摘要:

Cylindrically converging shock waves have been produced by detonating 20‐cm‐diam explosive shells in atmospheric air. Shadowgraphs were taken to monitor the production of waves. A spectroscopic measurement of temperature was made using a monochromator combined with a photomultiplier. The spectral radiant energy was compared with the blackbody function (Planck’s law). The dependence of temperature upon the initiation energy (the chemical energy of explosives) was also investigated. It was shown that temperature was approximately proportional to the square root of the initiation energy. The attained temperatures ranged from 13 000–34 000 K depending on the initiation energy. These are 3500–9500 K lower than those estimated from shock propagation speeds. The implosion pulse duration (the half‐value width) of 2.0–2.5 &mgr;s was observed. A possibility of the further increase of temperature as well as some problems was suggested.

ISSN:0021-8979    

DOI:10.1063/1.335925

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Presented are measurements on the generation of negative hydrogen ion beams via the conversion of positive ion beams on low work function surfaces placed outside the positive ion source. The converter surfaces are positioned parallel to the beam axis and the positive ion beam is directed onto them by the increase of the beam divergence caused by beam retardation. Results include a negative hydrogen ion beam current of 15 mA at a current density of 6.2 mA/cm2. The converter work function is lowered by the deposition of a Cs monolayer. The Cs coverage could be maintained during the bombardment by the intense H+beam through surface migration of the Cs from a reservoir.

ISSN:0021-8979    

DOI:10.1063/1.335926

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Time‐ and space‐resolved measurements of the axial and transverse velocity components of Mo macroparticles produced in a 1‐kA peak current, 30‐ms duration vacuum arc were performed using laser‐Doppler anemometry (LDA). Individual macroparticle velocity components in the range of 10–750 m/s were detected and average velocity components in the range of 100–400 m/s were determined. Using the results of the measurements of individual velocity components we obtain that a typical rms value of the macroparticle speed is in the range 400–700 m/s. Comparing the average values of the radial and axial components indicates that typical emission angles are at approximately 30°±5° with respect to the cathode surface. The relative time‐resolved macroparticle emission rate was measured by using the LDA apparatus as a particle counter. Peak macroparticle emission occurred at a time midway between peak current and peak average cathode surface temperature. This result, together with the observation that the macroparticle emission rate could be increased by increasing the current pulse repetition rate, indicate that the macroparticle emission rate is influenced by the average cathode surface temperature as well as the instantaneous arc current.

ISSN:0021-8979    

DOI:10.1063/1.335927

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

This paper describes a study investigating the possible application of penumbral imaging to thermonuclear neutrons generated in experiments on inertial confinement fusion. It is shown that the approach will allow neutron yields as low as 1011to be imaged with better than 10‐&mgr;m resolution over a 50‐&mgr;m field of view. This performance is such that penumbral imaging of neutrons may provide an important diagnostic in near term fusion experiments.

ISSN:0021-8979    

DOI:10.1063/1.335928

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Magnetohydrodynamic boundary‐layer flow with tensor electrical conductivity and transpiration number has been examined. The resulting nonlinear partial differential equations are solved using a local nonsimilarity solution method. It is found that suction will cause an increase in wall‐shearing stress and a decrease in the thicknesses of the boundary layer.

ISSN:0021-8979    

DOI:10.1063/1.335929

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

The gettering of cobalt in silicon during phosphorus diffusion under high surface concentrations (PDG) has been investigated by Mo¨ssbauer spectroscopy between 825 and 1000 °C. It has been found that cobalt, distributed uniformly in the specimen before PDG, is concentrated within a highly phosphorus doped Si‐surface layer thinner than 0.5 &mgr;m after PDG. It is also shown that PDG suppresses surface gettering and that the residual cobalt concentration in the bulk can be lower than the cobalt solubility. Mo¨ssbauer spectra of this layer show that cobalt occurs as two species there. The first of these has nearly cubic symmetry and is transformed into the second species upon annealing at 600 °C. This species is stable under the conditions of PDG. Neither the formation of phosphorus‐cobalt pairs nor the presence of CoSi2can provide a comprehensive explanation of all experimental facts.

ISSN:0021-8979    

DOI:10.1063/1.335930

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

A review is made of recent literature dealing with radiation‐induced point defects distributed volumetrically in thermally grown SiO2‐on‐Si or superficially at the silicon interface, with particular emphasis on the results of electron‐spin‐resonance experimentation. The observed defect types and their anneal kinetics are then compared with recent advances in the understanding of similar species and processes in irradiated bulk fused silica. It is concluded that radiolytic molecular hydrogen is formed in thermally grown SiO2layers, just as it is in bulk fused silica, and that the diffusion of this hydrogen determines the temperature and time dependencies of the post‐irradiation interface state buildups.

ISSN:0021-8979    

DOI:10.1063/1.335931

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

Depth distributions of energy dissipation and implantation ranges in the polymer resist polymethyl methacrylate (PMMA) have been calculated by using the TRIM computer code. The relevance of such calculations to experimentally obtained data in connection with ion‐beam lithography is discussed. It is concluded that the result of the computer simulations may be of value in order to explain the responsible mechanism for the modification (solubility, erosion rate) of a resist material due to ion irradiation. Experimental results of PMMA erosion during ion irradiation are also presented, showing a strong relationship between the erosion and electronic stopping.

ISSN:0021-8979    

DOI:10.1063/1.335932

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

The nitridation process and the annealing effects for Si‐nitride layers prepared by 20‐keV nitrogen ion implantation have been investigated by means of x‐ray photoelectron spectroscopy (XPS) and Auger electron spectroscopy (AES). The surface layer of samples implanted at a low dose is composed of a mixture of elemental Si regions and Si‐rich nitride regions. A continuous near‐stoichiometric Si‐nitride is formed without annealing as the implantation dose is increased. Shifts of the XPS spectra (Si2pand N1slines) toward higher binding energy with the implantation dose are observed. Similar shifts are also observed in AES spectra. The peak energy of the Si2pline is connected with a weighted average coordination number at a Si site in the SiNn(n=0,...,4) configuration, and the chemical shift per Si‐N bond is 1.0 eV. The shift of the N1sline is interpreted in terms of a change in the short‐range order at an N site.

ISSN:0021-8979    

DOI:10.1063/1.335933

出版商:AIP    

年代:1985

数据来源: AIP

摘要:

The rotation of the polarization plane of a polarized light beam through a hybrid aligned liquid‐crystal cell is described, by taking into account the joint effect of the weak anchoring and of the flexoelectricity in the presence of an electric field normal to the initial deformation plane and smaller than Fre´edericksz’ threshold [H. Kelker and R. Hatz,HandbookofLiquidCrystals(Chemie, Weinheim, 1980), pp. 160–188]. Such a rotation is shown to be proportional to the square root of the difference between the actual and the critical thickness of the cell in the case of small thicknesses (which are interesting in the display technology) whereas in the case of larger thicknesses the same relation deduced by Durand’s group for strong anchoring is obtained.

ISSN:0021-8979    

DOI:10.1063/1.336282

出版商:AIP    

年代:1985

数据来源: AIP