Bulletin of the Lebedev Physics Institute最新文献

{"title":"Compensation for Nonlinear Distortions in Optical Communication Systems Using Perturbation Theory and Multiparameter Optimization","authors":"A. A. Redyuk,&nbsp;E. I. Shevelev,&nbsp;V. R. Danilko,&nbsp;M. P. Fedoruk","doi":"10.3103/S1068335624601602","DOIUrl":"10.3103/S1068335624601602","url":null,"abstract":"<p>Nonlinear signal distortions are one of the main reasons limiting the throughput and length of modern fiber-optic communication lines. One of the developed approaches to nonlinear distortion compensation is based on the application of perturbation theory methods to the nonlinear Schrödinger equation, and allows one to obtain a relationship between transmitted and received symbols. Gradient methods that minimize the standard deviation between symbols are usually used to find the perturbation coefficients. However, the main parameter characterizing the data transmission quality is the bit error rate. We propose a modification of this approach in the form of a two-stage scheme for calculating the perturbation coefficients. At the first stage, the coefficients are calculated using the least squares method by minimizing the standard deviation, and at the second stage, the obtained solution is used as an initial approximation to minimize the error coefficient using the particle swarm method. In a numerical experiment, using the algorithm for compensating for received signal distortions based on the proposed scheme, a 0.9 dB gain in the signal-to-noise ratio is obtained for a multi-span line 20 × 100 km long and a 16QAM signal with a channel rate of 267 Gbit/s. An improvement in the accuracy of the algorithm (compared to a single-stage scheme) is shown, estimates of the computational complexity of the algorithm are obtained, and the relationship between its complexity and accuracy is presented.</p>","PeriodicalId":503,"journal":{"name":"Bulletin of the Lebedev Physics Institute","volume":"51 6 supplement","pages":"S449 - S457"},"PeriodicalIF":0.6,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142579462","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cryogenic Target Delivery for Laser IFE–Status and Future Challenges","authors":"I. V. Aleksandrova,&nbsp;A. A. Akunets,&nbsp;E. R. Koresheva,&nbsp;A. I. Nikitenko,&nbsp;V. D. Zvorykin","doi":"10.3103/S1068335624601638","DOIUrl":"10.3103/S1068335624601638","url":null,"abstract":"<p>New solutions for target delivery systems are essential for advanced inertial fusion energy (IFE) laser facilities. Original target delivery concept based on magnetic levitation (MAGLEV) technology has been proposed at the Lebedev Physical Institute (LPI). The operational principle is the quantum levitation of Type-II, high-temperature superconductors (HTSC) in gradient magnetic fields. In doing so, a cryogenic target is placed inside a levitating HTSC-sabot, which is accelerated above a permanent magnet guideway system. In this paper, we continue our researches on building a cyclotron accelerator with a limited magnetic track for noncontact target delivery. The target sabot models were made from second-generation high-temperature superconductor (2G-HTSC) tapes with a J-PI-04-20Ag-20 Cu structure and high vortex pinning to ensure levitation stability of the acceleration process. Careful execution of demo experiments (<i>T</i> ~ 80 K) clarify that the HTSC-sabot runs stably above the circular track during its acceleration. The calculation and experimental results are in a good agreement at <i>T</i> ~ 80 K, which allows estimating the running performance of the cyclotron accelerator at operating temperature <i>T</i> ~ 17 K. The estimations have shown that for magnetic fields <i>В</i> ~ 2 T with induction gradients ∂<i>B</i>²/∂<i>x</i> ~ 2 × 10² T²/m, the cyclotron accelerator with a radius of ~4 m can overcome the target injection velocity <span>({{{v}}_{{{text{inj}}}}})</span> = 200 m/s at <i>a</i> = 1000<i>g</i>, which is the lower limit for future IFE power plant. For existing laser facilities the velocities 20‒100 m/s can be easily reached for a more comfortable acceleration range <i>a</i> = 10‒250<i>g</i>. In addition, the article discusses promising research at the LPI in the field of cyclotron acceleration, both from the point of view of selecting new HTSC materials and improving the design of HTSC-sabots. The obtained results provide the design reference for building the higher-performance cyclotron accelerators for IFE.