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V S Belyaev

Publications and source records attributed to V S Belyaev.

5 recordsLinked to original sources
PubMed2005

Observation of neutronless fusion reactions in picosecond laser plasmas.

The yield of alpha particles in neutronless fusion reactions 11B +p in plasmas produced by picosecond laser pulses with the peak intensity of 2 x 10(18) W/cm2 has been observed. Experiments were carried out on the "Neodymium" laser facility at the pulse energy of 10-12 J and pulse duration of 1.5 ps. The composite targets 11B + (CH2)n were used. The yield of 10(3) alpha particles per pulse has been observed. The energy spectrum of alpha particles contains two maxima: at 3-4 MeV and at 6-10 MeV . The first of these peaks corresponds to the secondary alpha12 particles at the decay of the intermediate first excited state of 8Be, whereas the second peak demonstrates generation of alpha1 particles in the reaction 11B +p with the production of this excited state. Simultaneous measurements of neutrons result in zero yield, which proves the observation of neutronless fusion reactions in our experiments.

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PubMed2004

Analysis of high- n dielectronic Rydberg satellites in the spectra of Na -like Zn XX and Mg -like Zn XIX.

We have observed spectra from highly charged zinc ions in a variety of laser-produced plasmas. Spectral features that are Na - and Mg -like satellites to high- n Rydberg transitions in the Ne -like Zn XXI spectrum are analyzed and modeled. Identifications and analysis are made by comparison with highly accurate atomic structure calculations and steady state collisional-radiative models. Each observed Zn XX and Zn XIX feature comprises up to approximately 2 dozen individual transitions, these transitions are excited principally by dielectronic recombination through autoionizing levels in Na - and Mg -like Zn19+ and Zn18+. We find these satellites to be ubiquitous in laser-produced plasmas formed by lasers with pulse lengths that span four orders of magnitude, from 1 ps to approximately 10 ns. The diagnostic potential of these Rydberg satellite lines is demonstrated.

Journal Article↗
PubMed2003

Influence of optical thickness and hot electrons on Rydberg spectra of Ne-like and F-like copper ions.

Spectra in the 7.10 to 8.60 A range from highly charged copper ions are observed from three different laser-produced plasmas (LPPs). The LPPs are formed by a 15-ns Nd:glass laser pulse (type I: E(pulse)=1-8 J, lambda=1.064 microm), a 1-ps Nd:glass laser pulse (type II: E(pulse)=1 J, lambda=1.055 microm), and a 60-fs Ti:sapphire laser pulse (type III: E(pulse)=800 mJ, lambda=790 nm). The spectra of high-n (n<or=14) transitions in highly charged copper ions, Cu19+ to Cu21+, are recorded with a high energy resolution (lambda/deltalambda=3000-8000) spectrometer using a spherically bent mica or quartz crystal. Collisional-radiative models are computed for the emission from each plasma. The sensitivity of the model spectra to opacity effects and to populations of superthermal electrons is studied. For the type I LPPs, opacity effects, treated with escape factors, are necessary to get the correct relative intensities of high-n (n=5, 6) Ne-like Cu19+ emission features. In the case of the type II LPPs, the contrast between the laser prepulse and the main pulse has been varied from low, I(main)/I(pp)=7 x 10(4), to high, I(main)/I(pp)=3.8 x 10(7). For plasmas from low contrast shots, we find good agreement between the observed spectra and optically thin simulations with bulk electron temperatures T(bulk)=0.4 keV and a small population of superthermal electrons (T(hot)=5.0 keV) that is f(hot)<or=10(-5) of the bulk electron population. For high-contrast type II LPPs, we find higher densities and a combination of f(hot) approximately 10(-5) and escape factors best describes the data. For the type III 60-fs LPPs, a population of superthermal electrons (T(hot) approximately 5 keV) that is approximately 5 x 10(-5) of the bulk electron population (T(bulk) approximately 0.2 keV) is required to reproduce the observed spectra. The effect of both escape factors and hot electrons in the CR models is to increase the ionization balance and dramatically increase the number of strong lines for each ion considered. We have studied both opacity effects and hot-electron influence on high-n transitions of highly charged Ne-, F-, and O-like ions.

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