5,057 research outputs found
Field emission and lifetime of microcavity plasma
No full textMicroplasmas with cylindrical hollow cathode have been studied by means of two-dimensional particle-in-cell/Monte-Carlo collision (PIC/MCC) simulations. For a given input power, the onset of field emission from the cathode surface caused by the strong electric field generated in these discharges leads to a reduction of the discharge voltage and an increase in plasma density. The plasma density profile can be strongly influenced by localized enhancements of the electric field, which in turn will affect the erosion profile of the cathode. The cathode erosion profile is predicted in this work by combining the ion kinetic information obtained from the PIC/MCC simulation with the sputtering yield computed using SRIM [J. F. Ziegler, J. P. Biersack, and M. D. Ziegler, SRIM: The Stopping and Range of Ions in Matter (Lulu, Chester, 2008)]. The entrance of the cathode and the center region are the areas most susceptible to ion-induced damage. The lifetime of the device, however, can be extended by operating the device at high pressure and by reducing the operating voltage by means of field emission and/or additional electron emitting processes from the cathode.open1133sciescopu
Author Lili Mendoza discusses intellectual freedom in her work
No full textHear Lili Mendoza describe how intellectual freedom motivates her creative endeavors. Lili Mendoza is a fiction writer, poet, translator and was born in Panama. She is the author of the short story collection Corazón de charol a-go-gó (2009). Her stories and poetry have been anthologized in Panama, Costa Rica, Spain, Peru, and the U.S., and showcased at literary events in Europe. An active member of the Theater Guild of Ancon, Mendoza also collaborates in musical and dance performances.
Interviewer Brian JK Mille
Theory of wave propagation along waveguide filled with plasma in finite magnetic field
No full textRigorous analytical theory of wave propagation along a cylindrical waveguide filled with plasmas in a dielectric tube immersed in finite magnetic field is presented. The field components' expressions, eigenvalues, dispersion equations and complex wave power transmission equations have been obtained rigorously and discussed in detail. It is shown analytically that there is no disruption of the wave propagation in the ECR (omega = omega(oe)) case, although the electrical permittivities approach to infinite in the case, and it has been found that a real resonance takes place in this case while omega = (omega(oe)(2) + omega(pe)(2))(1/2), in which the wave propagation of any mode is broken. The effective collisions are taken into consideration in the theory. Based on the above theory, the analytical theory of corrugated plasma waveguide immersed in finite axial magnetic field is also presented. The Floquet's expansion of field components, the dispersion equations, and the coupling coefficients of the corrugated plasma waveguide have been derived rigorously and discussed in detail.X112sciescopu
Plasma characteristics and antenna electrical characteristics of an internal linear inductively coupled plasma source with a multi-polar magnetic field
No full textThe development of a large-area plasma source with high density plasmas is desired for a variety of plasma processes from microelectronics fabrication to flat panel display device fabrication. In this study, a novel internal-type linear inductive antenna referred to as "double comb-type antenna" was used for a large-area plasma source with the substrate area of 880 mm x 660 mm and the effect of plasma confinement by applying multi-polar magnetic field was investigated. High density plasmas on the order of 3.2 x 10(11) cm(-3) which is 50% higher than that obtained for the source without the magnetic field could be obtained at the pressure of 15 mTorr Ar and at the inductive power of 5,000 W with good plasma stability. The plasma uniformity < 3% could be also obtained within the substrate area. When SiO2 film was etched using the double comb-type antenna, the average etch rate of about 2, 100 angstrom/min could be obtained with the etch uniformity of 5.4% on the substrate area using 15 mToff SF6, 5,000 W of rf power, and -34 V of dc-bias voltage. The higher plasma density with an excellent uniformity and a lower rf antenna voltage obtained by the application of the magnetic field are related to the electron confinement in a direction normal to the antenna line.X111sciescopu
Theory of wave propagation along corrugated waveguide filled with plasmas immersed in an axial magnetic field
No full textAnalytical theory of wave propagation along a corrugated waveguide filled with plasmas immersed in a finite axial magnetic field is presented in this paper, Preliminary numerical calculations are also done, showing that the intensity of magnetic field has considerable influence on the dispersive characteristics of wave propagation and the properties of such devices.X116sciescopu
Sparse field level set method for non-convex Hamiltonians in 3D plasma etching profile simulations
