Table of contents

A designing procedure of a high resolution VUV spectrometer with fixed entrance and exit slits have been studied for estimating the ion temperature of highly energetic plasmas by measuring Doppler broadening of the resonance emission line of Fe XXIV ions (central wavelength; λ₀ = 255.29 Å) included as impurity in the plasma.

A newly developed cylindrical grating having straight grooves, with separations which decrease exponentially with increasing number of the groove is used. Wavelength scanning is achived by appropriate translation of the grating.

Less than 0.1 Å instrumental broadening of the line spectrum will be realized.

Deteriorations of resolution of the spectrometer caused by inaccuracies of the surface and groove direction of the grating are discussed, as well as the methods with which the resultant resolution can be corrected.

The present spectrometer with small size and simple structure is expected, under easy operation, to have a resolution high enough to estimate the ion temperature of a plasma down to about 2 keV.

Simultaneous measurement with several such spectrometers will be a powerful aid for finding the best operation of, for instance, tokamak-type plasma generators.

Recently it has been reported that the dependence of the mean normalized multiplicity, R_A, in hadron-nucleus collisions upon the effective number of projectile encounters, ⟨v'⟩ is projectile independent. We report the failure of this kind of scaling using the world data at accelerator and cosmic ray energies. Infact, we have found that the dependence of R_A upon the number of projectile encounters ⟨v⟩_hA is projectile independent. This leads to a new kind of scaling. Further, the scaled multiplicity distributions are found independent on the nature and energy of the incident hadron in the energy range ∼ (17.2–300) GeV.

Excitation of O III by He II is treated for sources over a useful range of densities to give accurate predictions of Bowen/non-Bowen line ratios. These are applied to recent observations of planetary nebulae to show that Bowen excitation increases monotonically with excitation class, and to deduce other important consequences.

The C IV, N V, O VI and F VII quartet term systems have been investigated using the beam-foil method, Wavelengths of more than 70 lines associated with these systems are reported. They are compared to theoretical predictions and to data on analogous transitions in singly excited four-electron ions.

Certain details of the term structure are discussed as are fine structure splittings and the separations of quartet terms arising from electron configuration 1s2p3p, 1s2p3d, and 1s2p4d. In the isoelectronic comparison the effect of configuration mixing becomes apparent for the last case.

The optical-ultraviolet spectrum of a classical Type I supernova (Type Ia) appears to be formed in a pure heavy-element plasma. During the first weeks after the explosion the spectrum forms in the outer, high-velocity layers of the ejected material, where the composition is a mixture of intermediate-mass elements from carbon to calcium. At later times the spectrum forms in deeper, slower material consisting of a time-dependent mixture of iron and cobalt, resulting from the decay of radioactive ⁵⁶Ni that was synthesized by nuclear fusion at the time of the explosion. In a Type Ia Supernova, unlike other astronomical sources of radiation, hydrogen and helium are not present to dominate the atomic process. Consequently, special atomic data needs arise.

Edléns polarization formula is found to fit the high-l solar infrared emission lines attributed to Mg I to the accuracy of the high-precision observations. For several previously unidentified weak lines, assignments are made, a few to Mg. I. With some revision of laboratory energy levels, a more precise ionization limit for Mg I is determined to be 61 671.056 (10)cm^-1. The fine structure of the two strongest lines at 811 and 818 cm^-1 is found to consist of 4 components spaced about 0.001cm^-1 apart with nearly equal intensities. Their behavior in the penumbra magnetic field is well described by the Paschen–Back effect. Their line profile, polarization, and directional properties are discussed.

The emission spectrum of laser-produced cobalt plasma has been recorded photographically in the 8-15Å spectral range by means of a flat T1AP crystal spectrograph. based on isoelectronic regularities from known spectra of other ions, most of cobalt spectral lines are classified as belonging to the Na, Ne, F, O, N, C, B, Be, and Li I isoelectronic sequences.

The spectroscopic methods for recognising and utilising precise regularities in atomic spectra that were presented in Bengt Edlén's classic Handbuch der Physik article "Atomic Spectra" are reviewed in the context of the present state of atomic spectroscopy. The persistence of the predicted trends is examined in the light of new data, and examples are presented which illustrate the continuing importance of these methods.

