[en] Published in summary form only

[en] Cluster beams of various gases have been produced by a versatile test setup, where the configuration of nozzles, skimmers and collimators has been studied and optimized. The parameters determining the cluster yield were investigated using elastic electron scattering. Functional dependences of the various quantities have been extracted. A detailed evaluation of the pumping capacities shows that, compared to existing cluster targets, much lower pumping capacities are required for gases of mass higher than that of hydrogen. (orig.)

[en] This study is motivated by the observation that recent investigations of dimpled surfaces employed for enhancing heat transfer rarely go beyond general parameters like pressure losses and heat transfer performance. Here, we explore a real world dimpled cross-flow heat exchanger. In particular, we are interested in the global parameters, but also in the local flow situation around a single dimplelike protrusion. Detailed PIV-experiments and simulations of the local flow around single protrusions and groups of them reveal the flow structures essential for heat transfer. These local results are brought in conjunction with the general performance of the heat exchanger. Based on local results, simulations of the complete heat exchanger are carried out which are found to be in reasonable agreement with the global parameters found experimentally.

[en] For a 500 MW nuclear heatig reactor optimum design variants, which meet given thermodynamic, flow-mechanical and vibration-technical requirements, can be calculated by computers. Gravity flow of heat transfer agents in tube bundles and vibration excitation due to vortex flow are considered. (author)

[en] Published in summary form only

[en] Atomic excitation and ionization processes affect the shape of yield curves of narrow nuclear resonances obtained with high beam energy resolution. Yield curves for the narrow resonances in the ²¹Ne + p reaction at E_p = 126, 272 and 291 keV and for the E_p = 309 keV resonance in ²³Na + p were measured with very low target densities (i.e., with thin targets fulfilling atomic single collision conditions). The ionization probabilities of K and L electron shells were determined at an impact parameter close to zero. Collision spectra were measured which provide information on the energy loss integrated over all impact parameters in a single collision. From an analytical description for the thin-target yield curve and the experimental collision spectra, the experimental thick-target yield curves with an intense Lewis peak could be reproduced with a Monte Carlo computer simulation. (author)

[en] The 400 kV accelerator at Muenster has been optimized with respect to high energy resolution and stability. Yield curves of narrow resonances in ²¹Ne(p, γ)²²Na have been investigated utilizing a windowless gas target of monolayer thickness (or less). The thermal Doppler broadening was the major contribution to the width of thin-target yield curves and was reduced by cooling the ²¹Ne target gas to temperatures as low as 25 K. Atomic effects on the shape of thin- and thick-target yield curves are discussed. (orig.)

[en] The E_R=126, 272 and 291 keV resonances in the ²¹Ne(p, γ)²²Na reaction have been investigated with a high-energy-resolution ion beam. The E_R=272 keV resonance was found to consist of two states separated by (888±5) eV, where the lower (higher) energy member is a high-spin (low-spin) state. All four resonances have widths less than a few eV, which is an improvement of nearly two orders of magnitude below previously reported limits. The influence of atomic effects on the determination of the correct value for the resonance energy is examined. (orig.)

[en] For high resolution studies of narrow (p, γ) resonances a computer controlled energy scanning system was developed at the 400 kV Muenster accelerator. The system, targetry and results of Lewis effect studies are described. (orig.)

[en] Improvements in targetry and ion beam energy resolution permit the observation of novel effects using narrow nuclear resonances as a probe. For the 400 kV Muenster accelerator the ion-beam energy resolution was reduced to 15-20 eV at full ion-beam current. The development of UHV, vapor, and gas target systems allowed the use of very clean targets with variable density and temperature. With the energy spread of the ion beam approaching the eV level, the dynamics of the nuclear environment (atomic shells and solid material) become observable. Some novel applications in nuclear, atomic, molecular, and solid state physics are discussed. (orig.)