No full textLevel set method [S. Osher, J. Sethian, J. Comput. Phys. 79 (1988) 12] is a highly robust and accurate computational technique for tracking moving interfaces in various application domains. It originates from the idea to view the moving front as a particular level set of a higher dimensional function, so the topological merging and breaking, sharp gradients and cusps can form naturally, and the effects of curvature can be easily incorporated. The resulting equations, describing interface surface evolution, are of Hamilton-Jacobi type and they are solved using techniques developed for hyperbolic equations. In this paper we describe an extension of the sparse field method for solving level set equations in the case of non-convex Hamiltonians, which are common in the simulations of the profile surface evolution during plasma etching and deposition processes. Sparse field method itself, developed by Whitaker [R. Whitaker, Internat. J. Comput. Vision 29 (3) (1998) 203] and broadly used in image processing community, is an alternative to the usual combination of narrow band and fast marching procedures for the computationally effective solving of level set equations. The developed procedure is applied to the simulations of 3D feature profile surface evolution during plasma etching process, that include the effects of ion enhanced chemical etching and physical sputtering, which are the primary causes of the Hamiltonian non-convexity. (c) 2005 Elsevier B.V. All rights reserved.X1130sciescopu
Theoretical modelling of an x-ray source based on stochastic acceleration of charged particles at electron cyclotron resonance
No full textThe motion of charged particles in the field of H-waves of a cylindrical and a rectangular waveguide in the presence of a uniform magnetic field is investigated analytically and numerically. We obtain the equations of charged particle motion in the H-wave field under cyclotron resonance conditions, evaluate the width of nonlinear resonances, and establish the criterion for dynamical chaos emergence. The criterion is used to analyse the possibility of stochastic acceleration of charged particles by the field of H-waves of circular and rectangular waveguides in the external magnetic field for x-ray production. The stochastic acceleration of particles in two and three standing waves of a circular resonator and two counter-propagating waves of a rectangular waveguide are investigated. It is shown that, over the course of several hundreds of periods of the microwave field, the kinetic energy of the electrons reaches values of around 1.0 MeV and the average kinetic energy reaches values of the order of 0.3 MeV.X111sciescopu
Sustainment of Plasma Density by a Low Magnetic Field in a Dual-Frequency Capacitively Coupled Plasma
No full textDual-frequency capacitively coupled plasmas (DF-CCPs) have been used to control the ion flux by the high-frequency source and the ion bombardment energy onto the electrode by the low-frequency (LF) source separately. However, an increase in the LF voltage. which extends the maximum ion energy to a higher value, causes the reduction of the bulk plasma length with a subsequent decrease of the plasma density. By using a one-dimensional particle-in-cell/Monte Carlo simulation code, the effect of the magnetic field on a DF-CCP is investigated to find whether the plasma can be sustained during the LF voltage increase. It is found that a low magnetic field can effectively maintain the plasma density and electron temperature constant with respect to the variation of the LF voltage.1144sciescopu
Modeling of Nanoparticle-Mediated Electric Field Enhancement Inside Biological Cells Exposed to AC Electric Fields
No full textWe present in this article the effect of alternating electric field at kilohertz (kHz) and megahertz (MHz) frequencies on the biological cells in presence and absence of nanoparticles. The induced electric field strength distribution in the region around cell membrane and nucleus envelope display different behavior at kHz and MHz frequencies. The attachment of gold nanoparticles,(GNPs), especially gold nanowires around the surface of nucleus induce enhanced electric field strengths. The induced field strengths are, dependent on the length of nanowire and create varying field regions when the length of nanowire is increased from 2 to 4 mu m. The varying nanowire length increased the induced field strengths inside nucleoplasm and region adjacent to the nucleus in the cytoplasm. We investigated a process of electrostatic disruption of nucleus membrane when the induced electric field strength across the nucleus exceeds its tensile strength. (C) 2009 The Japan Society of Applied PhysicsX11109sciescopu
A Numerical Twin Model for the Coupled Field Analysis of TEAM Workshop Problem 36
No full textA numerical twin model for the magneto-thermal analysis of an induction heating device is proposed. The non-linearity of magnetic permeability against temperature - which characterizes the workpiece - is captured by the model, while the use of a Convolutional Neural Network (CNN), trained by a number of finite-element analyses, makes it possible to reconstruct the temperature field map in the workpiece region. TEAM problem 36 is recalled as the case study
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