One of the main technical parameters of light emitting devices is their service life. The service life and stability of light radiation during operation determine the operating conditions of light sources. By the example of barrier discharge excilamps based on KrCl* (222 nm) and XeBr* (282 nm) exciplex molecules, an optoelectronic method for stabilizing excilamp UV radiation is proposed. The method consists in autocorrecting the radiation power of the excilamps using a UV radiation sensor and an electronic feedback that regulates the power of the excilamps. During of tests for the service life of KrCl and XeBr excilamps, the dependences of the change in the excilamp radiation power on time in a continuous mode of operation were obtained. A new approach to describing the reliability of excilamp operation is discussed. It is shown that instead of such a parameter of light-emitting devices as a useful service life, it is necessary to use a new quantitative characteristic, which is proposed to be called the guaranteed service life of the stable operation of the excilamp.
The work is devoted to identifying the features of plant growth and development under laboratory conditions after presowing stimulation of seeds of pine (Pinus sylvestris L.), thuja (Thuja occidentalis L.) and eggplant (Solanum melongena L., variety "Universal") by UVB radiation of XeCl-excilamp. In all cases, conditions were identified in which UVB stimulation accelerates the germination of these seeds and the formation of seedlings. Additionally, microcoping of germinating 10-day-old thuja seeds performed on sections shows that the seeds show clear differences compared to the untreated control. If in the control, the seeds were just beginning to germinate (the appearance of the germ root), then in the experimental samples, on average, 5% of the seeds passed to the stage of development and formation of the seedling, had a developed root, hypocotyl, colored cotyledons, which began to shed the seed rind. The obtained primary data confirm the prospects of using narrow-band UVB radiation of XeCl-excilamps for pre-sowing stimulation of plant seeds.
This work continues the cycle of our research on the physiological effect of UVB radiation on plants. The physiological effect of UVB radiation (308 nm, doses of 0.5, 1.4 and 2.7 J/cm2) on the structural and functional characteristics of wheat seedlings was determined. With an increase in the radiation dose, a decrease in plant height, leaf area and the amount of photosynthetic pigments was revealed, photosynthesis parameters decreased, and the content of low-molecular- weight antioxidants increased. This means that UVB priming of wheat sprouts should be carried out at even lower doses than were selected in the experiments.
Using an electrode with a ceramic coating, a new method for the formation of an apokampic discharge in the pressure range of 30-150 Torr has been obtained. It was found that the average plasma bullets velocity propagated from such an electrode can reach 520 km/s. The results obtained are in good agreement with the simulation results obtained earlier in the framework of the streamer model.
Using emission spectra, the electronic, vibrational, rotational, gas temperatures and the reduced electric field strength at different distances along the propagation of the apokamp from the discharge channel at an air pressure of 150 Torr, a voltage of 7.6 kV, and a frequency of 37.5 kHz were determined. To determine the above values of plasma parameters, the methods of optical emission spectroscopy were used, after which the experimentally obtained values were compared with the values obtained in the course of modeling the emission spectra of the discharge plasma using a code based on the radiation-collisional plasma model. It is shown that the values of the electron temperature and reduced field strength increase abruptly at a height of ~ 12 mm above the discharge channel, marking the transition from the offshoot zone to the positive streamer zone. The gas temperature along the distribution of the apokamp decreases exponentially and at a distance of 75 mm reaches about 530° C (which is about 3 times less than at the base of the apokamp). The data obtained are in agreement with the streamer model of the plasma plume of the apokamp and allow us to hope for the creation of a plasma source based on an apokampic discharge with a moderate gas temperature at the end of the plasma plume.
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.
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.
A new models of Xe2-excilamp (with maximum of radiation spectra at 172 nm) developed in Optical Radiation Laboratory of High Current Electronics Institute are presented. The task of creating a lamp with the most simple design embodiment was solved. The bulb of such an excilamp was made from a single quartz tube with a diameter of 22 mm and a length of 12 cm. The length of the discharge region was 4 cm. The lamp was supplied with voltage pulses from a generator of 2 μs with a repetition frequency up to 100 kHz. A radiant exitance of 3.5 mW/cm2 has been obtained. This value has not changed after 2400 hours of excilamp operation. The report will also describe other designs of Xe2-excilamps.
