N89-27519# National Academy of Sciences - National Research Council, Washington, DC. Committee on Magnetic Fusion in Energy Policy. PACING THE US MAGNETIC FUSION PROGRAM 1989 157 p (Contract DE-FG05-87ER-54034) (DE89-012959; NRC-9012959) Avail: NTIS HC A08/MF A01 This study addresses the priority and pace of the nation's magnetic fusion research and development program in the context of long-term national energy policy. In particular, the committee interpreted its task as follows: to review the implications of long-term national energy policy for current research and development in magnetic fusion; to identify factors that should enter the further development of such policy to reduce risks associated with the future electricity supply system; to propose criteria applicable to research and develop in electric generation in reaching long-term energy policy goals; to apply these criteria to magnetic fusion and alternative electric generation technologies in order to develop recommendations on the priority pace of the magnetic fusion program; and to present its results in a final report. The most important goals of the U.S. Department of Energy's current Magnetic Fusion Energy Program Plan are to demonstrate the scientific and engineering feasibility of fusion. Demonstrating engineering feasibility will require the design, construction, and operation of an engineering test reactor, which the plan envisions financing through a combination of domestic and international funding. The committee believes that current domestic program funding levels are inadequate to meet even the near-term objectives of the plan. N89-27520# Oak Ridge National Lab., TN. FAST WAVE CURRENT DRIVE MODELING FOR ITER AND PROSPECTS FOR A NEAR-TERM PROOF OF PRINCIPLE EXPERIMENT DOE D. B. Batchelor, E. F. Jaeger, M. D. Carter, and D. W. Swain 1989 5p Presented at the 8th Topical Conference on Radio Frequency Power in Plasmas, Irvine, CA, 1 May 1989 (Contract DE-AC05-84OR-21400) (DE89-013049; CONF-8905120-16) Avail: NTIS HC A02/MF A01 It is widely recognized that a key element in the development of an attractive tokamak reactor, and in the successful achievement of the mission of ITER is the development of an efficient steady state current drive technique. The two primary issues to be resolved are: An acceptable antenna design producing a k sub parallel spectrum with most power in the phase velocity range nu sub epsilon is less than nu sub phase is less than c and an efficient RF power that will be absorbed by electrons in the desired velocity range without unacceptable parasitic damping by fuel ions and alpha particles. To address these issues the Orion code is employed which gives a 3-D full-wave solution of the fast wave equations in tokamak geometry along with power absorption and current drive profiles. This 3-D code realistically models the launched antenna spectrum with radial focusing, includes toroidal eigenmode effects (multiple pass absorption) if present, and includes the effects of ion cyclotron harmonic and alpha particle damping. DOE N89-27521# Lawrence Livermore National Lab., CA. 1989 Ronald H. Cohen, Paul T. Bonoli, Miklos Porkolab (Massachusetts Inst. of Tech., Cambridge.), and Thomas D. Rognlien 5p Presented at the 8th Topical Conference on Radio Frequency Power in Plasmas, Irvine, CA, 1-3 May 1989 (Contract W-7405-eng-48) (DE89-013260; UCRL-100574; CONF-8905120-13) Avail: NTIS HC A02/MF A01 Providing lower-hybrid power in short, intense (GW) pulses allows enhanced wave penetration in reactor-grade plasmas. We examine nonlinear absorption, ray propagation, and parametric instability of the intense pulses. We find that simultaneously achieving good penetration while avoiding parametric instabilities is possible, but imposes restrictions on the peak power density, pulse duration, and/or RF spot shape. In particular, power launched in narrow strips, elongated along the field direction, is desired. DOE N89-27522# Lawrence Livermore National Lab., CA. MODELING OF LH CURRENT DRIVE IN SELF-CONSISTENT ELONGATED TOKAMAK MHD EQUILIBRIA D. T. Blackfield, R. S. Devoto, M. E. Fenstermacher, Paul T. Bonoli, Miklos Porkolab, and J. Yugo (Oak Ridge National Lab., TN.) May 1989 5 p Presented