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The implosion of combined loads consisting of an outer wire (fiber) array and inner cylindrical target was studied experimentally at the Angara-5-1 facility (3.5 MA, 100 ns) at currents of up to 3.5 MA. The experiments were carried out with 12- and 20-mm-diameter outer arrays made of 15-μm-diameter aluminum wires, composite arrays made of aluminum wires and 25-μm-diameter kapron fibers, and arrays made of kapron fibers with a 1-μm-thick aluminum coating. The number of wires varied from 10 to 40. The targets were made of agar-agar or low-density deuterated polyethylene. The parameters of the Z-pinch plasma were determined using the Angara-5-1 diagnostic complex, which included optical streak cameras, X-ray frame cameras, X-ray detectors, X-ray pinhole cameras, neutron detectors, and a mica-crystal X-ray spectrograph. It is established that the plasma compression dynamics and the formation of local plasma structures generating neutrons depend on the load configuration: the array diameter, the number of wires (fibers), and the diameter and density of the target. The most efficient compression and the highest plasma parameters (the compression ratio and plasma temperature), as well as the highest neutron yield, were achieved in experiments with 12-mm-diameter aluminum wire arrays inside which a 1-mm-diameter deuterated target with a mass density of 0.3 g/cm3 was installed As a result of collision of the bulk of the array mass with the inner target, a compact pinch with a diameter of ≈0.5 mm forms. The pinch formation is accompanied by the generation of a soft X-ray pulse. The development of MHD instabilities in the pinch plasma results in the formation of multiple hot spots (HSs) on the pinch axis with a typical size of 200–300 μm and an electron temperature of 0.4–0.7 keV. The HS formation is accompanied by emission of neutrons with a mean energy of 2.7 ± 0.2 MeV. The maximum neutron yield achieved in these experiments was 2.6 × 1010 neutrons/shot.

Results from experimental studies on the implosion of arrays made of kapron fibers coated with different metals (Al, In, Sn, and Bi) are presented. It is shown that the power, total energy, and spectrum of radiation emitted by the imploding array depend on the number of metallized fibers and the mass of the metal layer deposited on them but are independent of the metal characteristics (density, atomic number, etc.). Analysis of frame X-ray images shows that the Z-pinches formed in the implosion of metallized kapron fiber arrays are more stable than those formed in wire arrays and that MHD perturbations in them develop at a slower growth rate. Due to the lower rate of plasma production from kapron fibers, the plasma formed at the periphery of the array forms a layer that plays the role of a hohlraum wall partially trapping soft X-ray emission of the Z-pinch formed in the implosion of the material of the deposited metal layer. The closure of the anode aperture doubles the energy of radiation emitted in the radial direction.

Для практического применения Z-пинчей в качестве источников мягкого рентгеновского излучения, а также для понимания физических процессов и явлений, происходящих в горячей плазме, удерживаемой магнитным полем собственного тока, возникает необходимость определить размеры излучающей области Z-пинча, а также его основные макроскопические параметры, такие, как концентрация ионов и электронов, давление и температура плазмы. В работе определялись параметры Z-пинчей, получаемых при имплозии многопроволочных вольфрамовых сборок с начальным диаметром 12 мм и погонной массой 220 мкг/см на сильноточном электрическом генераторе «Ангара-5-1». Cредние поперечный и продольный размеры излучающей области сильноточного Z-пинча на финальной стадии его сжатия в диапазоне энергии квантов мягкого рентгеновского излучения 0,05—2,5 кэВ оказались равными 1,2 ± 0,4 и 12,0 ± 0,7 мм соотвeтственно. На основе измеренных размеров излучающей области, значения скорости сжатия оболочки, мощности и длительности излучения Z-пинча были оценены его плотность и газокинетическое давление (на финальной стадии сжатия), которые оказались равными 210 г/см, 1 Мбар соответственно. По произведённым оценкам значения плотности пинча превышают плотность ускоренной оболочки в 20—30 раз. Значения, полученные в работе, соответствуют физике устойчивого сжатия пинча. Полученные изображения Z-пинча показывают, что центральная область Z-пинча состоит в основном из горячей плазмы, а вокруг неё присутствует холодное «плазменное гало», интенсивность излучения которого значительно ниже, чем в центральной области.

