Undulator Parameter Workshop, May Undulator Parameter Workshop, May 21-23, 2003 21-23, 2003 Heinz-Dieter Nuhn, SLAC / Heinz-Dieter Nuhn, SLAC / SSRL SSRL Overview of Proposed Parameter Overview of Proposed Parameter Changes Changes [email protected][email protected]Linac Coherent Light Source Stanford Synchrotron Radiation Laboratory Stanford Linear Accelerator Center Overview of Proposed Parameter Changes Heinz-Dieter Nuhn, SLAC / SSRL October 24, 2003 Calculation of On-Axis Undulator Field Calculation of On-Axis Undulator Field Undulator Period Undulator Period Maximum Available Linac Energy Maximum Available Linac Energy Undulator Gap Selection Undulator Gap Selection New Break Distances New Break Distances Reduction in Focusing Strength Reduction in Focusing Strength
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Overview of Proposed Parameter Changes [email protected] Linac Coherent Light Source Stanford Synchrotron Radiation Laboratory Stanford Linear Accelerator.
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Undulator Parameter Workshop, May 21-23, Undulator Parameter Workshop, May 21-23, 20032003
Overview of Proposed Parameter ChangesOverview of Proposed Parameter Changes [email protected]@slac.stanford.edu
Linac Coherent Light Source Stanford Synchrotron Radiation LaboratoryStanford Linear Accelerator Center
Overview of Proposed Parameter ChangesHeinz-Dieter Nuhn, SLAC / SSRL
October 24, 2003
Overview of Proposed Parameter ChangesHeinz-Dieter Nuhn, SLAC / SSRL
October 24, 2003
Calculation of On-Axis Undulator FieldCalculation of On-Axis Undulator Field Undulator PeriodUndulator Period Maximum Available Linac EnergyMaximum Available Linac Energy Undulator Gap SelectionUndulator Gap Selection New Break DistancesNew Break Distances Reduction in Focusing StrengthReduction in Focusing Strength
Calculation of On-Axis Undulator FieldCalculation of On-Axis Undulator Field Undulator PeriodUndulator Period Maximum Available Linac EnergyMaximum Available Linac Energy Undulator Gap SelectionUndulator Gap Selection New Break DistancesNew Break Distances Reduction in Focusing StrengthReduction in Focusing Strength
Undulator Parameter Workshop, May 21-23, Undulator Parameter Workshop, May 21-23, 20032003
Overview of Proposed Parameter ChangesOverview of Proposed Parameter Changes [email protected]@slac.stanford.edu
Linac Coherent Light Source Stanford Synchrotron Radiation LaboratoryStanford Linear Accelerator Center
Halbach formula for hybrid undulator is used to Halbach formula for hybrid undulator is used to estimate relation between gap/period and on-axis estimate relation between gap/period and on-axis fieldfield
Measured prototype field 5.3% larger than estimatedMeasured prototype field 5.3% larger than estimated
Halbach formula for hybrid undulator is used to Halbach formula for hybrid undulator is used to estimate relation between gap/period and on-axis estimate relation between gap/period and on-axis fieldfield
Measured prototype field 5.3% larger than estimatedMeasured prototype field 5.3% larger than estimated
Adjusting Estimate of On-Axis Undulator FieldAdjusting Estimate of On-Axis Undulator FieldAdjusting Estimate of On-Axis Undulator FieldAdjusting Estimate of On-Axis Undulator Field
2gap gap
b cperiod periodB a e
3.44 T
5.08
1.54
a
b
c
3 cm1.325 T
6.00 mm
periodB
gap
6.35
3 cm1.325 T
mm
periodB
gap
5.08
1.5
3.6
4
2 Ta
b
c
Undulator Parameter Workshop, May 21-23, Undulator Parameter Workshop, May 21-23, 20032003
Overview of Proposed Parameter ChangesOverview of Proposed Parameter Changes [email protected]@slac.stanford.edu
Linac Coherent Light Source Stanford Synchrotron Radiation LaboratoryStanford Linear Accelerator Center
Undulator PeriodUndulator PeriodUndulator PeriodUndulator Period
Present undulator period length of 3 cm is near Present undulator period length of 3 cm is near optimum for shortest gain lengthoptimum for shortest gain length
