摘要:

Large‐amplitude solutions of the rate equations for the ruby laser have been obtained corresponding to the initial low value of photon density. The damping rate for these oscillations increases with optical pump rate in contrast to the decrease found experimentally by Walsh and Kemeny.Variation of the damping rate with loss rate is also examined; the damping rate becomes the same order as that of the usual flash lamp (∼103sec−1) for a loss rate corresponding to a rod.

ISSN:0021-8979    

DOI:10.1063/1.1702847

出版商:AIP    

年代:1964

数据来源: AIP

摘要:

Measurements have been made with a Geiger counter of photo‐exoemission from aluminum. The effects of time, temperature, and various adsorbates on the electron emission rate were measured. Adsorption reduces the electron emission rate; ion bombardment within the counter is shown to remove the effects of adsorbed gases. Adsorption of atmospheric gases can explain previously reported decay in emission and temperature effects.

ISSN:0021-8979    

DOI:10.1063/1.1702848

出版商:AIP    

年代:1964

数据来源: AIP

摘要:

This paper develops a procedure for the optimum detection of a deterministic, finite length signal obscured by Gaussian‐Markovian noise that approximates sea noise by employing the concept of a Likelihood Ratio. For the particular noise model, the optimum procedure is to use a cross‐correlation detector. The variables fed to the correlation device are additive combinations of each channel's signal and its derivative. This procedure is equivalent to filtering each channel to render the background noise white and then cross‐correlating the filter outputs.

ISSN:0021-8979    

DOI:10.1063/1.1702849

出版商:AIP    

年代:1964

数据来源: AIP

摘要:

We have observed the near‐field emission patterns of a number of GaAs diode lasers. The onset of laser action is accompanied by an abrupt increase in the intensity of light emission at one or several spots along the junction. The adsorption of a dielectric film at a constant rate on one or both surfaces of a laser causes the threshold current to vary periodically with time. The position of the threshold spot did not vary as long as the film was of uniform thickness along the junction; however, the emission pattern could be altered by a suitable nonuniform film. The variation of the threshold current with film thickness can be fitted by a simple model that assumes the gain in the active region is proportional to the current density. Calculated values for the loss and gain factors ranged from 10 to 60 cm−1and 0.5 to 4×10−2cm/A, respectively.

ISSN:0021-8979    

DOI:10.1063/1.1702850

出版商:AIP    

年代:1964

数据来源: AIP

摘要:

Beat‐frequency light generation in ammonium dihydrogen phosphate, arising from interaction of 3470‐Å ruby maser second harmonic and 7454‐Å ruby stimulated Raman scattering from benzene, has been investigated. A single crystal can serve to efficiently produce both the ruby second harmonic and the beat note, since in each process the phase matching condition is satisfied at nearly the same crystal orientation. The phase matching effect is readily observable when the crystal is rotated.

ISSN:0021-8979    

DOI:10.1063/1.1702851

出版商:AIP    

年代:1964

数据来源: AIP

摘要:

Neutral mercury atoms, formed by charge exchange processes between positive mercury ions and mercury vapor atoms, were found to liberate a copious yield of secondary electrons from a metal surface. Values of &ggr; as high as 0.40 were observed. The source of positive ions was the plasma of a mercury arc discharge. Since such a high yield of secondary electrons is not indicative of ground state neutral atoms, the atoms were assumed to be metastable. To test this hypothesis the neutrals were allowed to decay in their flight to the target. A second method of quenching the supposed metastable atoms consisted of admitting minute quantities of H2and Ar gas into their flight path. In both cases the secondary emission was reduced by several orders of magnitude thus verifying the metastability hypothesis. The 4.66‐, 5.43‐, and 9.0‐eV metastable states were observed along with a long‐lived state having a mean lifetime of 6.0 &mgr;sec. As an experimental side light of great importance, it was observed that Hg−ions were formed in the collimated beam of excited neutral atoms.

ISSN:0021-8979    

DOI:10.1063/1.1702852

出版商:AIP    

年代:1964

数据来源: AIP

摘要:

Measured values of electron density and collision frequency in shock‐heated argon are presented and compared with theoretical equilibrium values. Both parameters are measured as a function of time during a single shock tube experiment. The measured density at 1 and 3 Torr forepressure equals or exceeds the predicted 1016−1017electrons per cc at high Mach number (15–18); for lower Mach number, measured values fall far below the calculated curve, showing that loss mechanisms dominate thermal electron production over a significant interval of shock wave flow. The measured collision frequency compares well with the predicted value at 1 Torr but is lower by about an order of magnitude at 3 Torr. The experimental configuration comprises a theta pinch driven shock tube designed to drive a shock front into a coaxial waveguide. Two types of interference patterns are observed by transverse sampling of the longitudinal waves: the first, an anomalous pattern, is interpreted as a resonance caused by electrons ahead of the shock; the second, a well‐defined interference between incident and reflected waves, yields measurements of the plasma reflection coefficient magnitude and phase.

ISSN:0021-8979    

DOI:10.1063/1.1702853

出版商:AIP    

年代:1964

数据来源: AIP

摘要:

This paper proposes a novel method for dissociating high‐energy molecular ions, such as H2+, which are injected into a magnetic mirror container. The dissociating medium is a highly ionized plasma consisting of protons and high‐energy electrons ejected in the decay of dense thermal neutrons which exist within a nuclear research reactor. The plasma is accumulated within a weak magnetic mirror container inside the reactor and then transferred magnetically to the site where the H2+injection is to take place. Finally the dissociating plasma is compressed magnetically to a density of 1011/cm3and injection is begun. The plasma provides an efficient means for dissociating the injected H2+ions, but contributes negligibly to charge exchange losses of trapped high‐energy protons.

ISSN:0021-8979    

DOI:10.1063/1.1702854

出版商:AIP    

年代:1964

数据来源: AIP

摘要:

Microwave circuit theory is utilized to describe three devices which control coherent optical beams using birefringent crystals. A frequency demodulator uses the difference of the index of refraction along two axes of a birefringent crystal together with a Fabry‐Perot interferometer to obtain an ``s'' type frequency discriminator. An optical isolator consists of a crystal and a polarizer that function in such a way that the input of the device is isolated from the reflection which can occur at its output. An optical switch is based on the filter characteristics of a Fabry‐Perot interferometer which can be adjusted with an electrically activated birefringent crystal.

ISSN:0021-8979    

DOI:10.1063/1.1702855

出版商:AIP    

年代:1964

数据来源: AIP

摘要:

In this paper a simple derivation is given of the distribution of photons emitted when an energetic charged particle passes through a thin layer of dielectric material. This derivation emphasizes the individual microscopic events which occur during such a process. The distribution function is shown to agree with that obtainable from the transition radiation theory of Frank and Ginzburg and from the plasmon decay theory of Ferrell for the case of a thin foil. The special case of a double foil bounded by vacuum is considered in detail, and a general formula is found for the photon distribution function. An approximation analogous to that of Born's in quantum mechanics is developed to treat the case of a general composite foil whose thickness is small compared with &lgr; but which may be large compared withv&lgr;/c, where &lgr; is the wavelength of the light emitted andvis the speed of the charged particle.

ISSN:0021-8979    

DOI:10.1063/1.1702856

出版商:AIP    

年代:1964

数据来源: AIP