Results are presented from measurements of the anisotropy of energy losses in high-current Z-pinches produced by the implosion of wire arrays at the ANGARA-5-1 facility at load currents of up to 4MA. The energy losses were measured in the radial direction and along the pinch axis from the anode side. The main diagnostics were time-integrated thermocouple calorimeters, nanosecond X-ray diodes (XRDs) with different filters, and a foil radiation calorimeter with a time resolution of 2 μs. The azimuthal anisotropy of energy losses was measured for different wire array configurations and different shapes of the high-voltage electrode. The presence of strong initial azimuthal inhomogeneity of the wire mass distribution (sectioned arrays), as well as the use of conical electrodes instead of plane ones, does not increase the azimuthal inhomogeneity of the total energy losses. For cylindrical wire arrays, energy losses in the radial direction are compared with those along the pinch axis. According to XRD and calorimetric measurements, the radiation yield per unit solid angle along the pinch axis is two to three times lower than that in the radial direction. In the axial direction, the energy flux density of the expanding plasma is two to three times lower than the radiation intensity. The measured radiation yield across the pinch is 2.5–5 kJ/sr, while that along the pinch axis is 1–2 kJ/sr. The results obtained by means of XRDs agree to within measurement errors with those obtained using the radiation calorimeter. It is found that the energy per unit solid angle carried by the expanding plasma in the radial direction does not exceed 10% of the soft X-ray yield. Analysis of the structure of time-integrated pinhole images and signals from the radial and axial XRDs shows that radiation emitted in the radial direction from the hot central region of the pinch is partially screened by the less dense surrounding plasma halo, whereas radiation emitted in the axial direction is a superposition of the emissions from the hot dense central region of the pinch and the colder less dense peripheral plasma.

Results are presented from measurements of the radiation spectra of the Z-pinch tungsten plasma produced during the implosion of cylindrical wire arrays with a linear mass of 200–400 μg/cm and an initial diameter of 12–20 mm at a current of ∼3 MA in the experiments performed at the Angara-5-1 facility. The radiation spectra in the photon energy range of 50–900 eV were recorded on a UF-4 X-ray film by using a spectrograph with a transmission grating. The radiation spectrum in the photon energy range of 1–3 keV was recorded using a crystalline panoramic spectrograph. A curtain shutter was used to protect the transmission grating from fast microparticles produced due to the erosion of high-voltage electrodes. The total radiation yield was measured with a thermocouple calorimeter. It is shown that most of the tungsten plasma radiation energy is emitted in the photon energy range of 80–300 eV. Measurements of the spectral intensity of pinch radiation with a spatial resolution along the pinch radius showed that the effective transverse diameter of the pinch did not exceed 2 mm, which agrees with independent current measurements of the pinch size. The results of measurements of the spectral intensity of pinch radiation were compared with calculations per-formed under the assumption of a stationary homogeneous plasma.

Results are presented from experimental studies of the spatial distribution of the density of matter in the central part of the discharge gap and the formation of the temporal profile of the X-ray power in the course of implosion of quasi-spherical wire arrays at discharge currents of up to 4 MA. The spatial distribution of the X-ray intensity in the central part of the discharge gap and the temporal profile of the X-ray power are used as implosion characteristics of quasi-spherical wire arrays. The quasi-spherical arrays were formed by the radial stretching of unstrained wires of initially cylindrical and conical wire arrays under the action of the electrostatic field. The temporal profile of the output X-ray pulse in the photon energy range of 0.1–1 keV is shown to depend on both the geometrical parameters of the quasi-spherical array and the longitudinal distribution of its mass. It is found that a 40% increase in the wire mass due to deposition of an additional mass in the equatorial region of a quasi-spherical array leads to a 15% increase in the average current radius of the pinch and a 30% decrease in the X-ray yield. Experiments with quasi-spherical arrays made of kapron fibers with deposited Al and Bi conducting layers were also carried out. It is demonstrated that application of such arrays makes it possible to control the profile and duration of the generated X-ray pulse by varying the mass, material, and location of the deposited layer. It is found that deposition of an additional mass in the form of a thin Bi stripe on tungsten wires near the cathode end of the array allows one to mitigate the influence of the cathode zipper effect on the pinch compression and formation of the X-ray pulse in tungsten arrays.