at the 8th Tropical Conference on Radio Frequency Power in Plasmas, Irvine, CA, 1-3 May 1989 (Contract W-7405-eng-48) (DE89-013263; UCRL-100591; CONF-8905120-14) Avail: NTIS HC A02/MF A01 Calculations of non-inductive current drive typically were used with model MHD equilibria which are independently generated from an assumed toroidal current profile or from a fit to an experiment. Such a method can lead to serious errors since the driven current can dramatically alter the equilibrium and changes in the equilibrium B-fields can dramatically alter the current drive. The latter effect is quite pronounced in LH current drive where the ray trajectories are sensitive to the local values of the magnetic shear and the density gradient. In order to overcome these problems, a LH simulation code was modified to accommodate elongated plasmas with numerically generated equilibria. The new LH module was added to the ACCOME code which solves for current drive by neutral beams, electric fields, and bootstrap effects in a self-consistent 2-D equilibrium. The model is briefly described in the next section and then results of a study of LH current drive in ITER are presented. DOE N89-27523# Sandia National Labs., Albuquerque, NM. R. B. Spielman, R. J. Dukart, D. L. Hanson, B. A. Hammel, W. W. at the 2nd International Conference on High-Density Pinches, Laguna Beach, CA, 26 Apr. 1989 (Contract DE-AC04-76DP-00789) (DE89-013497; SAND-89-0289C; CONF-8904107-3) Avail: NTIS HC A03/MF A01 We have recently completed the first gas-puff z-pinch on Saturn (32 TW, 1.4 MJ, 1.9 MV, 40-ns FWHM, and 0.11 ohm). These experiments used the most powerful driver to date for fast z-pinch experiments. Saturn, a 36 module accelerator, uses a double post-hole vacuum convolute to deliver the total machine current to the load. The 10-nH Saturn z-pinch diode is capable of delivering a peak current of 10.5 MA. We diagnosed the current using segmented Rogowski coils at the insulator, resistive shunts in the vacuum transmission lines, and B-dot loops and piezoelectric pressure gauges near the load. On most shots electrical losses in the vacuum convolute were minimal with nearly complete current delivery to the z-pinch load. We have conducted experiments with deuterium, neon, argon, krypton, and xenon gas puffs. A maximum total radiation yield of 505 + or - 25 kJ was obtained with xenon. The peak keV X-ray yields were 100+ or - 5 kJ for neon K-shell radiation, 30 + or - 4 kJ for krypton L-shell radiation, and 39 + or - 4 kJ for argon K-shell radiation. DOE recombination values for impurity ion diagnostic studies, and those for assessing the feasibility of using a high efficiency plasma neutralizer for 0.5 to 1.0 MeV/u D(-) beams. We have also extended our theoretical understanding to H(+), He(++) and He collisions in order to be prepared for the modeling of helium and transport in the next generation of reactors. DOE N89-27525# Div. Argonne National Lab., IL. High Energy Physics EXPERIMENTAL MEASUREMENT OF NONLINEAR PLASMA J. B. Rosenzweig, P. Schoessow, B. Cole, W. Gai, R. Konecny, J. (DE89-014636; ANL-HEP-PR-89-45; CONF-890335-210) Avail: NTIS HC A02/MF A01 We report direct high resolution observation of nonlinear steepened plasma waves excited in the wake of an intense, self-pinched electron beam. Oscillators in both accelerating and deflecting fields are measured, and analyzed in the context of linear and nonlinear plasma wave theory. The degree of nonlinearity in the wake-fields is shown to be consistent with analytical predictions of the beam self-pinching. The impact of these results on plasma acceleration and focusing schemes is discussed. DOE (Contract DE-AC08-86NV-10571) (DE89-014699; DOE/NV-10571/T2) Avail: NTIS HC A04/MF A01 measure the Results from experiments designed to time-dependent distribution of ionization states in an argon plasma produced by laser irradiation of a high-Mach-number gas jet are presented. The gas valve/nozzle target system was designed for nominal Mach-10 performance and produced a jet of neutral gas several centimeters long from a nozzle exit of 1.5 mm diameter. The jet was irradiated at a position having an approximate atomic density of 1 x 10(18)/cu cm by 500 J of 351-nm