RESEACH FIELDS

PULSED POWER AND PRODUCTION OF INTENSE ELECTRON AND ION BEAMS
PRODUCTION OF HIGH-POWER X-RAYS, OPTICAL RADIATION, MICROWAVES
STUDY OF HIGH-CURRENT VACUUM AND GAS DISCHARGE PLASMAS
INTERACTION OF ELECTRONS, IONS, AND ELECTROMAGNETIC RADIATION WITH MATTER

PULSED POWER ENGINEERING

Different high-power electric pulse generation techniques are being developed, including conventional Marx pulse voltage generators (GAMMA) and transformer charged water pulsed power forming line generators (SNOP). The new "Marx generator - inductive energy storage - plasma opening switch - load" concept has been framed to develop high-power microsecond pulsed generator. The concept has been embodied in a GIT family of terawatt power installations.

The devices designed are used in experiments on high-power E-beam and Z-pinching to produce high-temperature dense plasma and high-power X-radiation fluxes.

Basic Performance Characteristics of Pulsed Terawatt Power Installations:
	GAMMA	GIT-4	GIT-8	GIT-12	GIT-16 (project)	SNOP-3	MIG	SGM
Voltage, MV	2	2	2	2	~2	1	6	1
Stored energy, MJ	1	2	3.3	5	6.8	0.2	0.35	0.2
load current, MA	0.3	2	4.2	6.2	7.6	1.5	2.5	1.5

Z-PINCH STUDY

One of the possible extreme action on the matter is the electrodynamic implosion of a light annular shell (liner) in responce to electric current of a few millions ampere. Recently our researchers have proposed and carried out a new methode of the liner form stabilization. It allows to rise the uniform compression ratio of implosing liner more than an order degree.

Investigation of a high-density hot plasma induced by Z-pinch allows to know more detailed data about the elementary processes cross-sections. They are used for engineering development of the inertial controlled thermonuclear fusion installations, the X-ray lasers, and the pulsed neutron sourses.

The effect of "the magnetic field freezing-in plasma" makes possible the pulsed magnetic strength up to a few millions oersted. In processing of the liner implosion a high-density and high-temperature plasma have been formed. It is a power source of the soft X-radiation which may be used extensively in the different applications.

PULSED HIGH DENSITY GAS LASERS AND SPONTANEOUS ULTRAVIOLET RADIATION SOURCES

Studies of gas lasers were started at the IHCE in 1969. During the years passed, high-skilled scientific staff has been formed, unique laser systems have been developed, new active media have been suggested and realized and new lasing wavelengths were obtained.

Two laboratories (the Laboratory of Optical Radiation, LOI, and the Laboratory of Gas Lasers, LGL) which staff includes four doctors of sciences and more than 10 candidates of sciences are pursuing investigations in this area.

The investigations are carried out on the basis of IHCE advancements in pulsed power and physics of high-current-density gas discharges.

Areas of study:

high-power discharge-pumped and e-beam-pumped lasers and laser systems on dense gases (XeCl, KrCl, KrF, CO2, Ar-Xe, SF6-H2, N2 and other);
efficient discharge and e-beam pumped sources of spontaneous radiation operating in various spectral regions;
experimental and theoretical studies of physical processes occuring in active and optical media and numerical simulation of pumping processes and output laser parameters;

Results of research:

High-power wide-aperture e-beam-pumped and discharge-pumped lasers on various gas mixtures have been created and their output parameters have been studied.

Output energy and a laser energy efficiency of 100 J and 2%, 90 J and ~4%, 2000 J and ~4%, 200 J and ~10%, 3000 J and ~25% were achieved on atomic transitions of Xe (l=1.73 m m), transitions of KrF* (l=248 nm), XeCI* (l=308 nm), HF (l=2.8 mm, non-chain chemical laser) and CO₂ (l=10.6 mm) molecules, respectively.

Laser systems based on discharge-pumped XeCI* lasers producing high-quality radiation beams of pulse energy up to 200 mJ have been developed. In these systems injection mode-locking, amplification, wave front inversion, pulse compression, wavelength tuning, and transformation into UV and visible spectral ranges are realised. Laser beams of pulse duration of 1, 10, 100 and 300 ns showing a diffraction and having the spectral line width of 0.1 - 100 pm have been produced.

A laser amplifying system operating at l=308 nm,has been developed and built wich consist of a discharge master oscillator, a pre-amplifier and a wide-aperture amplifier with two-side e-beam excitation.

The pre-amplifier with X-ray preionization and an active volume of V=7xl1x80cm³ produces an output energy of up to 15 J in a 100 ns pulse.

The amplifier being equipped with an optimized optical cavity produces an output energy of up to 200 J in a 300 ns pulse. The laser system can produce low-divergence optical beams with an energy of several tens of joules. An energy density of over 100 kJ/cm2 has been achieved when the beams were focused on a target.

Cylindrical, coaxial and planar excilamps excited by CW glow and pulsed barrier discharges and emitting in the VUV and UV spectra with an average power of up to 500 W and an efficiency up to 30% have been created.

A computer code has been developed which makes it possible to simulate physical processes occurring in gas mixtures of rare gases with halogen containing molecules, to optimize the pumping parameters, and to predict the output parameters of XeCI* lasers.