The self-demodulation of acoustic pulses in the near zone of an acoustic radiator is studied both theoretically and experimentally. In the experiment, the aforementioned nonlinear process is studied for three types of biological tissues.

A radiation foil bolometer intended for measuring radiation-energy fluxes and plasma flows in high-power pulsed plasma X-ray sources is studied. In the bolometer, the radiation or ion-flow energy is absorbed by a 13-μm-thick niobium foil preliminarily heated to T ≈ 1900 K by a quasi-constant current lasting 2 s. Radiation from the foil was fed through an 8-m-long light guide to a semiconductor photodetector. The sensitivity of the instrument obtained from the results of calibrations is 0.56 J/V cm2. The time resolution of this technique (∼2.5 μs) is determined by the foil heating time. In experiments with megaampere Z-pinches, the time resolution attained allows detection of the radiation energy independently of the energy of expanding plasma flows. In this case, the photoelectric effect from X-rays and the conductivity of expanding plasma do not affect the operation of the radiation bolometer. The working capacity of the bolometer was demonstrated at the Angara-5-1 facility in experiments with high-current Z-pinches with a radiation output energy of 50–100 kJ/pulse. The measurements performed have shown that the energy flux density of plasma expanding in the direction perpendicular to the pinch axis is at most 5% of the energy flux density of soft X-rays.

The results of a study of a radiating Z-pinch with a profiled initial gas-density distribution over the z axis are presented. The gas distribution with the density maximum and transverse-size minimum at the discharge-gap center is formed by a pulsed gas valve with a specially designed nozzle. The parameters of X-ray radiation are measured for pinches formed in gaseous neon at currents of up to 200 kA. The experimentally selected gas density ensures the formation of a region with a typical size of less than 1 mm at the discharge-gap center. This region emits X-ray radiation in the keV photon-energy range in a time of less than 5 ns. Prospects for the development of an X-ray source based on this mechanism are discussed.

This paper is devoted to the numerical simulation of the applicability of electronically scanning quasiresonant ultrasonic receivers, similar to those used in the ultrasonic studies, for noninvasive opto-acoustic diagnostics of turbid media under conditions of limited access of the medium surface. An advantage of such receivers is their ability to acquire a two-dimensional opto-acoustic image of the internal structure of the studied object in the case of its limited accessibility without the necessity of moving macroscopically the acoustic sensor itself.

The present study describes the data on the current implosion of arrays made of kapron fibers coated with layers of metals: Al, In, Sn, Bi. Experimental data on the energy and pulse power of soft X-ray radiation (SXR) in the axial and radial directions in the energy range 0.02–2 keV were obtained by two sets of XRD detectors [1]. Spectral characteristics of the SXR source in a Z-pinch implosion of kapron fiber arrays were obtained using a grazing incidence diffraction spectrometer (GIS) in the radial direction with spatial resolution along the radius of the array. It is shown that the presence of kapron fiber matter defines the characteristics of SXR emitted by a Z-pinch in the radial and axial directions. A distinctive feature of the time profiles of XRD signals, which measure the power of SXR in the axial direction, is the presence of the second peak, which is strongly suppressed in the radial direction. It was found that power, total energy and emission spectra depend on the amount of metal-coated fibers and the mass of the layer of metal deposited on them, but do not depend on the characteristics of the material: its density, atomic number, etc. Frames of X-ray images show that the Z-pinches obtained with metal-coated kapron fiber implosion are characterized by increased stability and a lower growth rate of MHD perturbations compared to wire arrays. Slower intensity of plasma production from kapron fibers [2] leads to the fact that the plasma formed in the fiber periphery out of its material forms a layer which acts as a hohlraum wall, locking in the SXR of the Z-pinch formed during the implosion of the material of the deposited layer. It is shown that the overlap of the anode aperture doubles emission energy in the radial direction.

In SRC RF TRINITI investigated implosion of cylindrical and quasi-spherical wire arrays. Such arrays are made of metal wires and plastic fibers both coated by metal. For three-dimensional quasi-spherical arrays implosion the technique was developed to produce wires or fiber with a given distribution of linear mass along the wires. That mass distribution needs for good implosion to the center of array. The wires and fibers was formed by spraying a metal on wire or fiber. We have also developed the technique of manufacture of only tungsten wire with a given distribution of mass per unit length.

