G. Miano

A Z-Pinch Plasma Lens for Focusing High-Energy Particles in an Accelerator

The high azimuthal magnetic field of a current-carrying plasma column (z-pinch) can be used to collect and focus high-energy charged particles in accelerators. The beam optics and the apparent advantages of such a linear lens compared with conventional focusing devices, such as magnets and magnetic horns, are described. When a plasma lens shall be operated in routine accelerator runs, the physics of the plasma dynamics must be largely understood and the technology has to be mastered. The results of plasma dynamics measurements and of long-term behavior tests with a plasma lens for antiproton collection are reported. The problems of the plasma dynamics control and of the plasma-wall interaction are discussed in view of the envisaged performance for antiproton collection.

A Transmission-Line Model for Full-Wave Analysis of Mixed-Mode Propagation

The paper presents a generalized transmission line model able to describe the high-frequency mixed-mode propagation along electrical interconnects. The model is derived from a full-wave formulation and extends the validity of the standard transmission line (TL) model to frequency ranges where the propagation is no longer of transmission electron microscopy (TEM)-type. This generalized TL model describes the high-frequency differential and common mode propagation and the mode conversion. Within its validity limits, the proposed model provides solutions in good agreement with those obtained through full-wave models. Case studies are carried out to evaluate the high-frequency mode conversion in asymmetric interconnects.

A new model of magnetic hysteresis, based on stop hysterons: an application to the magnetic field diffusion

A new model of scalar static magnetic hysteresis based on the superposition of Krasnoselkii hysterons of stop type is described. Unlike the magnetic hysteresis models known in literature, the present one naturally implements the constitutive relationship H=H[B]. In this respect it allows to formulate a field problem directly in terms of the vector magnetic potential. In the present work the new model has been applied to study the one-dimensional magnetic field diffusion in a hysteretic iron body by means of the Galerkin method.

Electrical behaviour of carbon nanotube Through-Silicon Vias

The paper investigates the high-frequency distribution of the current density in Through-Silicon Vias made by bundles of carbon nanotubes (CNTs). These bundles are described by means of a recently proposed circuit model which, in spite of its simplicity, accounts for the kinetic and quantum phenomena involved in the electrical propagation along CNTs and includes the effects of size, temperature and chirality. The particular electrical properties of such a new material make the CNT-based TSVs quite insensitive to skin-effect and proximity effect. This is shown with reference to a case-study of a TSV pair for the technology node of 22 nm, for which the effects of frequency and temperature variation are analyzed.

Numerical integration of Landau–Lifshitz–Gilbert equation based on the midpoint rule

The midpoint rule time discretization technique is applied to Landau–Lifshitz–Gilbert (LLG) equation. The technique is unconditionally stable and second-order accurate. It has the important property of preserving the conservation of magnetization amplitude of LLG dynamics. In addition, for typical forms of the micromagnetic free energy, the midpoint rule preserves the main energy balance properties of LLG dynamics. In fact, it preserves LLG Lyapunov structure and, in the case of zero damping, the system free energy. All the above preservation properties are fulfilled unconditionally, namely, regardless of the choice of the time step. The proposed technique is then tested on the standard micromagnetic problem No. 4. In the numerical computations, the magnetostatic field is computed by the fast Fourier transform method, and the nonlinear system of equations connected to the implicit time-stepping algorithm is solved by special and reasonably fast quasi-Newton technique.

Comparison of different hysteresis models in FE analysis of magnetic field diffusion

In this paper the diffusion of the magnetic field in a hysteretic iron core slab is considered. The dynamics of the field is described by means of a finite dimensional nonlinear dynamic system obtained by applying the Galerkin method. Two different models have been used to describe the magnetic hysteresis: the Preisachs scalar model and a new scaler model based on a sequential algorithm. Good agreement has been found between the simulations obtained by using the two models. >

A new model of scalar magnetic hysteresis

In this paper the scalar quasi-static magnetic hysteresis is described by means of a new model based on a sequential algorithm, which appears to he a possible alternative to the classical Preisach model. A procedure leading to the identification of the model parameters is described. The hysteretic behavior obtained by using the new model is in good agreement with experimental measurements as well as with the predictions of the Preisach model. Finally, both models have been applied to study the dynamics of a circuit with an hysteretic inductor, driven by a sinusoidal voltage source. Good agreement between the two simulations was found, but our model appears computationally less cumbersome than that of Preisach. >

Signal integrity analysis of carbon nanotube on-chip interconnects

The paper deals with the signal integrity performances of a nanoscale on-chip interconnect made by using the carbon nanotube technology. As conventional copper does, this material can be used for fabricating both horizontal traces and vertical vias. Carbon nanotubes interconnects outperform copper ones in terms of electrical, thermal and mechanical properties. However their inductance is much higher compared to that of conventional material, due to inertial effects. Usually this inductance is neglected in the circuit equivalent representation of carbon nanotube interconnects. Here we use a recently proposed circuit model to study the effects of the inductance on the signal integrity. The analysis is carried out by referring to a realistic configuration foreseen for the future 22 nm technology.

Carbon Nanotubes Interconnects for Nanoelectronics Circuits

Future nanoelectronics will be enabled only by providing the effective capability of connecting the nanometric devices to the circuit boards, therefore a major challenge is the design and fabrication of the nano-interconnects. For nanotechnology applications the limits imposed by physics, materials, assembly and design could not be overcome by simply scaling the conventional metal/dielectric systems: innovation in new materials, new technology and new system integration techniques is required. Carbon nanotubes (CNTs) are recently discovered carbon structures (Iijima, 1991), which have been soon considered as emerging research materials (ITRS, 2007) for nanoelectronics applications (Fig.1), because of their unique properties (Avouris et al., 2003; Saito et al., 2004; Anantram & Leonard, 2006). CNT interconnects are expected to meet many of the requirements for technologies below the 22nm node (ITRS, 2007) in terms of mechanical strength, thermal conductivity and electrical performances. This Chapter is devoted to CNT interconnects, proposed for wiring and for packaging nanotechnology ICs, with the aim of presenting the state-of-the-art of electrodynamics and circuit modelling of CNTs and to provide performance comparisons between conventional and CNT interconnects. Some case-studies of practical application are carried-out, referring to real-world wiring and packaging problems for future nanoelectronics.

High frequency and crosstalk analysis of VLSI carbon nanotube nanointerconnects

The paper investigates the EMC behavior of carbon nanotube interconnects, which are candidate to replace copper in future nanoscale technology. In particular, two problems are addressed: the influence of the kinetic inductance on the high-frequency behavior and the crosstalk performances of such interconnects. A recently proposed model is used to describe these interconnects within the frame of the classical transmission line theory, while retaining the necessary accuracy in describing the typical quantistic and inertial effects involved at such a scale.