نتایج جستجو برای: fel haye hessi
تعداد نتایج: 2393 فیلتر نتایج به سال:
The intensity of undulator radiation, not amplified by the FEL interaction, can be larger than the maximum FEL signal in the case of an X-ray FEL. In the commissioning of a SASE FEL it is essential to extract an amplified signal early to diagnose eventual misalignment of undulator modules or errors in the undulator field strength. We developed a numerical code to calculate the radiation pattern...
Using the recently proposed echo-enabled harmonic generation (EEHG) free-electron laser (FEL) scheme, it is shown that operating the Shanghai deep ultraviolet FEL (SDUV-FEL) with single-stage to higher harmonics is very promising, with higher frequency up-conversion efficiency, higher harmonic selectivity and lower power requirement of the seed laser. The considerations on a proof-of-principle ...
Simple formulas for optimization of VUV and X-ray SASE FELs are presented. The FEL gain length and the optimal beta-function are explicitly expressed in terms of the electron beam and undulator parameters. The FEL saturation length is estimated taking into account quantum diffusion in the undulator. Examples of the FEL optimization are given. Parameters of a SASE FEL, operating at the Compton w...
Electron beam microbunching in both the fundamental and second harmonic in a high-gain self-amplified spontaneous emission free-electron laser (SASE FEL) was experimentally characterized using coherent transition radiation. The microbunching factors for both modes (b(1) and b(2)) approach unity, an indication of FEL saturation. These measurements are compared to the predictions of FEL simulatio...
The aim of this paper is to investigate the spatial structure of the impulsive phase hard X-ray emission from solar flares. This work is motivated by the YOHKOH and the forthcoming HESSI observations. Summarizing past results, it is shown that the transport effects can account for the observations by inhomogeneous loops where there is a strong field convergence and/or density enhancement at the...
The quantum operation mode in the X-ray Compton free-electron laser (FEL) is presented. This FEL mode emerges when the quantum emission exceeds the electron beam energy spread and FEL homogeneous linewidth, determined by the optical undulator length. Such a FEL becomes a two-level quantum oscillator with a completely inverted active medium. In the nonlinear interaction regime, inversion can be ...
We report on a time-resolved measurement of self-amplified spontaneous emission free-electron laser (FEL) pulses. We observed that the spikes in such FEL pulses have an intrinsic positive chirp and the energy chirp in the electron bunch mapped directly into the FEL output. The measurement also provides rich information on the statistics of the FEL pulses. r 2003 Elsevier Science B.V. All rights...
The primary design study of a terahertz free-electron laser (FEL) is presented in this paper. The effects of optical cavity parameter, metal mirrors reflectivity and aberrations on the THz FEL radiation performance have been explored. The reflectivity characteristics of copper, silver and gold are tested in terahertz region. The effects of metal mirrors reflectivity and aberrations on the THz F...
The advent of free-electron laser (FEL) sources delivering two synchronized pulses of different wavelengths (or colours) has made available a whole range of novel pump-probe experiments. This communication describes a major step forward using a new configuration of the FERMI FEL-seeded source to deliver two pulses with different wavelengths, each tunable independently over a broad spectral rang...
This paper proposes an efficient Tracking method for velocity control of an electro-hydraulic servo system (EHSS) in the presence of flow nonlinearities and internal friction. The tracking method controller is a kind of feedback error learning structure. In the proposed method, the Feedback Error Learning (FEL) algorithm is used to control the velocity. There is no need to compute the system ja...
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