Testifying experiment of the multi-pulse phenomena of capillary discharge soft-X-ray laser

In a capillary discharge experiment for the neon-like argon lasing, we have proposed an experimental scheme to verify that the multi-spike of X-ray diode (XRD) signal is a multi-pulse laser or is a reflection of the laser pulse in the XRD.The ceramic capillary has an inner diameter of 3mm and a length of 200mm.At the gas pressure of 28Pa and discharge current of 27kA, stable lasing has been realized.The experimental results prove that the multi-spike of XRD signal is a reflection of the electromagnetic signal produced by the laser pulse in the XRD.The improved electrocircuit scheme of the XRD to minimize the reflection phenomena is also found.     

金刚石压腔结合拉曼光谱技术进行氢同位素分馏的实验研究

应用水热金刚石压腔结合拉曼光谱技术来进行石膏和重水间稳定同位素分馏的实验研究.氢同位素 D 与 H 的质量差百分比是所有稳定同位素里最大的,由质量引起的分馏更容易发生,更容易在实验中观测;石膏是浅部地壳重要的含水矿物,它与重水之间的同位素分馏效应对矿物-水体系的同位素平衡分馏研究具有重要意义.常用分馏系数是指两矿物或两...     

Mass dependence of calcium isotope fractionations in crown-ether resin chromatography

Benzo 18-crown-6-ether resin was synthesised by the phenol condensation polymerisation process in porous silica beads, of which particle diameter was ca 60μ Calcium adsorption chromatography was performed with the synthesised resin packed in a glass column. The effluent was sampled in fractions, and the isotopic abundance ratios of ⁴²Ca, ⁴³Ca, ⁴⁴Ca, and ⁴⁸Ca against ⁴⁰Ca were measured by a thermo-ionisation mass spectrometer. The enrichment of heavier calcium isotopes was observed at the front boundary of calcium adsorption chromatogram. The mass dependence of mutual separation of calcium isotopes was analysed by using the three-isotope-plots method. The slopes of three-isotope-plots indicate the relative values of mutual separation coefficients for concerned isotopic pairs. The results have shown the normal mass dependence; isotope fractionation is proportional to the reduced mass difference, (M – M′)/MM′, where M and M′ are masses of heavy and light isotope, respectively. The mass dependence clarifies that the isotope fractionations are originated from molecular vibration. The observed separation coefficient ? is 3.1×10^?3 for the pair of ⁴⁰Ca and ⁴⁸Ca. Productivity of enriched ⁴⁸Ca by crown-ether-resin was discussed as the function of the separation coefficient and the height equivalent to the theoretical plate.     

Characterization of a ferrofluid-based thermomagnetic pump for microfluidic applications

We experimentally characterize the performance of a miniature thermomagnetic pump, where suitably imposed temperature and magnetic field gradients are used to drive ferrofluid in a 2 mm diameter glass capillary tube, without application of any external pressure gradient. Such a pump can operate in a hermetically sealed micro electromechanical system configuration without any moving part, and is thus capable of handling microfluidic samples with little risk of contamination. In the experiment, the ferrofluid in the capillary is exposed to a magnetic field using a solenoid; a small resistive heater wrapped on the tube wall is used to create temperature gradient in such a way that the Kelvin body force in the medium produces a net unbalanced axial component. This causes a thermomagnetic pumping action, transporting the ferrofluid in the capillary tube from the colder end to the warmer end. Performance of the thermomagnetic pump is investigated experimentally to characterize the pump pressure head and discharge under different working conditions, namely, the magnetic field strength, heating power, and ferrofluid properties. A comparison with two other field actuation pumps at comparable length scales is also presented. The pump produces higher output at lower power supplies and magnetic field compared to the other two pumps.     

Continuous operation of a high power neon ion laser

A highly ionized neon low pressure discharge (p ≈ 1 torr) was operated in a 12 mm diameter segmented aluminium tube up to discharge currents i = 630 A. The threshold current of the isotope selective Ne II-line λ = 332.4 nm was lower than for the strongest Ar III-UV lines; the highest measured output power of this line was 6.3 W which is more than one order of magnitude higher than previously reported.     

