Surface profile measurement of low-frequency vibrating objects using temporal analysis of fringe pattern

A simple and accurate algorithm (phase scanning method) is proposed for 3D surface contouring and dynamic response determination of a vibrating object. A sinusoidal fringe pattern is projected onto a low-frequency vibrating object by a programmable liquid crystal display projector. The fringe patterns are captured by a high-speed CCD camera with a telecentric gauging lens. Phase values are evaluated point by point using phase scanning method. From the phase values of each point on the object, the contour of the specimen at different instants of vibration can be retrieved. In this paper, a small vibrating coin is used to demonstrate the validity of the method and the experimental results are compared with test results on a stationary coin using four-step phase shifting and fast Fourier transform methods. The technique is especially useful in applications where the vibrating object has a complicated shape.     

JET: Preparing the future in fusion

JET (Joint European Torus) is the largest tokamak in the world and the only fusion facility able to operate with Tritium, the fusion fuel, and Beryllium, the ITER first wall material. JET also features the most complete remote handling equipment for invessel maintenance. As a multinational research center, JET provides logistic experience in preparing for operation of the global facility, tokamak ITER.Experiments on JET are focused on ITER-relevant studies, in particular on detailing the operational scenarios (EL My H-modes and advanced regimes), on enhancing the heating systems, on developing diagnostics for burning plasmas etc. Pioneering real-time control techniques have been implemented that maximize performance and minimize internal disturbances of JET plasmas. In helium plasmas, ion cyclotron heating (ICRH) created fast α-particles, mimicking their populations in future burning plasmas. The recent successful Trace Tritium campaign provided important new data on fuel transport. Current enhancements on JET include a new ITER-like ELM-resilient high power ICRH antenna (7 MW) and over twenty new diagnostics that will further extend the JET scientific capabilities and push the facility even closer to the ITER parameters.A special mention is given to the involvement of the fusion experts from Association EURATOM-IPP.CR, who have been actively participating in the collective use of JET facility for more than three years.     

Adaptation of selected diagnostic techniques to magnetic confinement fusion experiments

The paper concerns several diagnostic techniques, which have been used in pulsed-power plasma experiments, i.e. Plasma-Focus and Z-Pinch devices, and which can be adapted to studies of Magnetic Confinement Fusion (MCF) facilities, e.g. Stellarators and Tokamaks. The application of Nuclear Track Detectors (NTDs) for time-integrated ion measurements in MCF experiments is described and the use of such detectors for time-resolved ion measurements is discussed. The application of special ?erenkov-type detectors for time resolved measurements of fast runaway electrons is considered. Also discussed is the use of selected nuclear reactions for measurements of fusion products, e.g. fast neutrons.     

A Numerical Calculation for Electron Impact Excitation of Copper

The scattering of electrons by atomic copper has been studied using Born approximation and the concept of the generalized oscillator strength (GOS). Differential and total cross-sections for the excitation of the 3d¹⁰ 4p² P state are calculated at incident energies of 100 eV and are compared with other available experimental and theoretical data. The agreement between our calculation for the differential cross-section and the available experimental results is fairly good at the forward angles, while the agreement at large angles is poor. The calculated total cross-sections are compared with the experimental data and those predicted by several theories. It is found that our calculation for the total cross-sections are in a good agreement with the close coupling calculation of Msezane and Henry (1986a, Physical Review A 33, 1631) for incident energies greater than 20 eV. The integrated cross-section measurements of Ismail and Teubner (1995, Journal of Physics B: Atomic, Molecular and Optical Physics 28, 4164) are in good agreement with the present calculation.     

Charge qubit rotations in a double-dot nanostructure

Quantum operations with a charge solid-state qubit whose logical states are formed by two spatially separated localized states of an electron in the double-dot structure are studied theoretically. We show that it is possible to perform various one-qubit rotations making use of the microwave pulses tuned to the resonances between the localized states and the excited state delocalized over the nanostructure. An explicit analytic expression for the time-dependent electron state vector is derived, and the appropriate pulse parameters are determined.     

Impurity-induced stabilization of Luttinger liquid in quasi-one-dimensional conductors

It is shown theoretically that the Luttinger liquid can exist in quasi-one-dimensional conductors in the presence of impurities in a form of a collection of bounded Luttinger liquids. The conclusion is based on the observation by Kane and Fisher that a local impurity potential in Luttinger liquid acts, at low energies, as an infinite barrier. This leads to a discrete spectrum of collective charge and spin density fluctuations, so that interchain hopping can be considered as a small parameter at temperatures below the minimum excitation energy of the collective modes. The results are compared with recent experimental observation of a Luttinger-liquid-like behavior in thin NbSe₃ and TaS₃ wires.     

Influence of impurities on the metallization of inert gases at high pressures

It is shown that the introduction of heavy inert gas impurities into the condensed phase of a lighter inert gas can significantly change the kinetic properties of the latter at high pressures. The electronic structure of the ordered Ar₁₅Xe solid solution is calculated. Doping of the condensed phase of a light inert gas with atoms of a heavier inert gas may become a new convenient tool in high-pressure experiments.     

On the possibility of terahertz wave generation upon dense gas optical breakdown

The possibility of applying the physical principles underlying the operation of a solid-state terahertz oscillator to plasma gas-discharge media is analyzed. A new method of electromagnetic wave generation in the terahertz frequency range is proposed. It is based on the excitation of plasma-oscillation current by a static electric field in a laser spark produced by an axicon lens, followed by the radiation of an electromagnetic pulse through the Cherenkov mechanism.