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Plasma production from shock compression of condensed matter

Description: The experimental investigation of HE-driven, phased, cylindrical, SS liner implosion has yielded many interesting results. Plasma and radiation are found to be copiously produced. Plasmas with velocity up to 17 cm/{mu}s are observed. The temperature in the expansion surface reaches 8 - 10 eV and stays hot for tens of microseconds. The signatures of plasma interactions with the imploding wall and the glass port are clearly identified. Finally, a cluster of cooler but still self-luminous, high-density debris is observed to travel at 1.8 cm/{mu}s. Additional experiments were carried out to study the plasma flow and reconvergence inside the liner cavity by inserting a diverting disk along the axis of implosion. Significant emission of vuv and soft x-rays is detected. All the experiments are guided by the calculations using the MESA 2D hydrocode and the results agree with many of the predictions.
Date: September 1, 1995
Creator: Tan, T.H. & Marsh, S.P.
Partner: UNT Libraries Government Documents Department

High efficiency ionizer using a hollow cathode discharge plasma

Description: A proposal for an ionizer using a hollow cathode discharge plasma is described. Ionization is via the very high current density electron beam component in the plasma, as well as from charge exchange with plasma ions. Extraction of a He/sup +/ current corresponding to approximately 50% of the incoming atomic beam flux should be possible.
Date: January 1, 1984
Creator: Alessi, J.G. & Prelec, K.
Partner: UNT Libraries Government Documents Department

Plasma production and flow in negative ion beams

Description: Plasma generated in low-density vapor by a negative ion beam has been studied experimentally and computationally. We show that space charge neutralization of the beam occurs at very low vapor density, and that correspondingly the electron density may be much less than the beam and plasma ion densities. When there is a large local gas density, as in a charge changing cell, the resulting high electron density is also localized to the same region. Therefore, very few electrons will reach a negative ion accelerator even if it is placed one or two beam diameters from such a cell.
Date: September 21, 1977
Creator: Anderson, O.A. & Hooper, E.B. Jr.
Partner: UNT Libraries Government Documents Department

X-ray laser studies using plasmas created by optical field ionization

Description: X-ray laser experiments involving the creation of fast recombining plasmas by optical field ionization of preformed targets were conducted. A nonlinear increase in the intensity of the 13.5nm Lyman-{alpha} line in Li III with the length of the target plasma was observed but only for distances less than the laser confocal parameter and for low plasma electron temperatures. Multiphoton pumping of resonant atomic transitions was also examined and the process of multiphoton ionization of FIII was found to be more probable than multiphoton excitation.
Date: January 1, 1995
Creator: Krushelnick, K. M.; Tighe, W. & Suckewer, S.
Partner: UNT Libraries Government Documents Department

Metallization technology for tenth-micron range integrated circuits. CRADA final report for CRADA number ORNL92-0104

Description: A critical step in the fabrication of integrated circuits is the deposition of metal layers which interconnect the various circuit elements that have been formed in earlier process steps. In particular, columns of metal 2-3 times higher than the characteristic dimension of the circuit are needed. At the time of initiation of this CRADA, the state-of-the-art was the production of 1-1.5 micron-high columns for 0.5 micron-wide features with an expected reduction in size by a factor of two or more within five to ten years. Present commercial technologies cannot deposit such features with the process temperature, aspect ratio (ratio of height to diameter), and/or materials capability needed for future devices. This CRADA had the objective of developing a commercial tool capable of depositing metal (either copper or aluminum) at temperatures below 300{degrees}C into features with sizes approaching 0.2 micron on 200-mm wafers. The capability of future modification for deposition of alloys of controllable composition was also an important characteristic. The key technical accomplishments of this CRADA include the development of a system capable of delivering highly ionized metal plasmas, refinement of spectroscopic techniques for in situ monitoring of the ion/neutral ratio, use of these plasmas for filling and lining submicron trenches used for integrated circuit fabrication, and generation of fundamental data on the angular dependent sputtering yield which will prove useful for modeling the time evolution of feature filling and lining.
Date: April 11, 1996
Creator: Berry, L.A.; Gorbatkin, S.M.; Rossnagel, S.M. & Harper, J.M.E.
Partner: UNT Libraries Government Documents Department

RF heating experiments in CHS and RF development for LHD

Description: The Lame Helical Device, LHD, is in its final construction phase. It is a 1=2, m=10 Heliotron/Torsatron type helical system with a major radius of 4 m. The compact helical system, CHS, is a 1=2, m=8 helical system of the same type with a major radius of 1m. CHS has been used for supporting experiments to clarify physics issues of helical systems and to examine the key ideas which will be applied to LHD. This paper summarizes the experimental results of those supporting experiments in CHS and how this knowledge is incorporated in the design of RF heating in LHD. ICRF Heating results in CHS by use of loop antennas are described in section II. The results of using a Nagoya type-III coil is described in Section III. Two types of antennas used in the initial phase of the LHD ICRF Heating: a loop antenna designed for steady state heating and a folded wave guide antenna designed for EBW, are described in section IV.
Date: April 1, 1997
Creator: Watari, T.; Kumazawa, R. & Nishimura, K.
Partner: UNT Libraries Government Documents Department

