Wrap-up 20 January 2004 [email protected] Linac Coherent Light Source Stanford Synchrotron Radiation Laboratory Stanford Linear Accelerator Center

LCLS Undulator Diagnostics WorkshopLCLS Undulator Diagnostics Workshop John N. Galayda, SLACJohn N. Galayda, SLAC

Wrap-up 20 January 2004Wrap-up 20 January 20041

[email protected]

Linac Coherent Light Source Stanford Synchrotron Radiation LaboratoryStanford Linear Accelerator Center

LCLS Undulator Diagnostics and Comissioning WorkshopWrap-up

John N. Galayda, Stanford Linear Accelerator Center20 January 2004

LCLS Undulator Diagnostics and Comissioning WorkshopWrap-up

John N. Galayda, Stanford Linear Accelerator Center20 January 2004

Challenges of Commissioning the FELChallenges of Commissioning the FELAlignmentAlignment

Undulator KUndulator K

Undulator DamageUndulator Damage

Undulator DiagnosticsUndulator DiagnosticsCommissioningCommissioning

OperationOperation

ChargeCharge

Challenges of Commissioning the FELChallenges of Commissioning the FELAlignmentAlignment

Undulator KUndulator K

Undulator DamageUndulator Damage

Undulator DiagnosticsUndulator DiagnosticsCommissioningCommissioning

OperationOperation

ChargeCharge



[email protected]


Beam-Based Alignment, Quad DesignBeam-Based Alignment, Quad Design

Tolerances on Trajectory are Tight for SASE at 1.5ÅTolerances on Trajectory are Tight for SASE at 1.5ÅBeam-based alignment, RFBPMs must deliver a good trajectoryBeam-based alignment, RFBPMs must deliver a good trajectory

Dispersion-free steering delivers a “straight” trajectoryDispersion-free steering delivers a “straight” trajectory

But beam is not centered in quads at completionBut beam is not centered in quads at completion

Absolute accuracy is not the crucial requirement- sensitivity is criticalAbsolute accuracy is not the crucial requirement- sensitivity is critical

Ability to change quad gradient would be a significant advantageAbility to change quad gradient would be a significant advantage

Iron/copper quads would be longer than 50mm-long permanent magnet Iron/copper quads would be longer than 50mm-long permanent magnet quadsquads

New gradient is ~60 T/m, about 11 mm bore: 3,000 gauss on the pole?New gradient is ~60 T/m, about 11 mm bore: 3,000 gauss on the pole?

NLC has struggled with “variable” permanent magnet designsNLC has struggled with “variable” permanent magnet designsDifficult to vary the gradient without moving the magnetic centerDifficult to vary the gradient without moving the magnetic center

Electromagnets still perform best in this regardElectromagnets still perform best in this regard

NLC needs beam centered in quads to 1 micron- we don’tNLC needs beam centered in quads to 1 micron- we don’t

Trim windings may be an acceptable option for LCLSTrim windings may be an acceptable option for LCLS

Trim windings still leave a residual uncertainty about actual location of quad Trim windings still leave a residual uncertainty about actual location of quad centercenter

““AC” center is not necessarily the same as the “DC” centerAC” center is not necessarily the same as the “DC” center

Tolerances on Trajectory are Tight for SASE at 1.5ÅTolerances on Trajectory are Tight for SASE at 1.5ÅBeam-based alignment, RFBPMs must deliver a good trajectoryBeam-based alignment, RFBPMs must deliver a good trajectory

Dispersion-free steering delivers a “straight” trajectoryDispersion-free steering delivers a “straight” trajectory

But beam is not centered in quads at completionBut beam is not centered in quads at completion

Absolute accuracy is not the crucial requirement- sensitivity is criticalAbsolute accuracy is not the crucial requirement- sensitivity is critical

Ability to change quad gradient would be a significant advantageAbility to change quad gradient would be a significant advantage

Iron/copper quads would be longer than 50mm-long permanent magnet Iron/copper quads would be longer than 50mm-long permanent magnet quadsquads

New gradient is ~60 T/m, about 11 mm bore: 3,000 gauss on the pole?New gradient is ~60 T/m, about 11 mm bore: 3,000 gauss on the pole?

