The free electron laser with inverse taper

Colson, W.B.; McGinnis, R.D

doi:10.1016/s0168-9002(00)00112-1

Cited by 7 publications

(5 citation statements)

References 6 publications

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“…One way to alter the undulator design is to introduce taper. Taper may be achieved by varying the magnetic field along the undulator, and it has been shown that positively and negatively tapered undulators have characteristics that can be advantageous for particular applications in strong optical fields [2][3][4][5][6][7][8]. Recently, Thomas Jefferson National Accelerator Facility (TJNAF) has experimentally explored many properties of the same FEL with no taper, positive taper, and negative taper [9].…”

Section: Introductionmentioning

confidence: 99%

Simulations of the TJNAF FEL with tapered and inversely tapered undulators

Christodoulou

Lampiris

Colson

et al. 2001

Nuclear Instruments and Methods in Physics Research Section A:

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Experiments using the TJNAF FEL have explored the operation with both tapered and inversely tapered undulators. We present here numerical simulations using the TJNAF experimental parameters, including the effects of taper. Singlemode simulations show the effect of taper on gain. Multimode simulations describe the evolution of short optical pulses in the far infrared, and show how taper affects single-pass gain and steady-state power as a function of desynchronism. A short optical pulse presents an ever-changing field strength to each section of the electron pulse so that idealized operation is not possible. Yet, advantages for the recirculation of the electron beam can be explored. r

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Section: Introductionmentioning

confidence: 99%

Simulations of the TJNAF FEL with tapered and inversely tapered undulators

Christodoulou

Lampiris

Colson

et al. 2001

Nuclear Instruments and Methods in Physics Research Section A:

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“…During the interaction, about half of the electrons in the beam lose energy to the light pulse, whereas the others take energy away from the light pulse. This process induces an energy spread in the electron beam that eventually leads to saturation and gain reduction in strong optical fields [20]. The design of the undulator or magnetic guide field can be modified to alter the light pulse/electron interaction and the final electron beam distribution.…”

Section: Discussionmentioning

confidence: 99%

“…The tapered FEL increases gain and efficiency in strong optical fields and extends the usual saturation limit to stronger optical fields. The enhancement of the efficiency in a tapered wiggler/guide magnetic field is accomplished by reducing the resonant energy for the interaction as the electron beam loses energy to the wave [14,20].…”

Section: Discussionmentioning

confidence: 99%

Self-field effects on small-signal gain in two-stage free-electron lasers

Jafari¹,

Mehdian²,

Hasanbeigi³

2011

Pramana - J Phys

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Self-field effects, induced by charge and current densities of the electron beam, on gain in two-stage free-electron laser with nonuniform guide magnetic field is presented. The gain equation for small-signal has been derived analytically. The results of numerical calculations show a gain decrement for group I orbits and a gain enhancement for group II orbits, due to the self-field effects. The wiggler-induced self-magnetic field has a diamagnetic effect for group I orbits, whereas for group II, it has a paramagnetic effect. It is also found that using a nonuniform guide field, rather than a uniform one, causes the gain to increase.

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“…With the rapid development of FEL theory and techniques in recent decades, many kinds of variableparameter undulators have been proposed and used more and more in FEL facilities with many new purposes for both high gain and low gain FELs [5][6][7][8]. For example, tapered undulators have been utilized in SASE FELs to improve their poor temporal coherence.…”

Section: Introductionmentioning

confidence: 99%