Experimental and theoretical studies of effective power supplies for plasma loads of the pulsed plasma accelerator type are presented. Increasing the power supply of plasma loads while maintaining the conditions of their matched operation and, as a result, increassing the total energy input into the plasma formations of a pulsed plasma accelerator, is an urgent research task. The comparative characteristics of the accelerator operation when using power sources based on capacitive storages and spiral-type explosive magnetic generators with a current pulse generation device are presented. A technique that allows working out the optimal operating modes of a pulsed plasma accelerator by conducting a series of preliminary experiments with high-voltage capacitive storages and calculations based on semiempirical models is described in order to proceed to explosive experiments with a generator in the future. The aim of this approach is to matched the output parameters of explosive magnetic generators with the dynamics of plasma motion in the accelerator. A series of laboratory experiments on the efficient transfer of energy from explosive magnetic generators to a pulsed plasma accelerator at current levels in the plasma load of over 3.5 MA is presented.

Explosive-magnetic generators (EMGs) unlike capacitive storages (CSs), as a rule, have growing power. The effective operation of pulsed plasma loads, such as pulsed plasma accelerators (PPAs), plasma foci, plasma breakers, etc, can be provided at realization of the mentioned advantage of EMG as a power source. A technique of laboratory experiments with PPA is presented in this paper. The experiments with PPA powered by CS precede the explosive experiment with EMG. The dependencies of the load operation modes on the start parameters are determined by the analysis of the experimental data. They included the dynamics of the inductance and the position of the current shell inside the PPA. The technique allows reducing the number of expensive explosive experiments and supplements the database of nonlinear dependencies of the load parameters under various amplitudes of the current pulse that is important for mathematical modeling. The technique based on experiments together with the estimations allowed solving the problem of matching of non-linear loads type PPA with EMG. Thus, the productivity of experiments with EMG increases greatly. The developed technique can be adapted to a wide class of nonlinear loads.

In this paper, we consider the model of engineering calculation for the matching of the explosive-magnetic generators (EMG) and pulsed plasma accelerator (PPA) at amplitudes of currents reaching 2.5 MA. The main features of the model are taking into account the dynamics of change in the inductance of PPA and the using of the concentrated mass approximation for the current shell. The taken assumptions were checked by experimental data on real PPA powered by EMG. It is shown that the built model has sufficient accuracy for preliminary calculations for design and installation of such technique.

A model of a high-power current pulse generator based on an explosive magneto-cumulative generator with electrically exploded copper-conductor breakers capable of generating a powerful electromagnetic pulse impact in a limited space of 16 m3 is described. An experimental setup has been constructed that contains tools for diagnostics of the parameters of the electromagnetic pulse impact. The results of experimental studies in the form of measured pulse values of the current in and voltage across the load are presented. An electric field intensity of ~0.5 MW/m has been achieved. The rate of the increase in the magnetic field density reached 0.12 T/μs.

Experimental models of microsecond duration powerful generators of current pulses on the basis of explosive magnetic generators and voltage impulse generator have been developed for the electromagnetic pulse effects on energy facilities to verify their stability. Exacerbation of voltage pulse carried out through the use of electro explosive current interrupter made of copper wires with diameters of 80 and 120 μm. Experimental results of these models investigation are represented. Voltage fronts about 100 ns and the electric field strength of 800 kV/m are registered.

This paper demonstrates the practical application of the explosive magnetic generator (EMG) as a source of high-power pulses for mobile testing complex EMG (MTC EMG). Hereinafter, the name of explosion generator is used on a par with the name of helical explosion-magnetic generator. Laboratory sample was brought to a level of modern complex, which is able to solve the applied problems in the grid power systems. MTC EMG is able to reproduce the output currents, similar to lightning currents, so it can be used to simulate a pulse impact on the energy system. The report contains: a description of the basic physical and electrical solutions underlying the construction of the generator of lightning currents, output characteristics, and results of MTC EMG field testing. Optimization of schemes including the different impedances of EMG and inductive resistive load with the use of transformer coupling allowed the effective energy transfer from the EMG to the load. Pulse currents and voltages on the load and also the response of soil between ground loops under the action of lightning currents, generated by MTC EMG, were registered in the testing. Autonomous measuring instruments included in the complex were protected from electromagnetic interference.

The report presents the results of the development and field testing of a mobile test facility based on a helical magnetic cumulative generator (MCGTF). The system is designed for full-scale modeling of lightning currents to study the safety of power plants of any type, including nuclear power plants. Advanced technologies of high-energy physics for solving both engineering and applied problems underlie this pilot project. The energy from the magnetic cumulative generator (MCG) is transferred to a high-impedance load with high efficiency of more than 50% using pulse transformer coupling. Modeling of the dynamics of the MEG that operates in a circuit with lumped parameters allows one to apply the law of inductance output during operation of the MCG, thus providing the required front of the current pulse in the load without using any switches. The results of field testing of the MCGTF are presented for both the ground loop and the model load. The ground loop generates a load resistance of 2–4 Ω. In the tests, the ohmic resistance of the model load is 10 Ω. It is shown that the current pulse parameters recorded in the resistive-inductive load are close to the calculated values.