</p>","PeriodicalId":503,"journal":{"name":"Bulletin of the Lebedev Physics Institute","volume":"51 6 supplement","pages":"S472 - S488"},"PeriodicalIF":0.6,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142579520","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Control of a High-Speed Channel Spectrum Using an Off-Center Signal Chirp","authors":"E. G. Shapiro,&nbsp;D. A. Shapiro","doi":"10.3103/S1068335624601614","DOIUrl":"10.3103/S1068335624601614","url":null,"abstract":"<p>A method is proposed for transferring the spectrum of an optical signal from the vicinity of one carrier frequency to the vicinity of another using an off-center chirp. This technique makes it possible to divide one channel into several using a time chirp, the duration of which is a multiple of the bit interval. It is shown that from the point of view of minimizing distortions, it is preferable to split the signal into channels at the beginning of the communication line.</p>","PeriodicalId":503,"journal":{"name":"Bulletin of the Lebedev Physics Institute","volume":"51 6 supplement","pages":"S458 - S466"},"PeriodicalIF":0.6,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142579349","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Afterglow Spectra of Cl2/Xe Mixtures Pumped by XeCl Laser Radiation","authors":"A. P. Shirokikh,&nbsp;S. B. Mamaev","doi":"10.3103/S1068335624601626","DOIUrl":"10.3103/S1068335624601626","url":null,"abstract":"<p>The paper examines afterglow spectra of chlorine–xenon mixtures excited by XeCl laser pulses (308 nm). The dependence of the spectra on the composition and pressure of the mixtures is shown. The mixtures are compared with the total luminescence spectra measured under similar conditions. The time characteristics of excitation and luminescence pulses are presented.</p>","PeriodicalId":503,"journal":{"name":"Bulletin of the Lebedev Physics Institute","volume":"51 6 supplement","pages":"S467 - S471"},"PeriodicalIF":0.6,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142579386","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Acousto-Optic Cell for Controlling Rotation of the Polarization Plane of Linearly Polarized Optical Radiation","authors":"V. M. Kotov","doi":"10.3103/S1068335624601596","DOIUrl":"10.3103/S1068335624601596","url":null,"abstract":"<p>An acousto-optic cell is developed that allows the polarization plane of linearly polarized light to be rotated by an angle depending on the acoustic wave frequency. The effect is based on the combining of two mutually orthogonal optical waves whose polarizations are close to circular, with the phase of one of the waves changing under the action of a sound wave. A cell made of paratellurite crystal allows the polarization plane angle of linearly polarized light with a wavelength of 0.63 μm from 0° to ∼30° to be changed by varying the sound frequency from 38 to 43 MHz.</p>","PeriodicalId":503,"journal":{"name":"Bulletin of the Lebedev Physics Institute","volume":"51 6 supplement","pages":"S441 - S448"},"PeriodicalIF":0.6,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142579350","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Method of Spatial Alignment of Focal Planes and Sample Positioning in the Pump–Probe Scheme","authors":"A. V. Ovchinnikov,&nbsp;I. V. Il’ina,&nbsp;M. A. Ovchinnikova,&nbsp;O. V. Chefonov","doi":"10.3103/S1068335624601584","DOIUrl":"10.3103/S1068335624601584","url":null,"abstract":"<p>A new method is proposed for determining the mutual position of the focal planes of focusing elements and their spatial alignment along the laser beam propagation axis in the optical pump–probe scheme. The method is based on the effect of nonlinear absorption arising from the interaction of femtosecond laser pulses with matter. The practical application of this method is demonstrated using the example of setting up an optical scheme for measuring the temporal shape of a terahertz pulse with the electro-optical gating method.</p>","PeriodicalId":503,"journal":{"name":"Bulletin of the Lebedev Physics Institute","volume":"51 6 supplement","pages":"S435 - S440"},"PeriodicalIF":0.6,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142579501","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Quenching Rate Constants of Excited States of N2 and ({mathbf{N}}_{2}^{ + }) in Interaction with Hydrocarbons","authors":"V. V. Mislavskii,&nbsp;V. V. Gubernov,&nbsp;G. I. Satdykova","doi":"10.3103/S1068335624601651","DOIUrl":"10.3103/S1068335624601651","url":null,"abstract":"<p>We report results of studies of luminescence decay processes in excited states of nitrogen molecules and ions in gas mixtures with hydrocarbon molecules. Use is made of emission spectroscopy methods to perform measurements. Nitrogen