Mechanisms of rectification of a high-frequency signal by a field-effect heterotransistor with a short channel

The effect of nonlinearity of the drift velocity of free charge carriers and the gradient-and concentration-related nonlinearities in the power-voltage sensitivity of a field-effect transistor with a short channel are studied theoretically. Theoretical results are compared with experimental data on the detection of terahertz radiation. It follows from the comparison that, in order to gain deeper insight into observed systematic features in the analysis of high-frequency characteristics of the transistor, one has to take into account some other mechanisms of the current nonlinearity, in addition to the plasma-related nonlinearity.     

The effect of electromagnetic fields on hydrogen-atom transport in steel

This article describes a model of hydrogen diffusion processes, shows the influence of protective cathode stations on the hydrogen saturation of underground-pipeline metal, and suggests a new method to find hydrogen-saturated sections in underground steel gas-supply systems.     

Activation energy of electron-stimulated quenching of the photoluminescence of n-type porous silicon

The degradation of photoluminescence of porous silicon by kilovolt electrons and the mechanism and activation energy of this process have been investigated. Quantitative relations between the integral intensity of the photoluminescence and the irradiation dose and substrate temperature are obtained. The mechanism of the process is discussed and its activation energy is determined. Pis’ma Zh. Tekh. Fiz. 23, 44–50 (September 26, 1997)     

Failure of hot gas sprayed coatings in combined deformation with the substrate

Conclusions The nature of failure of the examined hot gas sprayed coatings in combined deformation with the substrate metal depends on the relation between the cohesion strength of the coating material and adhesion strength of the coating-substrate boundary. This ratio is determined mainly by the porosity and degree of oxidation of the coatings. The main cracks form in these coatings at stresses similar to the yield stress of the substrate metal.Translated from Poroshkovaya Metallurgiya, No. 10(310), pp. 45–48, October, 1988.     

An analog of the hollow cathode effect in low-pressure high-frequency capacitive discharge

We have studied the process of ion flux formation in a low-pressure high-frequency capacitive discharge in the presence of a cavity on the electrode surface. If the cavity size is on the order of an electrode space charge sheath thickness, the spectrum of ions arriving at the cavity bottom surface contains a low-energy peak. The mechanism responsible for this peak is analogous to the hollow cathode effect in a dc discharge.     

Effect of the neutron spectrum on the characteristics of Np, Am, and Cm transmutation chains

It is shown by analysis of the influence of the neutron spectrum on the neutron balance of the transmutation chains of ²³⁷Np and ²⁴¹Am that in a fast-reactor spectrum these chains are short and more neutrons are created (excess 0.8–1 neutron per starting nucleus) than absorbed in them. In a thermal-reactor spectrum, these chains are longer and more neutrons are absorbed (deficit 0.7–0.83 per starting nucleus) than created in them. Additional nuclear fuel, for example, ²³⁵U and ²³⁹Pu, must be burned to cover the neutron deficit. __________ Translated from Atomnaya énergiya, Vol. 100, No. 6, pp. 452–458, June, 2006.     

Conductance fluctuations in solids caused by defect migration

Conductance fluctuations caused by defect migration in randomized potential profile within the specimen of solids are considered and the problem of spectrum evaluation is solved. The noise is presented in the time domain as a superposition of local disturbances in the conductance. Each disturbance is a clustered random telegraph signal (RTS). The evaluation of the resulting spectrum is reduced to Lorentzians' summation. The approach suggested is more general compared to the known model of two-level systems (TLS) which considers defect jumps between two selected states. The criteria which are decisive for the shape of the noise spectrum are formulated. Mechanisms of conductance modulation initiated by defect migration are considered in detail. Numerical estimations for the resultant noise magnitude are also presented.