The Neutralized Drift Compression Experiment (NDCX-II) is a user facility located at Lawrence Berkeley National Laboratory which is uniquely designed for ion-beam-driven high energy density laboratory physics and heavy ion fusion research. Construction was completed in March 2012 and the facility is now in the commissioning phase. A significant amount of engineering was carried out in order to meet the performance parameters required for a wide range of target heating experiments while making the most cost-effective use of high-value hardware available from a decommissioned high current electron induction accelerator. The technical challenges and design of this new ion induction accelerator facility are described.

The MEVVA (Metal Vapor Vacuum Arc) ion source that has been developed at LBL was reported on for the first time at the 1985 Particle Accelerator Conference [l]. This source can produce hundreds of milliamperes of beam current of metal species from lithium up to uranium. In the period since then we have developed the source further, and this work is summarized here. We have now run the source with over 30 different beam species, and with an extraction voltage up to 110 kV. We have made and operated a miniature source, the MicroMEVVA. A multi-cathode version, in which one can switch rapidly between cathodes of different materials, has recently been constructed and tested. Applications of the source include: as a synchrotron ion source, as an ion source for heavy ion fusion, and for metallurgical ion implantation; we have done some preliminary work in these directions.

Molecular dynamic (MD) simulations are used to probe the ability of Navier–Stokes-order theories to predict each of the constitutive quantities – heat flux, stress tensor and dissipation rate – associated with granular materials. The system under investigation is bounded by two opposite walls of set granular temperature and is characterized by zero mean flow. The comparisons between MD and theory provide evidence of higher-order effects in each of the constitutive quantities. Furthermore, the size of these effects is roughly one order of magnitude greater, on a percentage basis, for heat flux than it is for stress or dissipation rate. For the case of heat flux, these effects are attributed to super-Burnett-order contributions (third order in gradients) or greater, since Burnett-order contributions to the heat flux do not exist. Finally, for the system considered, these higher-order contributions to the heat flux outweigh the first-order contribution arising from a gradient in concentration (i.e. the Dufour effect)

A combination of molecular dynamics simulations, theoretical predictions and previous experiments are used in a two-part study to determine the role of the Knudsen layer in rapid granular flows. First, a robust criterion for the identification of the thickness of the Knudsen layer is established: a rapid deterioration in Navier-Stokes order prediction of the heat flux is found to occur in the Knudsen layer. For (experimental) systems in which heat flux measurements are not easily obtained, a rule-of-thumb for estimating the Knudsen layer thickness follows, namely that such effects are evident within 2.5 (local) mean free paths of a given boundary. Secondly, comparisons of simulation and experimental data with Navier-Stokes order theory are used to provide a measure as to when Knudsen-layer effects become non-negligible. Specifically, predictions that do not account for the presence of a Knudsen layer appear reliable for Knudsen layers collectively composing up to 20 % of the domain, whereas deterioration of such predictions becomes apparent when the domain is fully comprised of the Knudsen layer.

To understand how large systems of neurons communicate, we need to develop methods for growing patterned networks of large numbers of neurons. We have found that diamond-like carbon thin films formed by energetic deposition from a filtered vacuum arc carbon plasma can serve as "neuron friendly" substrates for the growth of large neural arrays. Lithographic masks can be used to form patterns of diamond-like carbon, and regions of selective neuronal attachment can form patterned neural arrays. In the work described here, we used glass microscope slides as substrates on which diamond-like carbon was deposited. PC-12 rat neurons were then cultured on the treated substrates and cell growth monitored. Neuron growth showed excellent contrast, with prolific growth on the treated surfaces and very low growth on the untreated surfaces. Here we describe the vacuum arc plasma deposition technique employed, and summarize results demonstrating that the approach can be used to form large patterns of neurons.

For rapidly flowing granular mixtures, existing kinetic-theory descriptions based on an assumed form of the velocity distribution function typically contain one of two simplifying assumptions: a Maxwellian velocity distribution or an equipartition of energy. In the current work, the influence of non-equipartition effects is explored in the context of two flow types: flow in which species segregation does not occur (namely, simple shear flow) and a segregating flow. For the former case, a comparison between existing kinetic theories and molecular-dynamics simulations of a binary system indicates that the incorporation of a non-Maxwellian velocity distribution is critical for reliable stress predictions, as is consistent with previous findings. However, the predictions are fairly insensitive to the equipartition versus non-equipartition treatment, despite the presence of a significant non-equipartition of energy. Nevertheless, an analysis of the diffusion equation for a segregating flow indicates that the presence of a non-equipartition of energy gives rise to additional components of the driving forces associated with size segregation. These additional components involve gradients of the species temperature, whereas theories based on an equipartition assumption only involve gradients in the mixture temperature. Molecular-dynamics simulations of the segregating flow, in conjunction with kinetic theory of binary systems, show that the non-equipartition effects are non-negligible for systems characterized by moderate values of mass differences and restitution coefficients. These simulations also reveal that the more massive particle may exhibit a lower species temperature than its lighter counterpart, contrary to previous observations in non-segregating systems. A physical explanation for this behaviour is provided.

