Investigation of the lasing characteristics of a barium vapor laser with pulse repetition frequencies up to 320 kHz for navigation

Results of experimental investigations into the characteristics of a laser on self-terminating transitions of the barium atom with λ = 1499 nm are presented for high pulse repetition frequencies (PRF). The frequency-energy characteristics are investigated in the self-heating mode of laser operation. Record values of PRF for the barium vapor laser, equal to ~320 kHz, have been attained. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only

Are the scientific foundations of temperate marine reserves too warm and hard?

The scientific literature (including some of the most high-profile papers) on the ecological and fisheries effects of permanent no-take marine reserves is dominated by examples from hard tropical and warm temperate ecosystems. It appears to have been tacitly assumed that inference from these studies can directly inform expectations of marine reserve effects in cooler temperate and cold temperate waters. Trends in peer-reviewed studies indicate that the empirical basis for this assumption is tenuous because of a relative lack of research effort in cooler seas, and differences between tropical and temperate regions in ecology, seasonality, the nature of fisheries and prevailing governance regimes. © Copyright Foundation for Environmental Conservation 2012

Development of multiple-wavelength oscillation in plasma of a pulse-periodic He+Ne+Sr laser

Mechanisms of multiple-wavelength oscillation at the lines of He I, Ne I, Sr I, and Sr II ions in the active medium of a high-voltage pulse-periodic laser based on a He + Ne + Sr mixture at a total pressure of ∼200 Torr and duration of the current pulse of about 150–300 ns are analyzed. An important role played by collisional thermal mixing of the laser levels of Ne I and Sr I in multiplets, as well as by collisions of the second kind between metastable and unexcited atoms, in populating and depopulating atomic levels is demonstrated. Absolute populations of the upper and lower levels of the laser transitions in Ne I are found. It is discovered that the degree of ionization nonequilibrium of plasma, both during and after the pulse of current, determines the mechanism of population inversion in laser transitions

Reflecting on the next generation of models for community-based natural resources management

Community-based natural resource management (CBNRM) has been a pervasive paradigm in conservation circles for three decades. Despite many potentially attractive attributes it has been extensively critiqued from both ecological and sociological perspectives with respect to theory and practice (for example Leach et al. 1999; Berkes 2004; Fabricius et al. 2004; Blaikie 2006). Nonetheless, many successful examples exist, although an equal number have seemingly not met expectations. Is this because of poor implementation or rather a generally flawed model? If the criteria and conditions for success are so onerous that relatively few projects or situations are likely to qualify, what then is the value of the model? The questions thus become: how and what can we learn from the past theory and practice to develop a new generation of flexible, locally responsive and implementable CBNRM models, and what are likely to be the attributes of such models

The efficiency of the pumping of the lasers based on self-terminating atomic transitions operating in the energy input cut-off mode

The analysis of the electro-physical processes in the discharge circuit of the lasers based on the self-terminating transitions of metal atoms (LSTM) and the electrodes placed in the cold buffer zones of the gas discharge tube (GDT) is occurred. That design of the GDT can provide the efficient lasing at the reduction of the current flowing through the switch to zero after the charging of the capacitive components of the circuit from the storage capacitor. Under the circumstances the pumping of the active medium is determined by the energy input from the peaking capacitor and, consequently, the efficiency of the pumping can be increased by an order of magnitude, if (using a managed switch) the energy input into the active medium from the storage capacitor is “cut-off” after charging the capacitive components of the circuit. It was shown that the efficiency values of ∼ 9-11 % and of ∼ 5-6 % for the copper and gold vapor, lasers could be achieved

Multi-wavelength metal vapor laser systems for solving applied problems of atmospheric spectroscopy

Results of a cycle of experimental investigations of a multi-wavelength metal vapor laser system based on original configuration of a multi-medium metal vapor laser source are presented. Novelty of our approach consists in that two gas discharge active elements (on copper bromide and strontium vapors) are arranged in a common cavity, and each of them is pumped by an independent power supply unit, which allows them to be optimized independently for excitation conditions and thereby the output set of lasing wavelengths and their relative power distribution to be regulated. This makes the above described system promising for a number of scientific and technological applications. The total output power of 11 spectral components lying in the range 0.43–6.45 μm reached ~17 W. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only

Computer control of the spectral composition of the powerful laser system irradiation with a wide range of laser transitions on metal vapors

The results of the experimental study cycle of the multiwave metal vapor laser system on the basis of the original configuration of the multimedia laser emitter. The spectral parameters of the setup have been controlled using a personal computer (PC). This allows carrying out their independent optimization according to excitation conditions, and, therefore, promptly allocating the output set of oscillating wavelengths and their relative distribution in power, which makes the system attractive for scientific and technological application

On boundedness of certain integral operators

We study mapping properties of two-dimensional linear integral operators in some weighted spaces with special kernels. The considered spaces are certain variant of Sobolev-Slobodetskii spaces and their generalizations related to Banach spaces. Sufficient conditions for boundedness for such operators in these spaces are obtaine