Change of undulator period length would require more Change of undulator period length would require more man-power and time than available before next reviewman-power and time than available before next review
Undulator period length will be kept at Undulator period length will be kept at
uu = 3 cm = 3 cm
Present undulator period length of 3 cm is near Present undulator period length of 3 cm is near optimum for shortest gain lengthoptimum for shortest gain length
Change of undulator period length would require more Change of undulator period length would require more man-power and time than available before next reviewman-power and time than available before next review
Undulator period length will be kept at Undulator period length will be kept at
uu = 3 cm = 3 cm
Undulator Parameter Workshop, May 21-23, Undulator Parameter Workshop, May 21-23, 20032003
Overview of Proposed Parameter ChangesOverview of Proposed Parameter Changes [email protected]@slac.stanford.edu
Linac Coherent Light Source Stanford Synchrotron Radiation LaboratoryStanford Linear Accelerator Center
1.5 Å at Reduced Electron Beam Energy1.5 Å at Reduced Electron Beam Energy1.5 Å at Reduced Electron Beam Energy1.5 Å at Reduced Electron Beam Energy
With the 8.2 mm gap the 1.5 Å radiation is produced With the 8.2 mm gap the 1.5 Å radiation is produced at lower energy (14.35 GeV 11.46 GeV) and at lower energy (14.35 GeV 11.46 GeV) and smaller undulator parameter (3.711 2.838).smaller undulator parameter (3.711 2.838).
FEL output power reduced by 50 %.FEL output power reduced by 50 %.
Problem for experiments that need as large a Problem for experiments that need as large a number of photons a possible, such as imaging of number of photons a possible, such as imaging of bio-molecules.bio-molecules.
Solution: New Field Adjustment Comb allows Solution: New Field Adjustment Comb allows tapering the undulator after the saturation point.tapering the undulator after the saturation point.
Tapering by about 0.3 % over the last 30 m more Tapering by about 0.3 % over the last 30 m more than restores the lost energythan restores the lost energy
With the 8.2 mm gap the 1.5 Å radiation is produced With the 8.2 mm gap the 1.5 Å radiation is produced at lower energy (14.35 GeV 11.46 GeV) and at lower energy (14.35 GeV 11.46 GeV) and smaller undulator parameter (3.711 2.838).smaller undulator parameter (3.711 2.838).
FEL output power reduced by 50 %.FEL output power reduced by 50 %.
Problem for experiments that need as large a Problem for experiments that need as large a number of photons a possible, such as imaging of number of photons a possible, such as imaging of bio-molecules.bio-molecules.
Solution: New Field Adjustment Comb allows Solution: New Field Adjustment Comb allows tapering the undulator after the saturation point.tapering the undulator after the saturation point.
Tapering by about 0.3 % over the last 30 m more Tapering by about 0.3 % over the last 30 m more than restores the lost energythan restores the lost energy
Undulator Parameter Workshop, May 21-23, Undulator Parameter Workshop, May 21-23, 20032003
Overview of Proposed Parameter ChangesOverview of Proposed Parameter Changes [email protected]@slac.stanford.edu
Linac Coherent Light Source Stanford Synchrotron Radiation LaboratoryStanford Linear Accelerator Center
New Break LengthsNew Break LengthsNew Break LengthsNew Break Lengths
Separations between undulator modules (breaks) Separations between undulator modules (breaks) designed to produce slippage by integer number of optical designed to produce slippage by integer number of optical wavelength.wavelength.
Break increments for adding slippage of 1 optical Break increments for adding slippage of 1 optical wavelength is wavelength is LLBB==uu (1+K (1+K22/2). /2).