The spectral characteristics of the plasma radiation of a gas Z-pinch with a rise time of 1μs and a current amplitude of 250 kA have been measured. The measurements were performed in the range of X-ray energy quanta from 30 eV to 600 eV. A spectrograph with a transmission grating and a polychromator on the basis of multilayer X-ray mirrors served as the diagnostic device. Absolutely calibrated semi-conducting detectors AXUV-5 were used as radiation detectors in the polychromator. The full pinch radiation loss was measured with a thermocouple calorimeter. The radiation of He-, Li- and Be-like ions has been shown to dominate at the stage of maximum compression of the nitrogen Z-pinch. The results of the spectral measurements were employed for the absolute calibration of various X-ray detectors. Some of these calibration results are presented in this paper.

A setup for metrological measurements of X rays in the energy range of 50–1000 eV is described. A Z pinch with a discharge time of a few microseconds is used as the X-ray source. Radiation of a given energy is selected with the help of multilayer X-ray mirrors in combination with special X-ray filters. Along with the tested detector, an absolutely calibrated reference AXUV-5 detector is used to determine the density of incident X-ray flux in each energy range. The measured characteristics of some detectors are presented.

A method for determining the substance density distribution in the plasma produced by a current-driven implosion of multiwire tungsten liners at the Angara-5-1 facility is described. This method is based on the X-ray probing of plasma with radiation from a point source. As a source of this radiation, an X pinch is used. The time resolution (

The set of diagnostic techniques used at the Angara-5-1 facility that make it possible to study the processes which accompany the ultrafast current-driven implosion of liners is described. This set includes electric methods and methods for the detection of various radiations. The liner-plasma shapes are visualized by detecting the intrinsic liner radiation in various wavelength ranges and actively probing liners in the visible and X-ray regions. Examples of the results of studying the current-driven implosion of cylindrical arrays of tungsten wires at the Angara-5-1 facility are presented.

Results are presented from experiments on the X-ray backlighting of the axial region of an imploding high-current multiwire liner. Backlighting was performed with the use of an X-pinch serving as a source of soft X-ray emission, which was recorded by pin diodes. The use of several filters with different passbands in front of the pin diodes allowed the interpretation of the results of measurements in experiments with cascade composite liners. The sensitivity of the diagnostics was ≈125 µg/cm2 for a plasma of high-Z elements (W) and ≈220 µg/cm2 for a plasma of low-Z elements (C, O, N) at a photon energy of the probing radiation of 1.0–1.5 keV. An advantage of the method is its high time resolution (≈1 ns) and the possibility of the separation in time of the emission bursts from Z-and X-pinches on the liner axis. The method does not impose restrictions on the pulse duration of the backlighting radiation source.

Results of experimental investigation and modeling of prolonged plasma production during implosion of cylindrical wire arrays are presented. Results of the radiography of dense cores of imploding wire array and the measurements of internal azimuthal magnetic field in wire array give new experimental evidences of prolonged plasma production phenomenon. This phenomenon is an important property of current-driven implosion of the wire arrays at current rise rates /spl sim/(0.5-1)10/sup 14/ A/s. The prolonged plasma production can determine the current and the density profiles before final stage of a Z pinch compression, and also in the moment of Z pinch stagnation. From this point of view, the requirement that residual uncompressed plasma should not shunt the current at the discharge periphery becomes of the greatest importance. The conditions exist when the prolonged plasma production isn't an obstacle for the achievement of high-power X-ray emission from Z pinch. Presented experimental results on multiwire array implosion can be explained on the basis of prolonged plasma production without referring to multiwire array azimuthal structure.

We report and discuss the results of x-ray radiation measurements in the Sino-Russian joint Z-Pinch experiments on Angara-5-1 facility with a load current of 2.5–3.6 MA. The measurements were conducted by using an x-ray power meter (XRPM) and a time-resolved one-dimensional x-ray imaging system developed in China Academy of Engineering Physics. The experimental results indicate that an x-ray power-platform prior to a main peak and a less intensive sub-peak after the main peak in the waveform exist for the nested-wire array implosions, and the radiation process is relatively faster than that in the case of the single array. Laser shadowgraph of the imploding plasma suggests that the prior power-platform is a result of the collision of the inner-outer plasma layers. The faster radiation process of nested array implosion can be explained by analysing the corresponding result of the time-resolved one-dimensional imaging system, which demonstrates a better axial imploding uniformity and synchronization. In comparison with x-ray diode, the XRPM yields a higher height of x-ray power-platform due to its flat energy response. The sub-peak after the main peak is proposed to be a result of the later-time additional implosion of plasma.

