Low energy surface sputtering of polycrystalline metals is explained theoretically by means of a three-body sputtering mechanism involving the impinging ion and two metal atoms. By means of quantum-statistical methods, a formula for the number S(E) of atoms sputtered on the average by an ion of energy E is derived from first principles. The theory agrees with experimental sputtering data in the low energy region above the threshold. As an application, mercury-metal atom scattering cross sections are determined by quantitative comparison of the theoretical and experimental S(E) values for sputtering mercury ions from various metals.
Based on the Debye model, the free energy of a nonideal electron-ion plasma is calculated for interaction parameters 0 < Y < Ye below the critical solid state value Ye (y = Ze 2 n 1 / 3 /KTis the ratio of mean Coulomb interaction energy to thermal energy), which takes into account the energy eigenvalues of (i) the thermal translational particle motions, (ii) the random collective electron and ion motions, and (iii) the static Coulomb interaction energy of the electrons and ions in their oscillatory equilibrium positions. From this physical model, the interaction part of the free energy is derived, which consists of a quasi-lattice energy, depending on the interaction parameter Y, and the free energies of the quantized electron and ion oscillations (long-range interactions). Depending on the degree of ordering, the Madelung 'constant' of the plasma is oc(y) = ii. for Y ~ 1, oc(y) :::; ii. for Y > 1 and oc(y) oc yl12 for y <{ 1, where ii. ~ 1 is a constant. The free energy of the high frequency plasmons (electron oscillations) is shown to be very small for y > 1, whereas the free energy of the low frequency plasmons (ion oscillations) is shown to be significant for y > 1, i.e. for proper nonideal conditions. From the general formula for the free interaction energy !!F of the plasma for
This paper reviews ac bridges developed for use in the Bell System for the measurement of impedance parameters, particularly at frequencies in the megacycle range. Three recent bridges designed for measuring networks and components for coaxial systems are described.
Analytical solutions are derived for the electromagnetic E, Hand T waves in coaxial wave guides of inner radius a and outer radius b and of infinite length, which are filled in the direction of propagation z with media of different electric permittivity 8 and magnetic permeabilityjz such that: 8 = 8b Il = III for - CIJ ~ Z < - d; 8 = 82, Il = 112 for - d < z < +d; 8 = 83, Il = 113 for +d < z ~ + CIJ. The power reflection and transmission coefficients of the E, Hand T waves are given as a function of frequency Q) and the guide parameters 81, Ill, a, band d. It is shown that the reflection and transmission coefficients exhibit a periodic fine structure in the frequency space above the 'cutoff frequency as a result of the spatial eigenvalue nature of the field solutions. The theory presented provides analytical foundations for the measurement of the frequency-dependent electric permittivity and magnetic permeability of samples in coaxial wave guides.
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.