Magnetic-compression/magnetized-target fusion (MAGO/MTF): A marriage of inertial and magnetic confinement

Description: Intermediate between magnetic confinement (MFE) and inertial confinement (ICF) in time and density scales is an area of research now known in the US as magnetized target fusion (MTF) and in Russian as MAGO (MAGnitnoye Obzhatiye--magnetic compression). MAGO/MTF uses a magnetic field and preheated, wall-confined plasma fusion fuel within an implodable fusion target. The magnetic field suppresses thermal conduction losses in the fuel during the target implosion and hydrodynamic compression heating process. In contrast to direct, hydrodynamic compression of initially ambient-temperature fuel (i.e., ICF), MAGO/MTF involves two steps: (a) formation of a warm (e.g., 100 eV or higher), magnetized (e.g., 100 kG) plasma within a fusion target prior to implosion; (b) subsequent quasi-adiabatic compression by an imploding pusher, of which a magnetically driven imploding liner is one example. In this paper, the authors present ongoing activities and potential future activities in this relatively unexplored area of controlled thermonuclear fusion.
Date: December 31, 1996
Creator: Lindemuth, I.R.; Ekdahl, C.A. & Kirkpatrick, R.C.
Partner: UNT Libraries Government Documents Department

Modeling of profile effects for the LLNL Large Area Inductively Coupled Plasma Source

Description: Inductively coupled plasma (ICP) sources are one of the most important high density plasma configurations developed in recent years. Next generation technology requires plasma processing systems with high uniformity over very large areas. The authors present here a comparison between computer modeling and experimental results from the LLNL Large Area ICP Source. The LLNL experiment has a 30 inches diameter and is designed to study 400mm. processing. Computer simulations using the fluid code, INDUCT94, are used to explain variations in the plasma density profile measurements as a function of inductive power and gas pressure. Trends in density profile versus pressure and power found in the simulation match those found in the experiment. Uniformity of the order of several percent was found to be possible over a 400mm diameter area.
Date: May 1, 1995
Creator: Vitello, P.; Parker, G.J. & Tishchenko, N.
Partner: UNT Libraries Government Documents Department

Magnetic compression/magnetized target fusion (MAGO/MTF), an update

Description: Magnetized Target Fusion (MTF) was reported in two papers at the First Symposium on Current Trends in International Fusion Research. MTF is intermediate between two very different mainline approaches to fusion: Inertial Confinement Fusion (ICF) and magnetic confinement fusion (MCF). The only US MTF experiments in which a target plasma was compressed were the Sandia National Laboratory ``Phi targets``. Despite the very interesting results from that series of experiments, the research was not pursued, and other embodiments of MTF concept such as the Fast Liner were unable to attract the financial support needed for a firm proof of principle. A mapping of the parameter space for MTF showed the significant features of this approach. The All-Russian Scientific Research Institute of Experimental Physics (VNIIEF) has an on-going interest in this approach to thermonuclear fusion, and Los Alamos National Laboratory (LANL) and VNIIEF have done joint target plasma generation experiments relevant to MTF referred to as MAGO (transliteration of the Russian acronym for magnetic compression). The MAGO II experiment appears to have achieved on the order of 200 eV and over 100 KG, so that adiabatic compression with a relatively small convergence could bring the plasma to fusion temperatures. In addition, there are other experiments being pursued for target plasma generation and proof of principle. This paper summarizes the previous reports on MTF and MAGO and presents the progress that has been made over the past three years in creating a target plasma that is suitable for compression to provide a scientific proof of principle experiment for MAGO/MTF.
Date: March 1, 1998
Creator: Kirkpatrick, R.C. & Lindemuth, I.R.
Partner: UNT Libraries Government Documents Department

Composite wire plasma formation and evolution

Description: The detailed understanding of the formation and evolution of plasma from rapidly heated metallic wires is a long-standing challenge in the field of plasma physics and in exploding wire engineering. This physical process is made even more complicated if the wire material is composed of a number of individual layers. The authors have successfully developed both optical and x-ray backlighting diagnostics. In particular, the x-ray backlighting technique has demonstrated the capability for quantitative determination of the plasma density over a wide range of densities. This diagnostic capability shows that the process of plasma formation is composed of two separate phases: first, current is passed through a cold wire and the wire is heated ohmically, and, second, the heated wire evolves gases that break down and forms a low-density plasma surrounding the wire.
Date: January 1, 2000
Creator: Spielman, R.B.
Partner: UNT Libraries Government Documents Department