laser light with a pulse width of 600 ps at the NLUF's OMEGA laser facility. It was necessary to pre-ionize the gas in order to couple-in sufficient laser energy to produce a plasma. An argon plasma was then created that was dominated by charge states of Ar VIII through Ar XI. Comparison with a theoretical model which solved the time-dependent rate equations indicates that a plasma temperature of approximately 70 eV was achieved. A subsequent development effort carried out at the Lockheed Palo Alto Research Laboratory (LPARL) to improve the gas jet target system is also described. This work indicated that by increasing the pressure in the valve by a factor of 5 increased the coupling to the laser and produced significantly larger signals and higher plasma temperatures. DOE N89-27527# Nagoya Univ. (Japan). Inst. of Plasma Physics. T. Watari, R. Kumazawa, K. Toi, Y. Hamada, A. Ando, Y. Oka, O. Kaneko, K. Kawahata, K. Adati, and R. Akiyama et al Apr. 1989 41 P (IPPJ-909) Avail: NTIS HC A03/MF A01 The H-mode, an improved confinement regime, was observed recently in JIPP T-IIU high power heating experiments. It was obtained in a limiter configuration without any shaping of the plasma cross-section. This H-mode is not common because it is obtained with ICRF heating. The H-mode is also obtained in a combined heating with NBI and ICRF and it is found that the threshold power level is similar to that of averaged ICRF heating. The power threshold of the H-Mode is then studied for its dependence on various plasma parameters: It increases with plasma current, insensitive to plasma density, and optimized against toroidal field intensity. The power deposition profile of ICRF heating is analyzed using a ray-tracing code, and used to explain the observed B sub T dependence. A class of strange shorts observed in the same series of experiments is studied. The shorts appeared at a power level close to the H-mode threshold with a remarkable improvement of confinement. However, the shorts are different from the H-mode in the time evolution of the profiles. Author N89-27528# Nagoya Univ. (Japan). Inst. of Plasma Physics. STOCHASTICITY AND SYMMETRY OF THE STANDARD MAP Y. H. Ichikawa, T. Kamimura, T. Hatori, and S. Y. Kim Apr. 1989 38 p (IPPJ-910) Avail: NTIS HC A03/MF A01 The stochasticity and symmetry of the standard map were discussed to explore the generic aspect of the statistical properties inherent to the low dimensional classical Hamiltonian systems. The accelerator modes of the standard map give rise to anomalous enhancement of the stochastic diffusion. Systematic analysis of symmetry of the standard map is undertaken to investigate structure of the periodic orbits around the stable fixed point, and the method is applied to the Poincare-Birkhoff chains around the accelerator mode. The squeeze effect of the period-3 accelerator orbits is examined explicitly, in terms of the reduced accelerator mode map. Furthermore, it is shown that the period-3 accelerator orbits are born as intrinsic nonlinear multifurcation, differing from birth of the Poincare-Birkhoff chains with the higher periodicity q equal to Author or greater than 4. (Contract W-7405-eng-36) (DE89-012621; LA-UR-89-1593; CONF-8903131-2) Avail: NTIS HC A03/MF A01 On the basis of a three-dimensional MHD simulation we discuss the magnetic topology of a plasmoid that forms by a localized reconnection process in a magnetotail configuration including a net dawn-dusk magnetic field component B sub yN. As a consequence of B sub yN ne 0 the plasmoid gets a helical flux rope structure rather than an isolated island or bubble structure. Initially all field lines of the plasmoid flux rope remain connected with the Earth, while at later times a gradually increasing number of flux tubes becomes separated, connecting to either the distant boundary or to the flank boundaries. In this stage topologically different flux tubes become tangled and wrapped around each other, consistent with predictions on the basis of ad hoc plasmoid DOE models. N89-27530# Sandia National Labs., Albuquerque, NM. Arian L. Pregenzer 1989 Analysis of the electrohydrodynamic (EHD) equations of motion of a planar liquid-lithium surface in the presence of a