Spectral lines emitted from the different ionization stages of various elements present (either naturally occuring or deliberately added) in high-temperature tokamak plasmas may be used for localized diagnostics of such plasmas. This fact has motivated a search for transitions suitable for these purposes. Such transitions are of essentially two types: Δn = 0 resonance transitions (in particular of one- and two-valence electron systems) and magnetic dipole transitions arising within the ground configurations of ions of highly-ionized, high-Z elements. The latter transitions are peculiar to the fairly low-density, quasisteady plasmas prevailing in tokamaks – and to celestial plasmas. In this paper we review the progress that has been made in the line identification program, paying particular attention to the high-Z members of the isoelectronic sequences of the second period. For these sequences, critical examinations of measured data and comparisons with theoretical calculations have been carried out by Professor Bengt Edlén, resulting in highly accurate wavelength predictions.

The spectrum of Mo IV was produced in a sliding-spark discharge and photographed with the 10.7 m normal-incidence vacuum spectrograph at the NBS in the 600-3200 Å spectral region. All 35 levels of the 4d³ and 4d²5s even configurations and all 45 of the levels of the 4d²5p odd configuration have been established from the 514 line classifications in the 800-3150 Å region. Parametric calculations have been made for the even level systems with configuration interaction and for the odd configuration.

Energy sites and relative intensities in X-ray emission spectra can yield information on the excitation mode and the chemical surroundings of the emitter atom. This paper is aimed at elucidating the chemical sensitivity of the L X-ray intensity ratio I(Lβ)/I(Lα) of Mn emitter atoms in various coordination compounds. A good correlation is found to occur between this L X-ray intensity ratio and magnetic properties as well as the energy site of a satellite on the high-energy side of the Mn 2p_3/2 ESCA peak.

Recent theoretical calculations of oscillator strengths for dipole allowed transitions of S I, S II, and S III are reviewed.

An overview is presented of a project to calculate large quantities of accurate atomic data for radiative processes of importance in the precise determination of opacities in stellar atmospheres, and for astrophysical and laboratory applications in general. Work is in progress on the oscillator strengths, photoionization cross sections, damping constants, etc., for all atoms and ions in hydrogen through neon isoelectronic sequences going up to iron.

A brief review of advances in the determination of atomic transition probabilities during the last 20 years is given. Several frequently studied transitions are used as examples to indicate the remarkable advances in accuracy and consistency between independent results. Major developing trends and some challenges for the future are also briefly discussed.

The MHD stability properties of a slightly non-circular z-pinch are studied, taking classical viscosity into account. A surface current model is used, and the perturbations are assumed to be incompressible with infinite axial wavelength.

It is found that the only unstable mode is that with m = 1, m being the poloidal mode number. This mode is unstable for all values of the viscosity coefficient μ. Although the growth rate can be made arbitrarily small, even a moderate reduction requires a very large of μ.

Clearly, the observed stability of Extrap, where the non-circularity is due to currents in a number of external conductors, can not be explained by viscosity alone. The required viscosity is about six orders of magnitude larger than the observed classical one.

The instantaneous position and shape of a localized Bloch electron wave packet is considered. Examples are given using Kronig-Penney wave packets near the bottom and near the top of the lowest two allowed bands. The hole-like behavior of a wave packet near the top of a band is shown to be an effect related to the propagation of backward waves.

The infrared absorption by molecules adsorbed onto surfaces is determined by the dynamical dipole moment of the molecules, their density and by the strength of the field at the sites of the molecules. This field, which is determined by the optical properties of the substrate, is generally weak, complicating IR experiments. In particular the signals from semiconductors are very weak compared to metals.

We have therefore studied the IR absorption by a layer of diatomic molecules adsorbed on a metal/semiconductor superlattice and compared with the absorption for the clean metal and the clean semiconductor respectively. We find that the superlattice gives signal strengths which are comparable with the metal, thus making it easier to study the particular adsorption chemistry for a semiconductor surface.