激光共振电离过程中铅同位素歧视效应研究

以速率方程为基础,通过数值模拟方法,对Pb的激光共振电离通道：“6s26p2 3P0—6s26p7s 3P0₁—电离”的激光诱导同位素歧视效应进行了研究,以探讨减小激光诱导歧视效应,准确测定Pb同位素比值的有效途径。通过考虑激光线型、原子吸收谱线线型、同位素位移及同位素超精细结构等因素的影响,对速率方程进行近似。在近似的速率方程基础上,以“1+1”激光共振电离过程为例,进而探讨激光峰值功率密度、带宽和中心波长对Pb的同位素歧视效应的影响。研究结果表明,利用最佳波长法,可基本消除同位素歧视效应的影响;提高激发光光强可使Pb同位素饱和电离,从而消除同位素歧视效应的影响;采用宽带激光激发,可减小同位素歧视效应的影响。     

Influence of the hollow cathode dimensions on the electron beamcurrent in a pseudospark discharge

Investigations on the electron beam current of a free running pseudospark discharge are presented. A single gap system with hollow cathodes of different dimensions is used. The filling gases are argon and helium. The electron beam signal consists of a first pulse with currents of several hundreds of mA and a main pulse with currents up to 20 A. A variation of length and diameter of the hollow cathode significantly influences the pressure range in which a free running pseudospark discharge exists and the peak current of both electron beam pulses. Plasma formation and electron beam generation are studied by high speed photography. The experimental results give some information on the discharge mechanisms that is integrated in a qualitative model of the pseudospark discharge     

Characterization of brush type discharge electrodes and impact of enhanced corona discharge on operation of electrostatic precipitators

This project presents the results of investigation of current/voltage characteristics of brush type discharge electrodes (BTDE) in tube type electrostatic precipitators and the effect on operation. Experimental investigations were conducted with discharge electrodes of different wire diameter and different brush diameter. The effect of electrode geometry on current/voltage behavior was recorded. Corona current with brush type discharge electrodes was modeled and compared with experimental data. Brush type discharge electrodes produce an enhanced corona current compared with wire type discharge electrodes. Limited enhanced corona has improving effect on collection efficiency. An adjusted correlation was therefore deduced from experimentally obtained current/voltage data with BTDE.     

大气压下石英毛细管内氩等离子体放电的发射光谱诊断

在长度为20 cm的石英毛细管内利用两个边缘锋利的中空的针型电极之间的氩气放电产生了高电子密度的大气压等离子体。利用发射光谱对所获得的等离子体的几个重要参数进行了诊断。利用计算机谱线拟合法合成了300 nm附近OH(A-X)的(0-0)转动谱带并通过与测量谱线的比较确定了等离子体的气体温度,根据H_β谱线Stark展宽法计算了等离子体的电子密度,采用玻尔兹曼曲线斜率法依据测得的有关氩的发射光谱估算了等离子体的电子温度。研究结果表明,这种石英毛细管内弧光放电等离子体的气体温度约为(1 100±50)K;电子密度数量级在1014 cm-3;电子温度约为(14 515±500)K。     

Asymmetry of spontaneous helium radiation in retarded excitation in an electric discharge

The dynamics of formation of optical radiation in spectral lines in a longitudinal nanosecond helium discharge under conditions of wave breakdown is investigated. A discharge tube with a diameter of 0.4 cm and a length of 50 cm was placed in a metallic shield 1 cm in diameter. The gas pressure was varied within 1–60 torr for an amplitude of the voltage pulses of up to 50 kV. Asymmetry of spontaneous radiation recorded from different ends of the discharge tube is detected. This is shown to be a consequence of nonuniform distribution of the functions of the primary brightness of the flux and the absorption coefficient along the tube length. Dagestan State University, 43a, M. Gadzhiev Str., Makhachkala, 367025, Russia. Translated from Zhurnal Prikladnoi Spektroskopii, Vol. 66, No. 3, pp. 415–420, May–June, 1999.     

