Electron temperatures of intense electron-beam-produced plasmas

A method of estimating the electron temperatures in intense, relativistic, electron-beam-produced plasmas is presented. This method compares spectral line intensities obtained from visible emission spectroscopy to those expected from local thermodynamic equilibrium (LTE) plasmas. The line intensities, particularly those originating from highly excited states, are corrected for the effects of the fast-beam electrons     

Emission continua of rare gas plasmas

Photoionization cross sections of rare gases have been calculated by using the scaled Thomas-Fermi method, including polarization effects. Absorption coefficients have been derived for bound-free transitions in thermal plasmas of 6000 K to 30000 K, for a wavelength range from 300 Å to 10000 Å.     

Observation of MeV ions in long-pulse, large-scale laser-produced plasmas

A new approach for investigation of the generation of fast ions and hot electrons inside the same plasma volume in laser-produced plasmas is proposed. It is based on the spectroscopic observation of line radiation from singly and doubly excited levels with simultaneous high spectral and spatial resolution. The experimental results demonstrate the observation of fast ions from highly charged target material inside the plasma volume and suggest that the generally accepted scaling relations are seriously invalid under certain conditions. Even at rather modest intensities ions with energies of several MeV are observed. Pis’ma Zh. éksp. Teor. Fiz. 70, No. 4, 262–267 (25 August 1999) Published in English in the original Russian journal. Edited by Steve Torstveit.     

石墨阴极用于重频长脉冲高功率微波产生的初步实验

 选取两种不同成分的石墨材料（普通石墨和掺铜石墨）分别设计制作了用于电子显微镜实验的阴极样品和用于重频长脉冲高功率微波产生实验的阴极,并开展了初步实验研究。实验结果表明:掺铜石墨与普通石墨在微观结构方面存在明显不同,且掺铜石墨阴极在发射性能、微波脉冲宽度和微波脉冲后沿离散性等方面可能优于普通石墨阴极,但优势并不明显,还待在以后的实验中进一步验证。     

石墨阴极用于重频长脉冲高功率微波产生的初步实验

选取两种不同成分的石墨材料（普通石墨和掺铜石墨）分别设计制作了用于电子显微镜实验的阴极样品和用于重频长脉冲高功率微波产生实验的阴极,并开展了初步实验研究。实验结果表明:掺铜石墨与普通石墨在微观结构方面存在明显不同,且掺铜石墨阴极在发射性能、微波脉冲宽度和微波脉冲后沿离散性等方面可能优于普通石墨阴极,但优势并不明显,还待在以后的实验中进一步验证。     

Vibrational investigation of 1-cyclopentylpiperazine: A combined experimental and theoretical study

FT-IR and Raman spectra of 1-cyclopentylpiperazine(1cppp)have been experimentally examined in the region of 4000–200cm-1.The optimized geometric parameters,conformational equilibria,normal mode frequencies and corresponding vibrational assignments of 1cppp(C9H18N2)are theoretically examined by means of B3LYP hybrid density functional theory(DFT)method together with 6-31++G(d,p)basis set.On the basis of potential energy distribution(PED)reliable vibrational assignments have been made and the thermodynamics functions,highest occupied and lowest unoccupied molecular orbitals(HOMO and LUMO)of 1cppp have been predicted.Calculations are employed for four different conformations in C1 and Cs point groups of 1cppp in gas phase.Comparison between the experimental and theoretical results indicates that B3LYP method is able to provide satisfactory results for predicting vibrational frequencies and the structural parameters,vibrational frequencies and assignments.Furthermore,C1(equatorial-axial)point group has been found as the most stable conformer of 1cppp.     