Calculations are presented for the thermoremanent magnetisation m(t) in magnetic materials using a cluster model for their spin-system. The distribution employed for the cluster sizes is Poissonian. We derive for m(t) a form which is a modified power law, consisting of the product of a power law (t/τ₀)^-α and a positive polynomial in α ln (t/τ₀). α is linear with temperature. The thermoremanent magnetisation decays linearly with ln (t/τ₀) over two distinct regimes, one which has been obtained previously, at short observation times, and another that results from the competition between the power law and the polynomial. This second regime occurs significantly for the observation times 10^-3 s ⩽ t ⩽ 10³ s probed mostly by experimental techniques. With increasing temperature, the power law dominates and m(t) decays strongly though non-exponentially.

Resonant conduction band photoemission measurements using synchrotron radiation are presented for UMn₂. The variation of the photon energy around both the U 5d → 5f and the Mn 3p → 3d excitation energy permits the identification of predominantly delocalized U 5f states at E_F and of Mn 3d states around 2.5 eV below E_F. A structure at 1.3 eV below E_F resonates only weakly at the U 5d as well as the Mn 3p threshold and is therefore attributed to U 6d states. The pronounced resonance behaviour of the oxygen 2p derived emission at the Mn 3p threshold indicates a preferential oxidation of Mn.

The influence of anomalous particle fluxes on the spectrum of the large scale magnetospheric turbulence is analysed. It is supposed that fluctuation oblique double-layers provide the main contribution to these fluxes. The nonstationary solution of the magnetospheric convection equations is found in the case of small amplitude perturbations.

A long lasting, widespread sporadic E-layer has been observed by the EISCAT radar during an experiment employing extensive latitudinal scans. The event lasted for about 4 h during local afternoon, and was very patchy in both latitude and time, with large variations in intensity, sometimes being below the threshold of detectability. The altitude of the layer first decreased gradually and then increased before the layer disappeared. It is suggested that the vertical motions are the result of normal atmospheric tidal motion which is modified by the effect of an ionospheric electric field.

Second only to auroral kilometric radiation as the Earth's most prominent radio emission, magnetospheric nonthermal continuum radiation has been the subject of numerous observational and theoretical investigations. It has been well established that nonthermal continuum radiation which exists in both ordinary (O) and extraordinary (X) electromagnetic modes, results from the frequency smearing of low frequency Terrestrial myriametric radiation (TMR) due to multiple reflections within the magnetospheric cavity; higher frequency TMR penetrates the magnetosheath and propagates away through the solar wind. TMR is inherently narrow banded and is produced by the mode conversion of electrostatic upper hybrid (ESUH) waves, with density gradients, possible normal to the magnetic field, playing an important part in the conversion process. Up to the present, most attention has been focussed on the plasmapause as the major source region. It will be shown, however, that the magnetopause far from being only a passive reflector of TMR is itself an important source region. This is not entirely unexpected since it has the three basic ingredients for TMR production – plasma frequencies greater than the cyclotron frequency, the presence of ESUH waves, and regions where the density gradient is large and perpendicular to the magnetic field. Data from satellites within the magnetospheric cavity are presented to illustrate that the magnetopause could well be as active a TMR source as the plasmapause. Results from the linear mode conversion theory will be reported which show that, in contrast to the plasmapause from which the TMR is in the O-mode, the TMR from the magnetopause can appear in both O and X modes.

A unique set of ionospheric radioemissions in the frequency range of 0.6-6.0 MHz has been registered on board of Intercosmos-19 satellite launched in 1979, i.e., during the peak of the last solar activity period. Many new characteristics of ionospheric radioemissions have been discovered in this set. In the above spectral range of emission the Intercosmos-19 data show the following features: If f_p ≲ 3 MHz and _FOF2 ≳ 5.5 MHz, there exists a broadband enhancement centred on 4 MHz, reaching the level of about-82dB; the shape of this enhancement shows minor variation of the order of 3 dBm along the satellite orbit in spite of broad variations of f_p and _FOF2, if the mentioned relations between frequencies are fulfilled; usually if _FOF2 drops even to 3 MHz, the man made radionoises add independently to this enhancement - the enhancement is strongly modified when f_p increases above 5 MHz and its shape is related to the changes of f_p. These characteristics suggest the hypothesis on nonglobal origin on the observed broad-band emission. The aim of the present paper is to discuss this question.

