High Spectral Density Research Articles

Dodge satellite observations of Pc 3 and Pc 4 magnetic pulsations and correlated effects in the ground observations

The analysis of the magnetic field observations from Dodge satellite magnetometer data at L = 6.25 RE shows dominant low‐frequency waves (Pc 3 and Pc 4) in three major frequency bands: 40–35, 25–20, and 8–12 mHz. During the observation period of July–August 1968 the 25‐ to 20‐mHz band always showed high spectral density, indicating the most dominant wave frequency. Similar results were obtained in the analysis of ground magnetometer observations from L = 6.9 to 1.5 near the local time of the satellite observations. The simultaneous observations of the waves at low as well as high L values are important in wave propagation models. This pattern of observations and the polarizations of certain wave events which occurred when Dodge was close to the ground observatory are discussed in terms of contemporary theoretical models.

On the spectral-density approach to the correlation functions of a linear magnetic model

We show that, when one uses the spectral-density method (SDM) to study the spin-spin correlation functions for a Heisenberg linear chain, a difficulty appears in a simple procedure usually utilized to avoid the decoupling in the higher spectral density. Such a difficulty does not exist at the first and second order in the SDM with the decoupling procedure. In these approximations the correlation functions are obtained for arbitrary values of the temperature, the magnetic field and the anisotropy parameter.

Injection locking of a xenon fluoride laser

Operation of a XeF laser at high spectral power densities on transitions within a single vibrational band has been demonstrated. An electron-beam-controlled discharge XeF laser was operated as an injection-locked regenerative amplifier. A narrow-band signal from an étalon-tuned XeF laser was used to lock the regenerative amplifier. Competition between the various components of the emission spectrum was observed. Homogeneous extraction is observed within each vibrational band, indicating that the rotational cross-relaxation time is substantially faster than the radiative lifetime of XeF. Coupling between vibrational bands was not observed. These measurements indicate that the efficient extraction from XeF on a single rotational transition should be possible. The band at 351 nm was found to consist of components arising from at least two different vibrational bands. The transitions in the 353-nm band and one component of the 351-nm band share a common vibrational level in the upper electronic state. These observations are consistent with current vibrational assignments of the XeF spectrum.