A mobile testing complex prototype on the basis of an explosive magnetic generator (MTC EMG) is developed to simulate a lightning current pulse. The main element of this complex is a current pulse generator comprising a EMG with a pulse transformer for energy release into the load. The electric chain of the MTC EMG is theoretically analyzed taking into consideration energy losses in active resistances in the primary circuit of the transformer and the inductive-resistive nature of the load, which resulted in the minimization of energy losses in the primary circuit depending on the electric chain parameters. It was found that, if the energy losses are minimized, the efficiency of transferring the EMG energy into the load exceeds 50%. As a result of the field tests of the MTC EMG, its basic characteristics were determined and the waveforms of the current pulses and voltages in the load were obtained. It is shown that the results of the mathematical simulation of current pulses in the load are in good agreement with the experimental data.

The results of experimental study of two-stage explosive magnetic generator with magnetic flux trapping (EMG MFT) and opening switch in the primary circuit are presented. It was shown that this type of generator demands less than 3 μs to achieve the maximum of current derivative (30 - 100 kA/μs) and maximum of the output voltage. The generators with such parameters are necessary for a number of loads, for example, for the plasma accelerator with growing inductance. At the same time the problem of emerging surge in the secondary circuit of the generator was solved through the introduction of a separate single-turn closing switch with high breakdown voltage. The comparison of the performance of two types of EMG MFT is described. The first type generator was with opening switch in the primary circuit, the second one was without breaking of the primary circuit. They had approximately the same initial input parameters (inductances of the primary and the secondary circuits and the coupling coefficients) and the same inductance of model load - 1.16 μH.

This paper describes in optical adaptive system with closed feedback for correcting the radiation of powerful femtosecond lasers. The characteristics of the clements of the system are briefly given; these include a defomable bimorph mirror and a Shack-Hartmann wave-front sensor. An algorithm based oil the principle of phase matching is presented for the operation of the system. Examples are given of the use of this system to enhance the radiation-focusing quality of lasers. For example, the use of two correctors in the ATLAS Ti:sapphire laser complex made it possible to increase the radiation-power density by more than a factor of 50. (C) 2004 Optical Society of America.

The two-beam interferometry and luminescence methods are used to measure the spatial and time characteristics of fluctuations of subsonic turbulent flow of molecular gas in a strong oscillatory nonequilibrium state. A gas discharge tube of a CO2 laser with fast axial pumping is the object under treatment. The turbulent component of fluctuation of the gas density is selected by the frequency selection of the recorded signal. The spectrum of the density fluctuations and the dependence of the amplitude of pulsations of small-scale nonuniformities on the energy input is determined. Further, the degree of cross correlation between fluctuations of the phase incidence of the wave front in turbulent flow is measured under nonequilibrium conditions of electric discharge.

Theoretical and experimental investigations showed that a diverging thermal gas lens, which forms in high-power industrial lasers with fast axial flow of the active medium, can influence the diffraction losses in the laser oscillator and the beam parameters, The nonlinear optical properties of the lens, demonstrated by the dependence of its optical power on the intensity of the output radiation, are described,

Influence of laser mixture relaxing beyond the discharge region upon the continuous wave CO2 laser radiation has been investigated. It has been shown that beyond the discharge region, the resonance nonlinear absorption of radiation can originate in the discharge-free area within the certain range of laser parameters. The absorption dependence on radiation intensity is complicated in its nature and involves the influence of saturation effect, as well as the variation of excited molecules relaxation length in the radiation field. The values of output mirror reflection factor and the geometry parameters have been determined whereby the laser efficiency is at its maximum with regard to extra amplification.

A study is reported of the influence of a laser mixture relaxing outside the discharge zone on the parameters of the radiation emitted by a cw CO2 laser. It is shown that resonant nonlinear absorption of the radiation may appear, in a certain range of the laser parameters, behind the discharge zone. The dependence of such absorption on the radiation intensity is complex because of saturation and also because of a change in the relaxation length of excited molecules in the radiation field. The reflection coefficient of the exit mirror and its geometric parameters ensuring the maximum laser efficiency are determined, taking account of the additional amplification in the relaxing laser mixture.

Experimental and theoretical investigations were made of turbulent diffusion in an industrial CO2 laser with crossed electrodes. The particle diffusion reduced considerably the spatial inhomogeneity of the gain. The results obtained were used to propose a new method for the determination of the turbulent diffusion coefficient.

A mathematical model is proposed for self-consistent calculation of nonlinear equations of heat and balance for charged particles in the positive column of glow discharge in lasers with diffusion cooling. The electron density distributions calculated according to this model make it possible to refine the value of total amplification corresponding to the threshold of laser generation.