[en] Arrays of interacting Josephson junctions have been studied experimentally. The Josephson element in these arrays consisted of indium microbridges having sub-micron dimensions. An external resistive inductor connected across the array provided long range interaction between the junctions. The results of these experiments have been analyzed in light of the theory developed recently for such systems by Likharev, Kuzmin and Ovsyannikov. Detailed experimental results on the simplest such array of two junctions are presented. The interaction leads to frequency pulling and then to phase locking (and voltage locking) as the unperturbed frequencies of the two jucntions are brought closer. The effects of the interaction on the current voltage characteristic of the junctions and the behavior of the radiation linewidth and power in the neighborhood of voltage locking have been studied. These experiments clearly show the differing effects of the junction and coupling loop resistance noise on the locking stability and radiation linewidth for the series and parallel biasing configurations. All these observations are in accordance with the calculations of Likharev, et al. In addition, measurements have also been made on two microbridge arrays coupled by a superconducting loop. In this case, the phase difference between the junction oscillations was dependent on the flux through the loop, and both the radiated power and the linewidth varied periodically with this flux. An additional normal shunt was found to considerably decrease the variation of the phase difference with the flux. Larger linear arrays containing up to 99 junctions have also been studied

[en] The primary purpose of Global Warming Potential (GWP) is to compare the effectiveness of emission strategies for various greenhouse gases to those for CO₂, GWPs are quite sensitive to the amount of CO₂. Unlike all other gases emitted in the atmosphere, CO₂ does not have a chemical or photochemical sink within the atmosphere. Removal of CO₂ is therefore dependent on exchanges with other carbon reservoirs, namely, ocean and terrestrial biosphere. The climatic-induced changes in ocean circulation or marine biological productivity could significantly alter the atmospheric CO₂ lifetime. Moreover, continuing forest destruction, nutrient limitations or temperature induced increases of respiration could also dramatically change the lifetime of CO₂ in the atmosphere. Determination of the current CO₂ sinks, and how these sinks are likely to change with increasing CO₂ emissions, is crucial to the calculations of GWPs. It is interesting to note that the impulse response function is sensitive to the initial state of the ocean-atmosphere system into which CO₂ is emitted. This is due to the fact that in our model the CO₂ flux from the atmosphere to the mixed layer is a nonlinear function of ocean surface total carbon

[en] We carried out essentially all the carbon cycle modeling calculations that were required by the IPCC Working Group 1. Specifically, IPCC required two types of calculations, namely, ''inverse calculations'' (input was CO₂ concentrations and the output was CO₂ emissions), and the ''forward calculations'' (input was CO₂ emissions and output was CO₂ concentrations). In particular, we have derived carbon dioxide concentrations and/or emissions for several scenarios using our coupled climate-carbon cycle modelling system

[en] Analysis of the variation in the saturation of the skew quadrupole (α₁) is presented for the 15m long, 50mm aperture SSC collider dipole magnet prototypes built at BNL. The variations within a magnet are shown to be correlated with local top-bottom asymmetry in the iron yoke weight. On the other hand, magnet to magnet variations in the saturation of integral skew quadrupole are shown to be correlated with the geometric α₁

[en] The NSLS-II light source is a proposed 3 GeV storage ring, with the potential for ultra-low emittance. Despite the reduced emittance goal for the bare lattice, the closed orbit amplification factors are on average >55 in both planes, for random quadrupole alignment errors. The high chromaticity will also require strong sextupoles and the low 3 GeV energy will require large dynamic and momentum aperture to insure adequate lifetime. This will require tight alignment tolerances (∼ 30(micro)m) on the multipole magnets during installation. By specifying tight alignment tolerances of the magnets on the support girders, the random alignment tolerances of the girders in the tunnel can be significantly relaxed. Using beam based alignment to find the golden orbit through the quadrupole centers, the closed orbit offsets in the multipole magnets will then be reduced to essentially the alignment errors of the magnets, restoring much of the dynamic aperture and lifetime of the bare lattice. Our R and D program to achieve these tight alignment tolerances of the magnets on the girders using a vibrating wire technique, will be discussed and initial results presented.

[en] A coherent array of Josephson oscillators is provided. Individual hysteresis-free Josephson junctions are longitudinally arranged in a gap of a central conductor in a line and have such a spacing as to substantially eliminate quasiparticle interactions. To provide a common frequency of operation, equal and opposite dc voltages are produced in adjacent pairs of the Josephson junctions by an arrangement of interlocking dc SQUID's (Superconductive Quantum Interference Device) connected to the longitudinal central conductor using microwave bias tees. Phase coherence for the array is provided by a rf current circulating in an inductive feedback path that loops between the ends of the array

[en] A coherent array of Josephson oscillators is provided. Individual hysteresis-free Josephson junctions are longitudinally arranged in a line and have such a spacing as to substantially eliminate quasiparticle interactions. To provide a common frequency of operation, equal and opposite dc voltages are produced in adjacent pairs of the Josephson juncitons by an arrangement of interlocking dc SQUID's (Superconductive Quantum Interference Device) connected to transversely extending biasing leads. Phase coherence for the array is provided by a rf current circulating in an inductive feedback path that loops between the ends of the array

[en] Past studies have revealed solar cycle changes in the sunspot activity, as well as in many other solar parameters, such as solar flares and solar coronal holes. These solar features in turn produce the observed cyclic variations in the interplanetary plasma and fields. Both the cosmic ray intensity as well as the intensity of geomagnetic disturbances are affected by the interplanetary changes and produce 11/22 year periodicity. An anomalous situation has been noticed during the year 1980 (period of high sunspot activity), when both the geomagnetic disturbance index Ap, as well as the magnitude and number of Forbush decreases, are small. Such an anomaly occurs in spite of the fact that both the sunspot numbers and the energetic solar flares are almost maximum during the present solar cycle

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No abstract available