A theoretical and experimental investigation of sound intensity distribution within a splitter silencer

Results are presented of an investigation into the sound intensity distribution in a ventilation duct splitter silencer subject to plane waves incident in the axial direction, under conditions of zero flow. A theory is developed which accounts for the generation of nonplane fields at the cross-sectional discontinuities of the duct-silencer-duct system. A local reaction model of the splitter material is employed, and analytical solutions and numerical results are presented for the sound intensity distribution within the silencer. Experiments were conducted to measure the distribution of sound intensity in a silencer subject to incident plane waves. The conventional cross-spectral method of measuring sound intensity could not be used because of the practical difficulties in manoeuvring the two-microphone assembly through the narrow air passage and obtaining measurements at positions close to the wall of the splitters. Instead, a modified cross-spectral method was devised which employs only one microphone for measurement. In this method, the transfer functions between the loudspeaker input signal and the microphone output signal were measured at an array of microphone positions within the air passages of the silencer. The divergence equation for sound intensity was employed to infer transverse intensity distributions from the computed axial distribution. Reasonable qualitative agreement is obtained between theoretical and observed sound intensity distribution, but the local reaction model of the splitter is found not to be satisfactory at the lower frequencies.     

A theoretical and experimental investigation of an in-band pumped gain-switched thulium-doped fiber laser

In this paper,the theoretical rate equation model of an in-band pumped gain-switched thulium-doped fiber(TDF) laser is investigated.The analytical formulations of pump energy threshold,peak power extraction efficiency,and pulse extraction efficiency are derived through analyzing the interaction process between the pump pulse and the laser pulse.They are useful for understanding,designing,and optimizing the in-band pumped TDF lasers in a 1.9 μm-2.1 μm wavelength region.The experiment with an all-fiber gain-switched TDF laser pumped by a 1.558-μm pulse amplifier is conducted,and our experimental results show good agreement with theoretical analysis.     

A revised theoretical model of vacuum arc spot plasmas

The quasi-stationary hemispherical expansion of the cathodic plasma in vacuum arcs can be modeled with hydrodynamic two-fluid equations. In any case, the state of the plasma is determined by the only variable (I/r)^2/5 (with current I , distance r). In order to avoid some deficiencies of the model (as published) and to investigate more carefully the dependence of the plasma parameters on the arc current, the known analytic solution to the problem is improved by taking into consideration the variability of the Coulomb logarithm and the dependence of the boundary conditions on I. These effects are treated separately. Examples are used to illustrate the new results, with particular emphasis on ion acceleration. The influence of the above factors turns out to be rather unimportant. Quantitatively, they cause some shifts, but no qualitative change of the basic behavior of the plasma is seen     

S波段长脉冲相对论返波振荡器实验研究

从物理机制上定性地分析了导致脉冲缩短的主要原因,给出了长脉冲重复频率运行下的相对论返波振荡器(RBWO)设计原则。结合传统谐振式返波振荡器的基本设计理论,设计和模拟优化了工作在S波段的长脉冲RBWO,并利用本实验室现有长脉冲脉冲功率驱动源开展了S波段长脉冲RBWO的实验研究。实验结果表明：在单次运行条件下,微波输出功率达到约2 GW、脉宽约90 ns;在10 Hz重复频率运行条件下,输出微波功率达到约1 GW、脉宽约100 ns。器件产生的微波频率为3.6 GHz,输出模式为TM01模,效率约20%。对实验结果分析表明,器件截止颈和第一个慢波结构结合处的爆炸发射是导致脉冲缩短的主要原因之一。     

H, C NMR and JCH coupling constants investigation of 4-Phenylpyridine: A combined experimental and theoretical study

Proton coupled and uncoupled ¹³C, ¹H, DEPT, COSY and HETCOR NMR spectra of 4-Phenylpyridine (4-Phpy) have been reported for the first time except for its ¹H NMR spectrum. In order to provide a precise structural elucidation for carbon atoms those have very close chemical shifts to each other, the magnitude of ⁿJ_CH (n=1,2,3) coupling constants of 4-Phpy (C₁₁H₉N) have also been investigated. ¹³C, ¹H NMR chemical shifts and ^1-3J_CH coupling constants of 4-Phpy have been calculated by means of B3LYP density functional method with 6-311++G(d,p) basis set. Moreover, the optimized parameters (bond lengths, bond and torsion angles) of 4-Phpy have been calculated with B3LYP at 6-31G(d) level in methanol (ε=32.63). Comparison between the experimental and the theoretical results indicates that density functional B3LYP method is able to provide satisfactory results for predicting NMR properties.     

