Faraday-rotation method for magnetic-field diagnostics in a laser plasma

The possibility of using the Faraday effect for the diagnostics of magnetic fields in a dense plasma is theoretically demonstrated. A procedure for measuring the plane of polariztion of the probing radiation is examined in detail, with account taken of the wave polarization and of the presence of plasma self-luminosity. A procedure for determining the spatial distribution of the magnetic field is described. A new three-channel polarointerferometer scheme is proposed. The idea behind the method is illustrated with reconstruction of the magnetic fields in a laser plasma as an example.Laser-Plasma Laboratory, Lebdev Physics Institute. Translated from Preprint No. 135 of the Lebedev Institute of Physics, Academy of Sciences of the USSR, Moscow, 1989.     

A pulse stacker for time-resolved laser plasma diagnostics

A passive splitter array is described which allows time-resolved plasma diagnostic measurements to be performed on a single shot basis. The advantage of this stacker is that it has high efficiency, is simple, easy to adjust, and can be inserted into an optical beam path without disturbance to alignment.     

Laser absorption and fluorescence diagnostics of a plasma

Diagnostics of a near-surface laser plasma, the plasma of a strong-current pulse gaseous discharge in inert gases, nitrogen, and carbon dioxide under conditions of intense evaporation of the wall of the discharge chamber, the plasma of a discharge with a hollow cathode, and the active medium of an excimer laser was conducted by methods of intracavity laser spectroscopy and laser-induced fluorescence. The dynamic fields and absolute concentrations of atoms, ions, molecules and electrons, the plasma temperature, and the velocities of flows of particles were measured. The quantitative determination of the density of particles in the erosion laser flame prior to breakdown and the phenomena associated with the formation of molecules in the laser plasma received primary consideration. To whom correspondence should be addressd. Instite of Molecular and Atomic Physics of the Academy of Sciences of Belarus, 70, F. Skorina Ave., Minsk, 220072, Belarus. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 64, No. 3, pp. 281–290, May–June, 1997.     

Giant pulsed molecular laser for plasma diagnostics

Report on the 5th All-Union Conference on High-Temperature Plasmas (June 18–22, 1990, Minsk).     

Resonant laser diagnostics of a planar plasma opening switch

The plasma opening switch (POS) is an integral part of inductive store pulsed power systems. Using flashboards coated with BaO and a dye laser tuned to the 493.4 nm ground state transition of the singly-ionized barium ion, resonant laser diagnostics have been employed to image the switch plasma and provide a measurement of the plasma density during conduction and opening. Gaps open during the conduction phase with their position in the inter-electrode region depending upon the initial fill plasma. There is little axial motion of the plasma, contrary to the predictions of analytical hydro model calculations performed using the measured switch parameters. This discrepancy may be due to a finite lifetime for ions in the switch that is less than the conduction time resulting in a larger effective mass. From a functional point of view modified bipolar model calculations best fit the data     

Schlieren diagnostics of the plasma focus using a mode-locked dye laser

By means of schlieren techniques the discharge characteristics of a 1 kJ plasma focus device were investigated. Different inner electrodes were used with diameters ranging from 4 mm to 10 mm and the working gases were hydrogen and neon. A spatial resolution in the m region and a temporal resolution in the ps region could be achieved using a mode-locked dye laser as schlieren light source. During the run-down and collapse phase of the discharge the spatially and temporally resolved electron density was determined from the schlieren pictures by means of numerical simultations of the beam deflection by the plasma. During the focus phase the temporal development of the plasma could be observed.     

The application of a raman-shifted tunable KrF excimer laser for laser-induced fluorescence combustion diagnostics

Four wavelength extensions have been investigated by stimulated Raman scattering in hydrogen or deuterium gas of the 248 nm fundamental output of a narrow-band tunable KrF excimer laser. They have been used to acquire laser-induced fluorescence spectra of NO and OH in flames at atmospheric pressure. NO is detected in relatively high rotational states within the -band electronic system at 225 nm. OH was excited at 291.5 nm in the (1–0), at 313 nm in the (1–1) and at 268.5 nm in the predissociative (3–1) band of the ²–² electronic band system, respectively. Prospects of 2D imaging for concentration and temperature measurements in flames using these wavelength extensions are discussed.     