Summary form only given. At TRINITI cylindrical and conical wire liners are being studied on the Angara-5-1. The design of quasi-spherical wire arrays has been tested. 3-D compression take place in the quasi-spherical arrays. At the implosion on Angara-5-1 of the quasi-spherical arrays with spatially profiled linear mass the increase of density of plasma energy up to 5 times in comparison with cylindrical wire arrays. The different soft x-ray spectra with the spatial resolution obtain for cylindrical and quasi-spherical wire arrays. To obtain this spectra reflecting grating spectrometer is developed. The dependence of radiating area diameter on wave length at implosion of cylindrical and quasi-spherical wire arrays from soft x-ray spectra with spatial resolution was received. The SRC RF TRINITI started building a thermonuclear installation "Baikal" of 50 MA current with the goal of undertaking experiments on thermonuclear target ignition. Pulse power systems for this installation is developed by Efremov institute.

A method of absolute intensity measurement of intensive impulse fluxes has been described. Method and primary absolute detector device - photoionization quantometer - are based on fundamental cross sections of photoionization and ionization by electron impact. New soft X-ray optic elements - multilayer mirrors (MLM) were tested and used for constructing a 10-channel spectroanalyzer (polychromator) for photon energy range 0.1-1.0 keV. Results of polychromator using at "Angara-5-1" installation are presented.

The work is devoted to some problems in numerical modelling plasma generated in the course of magnetic implosion of multiwire arrays (liners) in Z-pinch discharge mode, including numerical and theoretical analysis of quasispherical imploding conical wire arrays. Experiments were performed at ANGARA-5-1 facility (TRINITI) with the discharge current up to 3 MA. The numerical simulations were carried out on the base of 2D RMHD code MARPLE (IMM RAS). An appropriate description of the early phase of plasma generation during the electrical explosion of wires is a real challenge in MHD modeling of these experiments, in our computations we used the plasma ablation model, which allows to obtain more realistic results as compared with the models where the entire wires are considered to be initially already in plasma state. According to the experimental data we assume that the wire skeleton is stable during the overall time of the plasma generation as its density is significantly more than that of the surrounding plasma. Besides that the skeleton carries essentially less electric current than the plasma. The plasma ablation process lasts until the total wire skeleton evaporation. Experiments show that in the case of current pulse matched load the plasma generation is finished soon after the current maximum. Taking into account small diameter of the wires as compared with interwire gaps and the array dimensions plasma production is simulated by a steady source surface placed inside the computational domain. The mass ablation rate at the unit of the source surface is calculated with respect to the local distribution of the magnetic field induction. The numerical experiments showed that the plasma ablation model has a significant effect on both the entire scheme of plasma dynamics and such values as voltage drop at the load and soft X-ray yield power. The improvement of the ablation model parameters based on experimental and theoretical estimations is an issue of the day in 2D and 3D Z-pinch simulations.

The results of measuring the energy, power and spectrum of the soft X-ray radiation (SXR) pulse at the Angara-5-1 facility in the photon energy range of 0.02 – 2 kV are presented. A comparison of the SXR emitted in axial and radial directions is presented.

Experimental and mathematical modeling methods were used in an investigation of the influence of the degree of coherence at the entry to an optical projection system on the quality of the resultant images. It is shown that laser projection lithography is possible in a system with a nonscanning K?hler-type fly's eye illuminator and an excimer laser as the light source.

The coherence properties of light sources used in the projection lithographic systems strongly affect the photomask image quality reproduced on semiconductor wafer, because they determine the minimum resolvable feature size and the level of speckle in the image. The spatial coherence of excimer laser radiation is measured. A simple relation between the coherence of the excimer laser radiation and its divergency is presented. The dependence of excimer laser coherence on the width of intracavity apertures and the pulse duration is shown. The influence of the spatial coherence on the image quality in the projection system equipped with fly's eye element is considered. The optimization procedure of the radiation parameters and the fly's eye illuminator is described.

