The Fresh-Bunch' technique in FELs
The 'Fresh Bunch' technique is being proposed as a method of increasing the gain and power of FEL amplifiers in which the length of the optical radiation pulse is shorter than the length of the electron bunch. In multi-stage FEL, electron beam energy spread is increased by the FEL interaction in the early stages. In the 'Fresh Bunch' technique, the low energy spread of the electron beam is recovered by shifting the radiation pulse to an undisturbed part of the electron bunch, thus improving the gain and trapping fraction in later stages. A test case for the application of the Fresh Bunch method is demonstrated by numerical simulation. In this particular example we examine a subharmonically seeded VUV Free-Electron Laser. We begin with the generation of harmonic radiation, which takes place over one part of the electron bunch. Then the radiation is shifted by means of a strong dispersive section to a fresh part of the bunch for exponential amplification and tapered wiggler amplification. By starting over with a new ensemble of electrons, the energy spread introduced by the bunching in the fundamental is removed, leading to an increased gain. Furthermore, it is possible to use a much stronger seed in the fundamental without incurring the penalty of a large energy spread later on. We note that more than a single application of the 'Fresh Bunch' method may be done in a single FEL multiplier-amplifier. Thus x-ray wavelengths may be reached by successive multiplication in a chain of FEL amplifiers starting from a tunable seed laser. 5 refs., 2 figs., 2 tabs.
- Research Organization:
- Brookhaven National Lab., Upton, NY (United States)
- Sponsoring Organization:
- USDOE; USDOE, Washington, DC (United States)
- DOE Contract Number:
- AC02-76CH00016
- OSTI ID:
- 5113476
- Report Number(s):
- BNL-46688; CONF-9108118-16; ON: DE92002066; TRN: 91-031908
- Resource Relation:
- Conference: 13. international free-electron laser (FEL) conference, Santa Fe, NM (United States), 25-30 Aug 1991
- Country of Publication:
- United States
- Language:
- English
Similar Records
Parameter analysis for a high-gain harmonic generation FEL using a recently developed 3D polychromatic code.
Femtosecond free-electron laser by chirped pulse amplification
Related Subjects
42 ENGINEERING
FREE ELECTRON LASERS
GAIN
BEAM BUNCHING
ELECTRON BEAMS
ENERGY SPECTRA
FAR ULTRAVIOLET RADIATION
HARMONIC GENERATION
PULSES
WIGGLER MAGNETS
AMPLIFICATION
BEAM DYNAMICS
BEAMS
ELECTRICAL EQUIPMENT
ELECTROMAGNETIC RADIATION
ELECTROMAGNETS
EQUIPMENT
FREQUENCY MIXING
LASERS
LEPTON BEAMS
MAGNETS
PARTICLE BEAMS
RADIATIONS
SPECTRA
ULTRAVIOLET RADIATION
430303* - Particle Accelerators- Experimental Facilities & Equipment
426002 - Engineering- Lasers & Masers- (1990-)