Isotope engineering of carbon nanotube systems

The synthesis of a unique isotope engineered system, double-wall carbon nanotubes with natural carbon outer and highly 13C enriched inner walls, is reported from isotope enriched fullerenes encapsulated in single-wall carbon nanotubes (SWCNTs). The material allows the observation of the D line of the highly defect-free inner tubes that can be related to a curvature induced enhancement of the electron-phonon coupling. Ab initio calculations explain the inhomogeneous broadening of inner tube Raman modes due to the distribution of different isotopes. Nuclear magnetic resonance shows a significant contrast of the isotope enriched inner SWCNTs compared to other carbon phases and provides a macroscopic measure of the inner tube mass content. The high curvature of the small diameter inner tubes manifests in an increased distribution of the chemical shift tensor components.     

Experimental determination of one-and two-neutron separation energies for neutron-rich copper isotopes

A method is proposed to determine the one-neutron S_n or two-neutron S_(2n) separation energy of neutronrich isotopes.Relationships between S_n(S_(2n)) and isotopic cross sections have been deduced from an empirical formula,i.e.,the cross section of an isotope exponentially depends on the average binding energy per nucleon B/A.The proposed relationships have been verified using the neutron-rich copper isotopes measured in the 64 A Me V ~(86)Kr+~9Be reaction.S_n,S_(2n),and B/A for the very neutron-rich ~(77,78,79)Cu isotopes are determined from the proposed correlations.It is also proposed that the correlations between S_n,S_(2n) and isotopic cross sections can be used to find the location of neutron drip line isotopes.     

Theoretical study on isotope separation of an ytterbium atomic beam by laser deflection

Isotope separation by laser deflecting an atomic beam is analyzed theoretically. Interacting with a tilted onedimensional optical molasses, an ytterbium atomic beam is split into multi-beams with different isotopes like172Yb,173Yb, and174Yb. By using the numerical calculation, the dependences of the splitting angle on the molasses laser intensity and detuning are studied, and the optimal parameters for the isotope separation are also investigated. Furthermore, the isotope separation efficiency and purity are estimated. Finally a new scheme for the efficient isotope separation is proposed. These findings will give a guideline for simply obtaining pure isotopes of various elements.     

Oscillatory extraction — New method of similar elements and isotopes separation

The new separation extraction method was created based on oscillatory extraction/stripping process in two extractors coupled by bulk liquid membrane (LM). The experimental setup to investigate the kinetics of non-stationary processes was built in Saint Petersburg State Institute of Technology in the Rare Earth Department. To induce the oscillatory extraction-stripping process the cyclic Belousov-Zhabotinsky (BZ) reaction or cyclic electrochemical oxidation-reduction was used. The possibility to use oscillatory extraction approach to separate similar elements by using the differences in their kinetic properties is demonstrated. The experimental evidences of uranium, cerium and neodymium isotopes separation were obtained. The separation of ¹⁴²Ce and ¹⁴⁰Ce isotopes between aqueous phases of two extractors coupled by bulk LM in the experiments with cyclic chemical oxidation/reduction with enrichment factor about 2.5% was observed. Under the same conditions the separation of the Nd isotopes (heavy isotopes of Nd — ¹⁴⁴Nd, ¹⁴⁵Nd, ¹⁴⁶Nd, ¹⁴⁸Nd, and ¹⁵⁰Nd from the light isotope — ¹⁴³Nd) in the same experiment with enrichment factor about 0.7–1.4% was observed.     

Modelling of a nitrogen x-ray laser pumped by capillary discharge

We performed computer modelling of a fast electrical discharge in a nitrogen-filled alumina capillary in order to discover discharge system parameters that may lead to efficient recombination pumping of soft X-ray laser with active medium created by H-like nitrogen ions. The space-time dependences of pinch plasma quantities were found by means of a one-dimensional MHD code. Time dependences of populations of all ionisation states and populations of selected energy levels of lithium-, helium- and hydrogen-like nitrogen ions were evaluated using the FLY code as a post-processor. The population inversion was found at the quantum transition corresponding to the Balmer α-line of N⁶⁺ ions and the resulting gain factor was evaluated for different capillary radii, initial pressure, electric current peaks and periods. A gain factor of 1 cm⁻¹ spanning the time interval of 1 ns was found for an optimised arrangement with capillary radius 1.5 mm, peak current 50 kA, quarter period 40 ns and filling gas pressure 0.5 kPa. It is pointed out that even higher values of the gain factor may be achieved with thinner capillaries and shorter current pulses, e.g. a gain factor of 6 cm⁻¹ is achieved if the capillary radius is 0.5 mm, peak current 56 kA, quarter period 15 ns, and filling nitrogen pressure 3.9 kPa.     

