Relaxation to nonequilibrium in expanding ultracold neutral plasmas

We investigate the strongly correlated ion dynamics and the degree of coupling achievable in the evolution of freely expanding ultracold neutral plasmas. We demonstrate that the ionic Coulomb coupling parameter Gamma(i) increases considerably in later stages of the expansion, reaching the strongly coupled regime despite the well known initial drop of Gamma(i) to order unity due to disorder-induced heating. Furthermore, we formulate a suitable measure of correlation and show that Gamma(i) calculated from the ionic temperature and density reflects the degree of order in the system if it is sufficiently close to a quasisteady state. At later times, however, the expansion of the plasma cloud becomes faster than the relaxation of correlations, and the system does not reach thermodynamic equilibrium anymore.     

Relaxation into tunnel induced nonequilibrium states in metal-oxide semiconductor structures

The relaxation of a metal-oxide semiconductor structure from deep depletion towards a tunnel-induced non-equilibrium steady state is addressed in this work. A simple model was constructed, taking into account thermal generation, tunneling of both types of carriers and impact ionization. Experimental results obtained on p-and n-type Si substrates and oxides thinner than 6.5 nm are shown to be well fitted by the proposed model. A map describing the possible behavior patterns for a structure with given oxide thickness and effective generation velocity is presented. Fiz. Tverd. Tela (St. Petersburg) 41, 862–864 (May 1999) Published in English in the original Russian journal. Reproduced here with stylistic changes by the Translation Editor.     

Relaxation phenomena in nuclear orientation

A survey is given of relaxation phenomena relevant to nuclear orientation at temperatures below 1 K. Relaxation mechanisms, time dependence of the angular distribution of nuclear radiation and experimental methods for relaxation measurements are reviewed. Finally, some open questions related to simultaneous influence of rf fields and relaxation, the existence of a spin temperature and the role of domain walls are discussed shortly.     

Relaxation of the nonequilibrium domain structure in TGS and TGSP crystals

The relaxation behavior of the nonequilibrium domain structure in nominally pure triglycine sulphate and triglycine sulphate doped with phosphorus has been investigated. A significant difference in the state of the domain structure formed as a result of slow and rapid cooling of crystals into the ferroelectric phase has been found.     

Free nuclear induction in nonequilibrium spin systems

This paper considers the forming of nuclear induction signals upon their excitation by a periodically repeated series of two resonance RF pulses. The expressions obtained for the signals explain the regularities in the observed effects.Free induction and echo are possible only in nonequilibrium spin systems. Here the term nonequilibrium is used to characterize the state of a system previous to its excitation by induction or echo.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 4, pp. 64–69, April, 1978.     

Relaxation and lyapunov time scales in a one-dimensional gravitating sheet system

The relation between relaxation, the time scale of Lyapunov instabilities, and the Kolmogorov-Sinai time in a one-dimensional gravitating sheet system is studied. Both the maximum Lyapunov exponent and the Kolmogorov-Sinai entropy decrease as proportional to N(-1/5). The time scales determined by these quantities evidently differ from any type of relaxation time found in the previous investigations. The relaxation time to quasiequilibria (microscopic relaxation) is found to have the same N dependence as the inverse of the minimum positive Lyapunov exponent. The relaxation time to the final thermal equilibrium differs from the inverse of the Lyapunov exponents and the Kolmogorov-Sinai time.     

双色噪声驱动光学双稳系统的弛豫时间研究

研究乘性及加性噪声的自关联时间τ₁和τ₂,交叉关联时间τ对光学双稳系统的弛豫时间的影响.弛豫时间T由Mei等所采用的方法得到. 经数值计算, 结果表明: 两噪声间交叉关联时间τ及乘性噪声的自关联时间τ₁延缓系统涨落的消退(T随τ及τ₁的增大而增大);T随加性噪声的自关联时间τ 关键词： 关联噪声 弛豫时间 光学双稳系统     

Relaxation time measurements in zinc alloys

Relaxation times obtained by means of de Haas-van Alphen measurements have been investigated in dilute alloys ofZnMn andZnAg. In both series of alloys measurements have been made on the needle, monster and lens sections of the Fermi surface. In theZnMn alloys, which exhibit a Kondo resistance minimum, the results analysed followingPaton andMuir [2] give a value for the s—d interaction constant,J, agreeing with this previous work. Similarly, an analysis followingNagasawa [4] givesJ values in agreement with that work. The situation posed by the existence of these two approaches, concerned as they are with opposite extreme limits, is discussed. In addition, the behaviour found in the other periods ofZnMn is discussed; here the effects seen on the needles are completely absent. A preprint of this paper was introduced during the discussion at the Conference on Electron Mean Free Paths by the Chairman of the Session, Dr.D. Shoenberg.     

Entropy production and time asymmetry in nonequilibrium fluctuations

The time-reversal symmetry of nonequilibrium fluctuations is experimentally investigated in two out-of-equilibrium systems: namely, a Brownian particle in a trap moving at constant speed and an electric circuit with an imposed mean current. The dynamical randomness of their nonequilibrium fluctuations is characterized in terms of the standard and time-reversed entropies per unit time of dynamical systems theory. We present experimental results showing that their difference equals the thermodynamic entropy production in units of Boltzmann's constant.     

Friction and diffusion coefficients in coordinate in nonequilibrium nuclear processes

The influence of different sets of friction and diffusion coefficients on the dynamics of a nuclear system is investigated. Taking as an example a dinuclear system we show in a “classic” investigation that with zero diffusion in the coordinate, the uncertainty relation can be violated during short initial times. Sets of diffusion coefficients are found for which the “classic” and quantum diffusion equations give close physical results. The tunneling through an energy barrier is sensitively influenced by the friction and diffusion coefficients in coordinate in the diffusion equation.     

Relaxation time estimates for multipath catalytic reactions

Some results of studying the dynamic behavior of multipath catalytic reactions are given. Finitely and infinitely slow relaxations to stable stationary states were distinguished, and some relaxation time estimates are presented.     

Relaxation time of an adsorbing 4He film

The readsorption of ⁴He atoms on a constantan heater surface was studied after flash desorption by the heat pulse technique. The replenishment of the desorbed film after the heat pulse was found to be essentially linear with the time between the pulses, reaching saturation at some critical value, t_rc, which strongly depended on the pressure in the vapor, P_g. With the help of kinetic theory for the flux of atoms striking a surface, the measured value of t_rc could be calibrated to give P_g. We have verified this formula directly and used it to measure pressures down to 10^?9 Torr.     

Relaxation time of water's high-density amorphous ice phase

Dielectric relaxation spectroscopy of pressure amorphized hexagonal ice shows that water's high-density amorphous form relaxes in approximately 1 s at 140 K and 1 GPa and that the relaxation is virtually unaffected by pressure. This indicates that the amorph is an ultraviscous liquid above 140 K, the same as would be obtained by supercooling water at 1 GPa through its ice VI phase boundary, and that the glass transition temperature is independent of pressure and close to that of amorphous solid water produced at atmospheric pressure.