Hybrid gas-metal co-implantation with a modified vacuum arc ion source

Energetic beams of mixed metal and gaseous ion species can be generated with a vacuum arc ion source by adding gas to the arc discharge region. This could be an important tool for ion implantation research by providing a method for forming buried layers of mixed composition such as e.g. metal oxides and nitrides. In work to date, we have formed a number of mixed metal-gas ion beams including Ti+N, Pt+N, Al+O, and Zr+O. The particle current fractions of the metal-gas ion components in the beam ranged from 100% metallic to about 80% gaseous, depending on operational parameters. We have used this new variant of the vacuum arc ion source to carry out some exploratory studies of the effect of Al+O and Zr+O co-implantation on tribology of stainless steel. Here we describe the ion source modifications, species and charge state of the hybrid beams produced, and results of preliminary studies of surface modification of stainless steel by co-implantation of mixed Al/O or Zr/O ion beams. 5 figs, 21 refs

Monitoring international migration flows in Europe. Towards a statistical data base combining data from different sources

The paper reviews techniques developed in demography, geography and statistics that are useful for bridging the gap between available data on international migration flows and the information required for policy making and research. The basic idea of the paper is as follows: to establish a coherent and consistent data base that contains sufficiently detailed, up-to-date and accurate information, data from several sources should be combined. That raises issues of definition and measurement, and of how to combine data from different origins properly. The issues may be tackled more easily if the statistics that are being compiled are viewed as different outcomes or manifestations of underlying stochastic processes governing migration. The link between the processes and their outcomes is described by models, the parameters of which must be estimated from the available data. That may be done within the context of socio-demographic accounting. The paper discusses the experience of the U.S. Bureau of the Census in combining migration data from several sources. It also summarizes the many efforts in Europe to establish a coherent and consistent data base on international migration. The paper was written at IIASA. It is part of the Migration Estimation Study, which is a collaborative IIASA-University of Groningen project, funded by the Netherlands Organization for Scientific Research (NWO). The project aims at developing techniques to obtain improved estimates of international migration flows by country of origin and country of destination

High-gradient normal-conducting RF structures for muon cooling channels

We present a status report on the research and development of high-gradient normal-conducting RF structures for the ionization cooling of muons in a neutrino factory or muon collider. High-gradient RF structures are required in regions enclosed in strong focusing solenoidal magnets, precluding the application of superconducting RF technology [1]. We propose using linear accelerating structures, with individual cells electromagnetically isolated, to achieve the required gradients of over 15 MV/m at 201 MHz and 30 MV/m at 805 MHz. Each cell will be powered independently, and cell length and drive phase adjusted to optimize shunt impedance of the assembled structure. This efficient design allows for relatively small field enhancement on the structure walls, and an accelerating field approximately 1.7 times greater than the peak surface field. The electromagnetic boundary of each cell may be provided by a thin Be sheet, or an assembly of thin-walled metal tubes. Use of thin, low-Z materials will allow passage of the muon beams without significant deterioration in beam quality due to scattering. R and D in design and analysis of robust structures that will operate under large electric and magnetic fields and RF current heating are discussed, including the experimental program based in a high-power test laboratory developed for this purpose

The Track Imaging Cerenkov Experiment

We describe a dedicated cosmic-ray telescope that explores a new method for detecting Cerenkov radiation from high-energy primary cosmic rays and the large particle air shower they induce upon entering the atmosphere. Using a camera comprising 16 multi-anode photomultiplier tubes for a total of 256 pixels, the Track Imaging Cerenkov Experiment (TrICE) resolves substructures in particle air showers with 0.086deg resolution. Cerenkov radiation is imaged using a novel two-part optical system in which a Fresnel lens provides a wide-field optical trigger and a mirror system collects delayed light with four times the magnification. TrICE records well-resolved cosmic-ray air showers at rates ranging between 0.01-0.1 Hz

Modelling And Simulation Of The Operational Impacts And Value Of Distributed Renewable Resources In Electric Power Systems

Distributed renewable resources are, together with other novel decentralised power technologies, likely to play an increasingly important role in electric power systems. There are however, a number of operational issues that need addressing before their widespread use. These resources can have variable and somewhat unpredictable power outputs, while the presence of numerous small, and probably independently owned, plants distributed throughout the network has important implications for overall system coordination. This paper outlines the development of an object oriented software modelling and simulation tool for exploring power system operation with distributed resources. Initial studies with the tool have focussed on price-induced coordination and storage optimisation. INTRODUCTION Distributed resources are likely to play an increasingly important role in electric power systems. They include: . renewable energy from photovoltaics, solar thermal, wind, small hydro and biomass, . nov..

Optimised operation of electrical distribution systems with PV and storage using evolutionary programming

Distributed electrical resources seem likely to play an increasingly important role in power systems. This paper presents a novel approach for optimising energy storage operation in electric distribution systems with renewable energy sources. Initial studies presented here indicate that evolutionary programming can determine near optimal solutions for simple power system problems with a single energy storage. This evolutionary approach appears to offer important advantages over conventional techniques for exploring decentralised coordination of power system operation when there are high levels of distributed resources. Introduction Distributed electrical resources are increasingly cost effective as well as environmentally less damaging alternatives to conventional large-scale power generation. These resources include: . renewable energy from photovoltaics, solar thermal, wind, small hydro and biomass, . novel fossil fuelled generation including gas turbines and fuel cells, . energ..

MECHANICAL DESIGN OF A HEAVY ION RFQ

The mechanical design and construction of a 199.3 MHz heavy ion RFQ for charge states q/A as low as 0.14 is described. The vane supports and positioning adjustments are significant features of this design. They provide the capability of achieving the precision vane alignment required. The maximum difference between calculated and measured apertures between the vanes is 0.0035 inches, and the average difference is 0.0010 inches. Various important aspects of the design and construction including material selection and plating, RF joints, thermal loading and vacuum system are described. Assembly techniques, methods of mechanical measurement, alignment and structure stability are discussed in detail

Vacuum arc ion sources: micro to macro

Vacuum arc ion sources provide a convenient tool for the production of intense beams of metal ions. The sources are relatively easy to construct and they can produce beams from all of the solid metals as well as of compounds, alloys and mixtures. We have made a number of different kinds of such sources over the course of our development work at LBL in the past decade, from very small {open_quote}thumb-size{close_quote} versions to a very large one with 50-cm diameter extractor. Beam current ranges from a few milliamperes up to almost 10 amperes and extraction voltage from about 1 kV to 100 kV. Multicathode versions have been made so that one can switch between metal ion species simply and quickly. Most of the sources have been operated in a repetitively pulsed mode, and we`ve tested a dc version also. Here we outline some construction features of the array of vacuum arc ion sources that we`ve developed and used, and describe their performance and limitations