molecules N₂ and nitrogen molecular ions <span>({text{N}}_{2}^{ + })</span> are excited to the C³Π_u state and the <span>({{{text{B}}}_{2}}Sigma _{{text{u}}}^{ + })</span> state, respectively, by a repeated high-voltage nanosecond discharge in the gas mixture in question. As a result of processing the data obtained by varying the composition of the gas mixtures and their pressure (1–20 Torr), the quenching rate constants of the excited states of nitrogen N₂(C³Π_u) and <span>({text{N}}_{2}^{ + }({{{text{B}}}_{2}}Sigma _{{text{u}}}^{ + }))</span> in collisions with hydrocarbon molecules CH₄, C₂H₆, and C₃H₈ are determined. For the first time, the values of the quenching rate constants are obtained for a mixture of nitrogen and propane, as well as for the 3 → 7 transition of the emission band system N₂(C³Π_u → B³Π_g) of a nitrogen–methane mixture.</p>","PeriodicalId":503,"journal":{"name":"Bulletin of the Lebedev Physics Institute","volume":"51 6 supplement","pages":"S499 - S505"},"PeriodicalIF":0.6,"publicationDate":"2024-11-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142579521","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Adaptation of the Pavicom-1 Automated Scanning Facility for Processing Nuclear Emulsions of the SND@LHC Experiment","authors":"M. M. Chernyavsky,&nbsp;N. S. Konovalova,&nbsp;N. M. Okateva,&nbsp;N. G. Polukhina,&nbsp;Zh. T. Sadykov,&nbsp;T. V. Shchedrina,&nbsp;N. I. Starkov,&nbsp;E. N. Starkova","doi":"10.3103/S1068335624601158","DOIUrl":"10.3103/S1068335624601158","url":null,"abstract":"<p>The PAVICOM-1 scanning device is one of the automated microscopes of the PAVICOM optical measuring complex designed at Lebedev Physical Institute of the Russian Academy of Sciences for high-tech processing of experimental data obtained using solid-state track detectors in the field of nuclear physics, cosmic ray physics, and high-energy physics. A regular upgrade of the PAVICOM-1 device is presented, which makes it possible to scan photographic nuclear emulsions of the SND@LHC accelerator experiment.</p>","PeriodicalId":503,"journal":{"name":"Bulletin of the Lebedev Physics Institute","volume":"51 9","pages":"339 - 344"},"PeriodicalIF":0.6,"publicationDate":"2024-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142573669","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Key Notes on Fixed Point Programming in Particle Radiotherapy","authors":"A. E. Chernukha,&nbsp;V. O. Saburov,&nbsp;A. I. Adarova,&nbsp;N. A Skotnikova,&nbsp;O. Yu. Golovanova,&nbsp;A. I. Shestopalov,&nbsp;A. E. Shemyakov,&nbsp;S. N. Koryakin,&nbsp;I. A. Gulidov,&nbsp;S. A. Ivanov,&nbsp;I. N. Zavestovskaya,&nbsp;A. N. Solovev","doi":"10.3103/S1068335624601043","DOIUrl":"10.3103/S1068335624601043","url":null,"abstract":"<p>The paper examines the violations of monotonicity and semiconvergence of the inverse optimization problem to equilibrium iterative solutions under conditions of physical density discontinuities in therapy planning techniques. Additionally, it addresses aspects of quasi-Newton iterations of the obtained solution in both voxel representation and continuous approximation. Examples include radiation treatment plans for patients treated with proton beam at the Prometheus therapeutic facility at the A. Tsyb Medical Radiological Research Center, Obninsk, Kaluga oblast, Russia. The presented aspects of the theory and its applications form the basis of the dose-anatomical planning program.</p>","PeriodicalId":503,"journal":{"name":"Bulletin of the Lebedev Physics Institute","volume":"51 9","pages":"345 - 352"},"PeriodicalIF":0.6,"publicationDate":"2024-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142573668","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Method of Frequency Mapping of a Virus Using the Example of Tobacco Mosaic","authors":"A. F. Bunkin,&nbsp;M. A Davydov,&nbsp;A. N. Fedorov","doi":"10.3103/S1068335624600827","DOIUrl":"10.3103/S1068335624600827","url":null,"abstract":"<p>A set of vibrational eigenmodes of the tobacco mosaic virus is recorded in the frequency range of 4‒50 GHz in experiments on stimulated inelastic scattering of laser light in a liquid suspension of viral nanoparticles. The data obtained in this way is proposed to be used for rapid optical identification of viruses.</p>","PeriodicalId":503,"journal":{"name":"Bulletin of the Lebedev Physics Institute","volume":"51 9","pages":"315 - 318"},"PeriodicalIF":0.6,"publicationDate":"2024-11-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142573675","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"物理与天体物理","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}