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

LCLS Undulators October 14, 2004 Heinz-Dieter Nuhn, SLAC / SSRLMMF Review [email protected]@slac.stanford.edu

Introduction to the LCLS UndulatorsHeinz-Dieter Nuhn, SLAC / LCLS

October 14, 2004

Introduction to the LCLS UndulatorsHeinz-Dieter Nuhn, SLAC / LCLS

October 14, 2004

Undulator Overview Requirement Documents Undulator Fields and Tapering Cradle Components and Motion MMF Physics Requirements

Undulator Overview Requirement Documents Undulator Fields and Tapering Cradle Components and Motion MMF Physics Requirements


Linac Coherent Light Source

Near Hall

Far Hall

Undulator



Undulator Segment Prototype


Undulator Requirement Documents

Index URL: http://www-ssrl.slac.stanford.edu/lcls/requirements.html

Index URL: http://www-ssrl.slac.stanford.edu/lcls/requirements.html


Undulator Type planar hybridMagnet Material NdFeBWiggle Plane horizontalGap 6.8 mmPeriod Length 30.0 ± 0.05 mmEffective On-Axis Field 1.249 TStandard 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 mNumber of Modules 33Undulator Magnet Length 112.2 m

Standard Break Lengths 48.2 - 48.2 - 94.9 cmNominal Total Device Length 130.954 m

Quadrupole Magnet Technology EMQNominal Quadrupole Magnet Length 7 cmIntegrated Quadrupole Gradient 3.0 T

Undulator Type planar hybridMagnet Material NdFeBWiggle Plane horizontalGap 6.8 mmPeriod Length 30.0 ± 0.05 mmEffective On-Axis Field 1.249 TStandard 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 mNumber of Modules 33Undulator Magnet Length 112.2 m

Standard Break Lengths 48.2 - 48.2 - 94.9 cmNominal Total Device Length 130.954 m

Quadrupole Magnet Technology EMQNominal Quadrupole Magnet Length 7 cmIntegrated Quadrupole Gradient 3.0 T

Summary of Nominal Undulator Parameters


Micro Tapering V: K valuesMicro Tapering V: K values

The following list contains the nominal K values for the 33 undulator segments for the 6.8 mm gap height:

The following list contains the nominal K values for the 33 undulator segments for the 6.8 mm gap height:

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)

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)

Undulator Segment Keff

1 3.50002 3.49983 3.49964 3.49935 3.49916 3.49897 3.49878 3.49849 3.498210 3.498011 3.497812 3.497613 3.497314 3.497115 3.496916 3.496717 3.496418 3.496219 3.496020 3.495821 3.495522 3.495323 3.495124 3.494925 3.494726 3.494427 3.494228 3.494029 3.493830 3.493531 3.493332 3.493133 3.4929

To compensate energy loss from spontaneous radiationTo compensate energy loss from spontaneous radiation


Undulator Pole Canting

• 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 MoogSource: Liz Moog

Suggested by J. Pflueger, DESYSuggested by J. Pflueger, DESY


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 MoogSource Liz Moog


Effective B field vs. x

Measured slope of 6.6 Gauss/mm agrees with calculations(~ 5.7 Gauss/mm for 3 mrad cant)

Field variation allowance between segments is B/B = 1.5x10-4, or B = 2 Gauss, which translates to x = 0.3 mm ( or 1 micron in gap)

Source Liz MoogSource Liz Moog

See I. Vasserman’s Talk for Prototype Measurements

See I. Vasserman’s Talk for Prototype Measurements


Using Undulator Roll-Away and K Adjustment Function

Neutral; K=3.4965; x=+0.0 mm First; K=3.5000; x=-1.5 mm

Last; K=3.4929; x=+1.5 mm RollAway; K=0.0000; x=+100 mm

PowerTp; K=3.4804; x=+7.0 mm


Cradle Components

Cradle Components includeUndulator 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).

Cradle Components includeUndulator 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).


Motions of the Cradle and of Cradle Components

Remotely Controlled Motion:

Cradle: x, y, rollx, y motion of cradle ends are coupledroll motion capability is to be used to keep roll constant

Undulator: xHorizontal 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.

Remotely Controlled Motion:

Cradle: x, y, rollx, y motion of cradle ends are coupledroll motion capability is to be used to keep roll constant

Undulator: xHorizontal 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.


MMF Physics Requirements

Earth Magnetic Field CompensationEstablish 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 TemperatureAverage 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 toReduce phase error below 10 degrees at 0.15 nm.Reduce 1st Field Integral below ±40×10-6 TmReduce 2nd Field Integral below ±50×10-6 Tm2

Definition of Standard Undulator Axis (SUSA) so thatSUSA is Parallel to Undulator Center LineEffective K along SUSA is 3.4965 ± 0.0005

Alignment of Quadrupole on Cradle with respect to CA*.Tolerance: 40 m (rms).

Routine Operational Checking of Undulator SegmentsRemove 3 segments / month from undulator hall and replace with sparesCharacterize magnetic field of removed segments and prepare for re-installation.

Earth Magnetic Field CompensationEstablish 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 TemperatureAverage 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 toReduce phase error below 10 degrees at 0.15 nm.Reduce 1st Field Integral below ±40×10-6 TmReduce 2nd Field Integral below ±50×10-6 Tm2

Definition of Standard Undulator Axis (SUSA) so thatSUSA is Parallel to Undulator Center LineEffective K along SUSA is 3.4965 ± 0.0005

Alignment of Quadrupole on Cradle with respect to CA*.Tolerance: 40 m (rms).

Routine Operational Checking of Undulator SegmentsRemove 3 segments / month from undulator hall and replace with sparesCharacterize magnetic field of removed segments and prepare for re-installation.

*Cradle Axis (CA) is identical to SUSA when undulator segment is

in neutral horizontal position

*Cradle Axis (CA) is identical to SUSA when undulator segment is

in neutral horizontal position

See J. Welch’s and I Vasserman’s talks for details

See J. Welch’s and I Vasserman’s talks for details


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 areUndulator 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.

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 areUndulator 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.

Conclusions

http://ssrl.slac.stanford.edu/lcls/internals/requirements.htmlhttp://ssrl.slac.stanford.edu/lcls/internals/requirements.html


End of Presentation