NLC has struggled with “variable” permanent magnet designsNLC has struggled with “variable” permanent magnet designsDifficult to vary the gradient without moving the magnetic centerDifficult to vary the gradient without moving the magnetic center

Electromagnets still perform best in this regardElectromagnets still perform best in this regard

NLC needs beam centered in quads to 1 micron- we don’tNLC needs beam centered in quads to 1 micron- we don’t

Trim windings may be an acceptable option for LCLSTrim windings may be an acceptable option for LCLS

Trim windings still leave a residual uncertainty about actual location of quad Trim windings still leave a residual uncertainty about actual location of quad centercenter

““AC” center is not necessarily the same as the “DC” centerAC” center is not necessarily the same as the “DC” center



[email protected]


Challenges for Diagnostics in the Undulator ChannelChallenges for Diagnostics in the Undulator Channel

Tolerance on K of an undulator is around 1.5 x 10Tolerance on K of an undulator is around 1.5 x 10-4-4

At this time, canted undulator poles provide preferred At this time, canted undulator poles provide preferred solution for K fine-tuning (3 milliradians)solution for K fine-tuning (3 milliradians)

K tolerance equivalent to 300 micron horizontal K tolerance equivalent to 300 micron horizontal displacementdisplacement

K tolerance equivalent to 50 micron vertical misplacementK tolerance equivalent to 50 micron vertical misplacement

Piezo tuners may be deleted Piezo tuners may be deleted

This displacement does little to the electron opticsThis displacement does little to the electron opticsDispersion-free steering gets beam to within 20 microns of quad centersDispersion-free steering gets beam to within 20 microns of quad centers

If quads and undulators are aligned to within 25 microns, this tolerance If quads and undulators are aligned to within 25 microns, this tolerance is metis met

This is not quite impossible; still pretty difficultThis is not quite impossible; still pretty difficult

This displacement does little to the spontaneous spectrum of This displacement does little to the spontaneous spectrum of 1 und.1 und.

No one disputed thisNo one disputed this

Tolerance on K of an undulator is around 1.5 x 10Tolerance on K of an undulator is around 1.5 x 10-4-4

At this time, canted undulator poles provide preferred At this time, canted undulator poles provide preferred solution for K fine-tuning (3 milliradians)solution for K fine-tuning (3 milliradians)

K tolerance equivalent to 300 micron horizontal K tolerance equivalent to 300 micron horizontal displacementdisplacement

K tolerance equivalent to 50 micron vertical misplacementK tolerance equivalent to 50 micron vertical misplacement

Piezo tuners may be deleted Piezo tuners may be deleted

This displacement does little to the electron opticsThis displacement does little to the electron opticsDispersion-free steering gets beam to within 20 microns of quad centersDispersion-free steering gets beam to within 20 microns of quad centers

If quads and undulators are aligned to within 25 microns, this tolerance If quads and undulators are aligned to within 25 microns, this tolerance is metis met

This is not quite impossible; still pretty difficultThis is not quite impossible; still pretty difficult

This displacement does little to the spontaneous spectrum of This displacement does little to the spontaneous spectrum of 1 und.1 und.

No one disputed thisNo one disputed this



[email protected]


Challenges for Diagnostics in the Undulator ChannelChallenges for Diagnostics in the Undulator Channel

Radiation Damage to Undulators is a ConcernRadiation Damage to Undulators is a ConcernInterlocks will be implemented but tolerable losses are lowInterlocks will be implemented but tolerable losses are low

ANL-APS actively studying radiation damage to storage ring undulatorsANL-APS actively studying radiation damage to storage ring undulators

Can the diagnostics identify a damaged undulator?Can the diagnostics identify a damaged undulator?No one asserts that the LCLS diagnostics suite can do thisNo one asserts that the LCLS diagnostics suite can do this

Radiation Damage to Undulators is a ConcernRadiation Damage to Undulators is a ConcernInterlocks will be implemented but tolerable losses are lowInterlocks will be implemented but tolerable losses are low

ANL-APS actively studying radiation damage to storage ring undulatorsANL-APS actively studying radiation damage to storage ring undulators

Can the diagnostics identify a damaged undulator?Can the diagnostics identify a damaged undulator?No one asserts that the LCLS diagnostics suite can do thisNo one asserts that the LCLS diagnostics suite can do this



[email protected]


Charge – Will the Undulator Diagnostics Serve Commissioning and Operations Needs for the LCLS?Will the Undulator Diagnostics Serve Commissioning and Operations Needs for the LCLS? Charge – Will the Undulator Diagnostics Serve Commissioning and Operations Needs for the LCLS?Will the Undulator Diagnostics Serve Commissioning and Operations Needs for the LCLS?

CommissioningCommissioningCan diagnostics be used to troubleshoot the new hardware?Can diagnostics be used to troubleshoot the new hardware?

Can diagnostics be used to guide path to saturation?Can diagnostics be used to guide path to saturation?