To understand how large systems of neurons communicate, we need to develop, among other things, methods for growing patterned networks of large numbers of neurons. Success with this challenge will be important to our understanding of how the brain works, as well as to the development of novel kinds of computer architecture that may parallel the organization of the brain. We have investigated the use of metal ion implantation using a vacuum-arc ion source, and plasma deposition with a filtered vacuum-arc system, as a means of forming regions of selective neuronal attachment on surfaces. Lithographic patterns created by the treating surface with ion species that enhance or inhibit neuronal cell attachment allow subsequent proliferation and/or differentiation of the neurons to form desired patterned neural arrays. In the work described here, we used glass microscope slides as substrates, and some of the experiments made use of simple masks to form patterns of ion beam or plasma deposition treated regions. PC-12 rat neurons were then cultured on the treated substrates coated with Type I Collagen, and the growth and differentiation was monitored. Particularly good selective growth was obtained using plasma deposition of diamond-like carbon films of about one hundred Angstroms thickness. Neuron proliferation and the elaboration of dendrites and axons after the addition of nerve growth factor both showed excellent contrast, with prolific growth and differentiation on the treated surfaces and very low growth on the untreated surfaces.

To understand how large systems of neurons communicate, we need to develop, among other things, methods for growing patterned networks of large numbers of neurons. Success with this challenge will be important to our understanding of how the brain works, as well as to the development of novel kinds of computer architecture that may parallel the organization of the brain. Large in vitro networks could show, for example, the emergence of stable patterns of activity and could lead to an understanding of how groups of neurons learn after repeated stimulation. We have investigated the use of metal ion implantation using a vacuum arc ion source, and plasma deposition with a filtered vacuum arc system, as a means of forming regions of selective neuronal attachment on surfaces. Lithographic masks created by treating surfaces with ion species that enhance or inhibit neuronal cell attachment allow subsequent proliferation and/or differentiation of the neurons to form desired patterns. Plasma deposition of optically transparent, electrically conducting, ultra-thin metal films can also be used to form electrodes for extra-cellular electrical stimulation of neurons. Substrates tested in our work were primarily glass microscope slides; some of the experiments made use of simple masks to form patterns of ion beam or plasma deposition treated regions. PC-12 rat neurons were then cultured on the treated substrates coated with Type I Collagen, and the growth and differentiation was monitored. Particularly good results were obtained, for example, for the case of plasma deposition of carbon to form a diamondlike carbon film of thickness about one hundred Angstroms. Neuron proliferation and the elaboration of dendrites and axons after the addition of nerve growth factor both showed excellent contrast, with prolific growth and differentiation on the treated surfaces and very low growth on the untreated surfaces. Here we describe our preliminary investigations, and summarize the results to date.

Summary form only given. To learn about how large systems of neurons communicate, we need to develop, among other things, methods for growing patterned networks of large numbers of neurons. Success with this challenge will be important to our understanding of how the brain works as well as to novel kinds of computer architecture. Large in vitro networks could show, for example, the emergence of stable patterns of activity and could lead to an understanding of how groups of neurons learn after repeated stimulation. We have investigated the use of ion implantation and plasma deposition on the substrate on which neurons will subsequently be grown, using ion species that enhance or inhibit neuron cell attachment, as a means for forming regions of selective neurocompatibility. Lithographic masks, for example, can then be used to form desired patterns. Plasma deposition of optically transparent, electrically conducting, ultra-thin metal films can also be used to form electrodes for extra-cellular electrical stimulation of neurons. Ion implantation was carried out using a vacuum arc ion source (Mevva) to provide energetic (/spl sim/100 keV) broad beams of metal ions, and plasma deposition was done using a filtered vacuum arc system. Substrates were glass microscope slides; some of the experiments utilized simple lithographic masks to form patterns of ion beam or plasma deposition treated regions. PC-12 rat neurons were then cultured on the treated substrates and the growth monitored. Particularly good results were obtained, for example, for the cases of ion implantation with tantalum and of plasma deposition of carbon to form a diamond-like carbon film of thickness several hundred Angstroms. Neuron growth showed excellent contrast, with prolific growth on the treated regions and very low growth on the untreated regions. Here we describe our work along these lines and summarize the results to-date.

Rapid granular flows of two species with different material densities are examined via three-dimensional, hard-sphere simulations of simple shear flow. Simulation results are compared with existing theories for binary systems based on the kinetic theory analogy. The comparison between simulation data and theoretical predictions indicate that although non-equipartition is observed and well-predicted by the theory which accounts for its effects, the influence of non-equipartition on stress predictions is fairly small. The influence of non-Maxwellian effects, however, are critical for accurate stress predictions.

