A collimator for hot plasma x-ray diagnostics in ion sources

We present a collimator configuration for measuring energy resolved x-ray plasma volume bremsstrahlung emitted, e.g., by an ECRIS. Special attention we paid to shielding the detector against interfering Compton scattered radiation and wall bremsstrahlung stemming from the collimator entrance aperture. We estimate the efficiency for shielding of Compton scattered radiation at least attainable by this arrangement.     

Differential bremsstrahlung cross sections for collisions of electrons with unscreened nuclei of low atomic numbers

Differential bremsstrahlung cross sections for unscreened nuclei are calculated using Sommerfeld-Maue eigenfunctions for the electronic continuum states. The photon energy spectrum and the shape function, defined as the ratio of the differential bremsstrahlung cross section to the photon energy spectrum, are tabulated for incident electron kinetic energies T₁ = 5, 10, 50, and 100 keV and for atomic numbers Z = 8, 18, 26, and 36. For sufficiently low Z and for incident electron kinetic energies and emitted photon energies greater than the K-shell binding energy of the target atom, the present results for unscreened nuclei are in reasonable agreement with and easier to compute than the atomic-field bremsstrahlung cross sections.     

Determination of fracture stress and strain of highly oriented short fibre-reinforced composites using a fracture mechanics-based iterative finite-element method

For a tensile test specimen made of a short fibre-reinforced composite with the fibres oriented in the direction of force, a model was developed to describe the onset and propagation of microcracks, which finally lead to macroscopic failure of the specimen. The crack propagation theory used is based on a standard fracture mechanics method and was applied to the microstructure of the specimen by the finite element method. The results appear qualitatively correct. The micromechanical method applied gives a deeper insight into the fracture processes within short fibre-reinforced composites.     

Climate change and drinking water production in The Netherlands: a flexible approach.

Climate change increases water system dynamics through temperature changes, changes in precipitation patterns, evaporation, water quality and water storage in ice packs. Water system dependent economical stakeholders, such as drinking water companies in The Netherlands, have to cope with consequences of climate change, e.g. floods and water shortages in river systems, upconing brackish ground water, salt water intrusion, increasing peak demands and microbiological activity. In the past decades, however, both water systems and drinking water production have become more and more inflexible; water systems have been heavily regulated and the drinking water supply has grown into an inflexible, but cheap and reliable, system. Flexibility and adaptivity are solutions to overcome climate change related consequences. Flexible adaptive strategies for drinking water production comprise new sources for drinking water production, application of storage concepts in the short term, and a redesign of large centralised systems, including flexible treatment plants, in the long term. Transition to flexible concepts will take decades because investment depreciation periods of assets are long. This implies that long-term strategies within an indicated time path have to be developed. These strategies must be based on thorough knowledge of current assets to seize opportunities for change.     

An Electron-Cyclotron-Resonance Plasma as a Source of Multiply Charged Ions

The properties of an electron-cyclotron-resonance (ECR) plasma (3 cm microwaves up to 2.4 kW) have been investigated. A total of 80 ?A noble gas ion current has been extracted from a 1 mm dia. hole so far. The charge state distributions show a maximum above the 1+ state, indicating that multiple impact ionization is a dominant process. X-ray spectra, sheath potential and microwave reflection were measured to gain some physical understanding of the discharge. The applicability of our device as an ion source is discussed.     

An improved deconvolution method for bremsstrahlung spectra from hot plasmas

The influence of tip region cross sections and the energy resolution of X-ray detectors on the deconvolution of X-ray spectra from hot plasmas into the electronic distribution function is discussed. From the discussion an improved deconvolution method is derived starting from an integral equation of the second kind. Here numerical discontinuities can be handled by a differentiation process, the reliability of which increases with increasing refinement of the measurements.     

Sustainable Water Management through Flexible Method Management

Water management projects are complex and contain many dimensions, including the nature of the problem, technologicalchallenges, and political relevance. Experts and consultants in water management usually work with a limited set of analysis and project planning methods. This implies that expertsand consultants have a restricted spectrum for bidding on watermanagement projects and that the engagement of a specific expertor consultant introduces a biased approach to water management.To alleviate these limitations, experts and consultants shouldhave a readily accessible collection of analysis and project management methods at their disposal, coupled with guidelinesfor combining these methods to best approach a water managementproject. In this paper we propose a taxonomy for classifying methods used in water management. Using this taxonomy, we derivea Project Management Specification Model (PMSM) to help expertsselect, combine, and operationalize methods to match best therequirements posed by a project. The taxonomy and PMSM were derived and validated by analyzing more than 90 methods togetherwith experts in the field of water management, and by using themwithin two new project proposals made by an engineering company.We could conclude that PMSM's broad view on water managementhelps experts and consultants choose flexible analysis and project management approaches, and that it increases the involvement of, and acceptance by, all parties involved in water management.