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The resonant properties of the impedance of a two-layer circular metal-dielectric waveguide are investigated by taking into account the finite conductivity of the metallic pipe and the dissipation of the radiated energy in the dielectric layer. The dispersion relations for azimuthally symmetric monopole TM modes are analyzed. It is shown that, for an outer metallic layer with finite conductivity and a thin internal dielectric cover, the waveguide has only a single slowly propagatingTM01mode. The point charge longitudinal wake potentials are evaluated for thin and thick internal layers.

Various asymptotic representations for the longitudinal monopole impedance of a two-layer metal-dielectric cylindrical waveguide with finite-conducting external walls and a lossy internal dielectric layer are derived. Areas of their applicability are determined and their properties are investigated. New features for the resonance properties of the structure under consideration are revealed and described.

Extraordinary emittance requirements in the nm range (normalized) and pulse lengths down to a level of ∼10 fs for REGAE bunches demand both operation at low bunch charges on the sub-pC scale and a very careful beam handling. The S-band RF deflecting cavity is intended for diagnostics of the longitudinal bunch parameters. For the first time a deflecting structure, specially developed and optimized for bunch rotation has been realized for the REGAE RF deflector. The developed cavity provides a minimized level of aberrations in the distribution of the deflecting field combined with an improved RF efficiency. The main steps in the cavity design, construction and tuning are described.

The new traveling wave structure with a single synchronous mode resonantly excited by the relativistic charge is presented. The structure is composed of a metallic tube with an internally coated low conductive thin layer. It is shown that the impedance of the internally coated metallic tube has a narrow-band single resonance at a high frequency. The analytical presentation of the narrow-band impedance, the wake function, and the frequency of the synchronous mode are obtained. The analytical solutions are compared with exact numerical simulations using the field matching technique.

In this paper the problem of radiation from the open end of a semi-infinite circular metallic waveguide with perfectly conducting walls and a thin internal low-conducting metal coating is considered. Electromagnetic fields are generated by the ultrarelativistic point charge moving along the axis of the waveguide. The far fields of radiation are obtained using the near-field to far-field recovery technique. The technique is extended for the nonmonochromatic waves. It is shown that the radiation has a narrow-band and narrow-directional character.

We present the results of a study on localized electronic centers formed in crystals by external influences (impurity introduction and irradiation). The main aim is to determine the nature of these centers in the forbidden gap of the energy states of the crystal lattice. For the case of semiconductors, silicon (Si) was applied as model material to determine the energy levels and concentration of radiation defects for application to both doped and other materials. This method relies on solving the appropriate equation describing the variation of the charge carrier concentration as a function of temperature n ( T ) for silicon crystals with two different energy levels and for a large set of N 1 , N 2 (concentrations of electronic centers at each level), and n values. A total of almost 500 such combinations were found. For silicon, energy level values of ε 1  = 0.22 eV and ε 2  = 0.34 eV were used for the forbidden gap (with corresponding slopes determined from experimental temperature-dependent Hall-effect measurements) and compared with photoconductivity spectra. Additionally, it was shown that, for particular correlations among N 1 , N 2 , and n , curve slopes of ε 1 /2 = 0.11 eV, ε 2 /2 = 0.17 eV, and α  = 1/2( ε 1  +  ε 2 ) = 0.28 eV also apply. Comparison between experimental results for irradiation of silicon crystals by 3.5-MeV energy electrons and Co 60 γ -quanta revealed that the n ( T ) curve slopes do not always coincide with the actual energy levels (electronic centers).

We present the results of our recent experimental and numerical studies on femtosecond pulse spectrotemporal imaging in a similariton-induced temporal lens aimed to designing a femtosecond optical oscilloscope [1]. We have studied nonlinear and dispersive peculiarities of modern high-tech materials, such as photonic crystal fibers, hollow-core fibers etc, to use them in the scheme, and to provide compactness and reliability of the device. The use of hollow-core fibers, as a dispersive medium instead of a pair of prisms or gratings, is of special importance for constructing the industrial tool. Additionally, we are experimenting on the method of dispersive Fourier transformation, using the effect of chromo-modal dispersion in multimode fibers [2], to provide real-time performance of the device.

The paper describes a method for calculating the longitudinal and transverse impedances of the laminated round pipe with many layers of different materials. The charge is moving along the pipe axis with arbitrary constant velocity. The study is based on the field-matching technique applied for the arbitrary harmonic of the electromagnetic field. The matrix formalism has been developed to describe the field transitions through the subsequent layers that allow coupling the electromagnetic fields inside and outside the pipe. The number of equations to be solved is then reduced to four algebraic equations. The solutions and ultrarelativistic limits for the field harmonics in the inner and outer regions of the pipe are derived.

The exact analytical expression for the longitudinal impedance of two-layer cylindrical tube with finite wall thickness is obtained. The numerical results for the copper-NEG, stainless steel-copper, and ceramic-copper laminated vacuum chamber impedances are given.