Enhanced Harmonic Spontaneous Radiation using a Novel Undulator
- Brookhaven National Laboratory
In a typical free electron laser (FEL), the electron beam interacts with a dipole undulator that has a sinusoidal magnetic field variation; the electron motion is sinusoidal in the plane transverse to this field and emits odd-numbered harmonic radiations along the axis. However, one need not limit the choice of undulator field profile to the sinusoid, providing other profiles result in significant advantages. In connection with the IFEL accelerator, in the past we have pointed out that the use of an undulator profile that approximates a square wave will result in an enhanced acceleration gradient, by as much as a factor of two (equivalent in effect to an increase of laser drive intensity by a factor of four). This improvement (essentially at the fundamental FEL resonance) results largely from the fact that, for a given peak undulator field amplitude, the rms electron acceleration obtained from the square wave undulator is larger than that from the sinusoid; furthermore, the electron orbit is stable as well. In this paper, we find additional advantages that should result particularly at harmonic numbers f > 1 if the undulator field profile is nearly ''square wave'': namely, a large enhancement of the harmonic spontaneous power radiated, together with enhanced FEL gain. The modification of undulatory to enhance FEL gain has been examined in the past, usually with a particular design in mind, but with similar conclusions.
- Research Organization:
- Brookhaven National Lab., Upton, NY (US)
- Sponsoring Organization:
- USDOE Office of Energy Research (ER) (US)
- DOE Contract Number:
- AC02-98CH10886
- OSTI ID:
- 6261
- Report Number(s):
- BNL-66034; KA-04; KA-04
- Country of Publication:
- United States
- Language:
- English
Similar Records
Intensification of harmonic spontaneous radiation with a novel undulator
Intensification of harmonic spontaneous radiation with a novel undulator