光子加速器的理论研究

研究了光子加速器(即利用等离子体中的朗谬尔波实现光脉冲频率上转换)所涉及的基本物理问题.文中导出了在存在朗谬尔波的条件下,光脉冲频率对于等离子体本底密度及电子密度扰动的依赖关系,并就最大频率转换、光脉冲俘获、波的加速位相(accelerating phase)以及位相滑动(phase slippage)效应进行讨论.     

Combined experimental and theoretical investigation of the premartensitic transition in Ni2MnGa

Ultraviolet-photoemission (UPS) measurements and supporting specific-heat, thermal-expansion, resistivity, and magnetic-moment measurements are reported for the magnetic shape-memory alloy Ni2MnGa over the temperature range 100T(PM) is due to the Ni d minority-spin electrons. Below T(M) this peak disappears, resulting in an enhanced density of states at energies around 0.8 eV. This enhancement reflects Ni d and Mn d electronic contributions to the majority-spin density of states.     

Numerical and experimental investigation of burner device for anode gas reburning

A complex numerical and experimental investigation of burner devices for a reburning of the anode gas of aluminum production was carried out. The chosen mathematical model of the processes of aerodynamics, heat exchange, and gas burning was identified and adapted on the basis of data of real-scale measurements. Basing on computational experiments the optimization of the design of elements of the system for anode gas detoxication and transport was carried out. A new system was proposed and tested for reburning the anode gases of electrolysis production, which consists of an improved burner device and a dust-sedimenting chamber with a possibility of regulating the amount of gas suction.     

Comparison of the results of theoretical analysis and experimental investigation of dynamic volt-ampere characteristics

Dynamic volt-ampere characteristics are calculated for the case of the diffusionless approximation. The theoretical dependences obtained are compared with experimental curves for the system Si-SiO₂-Al. A method is developed allowing the mobility of the migrating ions and the magnitude of the mobile charge in the sample to be determined from the current maximum on the experimental dynamic volt-ampere characteristic and its position.Translated from Izvestiya Vysshikh Uchenbykh Zavedenii, Fizika, No. 11, pp. 47–54, November, 1984.     

Half metallic Co2TiGe—a theoretical and experimental investigation

Using first principle calculations the electronic structure and magnetic properties of the half metallic Co₂TiGe was investigated. The electronic structure calculations were performed using two different parameterization schemes. The band gap obtained in the minority spin state using LDA scheme in TB-LMTO method was smaller than that obtained using GGA scheme in FP-LAPW method. To explore the half metallic property experimentally bulk Co₂TiGe was synthesized by arc melting under argon atmosphere. The magnetic moment per formula unit determined from saturation magnetization at 2 K was 1.9 μ_B, which was close to the theoretically calculated value of 2 μ_B. A detailed analysis of the low temperature transport and magnetotransport properties exhibit characteristic features of half metals such as T^9/2 dependence of low temperature resistivity, negligible temperature dependence of resistivity below 20 K and a cross over from positive to negative MR around 100 K.     

An experimental and theoretical investigation of the valence shell photoelectron spectrum of cyanogen chloride

The valence shell photoelectron spectrum of cyanogen chloride has been studied using HeI and synchrotron radiation. In the outer valence region the molecular orbital model of ionization holds, and the main bands can be associated with single-hole states. However, in the inner valence region electron correlation effects become important, and these result in complex satellite structure being observed. Vertical ionization energies and spectral intensities have been computed using the Green's function approach, and the results have facilitated an interpretation of the experimental spectra. Photoelectron angular distributions and branching ratios have been measured and have been used to assess the bonding characteristics of the outer valence molecular orbitals. The experimental data for the 8σ orbital display an energy dependence which suggests that photoionization from this orbital may be influenced by the chlorine 3p Cooper minimum. The extent to which the 8σ orbital can be considered as a chlorine atom lone-pair is discussed. Vibrational structure has been observed in the [Xtilde] ²Π, Ã ²Σ⁺ and [Btilde] ²Π photoelectron bands recorded with HeI radiation, and has been assigned to progressions involving the ν⁺ ₁ and ν⁺ ₃ modes.