摘要:

The three nonlinear coupled differential equations for a three‐frequency backward‐traveling‐wave parametric interaction in a lossless dielectric are solved for the power density in the three fields as a function of position in the crystal. When the theory is applied to a single‐pass oscillator, it predicts the existence and magnitude of a threshold pump power even for lossless media. The theoretical curves showing the power outputs in the signal and idler waves for the single‐pass oscillator as a function of pump power and crystal parameters are given.

ISSN:0021-8979    

DOI:10.1063/1.1658024

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

ZnS LUMOCEN (luminescence from molecular centers) films typically 2000‐Å thick doped with rare‐earth and transition‐metal fluorides have been fabricated by vacuum coevaporation. Details of the fabrication techniques are presented for the 12 fluorides studied: PrF3, NdF3, SmF3, EuF3, TbF3, DyF3, HoF3, ErF3, TmF3, YbF3, CrF3, and MnF2. Concentration dependence of the brightness has been investigated for the ZnS/TbF3device, the maximum occurring at 1.8 at.% Tb. Studies of brightness as a function of input power indicate that the ZnS/TbF3device is the brightest with 50 foot‐lamberts readily obtained. The power efficiency for ZnS:TbF3is about 10−4. Emission spectra of the devices have been measured from 0.35 to 1.1 &mgr; and related to known energy level schemes where possible. The intensity distributions of the spectra generally differ from those obtained by doping ZnS with the bare ions; the ZnS:CrF3device yields a spectrum radically different from any Cr3+luminescence previously investigated.

ISSN:0021-8979    

DOI:10.1063/1.1658025

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

An experimental study is described of the formation and growth of gas bubbles in crosslinked elastomers. A critical condition for bubble formation is found to hold in most cases: The gas supersaturation pressure must exceed 5G/2, whereGis the shear modulus of the elastomer. The kinetics of bubble growth are shown to be in good accord with a simple diffusion‐controlled growth relation for a variety of gases, elastomers, temperatures, and pressures. The number of bubbles depends strongly upon the degree of supersaturation above the critical level. This effect is attributed partly to kinetic factors and partly to the presence initially of internal holes of a range of sizes.

ISSN:0021-8979    

DOI:10.1063/1.1658026

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

The induced photovoltaic effect and the change in transition‐layer capacitance in alloyed GaP&sngbnd;Cu diodes have been investigated. Both effects can be explained by hole capturing in acceptor levels with large binding energy. The holes can be released by ir illumination which generates a transient shortcircuit current and quenches the change in capacitance. The spectral sensitivity of the transient photoeffect and of the capacity change is in agreement with other experimental results obtained in homogeneous material. Due to the large binding energy, thermal ionization of acceptor levels is very small at room temperature. Finally, the voltage dependence of the transition‐layer capacitance is compared with theoretical considerations, taking into account not only deep lying acceptor levels but also donor levels with large binding energy.

ISSN:0021-8979    

DOI:10.1063/1.1658027

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

Spatially resolved measurements of parameters during the early afterglow of helium and argon plasmas are presented. The investigated plasmas were contained in a vessel with a wall temperature much less than the electron temperature at the center of the plasma. All measured parameters developed nonuniformly. In spite of the high thermal conductivity of the free electrons, a temperature gradient was supported; the electron temperature being highest in the center of the vessel. The mechanism by which these gradients were supported is discussed. Both the electron and neutral gas temperatures remained elevated at several thousand degrees for at least 200 &mgr;sec into the afterglow. Attention is also focused on the effect of spatially nonuniform plasma parameters on transport processes as well as the dependence of the net decay on the cold walls.

ISSN:0021-8979    

DOI:10.1063/1.1658028

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

Spectral emission from plasmas produced by ruby or Nd laser impact on an Al target was studied in the 100–200‐Å region using both flow proportional counter and photographic techniques. The maximum intensities of continuous and Al IV line emissions were found to occur in quite different spatial zones of the plasma. The results are compared with those for Al V and Al VI spectra. From the appearance times of the 160.073‐Å Al IV line a value of 107cm sec−1was obtained for the expansion velocity of the plasma.

ISSN:0021-8979    

DOI:10.1063/1.1658029

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

A highly ionized plasma was produced by laser‐induced breakdown in helium at a pressure of 360 Torr. Line and continuum emission from the plasma were studied as a function of time and of position along the axis of the laser beam. Plasma parameters were then deduced from Stark widths, line‐to‐continuum, and line‐to‐line intensity ratios. The applicability of the various methods used to the case of a rapidly decaying laser‐produced plasma is discussed. The decay of the plasma is analyzed and the observed decay coefficients are compared with theoretical calculations.

ISSN:0021-8979    

DOI:10.1063/1.1658030

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

Calculations are made of spatial moments ⟨zn⟩ for particles from a plane source brought to rest in an infinite medium of randomly located target atoms of several kinds. The relationships obtained are illustrated by the determination of the mean penetration ⟨z⟩ and the straggling parameter &OHgr;= (⟨z2⟩ − ⟨z⟩2)1/2/⟨z⟩ for kilovolt125Xe ions in WO3. Results compare favorably with published experimental data.

ISSN:0021-8979    

DOI:10.1063/1.1658031

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

The reflectivities have been calculated by the matrix method using a digital computer for light polarized parallel (P) and perpendicular (S) to the plane of incidence for dielectric materials with continuously varying index of refraction profiles. Assuming various index of refraction profiles up to the computed penetration depth for positive ions, it was found that the phase difference between theP‐ andS‐waves is sensitive to the magnitude and shape of the index perturbation. Results for 150 keV Ar+bombardments of transparent vitreous silica are presented which show that implanted argon increases the refractive index of the solid by 0.02. The implanted ions appear to out diffuse between 200° and 600°C.

ISSN:0021-8979    

DOI:10.1063/1.1658032

出版商:AIP    

年代:1969

数据来源: AIP

摘要:

Exposure of vitreous silica in a nuclear reactor is shown to introduce ionization expandability which is superimposed upon the ionization contractibility of ordinary vitreous silica and upon the ionization expandability associated with certain impurities. The ionization expandability developed in pile exposure consists of two parts. The principal part requires ∼104eV of ionization for a volume increase of an oxygen ionic volume (O.V.) and can exceed 5×1019O.V./cm3. Capacity for an earlier phase of ionization expansion, pre‐evident expansion, grows on pile exposure to a maximum ∼5×1018O.V./cm3, requires ∼32 eV/O.V., and declines when electron irradiation is intermitted. Accompanying the reversion is a recuperation phenomenon resulting in an increase in principle expansion on resumption of irradiation. The recuperation phenomenon is explained as caused by a redistribution of bond strain in the reversion of the pre‐evident expansion. The supervenient expansion observed after maximum compaction during pile exposure is explained as predominantly associated with the slowing down of atoms scattered by fast neutrons (also the cause of the original compaction) and indicates the existence of structure in the microregion being compacted.

ISSN:0021-8979    

DOI:10.1063/1.1658033

出版商:AIP    

年代:1969

数据来源: AIP