Acceleration of deuterons in a spherical ion diode with a laser-plasma anode

A physical model is proposed for a spherical pulsed ion diode with a laser ion source consisting of a plasma anode which varies in size while the accelerating voltage is applied. A study of this process was conducted using computer analysis of the nonlinear differential equations that are proposed in the article. From the results of the computer experiment, acceleration characteristics of the deuterons are established for similar diodes, and the effect of diode geometries, temporal and electrical characteristics on the energy spectra of the deuterons, the current pulse shape, and the deuteron acceleration charge are studied.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 67–71, February, 1988.In conclusion, the author expresses a deep gratitude to A. S. Tsybin for discussing results achieved and for useful advice.     

Heating and compression of laser-irradiated spherical targets

Heating and dynamics of compression of shell targets irradiated by a nanosecond laser pulse in the “Kal'mar” facility are investigated. Comprehensive procedures are developed and used to investigate the energy balance and the compression dynamics of the target scattered by the radiation plasma at the harmonic frequencies 2ω₀ and 3/2ω₀, and of the spectral distribution of the continuous x radiation. The use of the developed procedures has made it possible to clarify the dependence of the components of the energy balance on the target parameters, to establish new regularities governing the shell motion, to identify the phenomena that take place in the region of the critical and quarter-critical density, and to demonstrate experimentally the possibility of reaching in the “exploding pusher” regime densities much higher than the density of a solid body.     

Normal phase high performance liquid chromatography for determination of paclitaxel incorporated in a lipophilic polymer matrix

A normal phase (NP) high performance liquid chromatography (HPLC) method was developed for analysis of paclitaxel incorporated in poly(sebacic-co-ricinoleic acid), a lipophilic polymer matrix utilized for preparation of an injectable formulation for the localized delivery of paclitaxel. Thin layer chromatography experiments revealed that separation of paclitaxel from the polymer is dependent on the eluting strength (solvent strength) of the mobile phase. The HPLC system consists of a Purospher STRAR Si analytical HPLC column (5 microm, 250mm x 4mm, Merck), and 1-2.5% (v/v) methanol in dichloromethane as the mobile phase. Detection was by UV absorbance at 240 and 254 nm. The effect of the mobile phase composition on paclitaxel retention, peak shape and column efficiency, and the influence of the sample loading on the shape of the paclitaxel peak were studied. The mobile phases used for the chromatography consisted of 1.5% (v/v) methanol in dichloromethane. Paclitaxel was determined in the formulation and in the samples from degradation studies using UV detection at a wavelength of 254 nm. UV detection at 240 nm has advantages for following polymer matrix degradation products due to higher detector response at this wavelength. The utility of the proposed NP HPLC approach was demonstrated by assessment of intra- and inter-batch content uniformity, and by the determination of paclitaxel content after 7 and 60 days exposure of the paclitaxel-loaded polymer matrix to in vitro and in vivo degradation.     

Technological Possibilities of Realization of Sealed Accelerator Tubes Based on Diodes with Magnetic Isolation

Physics of Atomic Nuclei - Two technological schemes are considered, as well as the possibilities of their implementation for the manufacture of sealed accelerator tubes based on diodes with...     

Isolation of electron conductivity of a coaxial ion diode by the pulsed magnetic field of a spiral line

Engineering-Physics Institute, Moscow. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Radiofizika, Vol. 33, No. 8, pp. 965–969, August, 1990.     

Thermal conductivity of laser-produced plasma corona

Various methods of theoretically describing the thermal conductivity of a of plasma corona are considered. The processes of laser heating and ablating a spherical-shell target in the TRITON program (Inst. of Appl. Mech., USSR Acad. Sci.) are computer-simulated. Numerical and analytic methods are used to investigate the influence of heat-transport suppression on the principal hydrodynamic characteristics of the plasma. It is shown that the most sensitive to a reduction of the heat transport is the electron-density distribution in space and in time. The requirements imposed on experimental measurements capable of determining, in comparison with numerical computations, the degree of heat-transport suppression, are analyzed for a large range of flux densities. It is shown that when the flux density is decreased to 10¹³ W/cm² the present accuracy of measuring the position of the criticaldensity region in the corona, as well as the rate of evaporation of the material, becomes inadequate to determinethe deviation of the thermal conductivity from the classical value. Reliable conclusions concerning the transport coefficients can be drawn in this case from a comparison of high-speed interferometry data on the dynamics of a low-density corona (/_cr = 10^-3–10^-1) with the results of computer simulation.Division of Quantum Physics, Lebedev Physics Institute, Academy of Sciences of the USSR. Translated from Preprint No. 188 of the Lebedev Physics Institute, Academy of Sciences of the USSR, Moscow (1988).     

Efficient extraction of hydrogen ions from high-velocity plasma bunches by a pulsed electric field

The systematized results are presented of an investigation of the process of the efficient extraction of ions, by a pulsed electric field, from the surface of a plasma moving at a velocity of 10⁴ m/sec under the conditions of small accelerating diodes. A mathematical model is analyzed of the propagation of a plasma bunch formed by a laser pulse (E _las<1 J) in a quasicylindrical diode system. The possibilities are considered of increasing the current of the extracted ions by utilizing the phenomenon of magnetic confinement of electrons, and diode systems with a transparent anode. The designs of small acceleration tubes for generating neutron pulses are presented.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 65–74, April, 1996.     

Deuteron flux production in a small high-voltage high-current diode with pulsed magnetic insulation

Technical Physics - The results of new studies on the production of accelerated deuteron fluxes in a small ion diode with pulsed magnetic insulation of electrons have been presented. A plasma anode...     

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.     

Generation of nanosecond neutron pulses in vacuum accelerating tubes

The generation of neutron pulses with a duration of 1–100 ns using small vacuum accelerating tubes is considered. Two physical models of acceleration of short deuteron bunches in pulse neutron generators are described. The dependences of an instantaneous neutron flux in accelerating tubes on the parameters of pulse neutron generators are obtained using computer simulation. The results of experimental investigation of short-pulse neutron generators based on the accelerating tube with a vacuum-arc deuteron source, connected in the circuit with a discharge peaker, and an accelerating tube with a laser deuteron source, connected according to the Arkad’ev-Marx circuit, are given. In the experiments, the neutron yield per pulse reached 107 for a pulse duration of 10–100 ns. The resultant experimental data are in satisfactory agreement with the results of computer simulation.