The formation of cold dense structures in a hydrogen isotope plasma, caused by the penetration of impurities from a localized source, is modelled numerically. It is shown that a bubble structure with very high densities and low temperatures of all plasma components, i.e. electrons, main and impurity ions, arises if the density of impurity neutrals in the source exceeds a critical level. The maj...

Wet-chemical etching of the barrier oxide layer of anodic aluminum oxide (AAO) was systematically investigated by using scanning electron microscopy (SEM), secondary ion mass spectrometry (SIMS), and a newly devised experimental setup that allows accurate in situ determination of the pore opening point during chemical etching of the barrier oxide layer. We found that opening of the barrier oxid...

Growth conditions have a tremendous impact on the unintentional background impurity concentration in gallium nitride (GaN) synthesized by molecular beam epitaxy and its resulting chemical and physical properties. In particular for oxygen identified as the dominant background impurity we demonstrate that under optimized growth stoichiometry the growth temperature is the key parameter to control ...

Damage from ion implantation in Si can lead to dislocation formation during subsequent thermal annealing. These dislocations may sharply degrade device performance, making it desireable to suppress their formation. In this paper the criterion for dislocation formation is reviewed. Knowing this criterion suggests several ways to avoid dislocation formation in high dose implants for device applic...

The phosphorescence decay rates of thallium-doped ammonium chloride (NHUChTl) phosphors, prepared by crystallization from aqueous solution, have been studied at room temperature for near-ultraviolet emission. The effects of impurity concentration as well as thermal and/or mechanical treatment on the decay rates have been examined. Phosphorescence centres consisting of a Tl+ion and a nearby nega...

Trace impurity transport in tokamaks is studied using an electrostatic, collisionless fluid model for Ion-Temperature-Gradient (ITG) and Trapped-Electron (TE) mode driven turbulence in the presence of radio frequency (rf) fields in the ion cyclotron range of frequencies, and the results are compared with neoclassical predictions. Two separate effects of the rf field on ITG/TE-mode stability and...

We study the efFect of an isolated impurity on the low-energy properties of a half-odd-integerspin Heisenberg antiferromagnetic chain using both numerical and conformal field theory techniques. The impurity corresponds to the substitution of a magnetic ion by a difFerent ion with the same or different spin, or else to the coupling of a magnetic impurity to a single spin on the chain. Depending ...

An impurity placed in a plasma modifies the particle-particle correlations in the plasma. This impurity-plasma-plasma correction is relevant to ion-microfield calculations in hot dense plasmas as well as to models of the fractional quantum Hall excitations in terms of impurity-plasma systems. We show how to calculate such impurity-plasma-plasma corrections and apply them to a calculation of the...

Formation of a centrally peaked profile of the ion temperature by impurity seeding has been observed in all the largest tokamaks: JET, JT-60U, TFTR. A possible explanation of this phenomenon is proposed, which takes into account the suppression of ion temperature gradient instability induced anomalous transport through increasing ion effective charge Zeff and Doppler shift of unstable modes, S⊥...

Theory of the off-centre instability is developed for the impurity ions (Li', CuC, and Ag') in alkali halides on the basis of the charge transfer excitation model which is different in the involved electronic processes from the earlier theory based on the polarizable-point charge ion model. The lowest potential minima for the impurity ion along < 11 1 ), ( 110 ), and < 100 ) crystal axes are ca...