Draft commissioning document emphasizes easier Draft commissioning document emphasizes easier tolerances at long wavelengthtolerances at long wavelength

Implication is that achievement of saturation at 1.5 nm will Implication is that achievement of saturation at 1.5 nm will lead to easier path to 0.15 nm saturationlead to easier path to 0.15 nm saturation

Implication of implication is reliance on FEE diagnosticsImplication of implication is reliance on FEE diagnostics

Does the commissioning plan bear this out?Does the commissioning plan bear this out?

Do simulations show convergence of K-tweaking and Do simulations show convergence of K-tweaking and steering to optimum output?steering to optimum output?

CommissioningCommissioningCan diagnostics be used to troubleshoot the new hardware?Can diagnostics be used to troubleshoot the new hardware?

Can diagnostics be used to guide path to saturation?Can diagnostics be used to guide path to saturation?

Draft commissioning document emphasizes easier Draft commissioning document emphasizes easier tolerances at long wavelengthtolerances at long wavelength

Implication is that achievement of saturation at 1.5 nm will Implication is that achievement of saturation at 1.5 nm will lead to easier path to 0.15 nm saturationlead to easier path to 0.15 nm saturation

Implication of implication is reliance on FEE diagnosticsImplication of implication is reliance on FEE diagnostics

Does the commissioning plan bear this out?Does the commissioning plan bear this out?

Do simulations show convergence of K-tweaking and Do simulations show convergence of K-tweaking and steering to optimum output?steering to optimum output?



[email protected]



OperationsOperationsWill the diagnostics permit simple and speedy Will the diagnostics permit simple and speedy troubleshooting?troubleshooting?

Reliability/Availability goals of the LCLS will be those of a Reliability/Availability goals of the LCLS will be those of a light sourcelight source

Progressive installation of undulators may work for Progressive installation of undulators may work for commissioning, butcommissioning, but

In operation, this would require automated “removal” of In operation, this would require automated “removal” of undulatorsundulators

Routine replacement/measurement of undulators must be Routine replacement/measurement of undulators must be part of planpart of plan

Operations troubleshooting needs attentionOperations troubleshooting needs attention

OperationsOperationsWill the diagnostics permit simple and speedy Will the diagnostics permit simple and speedy troubleshooting?troubleshooting?

Reliability/Availability goals of the LCLS will be those of a Reliability/Availability goals of the LCLS will be those of a light sourcelight source

Progressive installation of undulators may work for Progressive installation of undulators may work for commissioning, butcommissioning, but

In operation, this would require automated “removal” of In operation, this would require automated “removal” of undulatorsundulators

Routine replacement/measurement of undulators must be Routine replacement/measurement of undulators must be part of planpart of plan

Operations troubleshooting needs attentionOperations troubleshooting needs attention



[email protected]



Light diagnostics are crucialLight diagnostics are crucialCan the Inter-undulator diagnostics survive at high power?Can the Inter-undulator diagnostics survive at high power?

No good solution for 800 eVNo good solution for 800 eV

If not, are we placing too heavy a reliance on data taken If not, are we placing too heavy a reliance on data taken with low charge?with low charge?

Will optimization at low charge allow us to reach optimum at higher Will optimization at low charge allow us to reach optimum at higher chargecharge

40 cm looks very tight40 cm looks very tightA lot of work required to develop inter-undulator diagnosticsA lot of work required to develop inter-undulator diagnosticsInter-undulaor diagnostics that work at all wavelengths are Inter-undulaor diagnostics that work at all wavelengths are challengingchallenging

Even at shorter wavelength, variable geometry of diagnostics is a Even at shorter wavelength, variable geometry of diagnostics is a mechanical challengemechanical challenge

Rollaway undulators?Rollaway undulators?How far must they move to be useful?How far must they move to be useful?

Variable Gap would require a lot of R&DVariable Gap would require a lot of R&D

Light diagnostics are crucialLight diagnostics are crucialCan the Inter-undulator diagnostics survive at high power?Can the Inter-undulator diagnostics survive at high power?

No good solution for 800 eVNo good solution for 800 eV

If not, are we placing too heavy a reliance on data taken If not, are we placing too heavy a reliance on data taken with low charge?with low charge?

Will optimization at low charge allow us to reach optimum at higher Will optimization at low charge allow us to reach optimum at higher chargecharge

40 cm looks very tight40 cm looks very tightA lot of work required to develop inter-undulator diagnosticsA lot of work required to develop inter-undulator diagnosticsInter-undulaor diagnostics that work at all wavelengths are Inter-undulaor diagnostics that work at all wavelengths are challengingchallenging

Even at shorter wavelength, variable geometry of diagnostics is a Even at shorter wavelength, variable geometry of diagnostics is a mechanical challengemechanical challenge

Rollaway undulators?Rollaway undulators?How far must they move to be useful?How far must they move to be useful?

