Calculation and analysis of the magnetic field of a linearly tapered undulator

Li, Heting; Guo, Fan; Li, Jia-Yu; Jia, Qika

doi:10.1088/1674-1137/39/8/088101

Cited by 5 publications

(4 citation statements)

References 13 publications

(9 reference statements)

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“…(6). Changing the tilted amplitude is more efficient for changing the time separation, because actually the transverse gradient is not easy to be changed for an existing TGU [36], but the tilted amplitude of the electron beam can be conveniently tuned by the methods mentioned in Section 2. In addition, for a fixed bunch length, increasing the tilted amplitude η or the transverse gradient α can make the width of each FEL pulse shorter.…”

Section: Discussionmentioning

confidence: 99%

Generation of coherent two-color pulses at two adjacent harmonics in a seeded free-electron laser

Zhao

Jia

2018

Phys. Rev. Accel. Beams

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The growing requirements of pump-probe techniques and nonlinear optics experiments greatly promote the studies of two-color free-electron lasers (FELs). We propose a new method to generate coherent two-color pulses in a high-gain harmonic generation (HGHG) FEL. In this scheme, an initial tilted electron beam is sent though the modulator and dispersive section of an HGHG FEL to generate the bunching at harmonics of the seed laser. Then a transverse gradient undulator (TGU) is adopted as the radiator and in such radiator, only two separated fractions of the tilted beam will resonate at two adjacent harmonics of the seed laser and are enabled to emit the coherent two-color pulses simultaneously. The time separation between the two pulses are on the order of hundreds of femtoseconds, and can be precisely controlled by varying the tilted amplitude of the electron beam and/or the transverse gradient of the TGU radiator. Numerical simulations confirm the validity and feasibility of this scheme in the EUV waveband.

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Section: Discussionmentioning

confidence: 99%

Generation of coherent two-color pulses at two adjacent harmonics in a seeded free-electron laser

Zhao

Jia

2018

Phys. Rev. Accel. Beams

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“…(11) the applicable range of the linear approximation of the vertical gradient is jΔyj ∼ 10 −2 λ u , corresponding to about several hundred microns. Comparing with the transversely tapered TGUs, whose field is very close to linearity though not strictly linear along the transverse position [18], the applicable range of linear approximation of the natural gradient is not so wide, but is sufficiently large for LPA beam due to its small transverse beam size. The situation will be better for an undulator with a long period.…”

Section: Methodsmentioning

confidence: 99%

Normal planar undulators doubling as transverse gradient undulators

Jia

2017

Phys. Rev. Accel. Beams

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The transverse gradient undulator (TGU) has important application in the short-wavelength high-gain free electron lasers (FELs) driven by laser-plasma accelerators. However, the usual transversely tapered TGUs need special design and manufacture, and the transverse gradient cannot be tuned arbitrarily. In this paper we explore a new and simple method of using the natural transverse gradient of a normal planar undulator to compensate the beam energy spread effect. In this method, a vertical dispersion on the electron beam is introduced, then the dispersed beam passes through a normal undulator with a vertical off-axis orbit where the vertical field gradient is selected properly related to the dispersion strength and the beam energy spread. Theoretical analysis and numerical simulations for self-amplified spontaneous emission FELs based on laser plasma accelerators are presented, and indicate that this method can greatly reduce the effect of the beam energy spread, leading to a similar enhancement on FEL performance as the usual transversely tapered TGU, but with the advantages of economy, tunable transverse gradient and no demand of extra field for correcting the orbit deflection induced by the field gradient.

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“…We are interested in the band-like interference pattern, which is broader with larger ∆ (Figure 3). Typical tapered undulators for FEL applications have relatively low tapering rates around 1-5% or less [18,19], for which the interference pattern is quite small, while for our purposes, strongly tapered undulators are needed. Therefore, we make scan simulations with a triangle envelope for different laser pulse and electron beam parameters, and then for a selected set of parameters several tapering rates are modeled.…”

Section: Scattering From One Electronmentioning

confidence: 99%

On the Usage of Tapered Undulators in the Measurement of Interference in the Intensity-Dependent Electron Mass Shift

2021

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In nonlinear Thomson scattering, the main emission line and its harmonics form a band-like structure due to the laser pulse shape induced ponderomotive broadening. We propose to use tapered undulators to mimic Thomson scattering and measure the intensity-dependent electron mass shift experimentally. We also numerically show that the effect is observable for realistic electron beams like in DESY or SKIF.

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Calculation and analysis of the magnetic field of a linearly tapered undulator

Abstract: Calculation and analysis of the magnetic field of a linearly tapered undulator * LI He-Ting( ) 1) GUO Fan( ) LI Jia-Yu( ) JIA Qi-Ka( )

Cited by 5 publications

References 13 publications

Generation of coherent two-color pulses at two adjacent harmonics in a seeded free-electron laser

Generation of coherent two-color pulses at two adjacent harmonics in a seeded free-electron laser

Normal planar undulators doubling as transverse gradient undulators

On the Usage of Tapered Undulators in the Measurement of Interference in the Intensity-Dependent Electron Mass Shift

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