用于激光等离子体诊断实验的二倍频探针光系统

为了满足基准物理实验的要求,准确地探测出靶面的等离子体的电子温度、密度、电子离子漂移速度等参数,在星光Ⅱ激光装置上发展了一束二倍频激光作为探针光。通过模拟实验已经证实了该探针光的二倍频总能量大于5J,焦斑尺寸小于100μm,可以满足激光与等离子体相互作用的高功率要求。目前,该探针光系统已经用于用于激光等离子体诊断实验的常规运行。     

正态分布随机数发生器及其在模拟光传输软件中的应用

利用计算机高级语言提供的伪随机数发生器,通过“高斯筛选”和“求平均值”两种方法,开发出满足正态分布的随机数发生器。将其应用于分析大型激光装置光路稳定性的模拟软件中,成功地完成了对“神光Ⅲ原型装置四程放大器”的光路稳定性分析。     

Increasing efficiency of laser fluorescence diagnostics of microbial diseases

The laser-induced fluorescence spectra of five types of mycobacteria are studied in various associations. The results obtained are used to demonstrate the possibility of a diagnostic system for the differential diagnostics of microbial diseases. The method employed for the specific analysis of microbial species in the substrate that contain various associations is based on a regression of the spectral characteristics of the fluorescence intensity to the principal components. The diagnostic efficiency is increased when the fluorescence spectra are reconstructed with regard to the optical characteristics of the medium. The detergent effect on the parameters of microbial fluorescence diagnostics is studied.     

Investigation of a near-surface laser plasma by the method of intraresonator laser spectroscopy

Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 53, No. 6, pp. 919–927, December, 1990.     

激光等离子体诊断用Wolter型X射线显微镜的设计

围绕着稠密等离子体硬X射线成像诊断,提出了一种基于阿贝正弦条件的Wolter型X射线显微镜的光学系统设计。详细介绍了Wolter显微镜的结构特点和设计方法,进行了参数优化,定量分析了包括物距、放大倍数、掠入射角和双曲面镜镜长在内的初始结构参数对物镜性能的影响。由光线追迹可以得出,在约±260 μm的视场范围内分辨率优于1 μm;在±460 μm范围内优于3 μm。有效视场可达约1 mm,几何集光立体角约为6.1×10^-5sr。同时,该系统具备平响应系统特性,在mm级的视场范围内,系统响应效率的一致性优于93.7%。     

Schlieren method and its application for plasma diagnostics

In recent years experiments were done with the application of the schlieren method for measuring electronic and atomic density gradients in plasma. The method proved to be useful. The aim of this paper is to point out the advantages of this rarely used optical method. The principle, characteristic and application of the mentioned method in plasma physics are described.     

A twin optically-pumped far-infrared CH3OH laser for plasma diagnostics

A twin optically-pumped far-infrared CH₃OH laser has been constructed for use in plasma diagnostics. The antisymmetric doublet due to the Raman-type resonant two-photon transition is reproducibly observed at 118.8 m. With the 118.8-m line, it is obtained from the frequency separation of the anti-symmetric doublet that CH₃OH absorption line center is 16±1 MHz higher than the pump 9.7-m P(36) CO₂ laser line center. It is shown that the Raman-type resonant two-photon transition is useful in order to get several-MHz phase modulation for the far-infrared laser interferometer. Some preliminary performances of this twin laser for the modulated interferometer are described.This work was carried out under the collaborating research program at the Institute of Plasma Physics, Nagoya University, Nagoya 464, Japan.     

A unipolar pulsed plasma generator in combination with a laser as a plasma jet source

A pulsed plasma generator ignited by plasma produced by laser radiation is described. The plasma generator can provide a relatively high-velocity plasma jet of specific chemical composition. The principal parameters of the plasma jet (its velocity, charged particle concentration, and temperature) have been measured and the properties of the plasma jet have been found to be independent of the polarity of the plasma generator ring electrode.The authors are grateful to M. A. El'yashevich for discussing the present paper.     

Picosecond X-ray radiography of superdense high-temperature laser plasma

The layout of an X-ray source for diagnostics of the compressed state of laser plasma is proposed, and its optimal parameters are calculated under the conditions required for nuclear fusion. Such a source operating in a pulsed regime is intended to be used for determining the spatial distribution of laser-plasma density with high temporal resolution by means of multiframe (pulses follow with a specified time interval) backlight imaging of the main target by X-ray pulses obtained by irradiation of a secondary target by picosecond laser pulses.     

Excitation of tantalum-181 nuclei in a high-temperature femtosecond laser plasma

The excitation of nuclei in a laser plasma is observed. Gamma rays from the radiative decay of the isomeric level 9/2⁻ (6.238 keV) ¹⁸¹Ta in a high-temperature femtosecond Ta laser plasma are detected. Pis’ma Zh. éksp. Teor. Fiz. 69, No. 5, 343–348 (10 March 1999)