LCLS Conceptual Design Report - Stanford Synchrotron Radiation ...

Quad ∆X/µm
Quad ∆Y/µm
−500
L C L S C O N C E P T U A L D E S I G N R E P O R T
500
0
500
0
−500
〈(X − X fit ) 2 〉 1/2 = 184.01 µm
0 20 40 60 80 100 120
〈(Y − Y fit ) 2 〉 1/2 = 59.53 µm
0 20 40 60 80 100 120
S/m
Figure 8.47 True (blue-solid) and calculated (black-dash) quadrupole positions. The BPM offsets are
similar but not shown here. The fine structure is reproduced well.
X/µm
Y/µm
600
400
200
0
600
400
200
0
〈X 2 〉 1/2 = 148.70 µm
0 20 40 60 80 100 120
〈Y 2 〉 1/2 = 98.78 µm
0 20 40 60 80 100 120
S/m
Figure 8.48 Trajectory (blue-solid) at 14.3 GeV after one iteration of steps 1-7. BPM readbacks
(green-circle) and quadrupole positions (red-cross) are also shown. The trajectory is
fairly straight but does not necessarily follow the line established by the linac axis. This
is due to the correlated BPM and quadrupole misalignments (random walk of the initial
tunnel survey).
position and angle at the undulator entrance is used to launch the electron beam down the center
of the undulator, and the beam follows along near the center of the quadrupoles. The tiny
8-84 ♦ U N D U L A T O R