The decomposition products of atmospheric pressure plasma of repetitive pulsed discharge in apokamp and corona modes were determined by optical and chemical methods. It is shown, that the decomposition products contain mainly nitrogen oxides NOx. A brief review of the plasma- and thermochemical reactions in the pulsed discharges was made. The review and experimental data allow us to explain the reactive oxygen species formation mechanisms in a potential discharge channel with apokamp. The possible applications of this plasma source for treatment of seeds of agricultural crops are discussed.
Here we present research data demonstrating how crop seeds response to ultraviolet produced by a barrier-discharge XeCl* excilamp with a wavelength of 290–320 nm (82–88 %). The data show that presowing ultraviolet treatment is stimulatory to seed germination and plant growth. Ultraviolet treatment increases the seed germinability by 20–30 % and the plant fresh weight by 54 %, compared to untreated control samples, and provides a developed root system with long twisted segments. The research results are encouraging for upgrading the UV technology to larger-scale seed irradiation.
The paper provides a review of research data on applications of XeCl excilamps in agriculture and animal breeding. The data demonstrate a favorable effect of radiation produced by the excilamps on the fertility of animals (outbred mice and pigs) and on the growth of plants (flaxes, potatoes, carrots, cucumbers, conifers). Excilamp models adapted specially for use in stock-raising and grain storage complexes are now available. The research data obtained in 2012–2015 suggest that XeCl excilamps hold promise for prevention of diseases in indoor-housed pigs and for pre-sowing seed preparation.
The paper proposes a new atmospheric pressure plasma jet (APPJ) source for operation in air and nitrogen. The conditions for the formation of stable plasma jets 4 cm long are determined. Energy and spectral measurement data are presented.
The inactivation of eggs of Opisthorchis felineus and Diphyllobothrium latum in the water under the action of UV excilamps at 222 and 282 nm in dependence on the surface dose of radiation was studied. It was observed that the water disinfection from eggs of helminthes was more efficient at 222 nm, than at 282 nm. At the surface dose up to 5 mJ/cm2 of UV radiation at 222 nm up to 85 % of Opisthorchis felineus eggs were inactivated. At the comparable surface dose of UV radiation at 222 nm up to 56 % of Diphyllobothrium latum eggs were inactivated.
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.
Transmission and luminescence spectra of natural or/and synthetic samples of corundum, diamonds and phianites are
obtained by irradiation of a KrCl-excilamp (222 nm) driven by the barrier discharge. It is offered to use a KrCl-excilamp
for development of devices for nondestructive identification of diamonds and their imitations.
Emission characteristics of a nanosecond discharge in nitrogen, inert gases and its halogenides without preionization of
the gap from an auxiliary source have been investigated. A volume discharge, initiated by an avalanche electron beam
(VDIAEB) was realized at pressures up to 12 atm. It has been shown that at VDIAEB excitation no less than 90%
energy in the 120-850 nm range is emitted by Xe, Kr, Ar dimers. Xenon spectra in the range 120-850 nm and time-amplitude
characteristics have been recorded and analyzed for various excitation regimes. In xenon at pressure of 1.2
atm, the energy of spontaneous radiation in the full solid angle was ~ 45 mJ/cm3, and the FWHM of a radiation pulse
was ~ 110 ns. The spontaneous radiation power rise in xenon was observed at pressures up to 12 atm. Pulsed power
densities of radiation of inert gases halogenides excited by VDIAEB was ~ 4.5 kW/cm2 at efficiency up to 5.5 %.
The study of features of XeBr-excilamp (282 nm) and low-pressure Hg-lamp (253.7 nm) radiation impact on Escherichia coli bacterial culture are presented. It is shown for the first time that both sources of radiation have comparable germicidal action. The prospects of a new bactericidal radiation source - XeBr-excilamp - are discussed.