normal electric field suggest that liquid lithium may provide a large-area ion source for intense ion-beam diodes. Such sources are being developed for the Particle Beam Fusion Accelerator 2 at Sandia National Laboratories. In this paper, theoretical and experimental studies of the planar EHD ion source will be reviewed. When a planar liquid surface is subjected to an electric field of sufficient magnitude, EHD instabilities produce an array of cusps on the surface. The electric field enhancement at the apex of each cusp is sufficient to permit field evaporation of ions. The time delay between application of the electric field and ion emission depends on the magnitude and rate of increase of the applied electric field, and on the initial amplitude of the surface perturbation. Above 10 MV/cm, theory indicates that field emission will occur on a nanosecond time scale and that the characteristic spacing of emitters will be less than one micrometer. At these fields, the source should have an intrinsic divergence of less than 6 mrad and the effects of space charge from neighboring emitters should not inhibit emission significantly. Experimental measurements of wavelength and cusp-formation-times for water and ethanol at electric fields near the critical field for instability have agreed well with theory. DOE N89-27531# Sandia National Labs., Albuquerque, NM. Conference on High-Density Pinches (ICHDP-2), Laguna Beach, (Contract DE-AC04-76DP-00789) (DE89-014188; SAND-89-0443C; CONF-8904107-4) Avail: NTIS HC A03/MF A01 Analytic modeling and magnetohydrodynamic simulations have been conducted to investigate two-dimensional effects in imploding plasma shells. These effects include short wavelength disturbances caused by instabilities at the plasma magnetic field interface, long wavelength instabilities associated with plasma annulus formation, and perturbations resulting from the power flow to the plasma annulus. The numerical calculations were carried out using the two-dimensional single-fluid magnetohydrodynamic (MHD) code MACH2 for different plasma density profiles and electrode geometries. Results for short wavelength perturbations show that these phenomena behave in a manner consistent with analytic linear and heuristic nonlinear models. At stagnation they have a negligible effect on the uniformity during the initial coupling to the target, even for large initial perturbations. The disturbances manifest themselves primarily in a rippling of the back of the plasma shell with significant effects, even in this region, not occurring until late in the stagnation process. Long wavelength perturbations produced by a straight axial gas injection for gas puff implosions can lead to pronounced axial nonuniformity, zippering, at stagnation. Variations of the injection conditions and electrode geometry can produce more uniform stagnation. Changes in the mass profile, gas injection angle, and electrode shape can all be used to achieve significantly greater stagnation uniformity. Consistent calculations for an entire implosion process from a gas injection to stagnation including vacuum power flow indicate the degree of coupling of short wavelength, long wavelength and power flow perturbations. Comparison with experimental data show agreement between analytic, numerical and experimental results. N89-27532# Los Alamos National Lab., NM. STUDY OF ATOMIC PHYSICS AND POPULATION INVERSIONS WITH PLASMA FOCUS H. Oona, M. L. Hodgdon, D. G. Rickel, and B. L. Freeman 7 р DOE 1989 Presented at the 5th International Conference on Megagauss Magnetic Field Generation and Related Topics, Novosibirsk, USSR, 3-7 Jul. 1989 (Contract W-7405-eng-36) (DE89-014282; LA-UR-89-2164; CONF-890710-14) Avail: NTIS HC A02/MF A01 The plasma focus can be used to generate high temperature and high density plasmas. Neon-like plasmas have previously been studied in Z-pinches and laser produced plasmas as sources for XUV and X-ray lasers. The plasma focus provides a simple and inexpensive source for studying atomic physics of highly ionized atoms. A detailed understanding of atomic physics at high temperatures, densities, and megagauss magnetic fields is necessary for possible X-ray laser designs. Methods that