Joe Frisch: Synchrotron radiation sources and free ... - Conferences
Joe Frisch: Synchrotron radiation sources and free ... - Conferences
Joe Frisch: Synchrotron radiation sources and free ... - Conferences
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Undulators for XFELs<br />
• Alternating magnetic field, wavelength of a few cm.<br />
– Shorter wavelength allows operation with lower energy<br />
electron beams (if they have enough brightness)<br />
– Short wavelength undulators require narrow gaps -><br />
alignment <strong>and</strong> wakefield problems<br />
• For XFELs, generally want as high a “K” as practical<br />
– Provides higher gain <strong>and</strong> efficiency<br />
– High K -> higher e-beam energy<br />
• Very tight tolerances: ~10 micron orbit in LCLS<br />
Beam Based Alignment of LCLS undulator H. Loos<br />
Fixed Gap Undulator: Simple, high fields, good tolerances.<br />
Need to change beam energy to change wavelength<br />
Adjustable gap Undulator: Can change wavelength with fixed<br />
e-beam energy: allows multiple undulators fed from a single<br />
linac.<br />
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LCLS fixed-gap undulator<br />
LCLS_II Test variable gap undulator<br />
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