共查询到20条相似文献,搜索用时 0 毫秒
1.
S. Vielhauer V. Babin M. De Grazia E. Feldbach M. Kirm V. Nagirnyi A. Vasil’ev 《Physics of the Solid State》2008,50(9):1789-1794
Using free electron laser excitation in the XUV range, CaWO4 samples were exposed to ultrashort intense photon pulses (photon energy, 89.84 eV; average pulse energy, 10 μJ; pulse length,
25 fs), and their luminescence was studied with time-resolved spectroscopy. In the decay curves measured in the temperature
range 8–300 K, a nonexponential emission decay with shortening of the lifetimes over the first few microseconds was observed,
depending on the excitation density. Using a model for dipole-dipole interaction of excitons under nonuniform excitation densities,
the structure of the decay curves can be reproduced in good agreement with the experimental data, and parameters for the initial
exciton interaction can be calculated.
The text was submitted by the authors in English. 相似文献
2.
Dodd J.W. Marshall T.C. 《IEEE transactions on plasma science. IEEE Nuclear and Plasma Sciences Society》1990,18(3):447-450
A report is presented on the observation of spikes of high-intensity radiation emitted from a 2-mm wavelength Raman free electron laser oscillator. The spikes are correlated with a well-developed sideband spectrum, including several sideband harmonics, together with the carrier. A pulse width ~150 ps is obtained from analysis of data obtained with a two-slit Young's experiment. An even shorter pulse width results from a numerical model. Using an elementary model of the spike, it is estimated that the peak spike pulse power is ~100 MW 相似文献
3.
E.L. Saldin 《Optics Communications》2008,281(5):1179-1188
We present a comprehensive analysis of coherence properties of the radiation from X-ray free electron laser (XFEL). We consider practically important case when XFEL is optimized for maximum gain. Such an optimization allows to reduce significantly parameter space. Application of similarity techniques to the results of numerical simulations allows to present all output characteristics of the optimized XFEL as functions of the only parameter, ratio of the emittance to the radiation wavelength, . Our studies show that optimum performance of the XFEL in terms of transverse coherence is achieved at the value of the parameter of about unity. At smaller values of the degree of transverse coherence is reduced due to strong influence of poor longitudinal coherence on a transverse one. At large values of the emittance the degree of transverse coherence degrades due to poor mode selection. Comparative analysis of existing XFEL projects, European XFEL, LCLS, and SCSS is presented as well. 相似文献
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In this paper, the mechanism of free electron laser with a guide magnetic field is investigated by analyzing spontaneous radiation spectrum of electrons. The physical relation between spontaneous radiation and stimulated radiation in FEL with a guide magnetic field is studied. It is found that this relation in FEL is similar to that in quantum lasers. The spontaneous radiation spectrum is discrete. The frequency of stimulated radiation in FEL is oneselected and amplified in the radiation spectrum. 相似文献
6.
研究自由电子激光器谐振腔内电子束和辐射的时间同步问题.这是激光器谐振腔设计中的一个重要问题.本文讨论了腔内布儒斯特窗片对光路的影响.研制出由微机控制谐振腔的精密微调装置,扫描范围为±3cm,微调精度达1μm. 相似文献
7.
J Gaudin C Ozkan J Chalupský S Bajt T Burian L Vyšín N Coppola SD Farahani HN Chapman G Galasso V Hájková M Harmand L Juha M Jurek RA Loch S Möller M Nagasono M Störmer H Sinn K Saksl R Sobierajski J Schulz P Sovak S Toleikis K Tiedtke T Tschentscher J Krzywinski 《Optics letters》2012,37(15):3033-3035
The interaction of free electron laser pulses with grating structure is investigated using 4.6±0.1 nm radiation at the FLASH facility in Hamburg. For fluences above 63.7±8.7 mJ/cm2, the interaction triggers a damage process starting at the edge of the grating structure as evidenced by optical and atomic force microscopy. Simulations based on solution of the Helmholtz equation demonstrate an enhancement of the electric field intensity distribution at the edge of the grating structure. A procedure is finally deduced to evaluate damage threshold. 相似文献
9.
N. A. Vinokurov B. A. Knyazev G. N. Kulipanov A. N. Matveenko V. M. Popik V. S. Cherkassky M. A. Shcheglov 《Technical Physics》2007,52(7):911-919
A thermosensitive interferometer based on a plane-parallel glass plate is used for visualization of a high-power terahertz radiation. The plane wavefront of visible radiation emitted by a semiconductor laser is reflected from the two surfaces of the plate and forms on a screen an interference pattern recorded by a digital video camera. Terahertz radiation being measured is incident on the outer surface of the plate and heats a thin surface layer, which causes a shift of interference fringes. For K8 glass, a shift by one fringe corresponds to an absorbed energy of 5.1 J/cm2. The problem of determining the sign of the phase shift was solved by comparing the interference patterns with the images obtained with an infrared imager sensitive to near IR radiation. The processing of interference patterns makes it possible to determine the power density distribution over the beam cross section of the Novosibirsk free electron laser. In these measurements, the absolute value of the beam power determined by integrating over the cross section was 65 ± 7 W for a 130-μm wavelength. Visualization of the complex image with a spatial resolution no worse than 1 mm and a frame repetition rate of 25 Hz is demonstrated. 相似文献
10.
