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The principle of operation and technical parameters of excilamps with a small-diameter output window from a series of portable narrow-band ultraviolet and vacuum ultraviolet radiation sources are described. An example of using a KrCl excilamp to excite photoluminescence of crystalline materials is given.

It is shown that the channel of apokampic discharge is a source of streamers at low air pressure and low frequencies (7–16 Hz) of high-voltage positive-polarity pulses and voltage amplitudes from 26 to 35 kV. The maximal starting speed of laboratory streamers was 560 km/s. A hypothesis about blue jet origination in nature is suggested based on experimental data. For their start, high frequencies of voltage pulses are not required, breakdowns in the Hz range are sufficient, but the discharge channel should bend and the field intensity should be high at the bending point.

Dielectric barrier discharge XeCl-excilamps can be used for detecting of surface defects in case of the luminescent liquid penetrant inspection method (LLPI). In case of LLPI, surface defects are detected by brightly glowing indications formed on the developing coating (developing agent) in the locations of discontinuities. This method differs from the color one that the inspection is performed under darkening conditions and requires ultraviolet irradiation, so it is more sensitive, since the visual luminescence of the display is detected better than the color contrast. This article experimentally compares the results of LLPI using different UV-light sources (two barrier discharge excilamps (portable and front-mounted), a mercury UV lamp and an led UV lantern). It is shown that the XeCl-excilamp gives a good detection and fixation of indicator traces in comparison with other sources of UV radiation.

Experimental studies of the heat release processes in the apokamp discharge were carried out via the plotting of intensity charts. The procedure was verified with measurement techniques similar to those used in the operation of a disappearing filament pyrometer. A criterion was formulated for its applicability for the study of apokamp discharge in air. The intensity charts obtained at different stages of the formation of discharge confirm the need for gas heating near the discharge channel to form streamers.

Miniature analogs of starters and blue jets that are observed in the upper atmosphere of the Earth and have dimensions of tens of kilometers are formed and studied in air and nitrogen at pressures of tens and hundreds of Torr. Ministarters and mini blue jets have been obtained in laboratory experiments owing to the application of a pulse-periodic discharge with a plasma jet referred to as apokamp. The velocities of propagation of apokamps have been measured at various pressures. It has been found that the average values of these velocities are about the velocities of propagation of starters and blue jets in the atmosphere of the Earth. It has been shown that jets (apokamps) with the maximum length are observed in the pressure range corresponding to the altitudes of appearance and propagation of starters and blue jets.

Now, agriculture strives for advanced technologies that would speed up the seed germination, reduce the plant disease incidence, and enhance the crop yield. In this connection, more and more studies address ultraviolet irradiation of seeds and plants as a way to increase their sowing quality. In this paper, XeCl-excilamp (λ~ 300-320 nm) ‒ as a simulator of solar short-wave radiation ‒ is used in the quality of source of ultraviolet radiation. A new data on morphometric and morphological indicators of development of a number of economically valuable crops (parsley, cucumber, pumpkin, zucchini) exposed to XeCl-excilamp are presented. In particular, it is shown that the ultraviolet treatment increases the number of zucchini fruits ("Tsukesha" sort) by an average of 40%, compared to untreated control samples and increases the area of the assimilating surface of leafs (in the first week after germination and further in a month and two months) by an average of one and a half times. Compared with the control 90-second treatment of seeds zucchini led to a higher content of vitamin C in fruits and more than a twofold reduction of nitrate to 64±7 mg/kg. Similar results were obtained for the pumpkins. First processing radiation of XeCl-excilamp were subjected parsley seeds. Found processing conditions in which you can increase the yield by an average of 20%. The obtained indicators allow us to draw a conclusion about the economic feasibility of XeCl-excilamp seeds illumination and confirm our conclusions about the prospects of such a procedure for pre-sowing plant seeds.

The paper demonstrates the possibility of studying blue jets in laboratory apokamp discharges as a source of blue streamers that move upward from the discharge channel. Research data are presented on the formation of such streamers in low-pressure air at a voltage of tens of kilovolts, showing for the first time that they do arise at low (∼8 Hz) pulse repetition frequencies under pressures at which gigantic blue jets develop 10–20 km above the Earth. At a voltage of positive polarity with an amplitude of 33 kV, the streamer velocity in a pulsed apokamp discharge reaches 560 km/s. When applying microsecond voltage pulses of amplitude 15 kV with a repetition frequency of 50 kHz, the length of streamers ranges to more than 120 cm.

The energy redistribution in barrier-discharge Xe2 excilamp in various excitation regimes is investigated using the pressure jump method. Analytic expressions are derived for calculating power W dissipated in the excilamp discharge plasma in the form of heat and for calculating total discharge heat power PT spent on heating the excilamp. It is shown that the mechanism of the thermal energy dissipation gradually changes upon an increase in the xenon pressure in the excilamp. The conditions for generating the maximal radiation power of the excilamp are determined. It is shown that the maximum of the average radiation power is attained for an excitation pulse duration of 500 ns and the maximal pulse power is attained for a pulse duration of 100 ns. It is found that the optimal operation regime for the excilamp corresponds to the maximal values of the PT–W difference.

Formation of a diffuse discharge at a short front of voltage pulse (less than 1 ns), as well as when placing water, water solutions, and dielectric film inside the discharge, is studied. A volumetric discharge was observed in water on the anode when placing dielectric film (polyethylene, vinyl chloride-methyl methacrylate (VCMMA), etc.), water, or aqueous solutions of 3% hydrogen dioxide or 18% KMgO4 inside the discharge. The change in the absorption spectrum of substance was found after multiple discharge switching on. Fourier analysis of the infrared absorption spectra showed the difference between the spectra of exposed and unexposed polyethylene film. The changes in the absorption spectra of water, 3% hydrogen dioxide and 18% KMgO4 aqueous solutions are related with expansion of the band of valence oscillations of OH-groups without clearly expressed maxima (for the studied liquids). Therefore, volumetric diffuse discharge in molecular and atomic gases can be used in modifying dielectrics, water and aqueous solutions.

