 • Alignment of Quadrupole on Cradle with respect to CA*. • Tolerance: 40 mm (rms). • Routine Operational Checking of Undulator Segments • Remove 3 segments / month from undulator hall and replace with spares • Characterize magnetic field of removed segments and prepare for re-installation. See J. Welch’s and I Vasserman’s talks for details *Cradle Axis (CA) is identical to SUSA when undulator segment is in neutral horizontal position

  14. Conclusions • Requirements and Specifications are available from the LCLS WEB site. • The main Physics Requirements Document (PRD) outlining the requirements for the undulator system is PRD1.4-001. The MMF specifications are found in PRD1.4-002. • Main Physics Task to be done at the MMF are • Undulator magnetic field tuning to specifications under same surrounding magnetic field and temperature conditions as at target location in undulator hall. • Quadrupole and BPM alignment on cradle with respect to undulator strongback • Characterization of undulators that have been used in operation • All undulator segments will be tuned identically. • Micro-tapering implies that every undulator core be at a slightly different K value, which will be accomplished by horizontal positioning. http://ssrl.slac.stanford.edu/lcls/internals/requirements.html

  15. End of Presentation

More Related