The combined decomposition method of chlorophenols (CP) is offered. The method is based on photolysis of CP through XeBr-excilamp UV irradiation at 283 nm in a flow photoreactor with subsequent treatment of photolysis products by microorganism-destructor B. cereus isolated from an aeration pond of Baikal pulp-and-paper mill. At initial concentration of CP of 20 mg/l the polluted solutions can be utilized directly by means of biological treatment using B. cereus under aerobic conditions. However, if the initial CP concentration is higher than 20 mg/l, the polluted solutions are low biodegradable. It is shown, that the combined treatment is most effective method in this case. At initial CP concentration of 50 mg/l and higher it is
suggested to use the deep preliminary UV-treatment with the purpose of removal 80-90 % of initial CP. It is revealed, that 4-CP is relatively persistent compound for B. cereus, easily decomposed by UV-radiation of XeBr-excilamp. As a
result of subsequent biological treatment during 10 days the utilization of basic CP photoproducts is obtained.
Experimentally, the preliminary UV-processing time was essentially less than that found earlier by E. Tamer, Z. Hamid, Aly A. (Chemosphere, 2006), where the half-life periods of initial CP were from 2.2 to 54 hours at the same value of initial concentration of CP. Correspondingly, the total CP decomposition process was accompanied by high power inputs. It is suggested to use mentioned above method for effective CP decomposition at high concentration values.
The extraordinary characteristics of excilamps (excimer and exciplex lamps) led to a great many of applications, which had been demonstrated in a number of previous studies. This review is principally dedicated to our advances in application of UV/VUV capacitive and barrier discharge excilamps in photoscience (photochemistry and photomedicine). In the present paper, the review of the basic results obtained at the Laboratory of Optical Radiation at High Current Electronics Institute SB RAS during 2003-2005 years is presented.
Clinical efficiency estimation of XeCl-excilamp application for psoriasis curing in comparison with other methods of phototherapy for has been carried out for the first time. Curing psoriasis by XeCl-excilamp assistance is shown to be an effective and present-date method. Such a phototherapy advantages suggested are the good tolerance, and absence of intact skin irradiation. The use of chemicals is no longer relevant, and the total doze of irradiation happens to be rather low.
A method of fluorescent spectroscopy is used to study phototransformations of 4-methyiphenol and its NH2-substitutes in water excited by UV radiation of different sources. It is demonstrated that the photophysical and photochemical properties of these molecules depend on the electronic state to which they are excited.
Experimental results on peculiarities of bactericidal effect of atmospheric plasma components and narrowband ultraviolet (UV) radiation of barner discharge XeBr- and KrBr-excilamps on the cultures Escherichia coli and Staphylococcus aureus are presented. Combination of such plasma components as UV radiation at 190 < λ < 220 nm and electroneutral particles is shown to possess the best sterilizing action. A KrBr-excilamp is shown to possess the unique spectrum, which corresponds to maximum of DNA inactivation section of microorganisms.
Efficient radiation of Xe2*, KrBr*, KrCl*, XeI*, Cl2, XeBr*, XeCl* molecules and Iodine atoms was obtained. Some types of UV and VUV excilamps with different discharge geometry excited by capacitive discharge, barrier discharge and glow discharge are presented.
The method of fluorescent spectroscopy is used to investigate the influence of the pH of the medium on phototransformations of o- and p-cresol in water under UV irradiation. It is demonstrated that the efficiency of cresol photodecomposition decreases with the increasing pH of the medium. The efficiency of cresol phototransformations in an alkaline medium is higher under irradiation at 283 nm, whereas in a neutral medium, it is higher under irradiation at 222 nm.
It is well known that pH value and excitation energy have a directly impact on photolysis rate of phenols under Hg-lamp irradiation and oxidation process. The purpose of the current study is the research of o-cresol and para-cresol photolysis in acidic medium under various spontaneous radiation sources irradiation. Photochemical degradation was carried out through a high pressure mercury lamp OΚH-11M, and also with a new capacitive discharge excilamps on working molecules KrCl* (λ~222 nm) and XeBr* (λ~283 nm). Exposure time was varied from 1 to 40 minutes that corresponds radiation doses from 0.5 to 20 J/cm2. A comparison between phototransformations under different light excitation shows that cresol aqueous solutions acidation leads to increase of phototransformations efficiency. It was been found that both in neutral, and in acidic medium the photodecomposition of cresols is carried out more effectively under KrCl-excilamp irradiation.
