Präzisionsmessungen am Spektrum des Wasserstoffplasmas

Detailed and precise investigations on the Balmer spectrum of a hydrogen arc have been made in order to compare the measured absolute values of the spectral emission coefficients with the existing theories, the results being of special interest with respect to line broadening calculations and to the lowering of the ionization energy. The plasma is generated in a stationary high power cascade arc at atmospheric pressure. The experiment covers the temperature range between 12000 and 20000 K, where all emission coefficients show maxima in their temperature dependence. To keep self-absorption within the plasma as low as possible, the investigations have been carried out in side-on observation. The extended gas layer of almost constant intensity surrounding the maxima ensures very accurate results of the side-on measurements. For the necessary precise calibration of the optical system both a standard carbon arc and tungsten strip lamps have been used. As the intensity of these different radiation standards only shows a few percent deviation, a very high accuracy can also be established for the measured hydrogen emission coefficients. After evaluating an average radial temperature distribution at first the absolute emission coefficients of five selected wavelengths are plotted vs. temperature and compared with theory, whereby a very good agreement is found. The emission coefficients of the continuous radiation thus confirm the lowering of the ionisation energy according to Griem used in the calculations. In the following the spectral intensities for 16250 K, i.e. the temperature in the neighbourhood of which all the maxima occur, are represented vs. wavelength to investigate the spectral dependence of the emission coefficients. Again an excellent agreement with theories of continuous radiation and line profiles is found. The experimental line shape ofH _α, however, is described much better by Vidal's ‘Unified Theory” than by Griem's standard profile. When the maxima of the emission coefficients appear appr. at half the tube radius, the side-on distributions of the intensity show a flat top in the center and their value is almost independent of the arc current. Because of these qualities and of the reliability of the theoretical calculations of the spectrum finally the hydrogen arc is recommended for a radiation standard both for the visible and the UV region.     

Ionisation und Zustandsgleichung eines Plasmas unter hohen Drucken und Temperaturen

Zeitschrift für Physik A Hadrons and nuclei - Es wird der Zustand eines thermischen Plasmas im Zustandsbereich: 104 °K< 106 °K undp?108 at diskutiert. In diesem Bereich...     

Quantenstatistische Zustandsgleichung von stark ionisierten Wasserstoffplasmen mittlerer Dichte

A quantum statistical formula for the equation of state of fully ionized plasmas in the mean temperature and mean density region is given. The complete second virial coefficient for the case of Debye screening is taken into account. The binary Slater sums are represented by interpolation between the analytical expressions for small and for large radii respectively. Using the interpolation formulae the equation of state is calculated numerically for the temperatures T = 20000 K and T = 80000 K. The resulting curves are in good agreement with the analytical equation of state for very small densities.     

Methodik und Anwendung des Radioimmunoassays

1. Einleitung

2. Tracerdarstellung

3. Geuinnung von Antiseren

4. Methoden zur Trennung von freier und antikörpergebundener Radioaktivität

5. Analysengang

6. Spezifität

7. Empfindlichkeit

8. Anwendungsbeispiele

9. Literatur     

Bedeutung und entwicklung des elektrobleches

In its approximately 70-year history, depending on the requirements of the users and the research activities of manufacturers, electrical steel sheets have been developed from the early use of a primitive mild steel with high core losses to today's variety of grades for many different applications. For this reason, thorough investigations of metallurgical questions were particularly necessary; furthermore, new manufacturing techniques together with the necessary production facilities, had to be developed, and questions concerning use of the final product, such as the effect of insulation and punching on the magnetic characteristics of the electrical sheet, had to be examined. The evolution in terms of quantity and quality of the product, Electrical Sheet, and its technical and economic significance, will be shown. In addition, indications will be given on trends in further developments.