Der Stromverlauf einer Elektronenlawine mit Diffusion

The electron current of an avalanche in a homogenous electric field is calculated taking into account the influence of the diffusion of the electrons and the boundary effect of the anode. The ionisation rate is assumed to be proportional to the current density. The results are significant in measurements of electron diffusion and electron drift velocities.     

Plasmadiagnostik einer Azetylen-Sauerstoff-Flamme mit Mikrowellen und Magnetfeld

In order to determine the electron-molecule collision frequency in an acetylene-oxygen flame (burning within aX-band wave-guide) the decrease of microwave attenuation caused by an increasing magnetic field is being measured. It is shown that this decrease is equivalent to the wellknown high pass character of a plasma. The small attenuation is enlarged by using a Perot-Fabry type waveguide resonator. Nothing has to be known about its properties, since relative attenuation data are used for evaluation only. For the same reason no knowledge of electron concentration is necessary. The collision frequency value is exact within 4%, which is sufficient for excluding Coulomb collision interaction. The comparison with data in the literature is satisfying only, if the collision model of an electron induced dipol is accepted. With this and a flame temperature of about 3350 °K the collision frequency amounts to 179±7 GHz.     

Algebraisch spezielle Einstein-Räume mit einer Bewegungsgruppe

In algebraically special Einstein spaces (R_v=0) with a hypersurfaceorthogonal spacelike Killing vector field _v, the trajectories of the multiple eigen null directions k lie — except one case — in the subspacesV ₃ orthogonal to _v (k=0) and are hypersurface-orthogonal. The solutions with vanishing expansion (k_,;=0, Kundt's class) can be determined explicitly.     

Ladungen in Medien mit einer Dielektrizitätsfunktion

The interaction of charges with matter is described by a phenomenological, linear theory of polarization. For a moving point charge in an infinite medium it is shown that a local, frequency-dependent dielectric function leads to infinite frictional forces. The image force is calculated for a charge moving outside a half-space with local frequency-dependent dielectric function. The integral over the image force converges and depends on the velocity of the particle. The maximum energy of photo-electrons does not, therefore, depend linearly on the photon frequency. The photoelectric effect and its inverse are not time reversed processes, since dissipation occurs.     

Ionisierung von Atom- und Molekularstrahlen mit einer Plasma-Ionenquelle

A method for ionizing atomic and molecular beams is described, in which use is made of a space charge compensated plasma ion source of the Duoplasmatron type. In such a device the ionization yield (ionization and extraction efficiency) can be increased considerably as compared to that in conventional electron bombardment ionizers. The maximum yield of H ₂ ⁺ -ions from a H₂-molecular beam was 3.7%. Further results are contained in the Table.     

Gitterdynamik der Ionenkristalle mit einer quantenmechanischen Behandlung der Ionendeformation

The problem of the electron-phonon coupling is selfconsistently solved by means of a Hartree-Fock approximation and a tight binding approximation for the wave functions. From this we derive a general system of equations of motion which involves both a polarization and a radial and axial deformation of the electronic shell of an ion. Moreover, it is shown under what restrictions the “breathing shell” model of Schröder can be derived.     

Lokale Diagnostik einer Argon-Niederdruckentladung mit Hilfe der resonanten Laserstreuung

We report on the experimental investigations on a laser-like low pressure argon gas discharge. The discharge parameters varied in the range from 0,05 to 1 Torr for the gas pressure and from 10 to 30 A for the discharge current. Local electron densities and temperatures have been measured with an adjustable spherical probe. Spatially resolved measurements of the temperatures and drift velocities of the Ar⁺-ions in the radial and axial direction of the positive column have been carried out by the resonant laser light scattering (fluorescence technique). The radial density profiles of the excited Ar⁺-ions have been determined in two different ways and have been compared with the calculations based on a simple collisional radiative model.     

Erfahrungen mit dem Einsatz eines filmbildenden Dekontaminatiosmittels und einer Dekontaminationspaste

In der kerntechnischen Praxis werden in den USA und Großbritannien filmbildende Dekontaminationsmittel zur Beseitigung von eingetrockneter und staubförmiger Kontamination eingesetzt [1, 2, 3,4]. Diese Produkte, die in den meisten Füllen im wäßrigen Medium vorliegen, haben einen ähnlichen Dekontaminationsmechanismus aufzuweisen wie Dekontaminationslösungen. Sie können als eine spezielle Form wäßriger Dekontaminationsmittel betrachtet werden, wobei gleichzeitig die auf der Oberfläche vorhandenen Schmutzkrusten und Staub in das Filmsystem eingebettet, fixiert und beim Abziehen mit dem Film zusammen entfernt werden. In Zusammenarbeit mit dem Institut für Lacke und Farben, Magdeburg, wurde ein filmbildendes Dekontaminationsmittel für die Amvendung in der kernteehnischen Praxis in der DDR entwiekelt.     

Messungen von Elektronenschauern in Blei und Kupfer mit Hilfe einer Blasenkammer

A propane bubble chamber containing lead or copper plates was used to study the development of cascade showers initiated by electrons with energies of 372, 192 and 92 MeV. For each set of absorbers and each energy the mean number of electrons as a function of the depth was determined. The number of showers was sufficiently large to additionally allow measurement of the fluctuations and the angular distribution of the electrons at various depths. Comparison of our data with conventional theories shows poor agreement whereas the agreement with Monte Carlo calculations byNagel and byZerby is satisfactory.     

Messung der Starkeffekt-Verbreiterungen von Ba II-Linien mit Hilfe einer radialsymmetrischen Gleitentladung

A discharge sliding along the surface of a liquid jet can be used to produce plasmas suited for the determination of atomic constants. Using such a plasma the Stark width of some Ba II lines have been measured. At an electron density of 10¹⁷ cm^?3 the half widths agree within 35% with recent calculations made byCooper andOertel.     

Theorie der Röntgenbeugung an einer planparallelen Platte mit idealem Gitter

Scattering of a plane wave (X-ray) by a plane parallel slab with perfect grating is treated by means of an integral equation. The formulas obtained include the cases of grazing incidence and grazing excidence which had to be excluded in the usual theory.