Simplified pretreatment of biological objects united chemical (HNO3+H2O2) and further photochemical sample oxidation has been suggested. Optimization of conditions was performed using the method of fractional factorial design of experiments. Availability of excimer gas discharge excilamp based on working molecule XeBr* has been shown as an alternative to mercury quartz at pretreatment of biological objects of complex organics. The XeBr-excilamp is remarkable by its long lifetime and operation reliability.
Simple configuration small-sized KrCl-, XeBr- and XeCl-excilamps based on near-surface capacitive discharge are offered. The devices are demonstrated to possess high specific energy characteristics (radiation power density of up to 10 mW/cm2), permanently small radiation volume, as well as narrow radiation band. Operating lifetime of a sealed-off excilamp is above 1000 hrs.
A reliable bactericidal effect on Escherichia coli cells irradiation by excilamps has been established. Both on primary and secondary irradiation there exists the reciprocally proportional dependence between irradiation doze (or exposure time) and survived cells number. The microorganisms survived after primary irradiation are shown to have not changed sensitivity to excilamps irradiation. The best results have been obtained during XeBr-excilamp irradiation. Owing to their technical parameters, the excilamps are promising systems for UV-sterilization. Comparison of capacitive discharge excilamp characteristics with other conventional UV light sources in presented. A comparative study on UV doze effect of a barrier discharge KrCl-excilamp (λ = 222 nm) on Staphylococcus aureus and Escherichia coli inactivation was carried out. KrCl-excilamp emission power is 65 W, and emitting area is 0.1 m2. It has been demonstrated that Staphylococcus aureus cell sensitivity to UV radiation at this wavelength is higher than that of Escherichia coli.
Kinetics of oil water solutions photodegradation under action of narrow band irradiation of XeBr*-excilamp (λ~283 nm) and iodine lamp (λ~206 nm) is presented. Power of lamps reached 10 mW/cm2. In all experiments TiO2 (rutile) powder was used as a catalytic agent. Photocatalytic degradation kinetics was controlled by laser fluorescence spectrometer. The measuring complex was based on the pulse-repetitive Nd:YAG laser (266 nm) with Q-switching. Dependencies of fluorescence intensity on irradiation time were made using laser-induced fluorescence spectra. It has been found that at initial time of irradiation, the photodegradation rate in oil aqueous solutions was higher in the case of XeBr* lamp, however, after 20 minutes of irradiation, major photodegradation was observed in the both cases.
To study of halogen a substituted phenols photochemical property in the neutral media under action of the man-made sources of excitation the purpose of the present work. There are exciplex KrCl laser and high-frequency excilamp of a grow discharge on same molecules. The efficiency of a photolysis by the spectroscopic methods estimated. Comparison of lamp and laser photolysis of substituted phenols occurs.
In a current report it is offered to provide chemical sample pretreatment by modern sources of spontaneous emission, so- called excilamps. The possible preferences and disadvantages is under discussion. Some experimental results are presented.
A study of the phenol, 4-chlorophenol and 4-bromophenol aqueous solutions, photolysis under UV-irradiation from capacitive discharge KrCl- and XeBr-excilamps at different wavelengths have been undertaken. To specify photolysis efficiency the irradiated solutions have been investigated by spectroscopic methods. To account for obtained results, the quantum-mechanical computation has been invoked.
Phenol and 4-chlorophenol water solutions photolysis under UV-excitation from KrCl-laser and capacitive discharge KrCl- excilamp are presented. The irradiated solutions have been investigated by spectroscopic methods. The comparison of the KrCl-excilamp and KrCl-laser irradiation effects has been realized for the first time.
Power characteristics of four excilamps with short-pulse duration discharge plasma radiation have been investigated experimentally. At mixture pressure of 30 Torr the radiation pulse power density has made at (lambda) approximately 222 nm 0.2 kW/cm2, 0.15 kW/cm2, 0.09 kW/cm2 for I-, H- and L-type excilamps, respectively. The maximal radiation pulse power density was received for modernized I-type excilamp and it has made 0.3 kW/cm2. It has been revealed that pulse radiation output is mostly determined by excilamp voltage value, discharge geometry, value of peaking capacitance, and gas medium density.