LLBB=23.7 cm (old); 15.1 cm (new)=23.7 cm (old); 15.1 cm (new)
Present design uses break pattern 1-1-2 which Present design uses break pattern 1-1-2 which corresponds to the lengths sequence corresponds to the lengths sequence 18.7 cm – 18.7 cm – 42.1 cm 18.7 cm – 18.7 cm – 42.1 cm
18.7 cm gives not enough space for quads, BPMs, etc. 18.7 cm gives not enough space for quads, BPMs, etc. 42.1 cm gives not enough space for x-ray diagnostics42.1 cm gives not enough space for x-ray diagnostics
New break pattern 3-3-4 (or 3-3-5) corresponding to lengthNew break pattern 3-3-4 (or 3-3-5) corresponding to lengthsequence 44.6 cm – 44.6 cm – 55.7 cmsequence 44.6 cm – 44.6 cm – 55.7 cm (or 44.6 cm – 44.6 cm – 70.8 cm) (or 44.6 cm – 44.6 cm – 70.8 cm)
Separations between undulator modules (breaks) Separations between undulator modules (breaks) designed to produce slippage by integer number of optical designed to produce slippage by integer number of optical wavelength.wavelength.
Break increments for adding slippage of 1 optical Break increments for adding slippage of 1 optical wavelength is wavelength is LLBB==uu (1+K (1+K22/2). /2).
LLBB=23.7 cm (old); 15.1 cm (new)=23.7 cm (old); 15.1 cm (new)
Present design uses break pattern 1-1-2 which Present design uses break pattern 1-1-2 which corresponds to the lengths sequence corresponds to the lengths sequence 18.7 cm – 18.7 cm – 42.1 cm 18.7 cm – 18.7 cm – 42.1 cm
18.7 cm gives not enough space for quads, BPMs, etc. 18.7 cm gives not enough space for quads, BPMs, etc. 42.1 cm gives not enough space for x-ray diagnostics42.1 cm gives not enough space for x-ray diagnostics
New break pattern 3-3-4 (or 3-3-5) corresponding to lengthNew break pattern 3-3-4 (or 3-3-5) corresponding to lengthsequence 44.6 cm – 44.6 cm – 55.7 cmsequence 44.6 cm – 44.6 cm – 55.7 cm (or 44.6 cm – 44.6 cm – 70.8 cm) (or 44.6 cm – 44.6 cm – 70.8 cm)
Undulator Parameter Workshop, May 21-23, Undulator Parameter Workshop, May 21-23, 20032003
Present design uses special values for the first three Present design uses special values for the first three break lengths: break lengths: 28.1 cm – 25.6 cm – 47. 3 cm 28.1 cm – 25.6 cm – 47. 3 cmcompared to the regular values of compared to the regular values of 18.7 cm – 18.7 cm – 42.1 cm 18.7 cm – 18.7 cm – 42.1 cm
Introduced by Nikolay Vinokurov to improve the overall Introduced by Nikolay Vinokurov to improve the overall FEL gain.FEL gain.
Estimate for new special lengths isEstimate for new special lengths is 46.6 cm – 45.0 cm – 59.0 cm 46.6 cm – 45.0 cm – 59.0 cm (74.1 cm) (74.1 cm)
New numbers will be checked by simulationNew numbers will be checked by simulationwith RON and other codes.with RON and other codes.
Present design uses special values for the first three Present design uses special values for the first three break lengths: break lengths: 28.1 cm – 25.6 cm – 47. 3 cm 28.1 cm – 25.6 cm – 47. 3 cmcompared to the regular values of compared to the regular values of 18.7 cm – 18.7 cm – 42.1 cm 18.7 cm – 18.7 cm – 42.1 cm
Introduced by Nikolay Vinokurov to improve the overall Introduced by Nikolay Vinokurov to improve the overall FEL gain.FEL gain.
Estimate for new special lengths isEstimate for new special lengths is 46.6 cm – 45.0 cm – 59.0 cm 46.6 cm – 45.0 cm – 59.0 cm (74.1 cm) (74.1 cm)
New numbers will be checked by simulationNew numbers will be checked by simulationwith RON and other codes.with RON and other codes.
