Search results for "BAND"
showing 10 items of 2610 documents
Design of a double-gap Hughes-type coupled-cavity for a Ka-band Extended Interaction Klystron
2020
In this paper, the design of a Ka-band Extended-Interaction Klystron (EIK) working at 2$\pi$ mode. The interaction structure is a three-gap Hughes-type coupled-cavity. Based on the results obtained with the 3D model developed by using CST, “cold electrical parameters” have been calculated, necessary to measure the interaction with the electron beam. The structure stability and the synchronization with the electron beam are analyzed The large-signal analysis is performed by 1D software AJDISK. Under the beam voltage and current of 19.55 kV and 0.95 A, respectively, an RF output power value of 3.86 kW and a bandwidth gain value of 37. 06 dB have been obtained
Influence of the input-stage architecture on the in-laboratory test of a mid-infrared interferometer: application to the ALOHA up-conversion interfer…
2020
ABSTRACT In the framework of the Astronomical Light Optical Hybrid Analysis (ALOHA) laboratory mid-infrared (MIR) up-conversion fibred interferometer in the L band, we report on the influence of the input-stage architecture. Using an amplitude division set-up in the visible or near-infrared is a straightforward choice in most cases. In the MIR context, the results are slightly different and we show that a wavefront division set-up is needed. These in-laboratory principle experiments allow us to measure a reliable 88 per cent instrumental contrast with high flux and to obtain fringes from faint sources at 3.5 μm with a spectral bandwith of 37 nm converted to 817 nm. An equivalent limiting L-…
Design of a Compact Dual Circular-Polarized Antenna for L-Band Satellite Applications
2020
In this paper, we propose the design of a dual circular-polarized antenna for L-band applications (1.1-1.6 GHz). The designed antenna has been developed by considering crossed-dipoles on top of which a circular patch has been placed to properly act on the mutual coupling between the dipoles. The dual circular polarization is achieved by feeding dipoles in quadrature. Moreover, to increase the antenna gain and polarization purity at high elevation angles, a fence of passive monopoles has been added. The proposed antenna can profitably used as primary feed of a low-frequency parabolic reflector.
An FPGA based demonstrator for a topological processor in the future ATLAS L1-Calo trigger “GOLD”
2012
Abstract: The existing ATLAS trigger consists of three levels. The level 1 (L1) is an FPGAs based custom designed trigger, while the second and third levels are software based. The LHC machine plans to bring the beam energy to the maximum value of 7 TeV and to increase the luminosity in the coming years. The current L1 trigger system is therefore seriously challenged. To cope with the resulting higher event rate, as part of the ATLAS trigger upgrade, a new electronics module is foreseen to be added in the ATLAS Level-1 Calorimeter Trigger electronics chain: the Topological Processor (TP). Such a processor needs fast optical I/O and large aggregate bandwidth to use the information on trigger…
Light-Induced Excited Spin State Trapping in Iron(II) Complexes
1987
In the course of our studies on the thermally induced high spin (HS) ↔ low spin (LS) transition in iron(II) complexes /1/, \({\!^5{\text{T}}_2}_{\text{g}}\) ↔ \({\!^1{\text{A}}_1}_{\text{g}}\) in the approximation of Oh symmetry, we have observed in 1984 a new photophysical effect /2/: If, at sufficiently low temperature, the solid spin crossover complex is irradiated with green light into the \({\!^1{\text{A}}_1}\)→ \({\!^1{\text{T}}_1}\) ligand field absorption band, the thermodynamically stable LS state can be converted to the metastable HS state and trapped with practically infinite lifetime. We have called this unusual phenomenon “Light-Induced Excited Spin State Trapping (LIESST)”.
Zero Temperature Magnetoresistance of the HF Metal: Enigma of $$\mathrm{Sr}_{3}\mathrm{Ru}_{2}\mathrm{O}_{7}$$
2014
To understand the nature of field-tuned metamagnetic quantum criticality in the ruthenate \(\mathrm{Sr}_{3}\mathrm{Ru}_{2}\mathrm{O}_{7}\) is one of the significant challenges in the condensed matter physics. It is established experimentally that the entropy has a peak in the ordered phase. It is unexpectedly higher than that outside latter phase, while the magnetoresistivity varies abruptly near the ordered phase boundary. We demonstrate unexpected similarity between \(\mathrm{Sr}_{3}\mathrm{Ru}_{2}\mathrm{O}_{7}\) and HF metals expressing universal physics that transcends microscopic details. Our \(T-B\) phase diagram of \(\mathrm{Sr}_{3}\mathrm{Ru}_{2}\mathrm{O}_{7}\) explains main featu…
Self-referenced phase reconstruction proposal of Ghz bandwidth non-periodical optical pulses by in-fiber semi-differintegration
2011
Abstract We propose two new techniques able to retrieve the phase profile of a given temporal optical pulse based on the use of in-fiber semi-differintegral operators, where by semi-differintegration we mean either a 0.5th-order differentiation or integration. In both cases, the signal's temporal phase can be obtained by simple dividing two temporal intensity profiles, namely the intensities of the input and output pulses of a spectrally shifted semi-differintegral operator. In both cases, we obtained simple analytical expressions for the phase profile. The techniques are self-referenced and well-suited for real-time applications. We numerically prove the viability of these proposals.
Second harmonic generation in multimode graded-index fibers: spatial beam cleaning and multiple harmonic sideband generation
2017
We study experimentally and numerically the spectral and spatial dynamics of second harmonic generation in an all-optically poled multimode graded-index fiber. In contrast with poled single-mode fibers, in a multimode graded-index fiber a pump can generate a series of sharp sidebands around its second harmonic (SH) that originate from the sub-millimetric periodic evolution of the intensity at the fundamental frequency. The mutual interaction between the fundamental and its SH may also strongly affect the spatial distribution of guided light for both colors: when increasing the pump power, both fundamental and SH output beams evolve from disordered multimode speckles into two bell-shaped bea…
Supercontinuum spectral control
2009
Supercontinuum (SC) generation in photonic crystal fibers (PCFs) is a cutting-edge phenomenon extensively studied in recent years [1]. SC has found many scientific and technological applications. The control of the SC spectral characteristics is crucial in most of them. A pioneering attempt in this direction was reported in Ref. [2]. We point out that SC is typically generated by accessing the anomalous dispersion regime of the fiber, i.e., when the group velocity dispersion (GVD) coefficient is lower than zero, β 2 ≪0. The recent achievement of soft-glass PCFs, namely, PCFs made up of a transparent material that shows higher nonlinear response than the widely used fused silica, opens new p…
Evidence for band termination in118Xe
1991
The yrast band of Xe118 has been extended up to tentatively I-pi = 34+ in a heavy-ion in-beam gamma-spectroscopic study using the NORDBALL detector array. A band crossing is observed at the highest ...