W.B. Colson 《Physics letters. A》1977,64(2):190-192
The free electron laser is analyzed by solving the one-body classical Lorentz force equation in the presence of periodic magnetic field and a plane electromagnetic wave. Phase space paths for electrons are related to those of a simple pendulum and describe laser gain, saturation, and coherent electron beam modulation. 相似文献
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12.
Yi-Jin Shi 《International Journal of Infrared and Millimeter Waves》1989,10(2):195-211
In terms of Bogoliubov's nonlinear theory, the first five betatron-synchrotron resonances of s=(p q)2K, p/q=1/2, 1, 3/2, 1/3, 2/3 which may occur during laser satulation establishing process have been generally examined. Contrast to previous studies we found that the most dangerous resonance does not take place in the vicinity of s=2k, but in that of s=k. The width of region of s=k is proportional to with (k
w
2
/k) remittance, the passing time over the region due to the laser field being amplified is only one pass over the undulator at most and depends on the gain, and the increment of synchrotron amplitude in passing time is proportional to .In summary we conclude that the betatron-synchrotron resonances do not have any significant effect for detrapping off-axis electrons in a practical case. 相似文献
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14.
C. Bruni R. Bachelard D. Garzella G. L. Orlandi M. E. Couprie 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2009,55(3):669-677
The chaotic nature of a storage-ring free electron laser (FEL) is investigated. The derivation of a low embedding dimension for the dynamics allows the low-dimensionality of this complex system to be observed, whereas its unpredictability is demonstrated, in some ranges of parameters, by a positive Lyapounov exponent. The route to chaos is then explored by tuning a single control parameter, and a period-doubling cascade is evidenced, as well as intermittence. 相似文献
15.
Ming Chang Wang Gun-Sik Park Jae Koo Lee 《International Journal of Infrared and Millimeter Waves》1997,18(4):797-809
An electron beam source based on pseudospark discharge was successful in operation at the beam voltage of 200keV and beam current of 2kA. The detailed design of a compact free electron laser using an electron beam by a pseudospark discharge is described. The
compact free electron laser consists of a smaller Marx generator with 6 capacitors and switches, a water capacitance of 6nF and a beam source with a high brightness of 3×1011
A/(m rad)2. The computer simulation shows that an output power of 101MW is expected at a frequency of 38GHz with a beam energy of 300keV, a current of 2kA and a beam emittance of 48mm mraa. 相似文献
16.
Spontaneous emission by electrons moving in a magnetic field constant in time and periodic in space (with circular polarization) is calculated using exact solutions of the corresponding Dirac equation. In addition to the known transitions we find two harmonics connected with spin flip processes, which are, however, strongly suppressed. The gain of the free electron laser is recalculated from the rate for spontaneous emission. The results obtained by classical methods are corroborated.Supported in part by Deutsche Forschungsgemeinschaft 相似文献
17.
R. Bonifacio 《Optics Communications》1980,32(3):440-442
We define electron-field coherent quasi-classical states of a free electron laser. In these states both the photon number and the electron momentum are given by a Poisson distribution centered on the classical trajectories. 相似文献
18.
Yuan-Zhao Yin He-Jun Yin 《International Journal of Infrared and Millimeter Waves》1994,15(7):1263-1274
The motion of a relativistic electron is analyzed in the field configuration consisting of a circular wiggler magnetic field, an axial magnetic field, and the equilibrium self-electric and self-magnetic fields produced by the non-neutral electron ring. By generating Poincare surface-of-section maps, it is shown that when the equilibrium self-fields is strong enough, the electron motions become chaotic. Although the realistic circular wiggler magnetic field destroys the integrability of the electron motion as the equilibrium self-fields do, the role the latter plays to make the motions become chaotic is stronger than the former. In addition, the axial magnetic field can restrain the occurrence of the chaoticity. 相似文献
19.
W. Becker 《Optics Communications》1980,33(1):69-74
A model of the free electron laser is proposed which is based on the classical current of the electron in the wiggler field interacting with a quantized radiation field. To calculate the gain, the quantum recoil for the processes of n-photon emission and absorption must be put in by hand from kinematical considerations. Apart from a spontaneous emission term the gain agrees essentially with the usual small signal expression, for the radiation field being in either an eigenstate of photon number or in a coherent state. The distribution of the electrons after the interaction is, however, essentially quantum mechanical. 相似文献
20.
B. Wellegehausen H. Welling C. Momma M. Feuerhake K. Mossavi H. Eichmann 《Optical and Quantum Electronics》1996,28(3):267-281
Starting from intense short-pulse KrF (248 nm, 25 mJ, 400 fs), ArF (193 nm, 10 mJ, 1 ps), and Ti:sapphire (810 nm, 100 mJ, 150 fs) laser systems, schemes for the generation of fixed-frequency and tunable VUV and XUV radiation by nonlinear optical techniques are investigated. With the KrF system, a four-wave mixing process in xenon yields tunable radiation in the range of 130–200 nm with output energies of, so far, 100 J in less than 1 ps. For the XUV spectral range below 100 nm, nonperturbative high-order harmonic generation and frequency mixing processes in noble gas jets are considered. To achieve tunability, the intense fixed-frequency pump laser radiation is mixed with less intense but broadly tunable radiation from short-pulse dye lasers or optical parametric generator-amplifier systems. In this way, tunability down to wavelengths of less than 40 nm has been demonstrated. 相似文献