Undulator Parameter Workshop, May 21-23, Undulator Parameter Workshop, May 21-23, 20032003
Overview of Proposed Parameter ChangesOverview of Proposed Parameter Changes [email protected]@slac.stanford.edu
Linac Coherent Light Source Stanford Synchrotron Radiation LaboratoryStanford Linear Accelerator Center
Reduction in Focusing StrengthReduction in Focusing StrengthReduction in Focusing StrengthReduction in Focusing Strength
Present focusing lattice uses 5-cm-long permanent Present focusing lattice uses 5-cm-long permanent quadrupoles with gradient of 106 T/m quadrupoles with gradient of 106 T/m (< (<> = 18 m at 14.35 GeV)> = 18 m at 14.35 GeV)
Gradient reduced to 60 T/mGradient reduced to 60 T/m (< (<> = 30 m at 14.04 GeV)> = 30 m at 14.04 GeV)
Transverse quadrupole displacement used for steeringTransverse quadrupole displacement used for steering
Reduced gradients require larger quadrupole Reduced gradients require larger quadrupole displacement for same kick angle.displacement for same kick angle.
Beam Based Alignment procedure has been checkedBeam Based Alignment procedure has been checked
Present focusing lattice uses 5-cm-long permanent Present focusing lattice uses 5-cm-long permanent quadrupoles with gradient of 106 T/m quadrupoles with gradient of 106 T/m (< (<> = 18 m at 14.35 GeV)> = 18 m at 14.35 GeV)
Gradient reduced to 60 T/mGradient reduced to 60 T/m (< (<> = 30 m at 14.04 GeV)> = 30 m at 14.04 GeV)
Transverse quadrupole displacement used for steeringTransverse quadrupole displacement used for steering
Reduced gradients require larger quadrupole Reduced gradients require larger quadrupole displacement for same kick angle.displacement for same kick angle.
Beam Based Alignment procedure has been checkedBeam Based Alignment procedure has been checked
Undulator Parameter Workshop, May 21-23, Undulator Parameter Workshop, May 21-23, 20032003
Overview of Proposed Parameter ChangesOverview of Proposed Parameter Changes [email protected]@slac.stanford.edu
Linac Coherent Light Source Stanford Synchrotron Radiation LaboratoryStanford Linear Accelerator Center
LCLS Operating Points for 1 nC Bunch Charge (Old)LCLS Operating Points for 1 nC Bunch Charge (Old)
LCLS Operating Point at LCLS Operating Point at 1.5 Å1.5 ÅLCLS Operating Point at LCLS Operating Point at 1.5 Å1.5 ÅLCLS Operating Point at LCLS Operating Point at 15 Å15 ÅLCLS Operating Point at LCLS Operating Point at 15 Å15 Å
Undulator Parameter Workshop, May 21-23, Undulator Parameter Workshop, May 21-23, 20032003
Overview of Proposed Parameter ChangesOverview of Proposed Parameter Changes [email protected]@slac.stanford.edu
Linac Coherent Light Source Stanford Synchrotron Radiation LaboratoryStanford Linear Accelerator Center
ConclusionsConclusions
New values have been proposed forNew values have been proposed forundulator gap, undulator gap, maximum electron beam energy, maximum electron beam energy, break length pattern, and break length pattern, and quadrupole gradientsquadrupole gradients
Benefits areBenefits aremore room for vacuum chambermore room for vacuum chambermore space for diagnostics components between undulator modulesmore space for diagnostics components between undulator modulesincrease of accessible wavelength rangeincrease of accessible wavelength range
Reduction in photon number can be more than compensated by tapering Reduction in photon number can be more than compensated by tapering using the new Field Adjuster Comb.using the new Field Adjuster Comb.
New values have been proposed forNew values have been proposed forundulator gap, undulator gap, maximum electron beam energy, maximum electron beam energy, break length pattern, and break length pattern, and quadrupole gradientsquadrupole gradients
Benefits areBenefits aremore room for vacuum chambermore room for vacuum chambermore space for diagnostics components between undulator modulesmore space for diagnostics components between undulator modulesincrease of accessible wavelength rangeincrease of accessible wavelength range
Reduction in photon number can be more than compensated by tapering Reduction in photon number can be more than compensated by tapering using the new Field Adjuster Comb.using the new Field Adjuster Comb.
Undulator Parameter Workshop, May 21-23, Undulator Parameter Workshop, May 21-23, 20032003