Derived thicknesses, using data from the Stratospheric and Mesospheric Sounder (SAMS) onboard the Nimbus 7 satellite, and 30-mbr height analyses, based on radiosondes, have been combined to provide monthly mean height charts of the upper mesosphere,(0.01-mbar level approx. 78-80km) Four years of charts are available, 1979-1982. Based on this material, the large interannual variability during the northern winter and spring is discussed, with emphasis on the effects of stratospheric warmings during midwinter and spring on the mesospheric circulation. It is shown that the effect of the winter and of the stratospheric disturbances on the upper mesosphere is different from year to year, depending on the timing of the stratospheric events. Such results are needed for the discussions about the representativeness of Reference Atmospheres.

The analysis of measurements of stratospheric wind and radio wave absorption in lower ionosphere in Central Europe and southern Spain shows that the apparent difference between the response of the lower ionosphere in Central (decrease of absorption) and Southern (increase of absorption) Europe to well-developed stratospheric warmings is essentially caused by the different response of the neutral middle atmosphere (Stratosphere) to stratwarms. The periods of dominant meridional wind (much less frequent in Central Europe) are accompanied by enhanced absorption of radio waves. A decrease of absorption (weakening or break-down of the winter anomaly) appears to be observed near or after the strong stratwarm maximum in both regions.

The behaviour of the midlatitude lower ionosphere (Central Europe, USSR, Spain) is studied for the winter of 1983/84. The lower ionosphere is found to be governed by neutral atmosphere variability. The ionospheric data are divided into two groups according to altitude (not latitude or longitude). The principal component analysis method shows that the opposite response to the meteor zone (∼ 95 km) meridional and partly also zonal wind variability appears to be responsible for this division. There is a negative correlation of ionospheric data and zonal wind (∼ 95 km) with the 10 hPa temperature, stronger for the North Pole than for the quasi-local Berlin temperature. This seems to be caused mainly by longer-term trends, i.e., by the fact that the polar 10 hPa temperature reflects well the global behaviour of polar vortex.

Doppler spectral properties of 50 MHz auroral echoes observed at several magnetic aspect angles are presented. The measurements were made with high resolution CW Doppler systems at 10 different aspect angles ranging between 1 and 14 degrees, during a series of experiments carried out the summers of 1981, 1982 and 1983 in western Canada. The extensive data set was representative of several backscatter periods and different geomagnetic conditions. We found that three basic spectral types associated with different irregularity groups and classified as type 1, 2 and 3, existed throughout the aspect angle range. Type 1 and 2 spectra are reminiscent of those observed in both the equatorial and auroral backscatter at small aspect angles, whereas type 3 is a newly established spectral signature possibly related to electrostatic ion cyclotron waves. The evidence suggests that 3 m primary and secondary plasma waves can exist in aurora with k_||/k_⊥ wavenumber ratios perhaps larger than 0.25. Statistical analysis of the data showed the magnetic aspect angle effect upon the Doppler spectrum properties to be weak for all types of irregularities at 50 MHz. It is now clear that equatorial E region instability theories, which had been applied directly to aurora, need important modifications, and possibly the inclusion of field aligned current effects, to account for the magnetic aspect angle observations.

Interferometer techniques, involving cross-spectral analysis and angles of arrival methods, have been used to measure the Doppler velocities and apparent locations of scatterers within the broad beam of the MF radar antenna. Attempts are made to follow the scatterers as they progress through the beam, advected by the wind. In the few cases in which this is possible, detailed comparisons between Doppler and spaced-antenna derived velocities are made. For the majority of cases the scatter is consistent with short lived scatterers and/or multiple wave motions, to which the spaced-antenna method is physically and practically more appropriate.

The azimuthal asymmetry of Doppler velocity fluctuations is used to infer gravity wave phase velocity directions, and to determine the momentum deposition due to wave saturation for short time intervals.