Momentum transport from nonlinear mode coupling of magnetic fluctuations

A cause of observed anomalous plasma momentum transport in a reversed-field pinch is determined experimentally. Magnetohydrodynamic theory predicts that nonlinear interactions involving triplets of tearing modes produce internal torques that redistribute momentum. Evidence for the nonlinear torque is acquired by detecting the correlation of momentum redistribution with the mode triplets, with the elimination of one of the modes in the triplet, and with the external driving of one of the modes.     

Zersetzungsdrücke und Phasengrenzen von Niobnitriden

Dissociation Pressures and Phase Boundaries of Niobium Nitrides Dissociation pressures of niobium nitrides in the region NbN_1.006–NbN_0.45 were measured by a thermogravimetric method at temperatures from 1300 to 1800°C. The results enabled us to make statements on the two phase regions η/δ, δ/γ and δ/β and on the homogeneity ranges of the δ and the β phase. Enthalpies of the conversions η → δ, δ → γ, δ(γ) → β, and of the formation of the δ phase were calculated. A partial three dimensional c,p,T diagram and a proposal for a twodimensional c,T diagram of the Nb? N system have been designed.     

CHEMICAL ACTINOMETRY IN THE VISIBLE (475 - 610 nm) BY meso-DIPHENYLHELIANTHRENE

Abstract The self-sensitized photooxidation of meso -diphenylhelianthrene to its endoperoxide was kincticallv examined. It is recommendable as a convenient, reliable, and wavelength independent actinometer for the visible wavelength range. The calibration values, the actinometric procedure and the evaluation method are given in detail.     

BOOK REVIEW

Modeling Fluctuating Populations by R.M. Nisbet and W.S.C. Gurney, John Wiley and Sons, 1982, 379 pp.     

Lattice defects of V3Si single crystals studied by positron annihilation

The sensitivity of positrons to point defects created by the irradiation of V₃Si with neutrons is demonstrated. We found no indication of thermal vacancies by thermal equilibrium measurement up to 1273 K which indicates that the monovacancy formation enthalpy for V₃Si isH _1V ^F ≧(1.84±0.14) eV. Investigations within the range of homogeneity for excess vanadium suppot the idea that substitutional defects are the dominating defect type, whereas for excess silicon a direct confirmation of existing structural vacancies as the dominating defect type is given.