Alexei N. Panchenko

Compact solid-State switched pulsed power and its applications

Power semiconductor devices, such as insulated-gate bipolar transistors, metal-oxide-semiconductor field-effect transistors, and static-induction thyristors, are used in different kinds of pulsed power generators developed for different applications. In addition, the semiconductor opening switch is found to have very effective applications in pulsed power generation by inductive energy storage. Semiconductor switches have greatly extended the scales of pulsed power parameters, especially in repetition rate and lifetime. They have also enabled new areas of pulsed power applications, such as accelerators, flue-gas treatment, and gas lasers.

Long-Pulse-Discharge XeF and KrF Lasers Pumped by a Generator with Inductive Energy Storage

The development of long-pulse-discharge XeF and KrF excimer lasers pumped by a generator with inductive energy storage and a semiconductor opening switch is reported. It is shown that the use of the inductive storage element enables sufficiently improved discharge stability and expands the laser pulse duration. The laser output pulses with a full-width at half maximum (FWHM) duration of 60 ns were obtained both in Ne–Xe–NF3 and Ne–Kr–F2 gas mixtures, corresponding to the laser specific output of 2.5 J/l and the intrinsic efficiency of over 1%.

Improvement of output parameters of glow discharge UV excilamps

Abstract KrCl* (λ∼222 nm) and XeCl* (λ∼308 nm) excilamps pumped by continuous glow discharges in different discharge geometries are studied. It was shown that the efficiency of rare gas halide molecule fluorescence over 25% can be obtained in a high-voltage glow discharge and positive column of a normal glow discharge. Coaxial XeCl* and KrCl* excilamps with UV output up to 200 W are developed.

Discharge lasers pumped by generators with inductive energy storage

Generators with inductive energy storage units and semiconductor opening switches designed for laser excitation are described. Operation of the generators on a gas-discharge load is considered and possible excitation modes are discussed. A longitudinal N/sub 2/ laser, transverse discharge nonchain HF laser, and CO/sub 2/ laser are developed based on this pumping technique. Output energies of 0.6 J and 3.2 J and laser efficiencies of 5.5% and over 17% were demonstrated on H/sub 2/-SF/sub 6/ and He-CO/sub 2/-N/sub 2/ gas mixtures, respectively. High laser parameters obtained demonstrate the considerable promise of such inductive generators for pumping different gas lasers.

Excilamp producing up to 130 W of output power and possibility of its applications

Results of an experimental study of a coaxial exciplex lamp pumped by glow discharge are presented. An average power of radiation in the wavelength region below 250 nm and as high as about 130 W has been achieved. Efficiency of the excilamp operation based on input power of 14% was demonstrated. The possibility of applications of this excilamp is discussed.

Glow discharge in low-pressure excilamps

This paper presents a review of the principal publications devoted to the study of the spontaneous radiation sources operating in the uv region and discusses the properties of a low-pressure glow discharge in binary mixtures of inert gases with halides. It has been demonstrated that for variation of the excitation parameters over a wide range more than 10% emission efficiencies are realized for exciplex molecules and thatXeCl* andKrCl* molecules are formed in the main by the harpoon reaction. The current-voltage characteristics of glow discharges in cylindrical, coaxial, and planar excilamps and the parameters of the radiation ofXeCl*,KrCl*, andXeF* molecules generated on excitation of inert-gas-halide mixtures by normal and high-voltage glow discharges are presented. It is pointed out that low-pressure glow-discharge excilamps enable one to use simple power supplies.

Capacitive Discharge Excilamps

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.

Efficient e-beam and discharge initiated nonchain HF(DF) lasers

The spectral and amplitude-temporal parameters of HF (DF) lasers pumped by nonchain chemical reactions initiated by radially convergent or planar e-beams and self-sustained discharge were studied. Intrinsic efficiency of the HF lasers up to ∼10% was obtained for both excitation methods. It was shown that the high efficiency of an e-beam-initiated HF laser may be attained as a result of the simultaneous formation of atomic and molecular fluorine and of the participation of F 2 in population inversion. A laser pulse has a complex profile caused by the successive generation of P-lines and the overlap during the radiation pulse of both the rotational lines of the same vibration band and of individual vibration bands. Experimental conditions providing high intrinsic efficiency of a discharge nonchain HF (DF) laser are determined. Intrinsic efficiency of HF and DF lasers up to η in ∼ 10% and 7%, respectively, is obtained using excitation by inductive and LC generators in the SF 6 -H 2 (D 2 ) mixtures. High discharge uniformity obtained with the use of special shaped electrodes along with uniform UV preionization is a key parameter for improving the intrinsic efficiency of discharge HF (DF) lasers. It was found that in this excitation condition, output spectra of the HF laser significantly widen and cascade laser action on some rotational lines of the vibrational transitions of HF molecules ν(3–2) → ν(2–1) → ν(1–0) is observed. This can explain the high intrinsic efficiency obtained. Specific output of the discharge HF laser over 8 J/L (140 J/L×atm) and total laser efficiency η t ∼ 4.5% were achieved. For the discharge DF laser, specific output and total efficiency were as high as 6.5 J/L and 3.2%, respectively.

Ultraviolet and infrared lasers with high efficiency

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.

High-power Raman conversion of a discharge XeCl-laser

Abstract Raman conversion of high-power discharge XeCl-laser radiation in hydrogen has been carried out. Simultaneous generation of four Stokes and two anti-Stokes outputs has been observed, every radiation line consisting of two close components, which correspond to the double structure of the pumping line.