are generally used for obtaining population inversions include collisional ionization of the inner shells of multi-electron atoms and ions, photoexcitation, and electron collisional excitation of ions, collisional combination of ions, and atom-ion resonant charge N89-27533# Los Alamos National Lab., NM. (DE89-014290; LA-UR-89-2144; CONF-8904107-5) Avail: NTIS HC A02 The global evolution of z-pinch has been studied with the assumption of a relaxed state consisting of ions and electrons, each in a rigidly drifting isothermal Maxwellian distribution. This speculative approach has the pragmatic feature of possessing phenomenologically useful global parameters such as drift velocity and temperature that vary in accordance with global physical quantities such as energy and entropy. The plasma gains energy from a time-dependent electric field by means of Poynting's vector. Coulomb collisions between electrons and ions are calculated with a Fokker-Planck treatment analogous to that used by Dreicer to calculate runaways. For a variety of initial conditions and time-independent applied electric fields, the pinch evolution always culminates in a time-independent (attractor) state whose current is the Pease-Braginskii current and whose final radius is proportional to (line density to the 3/4 power)/(electric field to the 1/2 power). Before the final state is attained, the pinch may bounce toward and away from a highly collapsed state. For the case of a Bennett pinch, the classical limit of the resistivity is attained when the line density is much greater than 4(eta)m(sub e)/e(2)mu(sub 0); i.e., 3.55 x 10(14) m(-1). DOE N. F. Roderick (New Mexico Univ., Albuquerque.) and T. W. (DE89-014482; SAND-88-3311C; CONF-890710-1) Avail: NTIS HC A03/MF A01 Analytic modeling and magnetohydrodynamic (MHD) simulations have been conducted to investigate two-dimensional effects in imploding plasma shells. These effects include short wavelength disturbances caused by instabilities at the plasma magnetic field interface, long wavelength instabilities associated with plasma annulus formation, and perturbations resulting from the power flow to the plasma annulus. The numerical calculations were carried out using the two-dimensional single-fluid MHD code MACH2 for different plasma density profiles and electrode geometries. Results for short wavelength perturbations show that these phenomena behave in a manner consistent with analytic linear and heuristic nonlinear models. At stagnation they have a negligible effect on the uniformity during the initial coupling to the target, even for large initial perturbations. The disturbances manifest themselves primarily in a rippling of the back of the plasma shell with significant effects, even in this region, not occurring until late in the stagnation process. Long wavelength perturbations produced by a straight axial gas injection for gas puff implosions can lead to pronounced axial nonuniformity, zippering, at stagnation. Variations of the injection conditions and electrode geometry can produce more uniform stagnation. Changes in the mass profile, gas injection angle, and electrode shape can all be used to achieve significantly greater stagnation uniformity. Consistent calculations for a entire implosion process form gas injection to stagnation including vacuum power flow indicate the degree of coupling of short wavelength, long wavelength and power flow perturbations. Comparison with experimental data show agreement between analytic, numerical and experimental results. DOE N89-27535# Sandia National Labs., Albuquerque, NM. MHD CALCULATIONS OF ANODE PLASMAS 15 P T. W. Hussey, S. A. Slutz, and M. P. Desjarlais 1989 (DE89-014485; SAND-89-0025C; CONF-890665-23) Avail: NTIS HC A03/MF A01 We have performed a series of idealized magnetohydrodynamic (MHD) calculations of the response of an anode plasma layer to the rising magnetic field in an applied-B ion diode. The purposes of this study were to consider Joule heating of the plasma layer, which could pose potential problems for lithium ion diodes, and the leakage of flux behind the ion-emitting surface, which is related to impedance collapse. We find that, as induced JxB forces move the plasma toward the