Energy, temporal and spectral characteristics of HF-laser pumped by non-chain chemical reaction initiated by radially converging e-beam, planar e-beam and non-self-sustained discharge have been investigated. The major channels of vibrationally excited HF molecules formation have been analysed. It has been confirmed that the high efficiency (~ 10 %) of non-chain HF laser can be reached only by simultaneous atomic and molecular fluorine formation under the action of e-beam and molecular fluorine participation in the inversion releasing process. It is shown that the laser pulse has a complex spectral-temporal structure caused by consecutive generation of the P-lines P2?P1?P3?P4?P5?P6 and overlapping of the rotary lines of the same oscillatory band and separate oscillatory lines during a pulse of radiation. With e-beam pumping of a 30 1 active volume laser, the output energy as high as 115 J and efficiency with respect to e-beam energy deposited into gas mixture up to 8 % were demonstrated. The optimal gas mixture SF6 : H2 =8 : 1 under pressure of 0.45 atm has been obtained. At pressure 1 .1 atm and non-uniform output distribution, total laser energy and efficiency with respect to e-beam energy deposited into gas were found to be up to 200 J and 1 1 %, respectively. Use of e-beam initiated low pressure pulsed discharge for excitation HF molecules leads to increase of radiation energy in 2.8 times. Also investigations on zeolite-based different absorbents influence on energy stability of HF-laser are presented and radiation energy decay after 103 shoots not more than 15-20 % is gained.
The possibility of creation of capacitive discharge excilamps with short pulse duration was studied. There were three types of pulsed excilamps in experiments: cylindrical glow discharge lamp, capacitive discharge lamp, high pressure volume discharge planar lamp with UV-preionization of discharge gap. In capacitive discharge cylindrical KrCl-excilamp, at (lambda) approximately 222 nm the radiation pulse power through the end face of a lamp up to 2.5 kW has been obtained. Powerful radiation pulses of 50 ns in duration were obtained at pulse repetition rate of 1 kHz. In case of high pressure volume discharge at operating pressure of several atmospheres the radiation peak power density values were as much as 5 kW/cm2 at (lambda) approximately 250 nm, and 3.5 kW/cm2 at (lambda) approximately 222 nm and at (lambda) approximately 308 nm. In cylindrical longitudinal excilamp with inner electrodes with Xe- I2 mixture the total pulse power of 75 kW has been obtained. The first experiments with harnessing of inductive energy stores for excilamp excitation have been carried out.
Investigation was made ofthe characteristics ofXeCl (λ ~ 308 nm), KrC1 (λ ~ 222 nm) and Xci (λ ~ 253 nm) capacitive discharge excilamps. High efficiency of exciplex molecules and simple design have been obtained under capacitive HF discharge excitation. Cylindrical excilamps with radiation output through side surface ofthe cylinder and through one or two windows placed on the tube ends have been developed. High UV radiation power and electrical power deposition to fluorescence conversion resulted in efficiencies of up
to 12%. The study of XeC1, KrCl and XeI excilamps have shown, that it is possible to create sealed-off samples with lifetime more than 1000 hours. The stability of output parameters ofthe capacitive discharge excilamps is studied and the mechanism of chlorine losses in low pressure halogencontaimng excilamps made of quartz was determined.
The possibility of creation of capacitive discharge excilamps with short pulse duration was studied. In capacitive discharge cylindrical KrClexcilamp, at λ~222 nm the radiation pulse power up to 2.5 kW was obtained. Powerful radiation pulses 50 ns in duration were obtained at pulse repetition rate of 1 kHz.
