Resonance between betatron and synchrotron oscillations in a free electron laser: A 3D numerical study
Abstract
We analyze the effect of betatron and synchrotron resonance on the gain process of the free electron laser (FEL) including betatron oscillations, finite beam emittance, selfconsistent electron dynamics and a 3D radiation field. Betatron oscillations force the electrons to be affected by an oscillatory radiation amplitude and phase in a Gaussian resonator radiation field. We show that not only can the radiation phase variation cause a resonance between approximately twice the betatron wavenumber and the synchrotron wavenumber, but the radiation amplitude variation in an FEL with efficiency enhancement schemes or just a tapered magnetic wiggler field amplitude Bw can also have a similar resonance effect. Numerical results for a 10 micrometer FEL are given. We find that for short wigglers, the effect of the betatronsynchrotron instability on the gain is negligible for Gaussian electron beams with radius less than 0.8 times the radiation beam spot size.
 Publication:

Naval Research Lab. Report
 Pub Date:
 January 1985
 Bibcode:
 1985nrl..reptT....T
 Keywords:

 Amplification;
 Amplitudes;
 Betatrons;
 Free Electron Lasers;
 Oscillations;
 Synchrotron Radiation;
 Dimensions;
 Electrodynamics;
 Electrons;
 Magnetic Fields;
 Numerical Analysis;
 Resonance;
 Lasers and Masers