An investigation was made of the spatial coherence of excimer lasers in different resonator geometries. Lasing with a spectral width of 5 nm was obtained in a scheme using a grating in the autocollimation regime and a four-prism telescope. A discussion is given of the questions involved in employing excimer lasers having a narrow laser emission line in photolithographic projection systems.

The results of the experiments on Z‐pinch produced from wire arrays performed on the facility Angara‐5‐1 are presented. The models of liner implosion, i.e. prolonged plasma production have found their confirmation. Estimation based on our experimental data show that W wire cores are heterogeneous. The velocity of core expansion is determined by energy deposited at the first nanoseconds after current start. The effect of the inner array on the current distribution in the region between the arrays has been revealed. The «lost mass » was measured at initial radius of array at the moment of X‐ray pulse maximum.

The results of the experiments performed on the Angara-5-1 facility of Z-pinch produced from wire arrays are presented. The models of liner implosion, i.e. prolonged plasma production and "plasma rainstorm" have found their confirmation. The effect of the inner array on the current distribution in the space between the arrays has been revealed.

A gear with increased axial dimension is proposed for the oil and gas industries. That design increases the load capacity without increasing the radius. The possible skewing in this design is compensated by means of a special planetary transmission.

Spatial distributions of mass and current inside current-driven wire array during implosion were investigated on Angara-5-1 facility. Radiography of dense cores of imploding wire array, measurements of internal azimuthal magnetic field in wire array and electron density measurements on the periphery of initial array position at the moment of stagnation give new experimental evidences of prolonged plasma production phenomenon. The measurement of current density inside the array shows that about half the current flows on the liner periphery at the moment of maximum compression. At this time up to 10% of the liner mass is present on the periphery of the initial wire array.

Z pinches and tungsten wire arrays, compressing under action of current, are widely studied in ICF nowadays1,2,3. The wires have typical diameter 5–10 microns. Duration of output soft x-ray emission about 5–10ns. Spatial distribution of mass inside current — driven array during implosion has crucial importance for process of array implosion.

The study of the wire array implosion on installation Angara-5-1 is devoted. Magnetic probes and the x-ray backlighting technique were used to investigate a current and mass distribution during the implosion. The experimental data confirm the concept of prolonged plasma production: the long time of implosion the hot plasma flows from dense fixed wire cores and is accelerated by the Lorentz force to the array center together with frozen magnetic field.

A charge-coupled device K1200CL4 (K1200IIJI4) was used as a pulsed X-ray detector to investigate high-temperature plasma. The sensor was incorporated in a module providing a special control mode of the CCD. The module was successfully employed in a spectrograph for investigating the spectrum of high-temperature plasma over the energy range from 0.7 keV to 3 keV in the thermonuclear plant ANGARA-5 (Russia) and GAEL (France). The paper gives the basic technical characteristics of the module based on CCD K1200CL4.

1. The method used for experimentally determining the value of the coefficient of stress intensity based on data from measuring the pliability of a small sample (CT), which has increased accuracy and economy, gives results which agree well with the theoretical solution of the corresponding plane problem. 2. An equation was obtained for calculating the coefficient of intensity of the three-dimensional field of stresses in a CT sample with side grooves. 3. On the basis of an analysis of the results of this investigation and literature data, it was concluded that there is a weak relationship between the correction for the side grooves and their form and dimensions, the type of sample, the crack length, and the properties of the test material.

A Michaelson interferometer was used in determination of longitudinal and transverse correlation functions of the radiation field of an XeCl laser. The coherence of the radiation emitted by this excimer laser was investigated. The coherence lengths, radii, and coefficients were determined. The coherence radii were found to be different for different directions across the aperture of the laser beam. The role of coherence of the radiation in the applications of excimer lasers in projection photolithography was analyzed.

The spatial coherence of the excimer laser radiation seriously affects the quality of the images being reproduced by diffraction limited optics in photolithography. It is shown that the coherence parameters of excimer laser radiation exceed the necessary level in 102–103 times. To decrease the coherence down to the optimal level a fly’s eye element is used. The concept of Kirchhoff integrals has been applied to calculate the mutual intensity function transformation by the illuminator of the projection system equipped with fly’s eye element.