Energy, temporal and spectral characteristics of HF-laser pumped by non-chain chemical reaction initiated by radially converging e-beam, planar e-beam and non-self-sustained discharge have been investigated. The major channels of vibrationally excited HF molecules formation have been analyzed. It has been confirmed that the high efficiency of non-chain HF laser can be reached only by simultaneous atomic and molecular fluorine formation under the action of e-beam and molecular fluorine participation in the inversion releasing process. It is shown that the laser pulse has a complex spectral-temporal structure caused by consecutive generation of the P-lines and overlapping of the rotary lines of the same oscillatory band and separate oscillatory lines during a pulse of radiation. With e-beam pumping of a 30 1 active volume laser, the output energy as high as 115 J and efficiency with respect to e-beam energy deposited into gas mixture up to 8 percent were demonstrated. The optimal gas mixture SF6: H2 equals 8:1 under pressure of 0.45 atm has been obtained. At pressure 1.1 atm and non-uniform output distribution, total laser energy and efficiency with respect to e-beam energy deposited into gas were found to be up to 200 J and 11 percent respectively. E-beam initiated low pressure pulsed discharge for excitation HF molecules leads to increase of radiation energy in 2.8 times.
In the recent years, great progress in development of spontaneous UV and VUV sources, radiating on the transitions of excimer and exciplex molecules has been achieved. However, practical use of sealed-off excilamps is limited by low lifetime of gas mixture. In this paper, stability of output parameters of the excilamps pumped by glow, barrier and capacitive discharges is studied and the mechanism of chlorine losses in low pressure halogen containing excilamps made of quartz is determined.
KEYWORDS: Electron beams, Halogens, Diodes, Hydrogen fluoride lasers, Monte Carlo methods, Laser energy, Pulsed laser operation, Mirrors, Gas lasers, Chemical reactions
The results are presented of experimental and theoretical investigations of excitation and generation of the HF laser pumped by nonchain chemical reaction initiated by a beam of electrons as well as of the KrF and XeCl lasers pumped by beams of electrons. The effect of the volume charge field on the distribution of energy over the cross section of a laser cell and of the radiant energy density over the cross section of an output laser beam in mixtures with different concentrations of halogen is analyzed. The output energy density distribution over the beam cross section for lasers excited by the radially convergent beam of electrons and the total pump energy are determined. The pump energy distribution over the laser cell cross section and the total pump energy in various gas mixtures are calculated.
Operating parameters of powerful excilamps with different discharge geometry pumped by glow discharges, high-pressure volume discharge with UV-preionization and barrier discharge are presented. Intense radiation of Ar2*, Kr2*, Xe2*, ArF*, KrBr*, Cl2, KrCl*, KrF*, XeI*, XeBr*, XeCl*, XeF*, I2 and IBR molecules was obtained in rare gas or in rare gas -- F2 (CH3Br, Cl2, HCl, I2, NF3) mixtures. Excilamps with high spatial uniformity of the output, narrow emission line and high gas life-time were developed. It was shown that efficiency of luminescence of exciplex molecules KrCl* of about 30% can be obtained in high- voltage glow discharge and positive column of glow discharge. Output at (lambda) approximately 222 and 308 nm up to 200 W from single excilamp and 500 W from three excilamps operating in parallel was demonstrated. It was shown that the efficiency of barrier discharge excilamps pumped by sinusoidal pulses several tens microseconds in duration can be sufficiently improved.
The results of the experimental study of UV and IR lasers pumped by various methods are presented. The accelerators with radially converging or planar e-beams pumping gas mixtures at pressures up to 3 atm and self-sustained discharges were used. The highest laser radiation energies in the UV up to 2 kJ have been obtained at (lambda) equals 308 nm. Output of 100 J at (lambda) equals 1.73 micrometer in Ar-Xe mixture and 50 J at (lambda) equals 2.03 micrometer in He-Ar-Xe mixture was obtained from the e-beam laser with active volume of 600 l. Output energies of 110 J at (lambda) equals 308 nm and 90 J at (lambda) approximately 250 nm, respectively, were achieved in compact high-power e-beam laser with chamber of 20 cm in diameter and 30 l active volume. This e-beam geometry was shown to be very promising for excitation of non-chain HF- laser media. HF-laser efficiency with respect to deposited energy as high as approximately 10% and energy up to 200 J at (lambda) approximately 2.8 micrometer were demonstrated. Amplification of XeCl-laser beam from master oscillators and amplifiers under conditions of strong amplified spontaneous emission is considered. Investigations of CO2 laser excited by e-beam controlled discharge and e-beam ignited discharge were performed. The highest laser output in the IR of 3 kJ have been obtained at (lambda) equals 10.6 micrometer.