wall, the entrained, initial field is compressed until it just equals the rising external field. Achieving such equilibrium decreases both Joule heating and flux leakage into the plasma. For relatively thin (approximately 1 mm) plasma layers at moderate densities (10 to the 16th power to 10 to the 17th power cm(-3)) we calculate that this equilibrium is achieved quite rapidly, leading to acceptably low levels of both flux penetration and Joule DOE heating. N89-27536 (Germany, F.R.). Max-Planck-Inst. fuer Plasmaphysik, Garching ON BOOTSTRAP CURRENTS IN TOROIDAL SYSTEMS (IPP-2/297; ETN-89-94571) Copyright Avail: Eggenstein-Leopoldshafen 2, Fed. Republic of Germany The diffusion driven current in tokamaks and stellarators is investigated. It can be shown that in stellarator configurations with symmetry - axisymmetry, helical symmetry, quasi-helical symmetry, bootstrap current and radial particle loss are proportional to each other. This relation follows directly from the momentum balance and the plasma viscosity given in Chew-Goldberger-Low formulation. This general relation, which is already known for tokamaks can be derived without solving the kinetic equation. If the symmetry of the configuration is destroyed, it is possible to minimize the bootstrap current by a suitable choice of the magnetic field geometry. The parallel and the perpendicular viscosities have to be calculated for the various regimes of collisionality starting from the kinetic equation. In a collision dominated plasma these effects are small. The viscous tensor of a collisional plasma given by Braginskii allows one to calculate these average viscous forces for an arbitrary stellarator geometry and a geometrical factor Cb can be defined which characterizes the dependence of the bootstrap current on the topology of the magnetic surface. Such a geometrical factor also exists in the plateau regime; in the long-mean-free-path regime the bootstrap current depends on the collisionality and the radial electric field and thus a factor Cb depending on the magnetic field alone cannot be defined. N89-27537 ESA Max-Planck-Inst. fuer Plasmaphysik, Garching (Germany, F.R.). (IPP-5/25; ETN-89-94575) Copyright Avail: Eggenstein-Leopoldshafen 2, Fed. Republic of Germany A user manual for a new version of the FISIC code which is now applicable to arbitrary (toroidal) geometry is presented. It describes the input parameters and quantities of all subroutines and contains a list of all common blocks. N89-27538 (Germany, F.R.). ESA Max-Planck-Inst. fuer Plasmaphysik, Garching INTEGRAL CONSTITUTIVE RELATION FOR THE INVESTIGATION OF ION BERNSTEIN WAVES IN NON-HOMOGENEOUS PLASMAS Marco Brambilla Jan. 1989 25 p (IPP-5/27; ETN-89-94576) Copyright Avail: By integrating the linearized Vlasov equation, an integral form of the constitutive relation (the relation between the HF electric field and the HF current) valid to all orders in the Larmor radius in axially magnetized inhomogeneous plasmas is derived. It has the form of a convolution integral in Fourier space, whose kernel can be expanded in Bessel functions, or put in a form analogous to the Gordeev integral form of the usual uniform plasma conductivity tensor, to which it reduces in the uniform plasma limit. Alternatively, it can be formulated as an integral equation in real space. Both formulations can be useful for the investigation of ion Bernstein waves near ion cyclotron resonances and near the lower hybrid resonance, where a WKB analysis alone is insufficient. ESA N89-27539 Max-Planck-Inst. fuer Plasmaphysik, Garching (Germany, F.R.). ON THE ECONOMIC PROSPECTS OF NUCLEAR FUSION D. Pfirsch and K. H. Schmitter Dec. 1987 56 p Revised A method of cost and construction energy estimation for tokamak fusion power stations conforming to the present stage of fusion development is described. The method is based on first-wall heat load constraints rather than Beta limitations, which, however, might eventually be the more critical of the two. It is used to discuss the economic efficiency of pure fusion, with particular reference to the European study entitled Environmental Impact and Economic Prospects of Nuclear Fusion (1986). It is shown that the claims made therein for