激励类氖氩软X射线激光的最佳放电电流波形

 为了提高毛细管放电类氖氩46.9 nm软X射线激光的强度,研究了主脉冲电流波形对等离子体Z箍缩过程、激光的产生时间及激光强度的影响。通过改变主开关导通电感,实现了对主脉冲电流上升沿的改变。随着电流上升沿的增加,激光尖峰幅值减小,激光产生时间增加。实验进一步研究了平均电流变化率对激光强度的影响:在毛细管内径3 mm、管内初始气压30 Pa的情况下,产生46.9 nm激光的最佳平均电流变化率约为7.0×10¹¹ A/s。     

基于正交试验方法的涡流管优化设计

为了寻求涡流管最大能量分离效果的最优化几何尺寸参数,该文探讨了喷嘴数目、分离孔板直径、涡流管长度、热端调节阀角度对涡流管最大制冷效应的影响,并采用极差分析法分析了试验结果。得出:喷嘴数目对涡流管能量分离影响程度最大,而调节阀锥度的影响程度最小,涡流管长度和分离孔板直径对其影响程度处在两者之间。该文利用正交试验法设计涡流管实验,为涡流管的研究提供了一个新的思路。     

Isotopic catalysis and isotopic analysis

Isotopes with magnetic nuclei accelerate the biochemical reactions of adenosine triphosphate synthesis by a factor of two to three. An isotope effect in which isotopes are preserved in the reaction system is known as isotopic catalysis. It has been revealed in enzymatic reactions catalyzed by magnesium, zinc, and calcium ions. Isotopic catalysis is sensitive to paramagnetic impurities, which inhibit it. It is shown that the presence of paramagnetic iron ions eliminates isotope effect and suppresses the isotopic catalysis of adenosine triphosphate synthesis.     

Separation of Isotopes of Lithium and Uranium by Electromigration Using Cation-Exchange Membranes

Isotope separation by chromatographic electromigration has been studied for lithium (⁶Li and ⁷Li) and uranium (²³⁵U and ²³⁸U), using cation-exchange membranes as migration media. The membranes were pulled back against the direction of the movement of isotopic cations in a countercurrent manner. In both cases of the elements the lighter isotope, ⁶Li or ²³⁵U, was concentrated at the frontal part of a migration zone; at the extreme front the ⁶Li atom % increased to 16.8% from the original value of 7.5% after 386 cm migration, and the ²³⁵ U atom % rose to 0.743% from the original value of 0.723% after 200 cm migration. Isotope separation coefficients were experimentally determined: ε = (3.7 ± 0.4) μ 10^?3 for lithium isotopes, and two slightly different values ε = (4.9 ± 1.0) μ 10^?5 and (5.4 ± 1.1) μ 10^?5 for uranium isotopes. The steep isotope accumulation was observed in a narrow boundary region. A mathematical expression for the isotope accumulation curve was derived, and the slope of the curve was assessed for each experimental result.     

Modification of the texture of a polymer material surface in dust plasma

We have analyzed the modification of the texture of polymer particle surface in a dust plasma. Monodisperse spherical melamine formaldehyde particles were injected into the glow discharge plasma in neon. At a certain discharge current and gas pressure in the discharge tube, the particles were suspended in dust-plasma traps and experienced the action of the plasma of 5–25 min. Then, the particles were extracted and the collected material was studied using the scanning electron microscope. Among the results, a change in the diameter and roughness of the surface depending on the residence time of particles in the dust plasma was established. It was found that the absolute deviation of all points of the surface profile averaged over the evaluation length were in the nanometer range. The time of complete degradation of particles in the experimental conditions has been established.