We are developing an embodiment of metal vapor vacuum arc (Mevva) ion source which will operate dc and have a very large area beam. In preliminary testing, a dc titanium ion beam was formed with a current of approximately 0.6 A at an extraction voltage of 9 kV (about 18 keV ion energy, by virtue of the ion-charge state distribution) using an 18-cm-diameter set of multiaperture extraction grids. Separately, we have tested and formed a beam from a 50-cm-diameter (2000 cm2) set of grids using a pulsed plasma gun. This configuration appears to be very efficient in terms of plasma utilization, and we have formed beams with a diameter of 33 cm (FWHM) and ion current up to 7 A at an extraction voltage of 50 kV (about 100 keV mean ion energy) and up to 20 A peak at the current overshoot part of the beam pulse. Here we describe this part of our Mevva development program and summarize the results obtained to date.

A metal ion implantation facility has been developed with which high current beams of practically all the solid metals of the periodic table can be produced. A multicathode, broad-beam, metal vapor vacuum arc ion source is used to produce repetitively pulsed metal ion beams at an extraction voltage of up to 100 kV, corresponding to an ion energy of up to several hundred kiloelectronvolts because of the ion charge state multiplicity, and with a beam current of up to several amps peak pulsed and several tens of milliamps time averaged delivered onto a downstream target. Implantation is done in a broad-beam mode, with a direct line of sight from ion source to target. Here we summarize some of the features of the ion source and the implantation facility that has been built up around it.

A simple and economical microwave plasma-assisted chemical vapor deposition facility has been developed and used for synthesis of diamond thin films. The system is similar to those developed by others but includes several unique features that make it particularly economical and safe, yet capable of producing high quality diamond films. A 2.45-GHz magnetron from a commercial microwave oven is used as the microwave power source. A conventional mixture of 0.2% methane in hydrogen is ionized in a bell jar reaction chamber located within a simple microwave cavity. By using a small hydrogen reservoir adjacent to the gas supply, an empty hydrogen tank can be replaced without interrupting film synthesis or causing any drift in plasma characteristics. Hence films can be deposited continuously for arbitrarily long periods while storing only a 24-h supply of explosive gases. System interlocks provide safe start-up and shut-down and allow unsupervised operation. Here we describe the electrical, microwave, and mechanical aspects of the system, and summarize the performance of the facility as used to reproducibly synthesize high quality diamond thin films.

A plasma immersion ion implantation (PIII) reactor compatible with integrated-circuit fabrication has been developed. Using this system, metallic impurity gettering with a noble gas plasma, sub-100-nm p+/n junction formation with SiF4 plasma for preamorphization and BF3 plasma for doping, trench conformal p+ doping, and Pd ion seeding implantation for selective Cu electroless plating were successfully carried out. The PIII system consists of an electron cyclotron resonance plasma source, a processing chamber with wafer bias supply, a sputtering target with bias supply, gas handling and plasma diagnostic tools. The apparatus is described in this paper. Plasma characterization and reactor performance are also presented.

A novel high current metal ion implantation facility has been developed in which a metal vapor vacuum arc ion source is used. The source is operated in a pulsed mode, with pulse width 0.25 msec and repetition rate up to 100 pps. Beam extraction voltage is up to 100 kV and beam current up to several amperes peak and 10–20 mA time averaged delivered onto target. Implantation is done in a broad beam mode with a direct line of sight from ion source to target. Virtually all of the solid metals of the Periodic Table can be used. The facility has been used for a variety of different research applications, including metallurgical surface modification, high temperature oxidation resistance, ‘fine tuning’ of the composition of highT c superconducting thin films, formation of buried conducting layers in silicon, and other research purposes. Here we describe the implantation facility and some of the research programs carried out at our laboratory and collaboratively with others.

We have developed a high-current metal-ion implantation facility with which high-current beams of virtually all the solid metals of the periodic table can be produced. The facility makes use of a metal-vapor vacuum-arc ion source which is operated in a pulsed mode, with 0.25 ms pulse width and a repetition rate up to 100 pps. Beam extraction voltage is up to 100 kV, corresponding to an ion energy of up to several hundred keV because of the ion charge-state multiplicity; beam current is up to several amperes peak and around 10 mA time-averaged delivered onto target. Implantation is done in a broad-beam mode, with a direct line-of-sight from ion source to target. Here we describe the facility and some of the implants that have been carried out using it, including the “seeding” of silicon wafers prior to CVD with titanium, palladium or tungsten, the formation of buried iridium silicide layers, and actinide (uranium and thorium) doping of III–V compounds.