The areas of stable and unstable operation of space utilised for pumping gas lasers determined; and the mechanism for the development of discharge instabilities has been. The methods for improving the discharge plasma homogeneity and forincreasing the discharge operating time in the spatial stage of volume discharge have been suggested.

Pulse generators with inductive energy storage for pumping gas lasers (HF, CO2, XeCI*, N2) have been developed and studied. The features and advantages of these pumping systems have been determined.

Wide-aperture X-ray-ionized discharge XeCI* lasers with an output of up to 15 J and an efficiency of up to 4% have been created.

A series of prototypes of exciplex, CO₂ and N₂ lasers and excilamps have been developed.

HIGH POWER RELATIVISTIC MICROWAVE ELECTRONICS

Work is now underway towards generation and amplification of microwave radiation due to interaction between relativistic E-beams and electrodynamic slow-wave structures. The high-power pulse microwave generators have been designed unrivalled both for power and efficiency. Prototypes of microwave pulsed and repetitively pulsed oscillators developed at IHCE exhibit unexcelled performance.

Single mode microwave oscillators:
Wavelength, cm	3	3	0.8	0.8
Power, GW	3	0.5	0.1	0.5
Pulse repetition rate, pps	0.1	100	0.1	0.1

Multiwave oscillators with supersized electrodynamics structures:
Wavelength, cm	0,5	0,65	0,97	1,13	3,2
Power, GW	1	2,8	3	4,5	15
Pulse duration, ns	700	700	70	200	60

VACUUM AND GAS DISCHARGE

Basic research of gas and vacuum discharges is one of the traditional Institute science directions. An electric discharge plasma is used in the different devices which designed in the Institute: effective electron and ion

effective electron and ion sources
current switches
gas lasers
plasma chemical reactors

The unique high-qualitative group of speicialists on the discharge phenomena have been formed. The most modern research equipment is used.

Within the last few years attention of the our scientists have been focussed on a new conception of the electric current transition in gas and vacuum discharge. It appears to have considerable promise both the explanation a number of discharge phenomena and the development of an interesting theory.

INTERACTION OF ELECTRONS, IONS,
AND ELECTROMAGNETIC RADIATION WITH MATTER

In parallel with creation of powerful corpuscular and electromagnetic radiation sources, investigations on interaction of radiation with materials are well-established at the Institute. In this direction, at the IHCE, a cycle of fundamental studies on influence of dense electron beams interaction with solid targets has been carried out.

The following results obtained in the course of those studies can be presented:

An important modification for the half-infinite medium model of the existent theory of amorphous and polycrystalline solid matters atomization by ion bombardment has been done. In the well-known analytical theory of atomization (Sigmund theory), in the attempt to simplify the problem, a half-infinite medium model is being implied, that leads to a row of known artifacts arisen in the data and common distortion of solutions. At the IHCE, a new method of attack has been suggested which at preserving all positive moments of Sigmund theory takes into account vacant surface presence more correctly. It has been shown that findings of general characteristics of atomization process can be reduced to solving one integral equation, i.e. the self-functions of such an equation and that conjugated to it determine the atomization coefficient dependence versus ion incidence angle and differential distribution of the particles atomized in angles of escape, and behavior of the self-notions defines dependence of atomization coefficient on the energy of ion and scattered particles distribution versus energy.
Theoretical study cycle on threshold energy effects in the problem of impulse absorption at ion bombardment of the solid matter has been completed. It is shown that the conventional methods to solve kinetic equation used in order to find spatial distribution of the impulse absorbed taking into account the threshold effects in many cases give such solutions which are rather different from the true ones. A new method for calculation of absorbed impulse distribution has been suggested and analytical formulas have been obtained which describe the dependence of distribution on near surface threshold energy rather correctly from physics point of view, that is very important to know while constructing an adequate theory on solid matters scattering by ion bombardment effect. (For those works, senior researcher of the Laboratory of Theoretical Physics Ph.D. Lev G. Glazov was awarded with Medal of the Russian Academy of Sciences for research in the field of General Physics and Astronomy in 2000).
For the first time, fine structure of antisymmetrical acoustic modes (flexural type waves) excited in thin samples of various classes of solid matters by dense pulsed electron beams was experimentally observed and studied by laser interferometry method. Based on correlation of thermal acoustic fields theoretical simulations with the experimental results, the new efficient method for determination of elastic rates and Gruneizen coefficients of solid matters, compositional including, has been suggested.

The Institute is deeply involved in experimental research on modification of material properties by charged particle beams and plasma flux. Peculiar feature of such research is that the results obtained can find very wide practical use. Such research as a rule results in development of new promising radiation technologies. Thus, Dr. P.M. Shchanin, Dr. N.N. Koval and colleagues have developed unique ion-plasma technology of composite coatings deposition on the surface of constructional steels, and Dr. D.I. Proskurovsky, Dr. V.P. Rotshtein and colleagues have conducted investigations on low-energy high-current electron beams (LEHCEB) influence on metals, which showed that such a treatment allows to smooth and clean surface of a material, to increase corrosion resistance of hard alloy cutting tools by 3-4 times, to increase corrosion resistance of a row of metallic materials about 100 times and to create high strength alloys.

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