Variable Gap would require a lot of R&DVariable Gap would require a lot of R&D



[email protected]



Do we have redundant diagnostics capability where Do we have redundant diagnostics capability where appropriate?appropriate?

Diagnostics that check the diagnosticsDiagnostics that check the diagnostics

We are heavily dependent on FEE diagnosticsWe are heavily dependent on FEE diagnosticsI don’t see much redundancy yetI don’t see much redundancy yet

FEL/Spont is very bad for the 0.15nm caseFEL/Spont is very bad for the 0.15nm caseNothing to tune on in the first 40 metersNothing to tune on in the first 40 meters

What is the smallest PROJECTED energy spread we What is the smallest PROJECTED energy spread we can produce at any (lower) charge? Can can produce at any (lower) charge? Can spontaneous radiation serve as our diagnostic?spontaneous radiation serve as our diagnostic?

Do we need a hi-res monochromator on day 1?Do we need a hi-res monochromator on day 1?

Do we have redundant diagnostics capability where Do we have redundant diagnostics capability where appropriate?appropriate?

Diagnostics that check the diagnosticsDiagnostics that check the diagnostics

We are heavily dependent on FEE diagnosticsWe are heavily dependent on FEE diagnosticsI don’t see much redundancy yetI don’t see much redundancy yet

FEL/Spont is very bad for the 0.15nm caseFEL/Spont is very bad for the 0.15nm caseNothing to tune on in the first 40 metersNothing to tune on in the first 40 meters

What is the smallest PROJECTED energy spread we What is the smallest PROJECTED energy spread we can produce at any (lower) charge? Can can produce at any (lower) charge? Can spontaneous radiation serve as our diagnostic?spontaneous radiation serve as our diagnostic?

Do we need a hi-res monochromator on day 1?Do we need a hi-res monochromator on day 1?



[email protected]


ConclusionsConclusions

Gain versus z can be measured by turning off gain Gain versus z can be measured by turning off gain with an orbit kinkwith an orbit kink

In early commissioning there may be no measurable In early commissioning there may be no measurable gain signal for 40-50 meters when attempting to lase gain signal for 40-50 meters when attempting to lase at 0.15 nmat 0.15 nm

1010-3-3 energy resolution is a must, to get rid of energy resolution is a must, to get rid of spontaneousspontaneous

Gain versus z can be measured by turning off gain Gain versus z can be measured by turning off gain with an orbit kinkwith an orbit kink

In early commissioning there may be no measurable In early commissioning there may be no measurable gain signal for 40-50 meters when attempting to lase gain signal for 40-50 meters when attempting to lase at 0.15 nmat 0.15 nm

1010-3-3 energy resolution is a must, to get rid of energy resolution is a must, to get rid of spontaneousspontaneous



[email protected]


Issues to be Addressed Issues to be Addressed

It is important to estimate how many gain lengths It is important to estimate how many gain lengths needed to produce a gain signal above spontaneous needed to produce a gain signal above spontaneous backgroundbackground

~10~10-3-3 energy resolution is a must, to get rid of energy resolution is a must, to get rid of spontaneousspontaneous

investigate whether spontaneous radiation become a investigate whether spontaneous radiation become a diagnostic for undulator alignment and qualitydiagnostic for undulator alignment and quality

Investigate whether roll-away undulators provide a useful Investigate whether roll-away undulators provide a useful degree of freedom for diagnosing problems in degree of freedom for diagnosing problems in commissioning or operationscommissioning or operations

It is important to estimate how many gain lengths It is important to estimate how many gain lengths needed to produce a gain signal above spontaneous needed to produce a gain signal above spontaneous backgroundbackground

~10~10-3-3 energy resolution is a must, to get rid of energy resolution is a must, to get rid of spontaneousspontaneous

investigate whether spontaneous radiation become a investigate whether spontaneous radiation become a diagnostic for undulator alignment and qualitydiagnostic for undulator alignment and quality

Investigate whether roll-away undulators provide a useful Investigate whether roll-away undulators provide a useful degree of freedom for diagnosing problems in degree of freedom for diagnosing problems in commissioning or operationscommissioning or operations



[email protected]


Point of No ReturnPoint of No Return



[email protected]


End of Presentation

Documents

Wrap-up 20 January 2004 [email protected] Linac Coherent Light Source Stanford Synchrotron Radiation Laboratory Stanford Linear Accelerator Center