Excilamps with different tube geometry pumped by continuous glow and barrier discharges are described. It was shown that the efficiency of barrier discharge excilamps pumped by sinusoidal pulses with duration of several tens microseconds can be sufficiently improved. The range of UV wavelength emitted by glow discharge excilamps was extended. Intense radiation of KrBr*, XeBr*, I2* and IBr* molecules was obtained in rare gas - CH3Br (I2) mixtures pumped by glow discharge KrCl* excilamp ((lambda) approximately 222 nm) with output power up to 200 W was developed. UV power of 500 W from three KrCl* excilamps operating in parallel was demonstrated. Efficiency of exciplex molecule luminescence in the positive column of glow discharge was found to be as high as approximately 30%.
KEYWORDS: Hydrogen fluoride lasers, Energy efficiency, Pulsed laser operation, Laser energy, Electron beams, Chemical lasers, Switches, Chemical reactions, Diodes, Argon
Non-chain HF lasers initiated by electric discharge and e- beam are described. A generator with an inductive energy storage and semiconducting opening switch was used for discharge formation. The generator was shown to be very promising for development of efficient discharge HF lasers with high output energy. It produces very uniform discharge in SF6-H2(C3H8) gas mixtures at elevated pressure and increases its stability. Discharge HF laser efficiency up to 5.5% was demonstrated. Radially convergent e-beam was used to pump 30 1 HF laser. Optimal gas mixture SF6:H2 equals 8:1 under pressure of 0.45 atm was chosen to provide no more than two-fold specific output power variations across the laser beam area. Output energy as high as 115 J and efficiency with respect to e-beam energy deposited into gas mixture up to 7-8% were demonstrated. Total laser energy and efficiency with respect to deposited energy at pressure of 1.1 atm when the output distribution was non-uniform were found to be up to 200 J and 11%, respectively. The `jump' of pressure in SF6-H2 mixture at the instance of e-beam injection was found to be lower than that in excimer laser mixtures due to SF6 high density. This simplifies creation of wide-aperture e- beam HF-lasers. We expect that the use of pulse generators and wide-aperture laser setup available at HCEI enable us to develop 1 kJ non-chain HF laser initiated either by self- sustained discharge or e-beam.
Design and operating parameters of powerful KrCl((lambda) approximately 222nm), XeCl((lambda) approximately 308nm) excilamps with different discharge geometry pumped by continuous glow discharges along with Ar2((lambda) approximately 126nm) and Kr2((lambda) approximately 146nm) excilamps pumped by barrier discharge are presented. Excilamps with high spatial uniformity of the output and gas lifetime up to 100 hours were developed. It was shown that efficiency of luminescence of exciplex molecules of about 30 percent can be obtained in high-voltage glow discharge and positive column of glow discharge. Output at (lambda) approximately 222nm up to 200 W from single excilamp and 500 W from three excilamps, operated in parallel, was demonstrated.
Results of the experimental study of powerful lasers pumped by a radially convergent electron beam and powerful excilamps are presented. Laser radiation energies of 110, 90, 100, and 50 have been obtained at (lambda) equals 308, 249, 1730 and 2030 nm, respectively. Excilamp average power of 130 W have been obtained at (lambda) approximately 222 and 208 nm, the efficiency was up to 14%.
The results of an experimental study of coaxial exciplex lamps pumped by various types of discharge (the longitudinal discharge, barrier discharge, or continuous glow discharge) are presented. The mixture compositions and pressures as well as the pumping pulse parameters have been optimized for the production of radiation with (lambda) equals 350, 308, 249, 222, and 193 nm. Exciplex lamps with a radiating surface area of 570, 840 and 1300 cm2 have been created. The average radiation power achieved for (lambda) equals 222 nm is up to 4 W and for (lambda) approximately 308 and 350 nm is approximately 10 W. The possibility of an inductive energy store with a semiconductor opening switch being used for pumping a longitudinal-discharge-based exciplex lamp has been demonstrated.
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.