摘要:

In a framework where a flaw is regarded as the spatial variation of the density and the elastic constants of the host medium, we derive a matrix scattering formalism. We introduce a bivariational principle for the scattering amplitude and use it to develop an optimal‐type approximation scheme. We consider the implications of reflection‐plane symmetry and show that when the incident and scattered waves lie in this plane, certain polarized, scattering amplitudes are zero. We develop a ’’partial‐wave’’ expansion for any flaw of spherical symmetry and reduce this scattering problem to a feasible numerical computation.

ISSN:0021-8979    

DOI:10.1063/1.329833

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

The temperature of meltingTffor most metals can be related to bond distanced, the number of electrons per atom (V) in ansp,sd, orsf band, and electron interactions through a parameterK3≡Tfd2/V. The value of this parameter varies systematically with the quantum states of the elements or their positions in the periodic table.

ISSN:0021-8979    

DOI:10.1063/1.329834

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

We determine the optimal motion of a piston fitted in a cylinder containing a gas, pumped with a given time‐dependent rate of heating and coupled to a heat bath, in order to maximize the power obtained. The dependence of the optimal power, and the corresponding optimal operating time, on the form of the heating function is studied. Furthermore, we determine the maximum work production obtainable from the system for a given specific power output.

ISSN:0021-8979    

DOI:10.1063/1.329835

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

We determine the optical heating of an ideal gas, which is contained in a cylinder equipped with a piston having a given arbitrary motion and which is coupled to a heat bath, so that the work produced is maximal given a total pumping energy. We show that the optimal heating is impulsive and we determine the location of the impulse. Efficiency and thermodynamic analyses are obtained for sinusoidal piston motion.

ISSN:0021-8979    

DOI:10.1063/1.329836

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

In this article we report an investigation of micellar systems by photon correlation technique for the first time. The systems investigated are two very commonly occurring Directo dyes (Congored and Benzopurpurine 4B) in aqueous solutions. From these studies, we are able to exploit their aggregation trends at different dye and salt concentrations and to also compare with available data from other conventional techniques used so far. The conventional methods (microdiffusion cells, ultracentrifuge methods, etc.) often produce controversial results unlike the present technique which is consistent, accurate, and very fast.

ISSN:0021-8979    

DOI:10.1063/1.329837

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

The detailed structure of electron momentum distribution in relativistic diodes is studied. It is proven that in most of the diode region the momentum distribution is isotropic in fluid rest frame, with azymuthal temperature which, in general, is much larger than the cathode temperature. A diode model based on these conclusions is presented. The model allows for a continuum of electron trajectories at each point. In various limits the results are reduced to well‐known cold fluid model results.

ISSN:0021-8979    

DOI:10.1063/1.329838

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

An injector design is described which uses a space‐charge‐limited source of alkali ions and accelerates the ions through two stages of acceleration and slight deceleration stage (to retard the neutralizing electrons) before matched phase space neutralization with an electron reflex triode source occurs. For typical conditions of a 200‐ns pulse and a 1‐MeV 1‐10 A/cm2lithium ion beam, computer simulation experiments demonstrate that 55% of the beam trajectories have an angular divergence less than 250 &mgr;rad (thereby meeting an order of magnitude more stringent constraint at more than an order of magnitude higher power density than any previous electrostatically focused injector design). The method of achieving the low angular divergence profile at readily attainable voltages of 200 kV, current densities of 150 mA/cm2, and vacuum stresses of 50 kV/cm is described. By simply increasing the voltage towards 1 MV, state‐of‐the‐art advances in all the parameter areas can be made without altering the angular divergence profile. Discussions of other issues, such as source temperature, neutralization, self‐magnetic fields, and electrostatic field error contributions to the angular divergence are presented. Finally, the benefits of additional stages of acceleration (needed for future MeV operation) are disclosed and justified.

ISSN:0021-8979    

DOI:10.1063/1.329839

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

An analytic atomic independent particle model potential adjusted to experimental single‐particle energy levels is used to generate wave functions for the valence and excited states of Cl, Ar+1, K+2, Ca+3, Sc+4, these wave functions in conjunction with the Born approximation and theLS‐coupling scheme, we calculate optical oscillator strengths for excitations from the 1s22s22p63s23p5(2P3/2) ground state. Reasonable agreement is obtained with available experimental and theoretical data.

ISSN:0021-8979    

DOI:10.1063/1.329840

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

The frequency shift of theR1ruby fluorescence peak has been measured in the diamond anvil cell along the ice/water melting curve in the temperature interval 25–200 °C and pressure interval 0–40 kbars. The temperature and pressure coefficients of the frequency shift were found to be independent in this region. Using a least‐squares‐fitting program to find the fluorescence peak positions, we could reproducibly measure pressures to ±0.2 kbar at 25 °C and to ±0.5 kbar at 300 °C. The temperature coefficient of the frequency shift ofR1in the interval 25–300 °C was determined to be −0.149 cm−1/°K. Large systematic errors in the pressure determination were found to arise when nonuniformity of temperature in the diamond anvil cell caused uncertainty in the ruby temperature.

ISSN:0021-8979    

DOI:10.1063/1.329841

出版商:AIP    

年代:1981

数据来源: AIP

摘要:

Chemiluminescence from vibrationally excited carbon monoxide formed by the reaction CS+O→CO(v)+S was observed in CS2/O2and CS2/O2/N2O flames to which an electric discharge was applied. Although the total amount of chemiluminescence increased with increasing discharge current probably due to enhanced reaction rates as a result of radical formation, the vibrational distribution was quenched, becoming thermal in character. The thermalization is attributed to superelastic electron collisions [e+CO(v)→e+CO(v−1)]. The technique demonstrates a sensitive method for detecting collisional transfers between excited states by separating the perturbation (electron collisions) from the initial excitation mechanism (chemical reactions).

ISSN:0021-8979    

DOI:10.1063/1.329215

出版商:AIP    

年代:1981

数据来源: AIP