Electron beam expansion by target heating

Description: An intense, pulsed, relativistic electron beam can heat a thin metal plate to a plasma state as it traverses. This rapid heating creates a large radial temperature gradient in the material. As heat flow is primarily by electron motion, currents arise because of the thermal gradient. This effect magnetizes the target material during the course of the beam. If this magnetization exceeds that of the vacuum field of the electron beam then it dominates beam dynamics within the material. Plasmas of interest easily cancel the space charge of the electron beam, so target magnetization would either add to the self-pinch of the electron beam, or cancel it and cause beam expansion. The analysis described here finds that target heating causes beam expan
Date: July 2, 1998
Creator: Garcia, M
Partner: UNT Libraries Government Documents Department

Parametric study of compound semiconductor etching utilizing inductively coupled plasma source

Description: Inductively Coupled Plasma (ICP) sources are extremely promising for large-area, high-ion density etching or deposition processes. In this review the authors compare results for GaAs and GaN etching with both ICP and Electron Cyclotron Resonance (ECR) sources on the same single-wafer platform. The ICP is shown to be capable of very high rates with excellent anisotropy for fabrication of GaAs vias or deep mesas in GaAs or GaN waveguide structures.
Date: July 1, 1996
Creator: Constantine, C.; Johnson, D. & Barratt, C.
Partner: UNT Libraries Government Documents Department

Vacuum-spark metal ion source based on a modified Marx generator

Description: The plasma generating parts of ion sources including their power supplies are usually floated to high potential (ion extraction voltage), thus requiring great insulation efforts and high costs for high-energy ion beams. A new concept for pulsed ion sources is presented in which a single power supply is used to simultaneously produce the plasma and high extractor voltage via a modified Marx generator. Proof-of-principle experiments have been performed with high-current spark discharges in vacuum where multiply charged ions are produced with this Marx-generator based ion source (Magis). Using Magis, it has been demonstrated that pulsed ion beams of very high energies can be obtained with relatively low voltage. For copper, ion of charge states up to 7+ have been found whose energy was 112 keV for a charging voltage of only 10 kV.
Date: April 1, 1996
Creator: Anders, A.; Brown, I.G.; MacGill, R.A. & Dickinson, M.R.
Partner: UNT Libraries Government Documents Department

Design and fabrication of a 30 second pulsed plasma generator

Description: The design and fabrication techniques for a large hybrid magnetic cusp plasma generator developed for 30 sec pulse length are described. Included are the magnetic cusp geometry features, water cooling characteristics, filament structures, and the high energy density actively cooled anode and electron dump employed.
Date: October 1, 1983
Creator: Biagi, L.A.; Ehlers, K.W.; Lietzke, A.F.; Matuk, C.A.; Maruyama, Y.; Paterson, J.A. et al.
Partner: UNT Libraries Government Documents Department

System requirements for the Los Alamos foil-implosion project

Description: The goal of the Los Alamos imploding foil project is the development of an intense source of soft x rays and hot plasma produced from the thermalization of 1 to 10 MJ of plasma kinetic energy. The source will be used for material studies and fusion experiments. Specifically, thin, current-carrying cylindrical metallic plasmas are imploded via their self-magnetic forces. Features of this project are the use of high-explosive-driven flux-compression generators as the prime power source to achieve very high energies and fast opening switches to shorten the electrical pulses. To reach a load kinetic energy of 10 MJ, it is expected that the foil-plasma must carry about 50 MA of current and must implode in less than 1/2 ..mu..sec. This imposes the requirements that switch opening times must be less than 1/2 ..mu..sec and the transmission line must withstand voltages of about 1 MV. The system being pursued at Los Alamos is described, and model calculations are presented.
Date: January 1, 1983
Creator: Brownell, J.; Bowers, R.; Greene, A.; Lindemuth, I.; Nickel, G.; Oliphant, T. et al.
Partner: UNT Libraries Government Documents Department

Method of forming a thin unbacked metal foil

Description: The present invention relates generally to metal foils and methods of making the same. More particularly, this invention pertains to the fabrication of very thin, unbacked metal foils.
Date: February 23, 1983
Creator: Duchane, D.V. & Barthell, B.L.
Partner: UNT Libraries Government Documents Department

New developments with H-sources.

Description: Existing spallation neutron source upgrades, planned spallation neutron sources, and high-energy accelerators for particle physics place demanding requirements on the Hsources. These requirements ask for increased beam currents and duty factor (df) while generally maintaining state-of-the art H' source emittance. A variety of H sources are being developed to address these challenges. These include volume sources with and without the addition of cesium for enhanced He production, increased df cesiated H' Penning and magnetron sources, and cesiated surface converter H- sources. Research on surface films of tantalum metal for enhanced volume H- production is also being studied. Innovative plasma production techniques to address the longer df requirement without sacrificing H- source reliability and liktime will be reviewed. The physical bases, the goals, and perceived challenges will be discussed.
Date: January 1, 2002
Creator: Sherman, Joseph D. & Rouleau, G. (Gary)
Partner: UNT Libraries Government Documents Department