Seeded Free-Electron Lasers and Free-Electron Laser Applications

Several decades after the groundbreaking discovery of X-rays in 1895 by Wilhelm Conrad Roentgen, it became quite evident that the possibility of building X-ray sources with controlled photon beam parameters was a revolutionary step to address some of the important challenges facing humanity. The awareness that these sources could dramatically improve mankind's scientific knowledge and technological ability was at the base of significant investments and scientific programs worldwide that brought X-ray sources into the present “golden age.”     

Laser-Seeded Free-Electron Lasers at the NSLS

The National Synchrotron Light Source (NSLS) has a long tradition of research and development in accelerator physics and light source technologies. Over the past two decades, the NSLS has made many pioneering contributions to the development of storage-ring-based light sources, such as the Chasman-Green lattice, global orbit feedback systems, and in-vacuum insertion devices. Even from the earliest days of the NSLS, the staff also had started to explore the potential of free-electron-laser (FEL)-based light sources, leading to some seminal work on the theory of self amplified spontaneous emission (SASE) FELs [1 Bonifacio, R., Pellegrini, C. and Narducci, L. 1984. Optics Comm., : 373 [Google Scholar],2 Wang, J.M. and Yu, L.H. 1986. NIM A, 250: 484 [Google Scholar]].     

远红外自由电子激光器和螺旋电流扭轨磁体

报道了作者近年来在美国斯坦福大学直接参与合作研制的１００μｍ－１０００μｍ可调谐远红外自由电子激光器概况，以及研制过程中所运用的独创的新技术。文中对它的主要部件扭轨磁全体的新型设计和磁场特性进行了深入的分析和研究。     

Generation of X-Ray Radiation in Free-Electron Lasers with Two-Frequency Undulators

Russian Physics Journal - The possibility of creating an x-ray laser with a two-frequency undulator with the help of the phenomenological model of a single-pass free-electron laser (FEL) that takes...     

Theoretical Analysis of Radiation Properties of X-Ray Free-Electron Lasers

Radiophysics and Quantum Electronics - We perform a comparative analysis of the radiation of X-ray free-electron lasers (FELs) LCLS, PAL-XFEL, SwissFEL, SACLA, FLASH2, and European XFEL, as well as...     

X-Ray Free-Electron Lasers with Variable Deflection Parameter of Undulators

Russian Physics Journal - The paper deals with X-ray free-electron lasers (FEL) with the variable deflection parameter of undulators with the electron buncher and harmonic amplifier. The analysis...     

Generation Spectrum of Long-Pulse Free-Electron Terahertz Lasers: Quasilinear Theory

JETP Letters - A quasilinear theory is developed for free-electron lasers in which intense electron beams with a significant velocity dispersion are used to implement the kinetic regime of...     

Many-Electron Effects in Co 3s X-Ray Photoelectron Spectra of Diamagnetic ScCoO3 and Paramagnetic BiCoO3 Cobaltites

JETP Letters - A new method based on the solution of the Dyson equation in the basis of atomic wavefunctions has been developed to quantitatively describe the influence of the dynamic effect on the...     

Pumping Systems for Compton Free-Electron Lasers: Microwave Undulators and Powering Sources

Radiophysics and Quantum Electronics - The concept of Compton-type free-electron lasers (FELs) operating in short wavelength ranges with a high efficiency and power level is currently underway at...     

On Harmonic Generation in X-Ray Free-Electron Lasers with Variable Undulator Deflection Parameter

Technical Physics - X-ray free-electron lasers (FELs) generate ultrashort bursts at wavelengths ~1 –100 Å. The possibility of harmonic generation in the X-ray range in FELs with a...     

Generation of Spatially Coherent Radiation in Free-Electron Lasers with Two-Dimensional Distributed Feedback

