Outline

1. Outline • 1.LCLS Requirements • 2.Magnetic Moment Measurements • 3. Sorting • 4. Vertical Field Measurements • 5. Horizontal Field Measurements • 6. Conclusion I. Vasserman, ANL/APS/ID&FEL

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3. Sorting • 1.Main component of magnetic moment • 2.    Field integrals • 3.    Pole height and cant • 4.    Phase errors I. Vasserman, ANL/APS/ID&FEL

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6. X-axis: Slot Number Y-axis: Total magnetic moment I. Vasserman, ANL/APS/ID&FEL

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9. Data From Half-period Model Here J1 is first field integral,  is an undulator period, and  is the phase. I. Vasserman, ANL/APS/ID&FEL

10. Phase calculations are very sensitive to initial conditions: Special software was created. • It gives us some approximation about quality of magnets. • Measurements: Bottom magnet is in place all the time. • Horizontal field integrals were negligible. • Tuning of magnets includes the first field integrals rather than the vertical component of magnetic moment. I. Vasserman, ANL/APS/ID&FEL

11. Example of vertical component of magnetic moment measurement. Red: measured, blue: calculated (Radia). Signature was obtained by subtracting data with vertical components of top and bottom magnets in one direction and in opposite direction. I. Vasserman, ANL/APS/ID&FEL

12. 100 80 60 40 20 0 -20 -40 -60 J1p Aver=27.1 Jin Aver= -10.6 -80 -100 0 50 100 150 200 250 300 350 400 450 500 Magnet First Field Integral (G-cm) for LCLS prototype magnets with positive component of magnetic moment (red) and negative (blue). I. Vasserman, ANL/APS/ID&FEL

13. 2.0 1.5 1.0 0.5 0.0 -0.5 -1.0 -1.5 -2.0 -2.5 -3.0 -3.5 -4.0 V_sdev= 1.34691 -4.5 0 50 100 150 200 250 300 350 400 450 500 Magnet 2.0 1.5 1.0 0.5 0.0 -0.5 -1.0 -1.5 -2.0 -2.5 -3.0 -3.5 V_sdev(-)= 1.25171 -4.0 V_sdev(+)= 1.201 -4.5 100 150 200 250 300 350 400 450 500 0 50 Magnet Phase errors vs. magnets for LCLS prototype Top: all magnets, bottom: separate, for positive vertical componentof magnetic moment (blue) and negative (red) I. Vasserman, ANL/APS/ID&FEL

14. Poles height and cant • Sorting of pole height was done to achieve the best possible gap uniformity along the device. • Cant was sorted in such a way as to provide easy access for mechanical measurements of the gap using gauge ceramic blocks and to avoid accumulation of horizontal field integrals. • Device ends will have a possibility of remote gap tuning. I. Vasserman, ANL/APS/ID&FEL

15. Measurements of First 2 Sections • First 2 sections (79 poles) were installed. • First and second field integrals were measured. • Vertical Field: Some tuning was necessary due to gap difference. Main tuning was required for the ends (1/3 of maximum shim strength) • Horizontal Field: No tuning was required. • Keff is 3.91 instead of 3.71. Gap will be increased to achieve design value. • Keff temperature dependence was measured. Keff/Keff is 0.0005 per 1C. It is close to calculated numbers, taking into account gap and magnetic moment temperature dependence. I. Vasserman, ANL/APS/ID&FEL

16. 2.0 2 1.0 1 0.0 0 Trajectory after tuning(µ) -1.0 Trajectory before tuning(µ) -1 -2.0 -2 -3.0 -3 -4 -4.0 -800 -600 -400 -200 0 200 400 600 800mm Z(mm) Horizontal trajectory vs. distance before tuning (red) and after (blue) for first 2 sections. Tolerances are 2µm I. Vasserman, ANL/APS/ID&FEL

17. 2. 1. Vertical Trajectory(µ) 0.0 - -1. -2. -800 -600 -400 -200 0 200 400 600 800 Z (mm) Vertical trajectory without tuning I. Vasserman, ANL/APS/ID&FEL

18. Conclusion • First measurements results show: Quality of magnets Design of the device and sorting are good enough already. • Tuning was rather modest. • It is clear how to implement further improvements to decrease/eliminate necessary tuning. I. Vasserman, ANL/APS/ID&FEL