A model of disordered non-degenerate semiconductors is investigated in which the bands are randomly undulated. A compact formula is derived for the averaged canonical density matrix of the conduction electrons in the presence of il magnetic field. A generalization of the formula of Sondheimer and Wilson is thus achieved. The magnetic susceptibility due to the conduction electrons is calculated. The enhancement of the diamagnetism with increasing disorder is discussed and interpreted as a consequence of the increase in the average density of the conduction electrons. Es wird ein Model1 ungeordneter, nichtentarteter Halbleiter untersucht, in dem die Energiebander zuflllig oszillieren. Ein kompakter Ausdruck fur den mittleren Wert der kanonischen Dichtematrix der Leitungselektronen im magnetischen Feld wird abgeleitet. Damit kommt man zu einer Verallgemeinerung der Formel von Sondheimer und Wilson. Der Beitrag zur magnetischen Suszeptibilitat, den die Leitungselektronen liefern, wird berechnet. Die Erhohung des Diamagnetismus bei groBerer Unordnung wird als Konsequenz der wachsenden mittleren Leitungselektronendichte interpretiert. 816 31 Bratislava, Czechoslovakia. 2, 040 00 Kogice, Czechoslovakia. 37 physiea (b) 76/2
Intermetallic compounds (IMCs) are essential part of lead-free solders microstructure. In 96.5Sn3AgO.5Cu (SAC305) solder is dominant element tin (Sn). But despite this Sn dominancy only 3% weight contain of silver (Ag) has influence on final structure of solid solder joint. Fundamental impact on strength properties of solder joint has also interaction between the solder and printed circuit board (PCB) pad. Another important factor is effect ofageing process. Analysis ofpresence of IMCs in solder joints is essential key to understand behaviour ofthe lead-free solder joints.
In order to implement a new setup for neutral–beam activated impact excitation spectroscopy at the nuclear fusion experiment ‘‘TEXTOR’’ (Tokamak Experiment for Technology Oriented Research) a 2.45 GHz ECR multicusp ion source was built. Special emphasis was given to extract an intense He+-ion beam, which will be used in the forthcoming experiment. After neutralization the slow (2.2 × 107 cm/s, 1 keV) He atoms are injected into the tokamak plasma. Necessarily the atom beam has to have a small divergence. To optimize the extraction optics, calculations concerning the multihole extraction aperture have been made, taking different ECR-plasma parameters into account. The divergence shows a strong dependence on the extracted beam current density (≳5 mA/cm2) and the chosen optics. The ion source has to be operated in a pulsed mode (max. 5 kHz, duty cycle 50%) due to experimental requirements.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.