The dynamics of diffuse discharge formation under the action of nanosecond voltage pulses with short fronts (below 1 ns) in the absence of a source of additional preionization and the influence of a dielectric film on this process have been studied. It is established that the diffuse discharge is induced by the avalanche multiplication of charge initiated by high-energy electrons and then maintained due to secondary breakdowns propagating via ionized gas channels. If a dielectric film (polyethylene, Lavsan, etc.) is placed on the anode, then multiply repeated discharge will lead to surface and bulk modification of the film material. Discharge-treated polyethylene film exhibits a change in the optical absorption spectrum in the near-IR range.

A review of studies of thermodynamic processes in KrBr (207 nm), KrCl (222 nm), and XeBr (282 nm) barrier-discharge excilamps and XeBr (282 nm) and XeCl (222 nm) microwave-discharge excilamps is presented. Using various pressure gauges, it was experimentally shown that a pressure jump that occurs upon excilamp switching-on (-off) contains a fast (with a characteristic time of ∼100 ms) and a slow (∼100 s) component. The fast pressure-jump component is associated with gas heating during the discharge and allows evaluation of the fraction of the discharge power that is thermalized in the gas. From the analysis of the pressure decay after the jump, it follows that the gas is heated as a result of two processes: direct gas heating during the discharge (∼100 ms) and the energy dissipation of acoustic waves in the gas (∼10 ms). The slow component of the pressure jump is caused by the general heating of the excilamp and can be used to determine the fraction of the discharge power that is converted to thermal energy and to study various excilamp cooling modes.

Energy and spectral characteristics of infrared radiation of a porous ceramic metal burner fabricated by the self-propagating high-temperature synthesis technology are studied. Radiant energy release of the burner in the regime of filtration combustion of natural gas is demonstrated to be greater than a similar parameter of plume combustion up to two times and to be determined by the intensity of radiation of the ceramic metal open surface and gaseous products of combustion. More than 70% of the radiant flux energy are concentrated in the wavelength range from 3 to 11 ?m. The maximum density of radiation reaches 0.31 MW/m2 for the burner power density of 1.32 MW/m2.

Traditional (in the AlGaAs/GaAs system) and phosphorus-compensated (in the AlGaAs/AlGaPAs/GaAs system) laser heterostructures emitting at a wavelength of 850 nm are grown by MOVPE and studied. Laser diode bars are fabricated and their output characteristics are studied. The method used to grow heterolayers allowed us to control (minimise) mechanical stresses in the AlGaPAs/GaAs laser heterostructure, which made it possible to keep its curvature at the level of the initial curvature of the substrate. It is shown that the use of a compensated AlGaPAs/GaAs heterostructure improves the linear distribution of emitting elements in the near field of laser diode arrays and allows the power - current characteristic to retain its slope at high pump currents owing to a uniform contact of all emitting elements with the heat sink. The radius of curvature of the grown compensated heterostructures turns out to be smaller than that of traditional heterostructures.

In the work, we studied the influence of convection on the energy characteristics of coaxial XeCl excilamps driven by a dielectric barrier discharge (DBD). For the study, a special bulb with axially offset outer and inner tubes was manufactured and a gas convection model was developed. It is shown that convection of the mixture can provide an increase of 10–30% in excilamp radiation intensity compared to excilamps with no convection. The presence of convection of the working mixture increases the excilamp lifetime.

The energy dissipation processes in dielectric barrier discharge KrCl- and XeCl-excilamps at various voltage, frequencies and pulse duration are revealed by a pressure jump method. It is offered and tested a way of radiation power calculation in conditions of non-uniform filling of device bulb by discharge plasma. The previous data (Pikulev A.A., Sosnin E.A., 2010-2013) are confirmed. The regularity was formulated: conditions of maximal ultraviolet radiation power corresponds to conditions of maximal heat release in plasma. © (2015) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.

The energy and spectral parameters of a barrier discharge in a mixture of argon with hydroxyl ?OH are studied experimentally. A sealed lamp with the radiation intensity maximum at ? = 309.2 nm, an emitting surface area of ~700 cm2, and a radiant excitance of 1.5 mW cm-2 has been fabricated. The radiant power of the lamp is 1.1 W.

A photoreactor developed on the basis of a Xe2 excilamp with a power of ∼10 W (with a power density of 15 mW/cm2 emitted from a surface of ∼700 cm2), which can operate in liquids and gases at a pressure of up to 40 atm, and a multifunctional cell with an active volume of ∼760 cm3 is described. Data on water photolysis in a natural gas exposed to VUV radiation with λ=172 nm are presented.

Experiments and theoretical simulation were performed to study the acoustic characteristics of a planar KrCl excilamp driven by a dielectric barrier discharge (DBD) with a mixture ratio of Kr:Cl2 = 400:1 at a pressure of 20 kPa. The acoustic spectrum of the excilamp bulb was measured and resonances at 4.96, 5.36, 9.92, 10.8, and 21.6 kHz were detected. The natural frequency of the bulb walls and the acoustic frequency of the gas were calculated. The acoustic energy of the gas was determined depending on the vibration frequency of the bulb walls. Comparison of the experimental and simulation data shows that in the frequency range >10 kHz, acoustic peaks occur at natural frequencies of the gas in the excilamp bulb.