Harmonic Generation at Lower Electron Energies for a Hard X-ray FEL

Conference · Sat Jan 01 04:00:00 EST 2011

OSTI ID:1011072

Marksteiner, Quinn R ^[1]

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1. Los Alamos National Laboratory

There are several schemes currently being investigated to pre-bunch the electron beam and step the coherent bunching up to higher harmonics, all which require modulator sections which introduce additional energy modulation. X-ray FELs operate in a regime where the FEL parameter, {rho} is equal to or less than the effective energy spread introduced from the emittance in the electron beam. Because of this large effective energy spread, the energy modulation introduced from harmonic generation schemes would seriously degrade FEL performance. This problem can be mitigated by incorporating the harmonic generation scheme at a lower electron kinetic energy than the energy at the final undulator. This will help because the effective energy spread from emittance is reduced at lower energies, and can be further reduced by making the beam transversely large. Then the beam can be squeezed down slowly enough in the subsequent accelerator sections so that geometric debunching is mitigated. The beam size inside the dispersive chicanes and in the accelerator sections must be carefully optimized to avoid debunching, and each subharmonic modulator section must generate enough energy modulation to overcome the SASE noise without significantly increasing the gain length in the final undulator. Here we show analytical results that demonstrate the feasibility of this harmonic pre-bunching scheme.

• Research Organization: Los Alamos National Laboratory (LANL)
• Sponsoring Organization: LDRD
• DOE Contract Number: AC52-06NA25396
• OSTI ID: 1011072
• Report Number(s): LA-UR-11-10252
• Country of Publication: United States
• Language: English

Related Subjects

ACCELERATORS
Accelerator Design, Technology, and Operations
ELECTRON BEAMS
ELECTRONS
HARMONIC GENERATION
HARMONICS
KINETIC ENERGY
MODULATION
PERFORMANCE
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