We study the possibility of using two-dimensional distributed feedback (DF) to generate spatially coherent radiation of ribbon and hollow relativistic electron beams whose transverse dimensions exceed the wavelength by several orders of magnitude. Such a feedback can be realized in planar and coaxial two-dimensional Bragg resonators with a two-period corrugation of their side walls. This corrugation gives rise to additional transverse (with respect to the reciprocal motion of the electrons) fluxes of electromagnetic energy which synchronize emission from different parts of the electron beam. Simulations of the onset of autooscillations in free-electron lasers (FELs) with a two-dimensional DF show the possibility of obtaining single-mode monochromatic coherent generation by beams with transverse dimensions up to 10²-10³ wavelengths. We also analyze the use of hybrid resonators composed of two-dimensional input and one-dimensional output Bragg mirrors. In such a scheme, the two-dimensional mirror ensures synchronization of the emission perpendicular to the electron beam, while reflection from the output one-dimensional mirror is sufficient for the self-excitation of the generator. In the case of a system closed in the transverse direction, such a scheme permits one to reduce significantly the ohmic losses resulting from the electromagnetic fluxes locked in the transverse direction. It is shown that the two-dimensional DF can also be used to synchronize radiation in a multibeam generator consisting of planar FEL modules fed by a ribbon electron beam and coupled via the transverse electromagnetic-energy fluxes which are formed by two-dimensional Bragg structures. The experimental studies aimed at realization of ultrahigh-power FELs with a two-dimensional DF are discussed.     

Comparative Analysis of Phenomenological and Numerical Modeling of Experimentswith Single-Pass Free-Electron Lasers

Radiophysics and Quantum Electronics - We model the evolution of radiation harmonics in a single-pass free-electron laser using a phenomenological model, in which the main losses are taken into...     

Harmonics Generation in Experiments with Free-Electron Lasers in the X-Ray Wavelength Range: a Theoretical Analysis

Technical Physics - The generation of undulator X-ray radiation harmonics in free-electron lasers (FELs), which has been observed in different experiments, has been given an analytical explanation....     

Development of High-Power Long-Pulse Submillimeter-Wave Free-Electron Lasers on the Basis of the Linear Induction Accelerator Complex

Radiophysics and Quantum Electronics - The high-power long-pulse submillimeter-wave free-electron laser (FEL) is developed jointly by the Institute of Nuclear Physics and the Institute of Applied...     

Noncovalent Hydrogen Isotope Effects in Paramagnetic Molecules

Zero-point energies (ZPE) of intermolecular, non-bonded vibrations and isotope effects, induced by noncovalent interactions, are computed for paramagnetic molecules. They appear to be not significant for complexation of HO₂ and oxygen with C–H bonds and results to isotope effect, which deviates from unit by 5–10%. However, ZPE and isotope effects in complexes of HO₂ and nitroxyl radicals with water are larger and reach 50–70%. The largest effect, about 12, is found for complexation of hydrogen atom with water. Complexation of nitroxyl and peroxy radicals by hydrogen bonds is accompanied by transfer of spin density of unpaired electron from radical to the ligand molecules and induces high field paramagnetic shifts of the ligand NMR lines. It evidences that the spin transfer via intermolecular bonds occurs by mechanism of spin polarization.     

Diamagnetic domains and magnetostriction in beryllium

Magnetostriction was for the first time studied under the conditions of formation of diamagnetic domains (Condon domains). Transverse magnetostriction oscillations on a beryllium single crystalline plate oriented normally to magnetic field were measured in magnetic fields up to 7 T at temperatures down to 1.5 K. The relative amplitude of oscillations increased almost as the square of magnetic field and reached 10^?5. The signal had a sawtoothed shape corresponding to alternation of homogeneous and inhomogeneous (domain) states in the region of the existence of magnetic domains. The arising of domains was accompanied by singularities in the observed signals which is explained by an anomalous increase in the compressibility coefficient of the domain state: coefficient oscillations were more than 100 times larger than the value predicted by the standard theory. The observed relation between magnetization current and deformation led us to conclude that the compressibility of the metal was fully determined by conduction electrons. Magnetostriction then exactly compensated Fermi level oscillations. The position of the Fermi level therefore remained constant under magnetic field variations. In addition, the domain wall thickness had to increase as the plate grew thicker.     

部分抽运的板条激光器的热效应分析

基于热传导方程和高斯赛德尔数值计算方法,对部分抽运板条激光器的温度分布、热应力和热致折射率变化等热效应进行了详细分析,并与单侧抽运及双侧抽运方式进行了比较。结果表明,设计合理的部分抽运板条激光器,可以获得较高的抽运效率,其热效应相比于均匀抽运的情况并没有显著劣化,不论是采用锯齿形传播方式还是直线传播方式的激光器都可以获得较好的光束质量,当一束高斯激光直线经过板条晶体中部时,光束质量因子为1.4,若采用锯齿形传播方式,则光束质量因子可提高到1.1。