the economic prospects of pure fusion with tokamaks, when discussed on the basis of the present-day technology, do not stand up to critical examination. A fusion-fission hybrid, however, could afford more positive prospects. Support for the stated method is derived when it is properly applied for cost estimation of advanced gas-cooled and Magnox reactors, the two examples presented by the European study to disprove it. ESA N89-27540 Max-Planck-Inst. fuer Plasmaphysik, Garching E. Canobbio (Commission of the European Communities, Brussels, Belgium) and R. Croci Dec. 1988 70 p Submitted for publication (IPP-6/278; ETN-89-94578) Copyright Avail: The mechanisms underlying radiofrequency plasma heating and current drive in closed configurations are considered together with the theoretical tools describing them. The heating schemes of interest for thermonuclear devices span a wide range of frequencies from the Alfven wave resonance to the ion-cyclotron, lower hybrid, and electron-cyclotron resonances. Heating at frequencies below the Alfven wave resonance (magnetic pumping in its numerous versions), which is of limited thermonuclear relevance, is presented for its fundamental aspects - more than any other heating scheme it involves properties of particle motion in the large which are specific to the magnetic traps, in order to provide a broader and more integrated view of the whole subject. ESA High-resolution numerical studies of decaying two-dimensional magnetohydrodynamic turbulence using up to 768 sq modes in general periodic systems are reviewed. The evolution proceeds in a quasi-selfsimilar way with constant kinetic to magnetic energy ratio and constant micro- and macro-scale Reynolds numbers. The energy dissipation rate is independent of the values of the dissipation coefficients. The inertial-range energy spectra follow a Kolmogorov law, Ek = C epsilon sup 2/3 K sup (-5/3) with C = 3.7 + or 0.3. Small-scale fluctuations are concentrated in the region of weak large-scale magnetic fields. The resulting strong intermittency is analogous to the behavior observed in two-dimensional hydrodynamic turbulence (J. Fluid Mech. (1988) 194, 333), with the magnetic field intensity taking the role vorticity plays in hydrodynamic systems. N89-27542# Swedish Inst. of Space Physics, Kiruna. IONOSPHERIC PLASMA ESCAPE BY HIGH-ALTITUDE ELECTRIC FIELDS: MAGNETIC MOMENT PUMPING ESA Richard Lundin and Bengt Hultqvist Jan. 1989 39 p Submitted for publication Sponsored by the Swedish Board for Space Activities (IRF-Preprint-111; ETN-89-94941) Avail: NTIS HC A03/MF A01 Viking results of the temperature and mass-composition of individual ion beams suggest that upward flowing ion beams can be generated by a magnetic moment pumping mechanism caused by low-frequency transverse electric field fluctuations, in addition to a field aligned quasi-electrostatic acceleration process. Magnetic moment pumping within transverse electric field gradients can be described as a conversion of electric drift velocity to cyclotron velocity by the inertial drift in a time-dependent electric field. This gives an equal cyclotron velocity gain for all plasma species irrespective of mass. Oxygen ions thus gain 16 times higher transverse energy as compared to protons. In addition to a transverse energy gain above the escape energy, a field aligned quasi-electrostatic acceleration is considered primarily responsible for the collimated upward flow of ions. The field aligned acceleration adds a constant parallel energy to escaping ionospheric ions. Thus, ion beams at high altitudes can be explained by a bimodal acceleration from both a transverse (equal velocity) and a parallel (equal energy) acceleration process. The Viking observations also show that the thermal energy of ion beams, and the ion beam width are mass dependent. The average O+/H+ temperature ratio is found to be 4.0 from the Viking observations. This is less than the factor of 16 anticipated from a coherent transverse electric field acceleration but greater than the factor of 1 (or even less than 1) expected from a turbulent acceleration process. 76 SOLID-STATE PHYSICS Includes superconductivity. ESA For related information, see also 33 Electronics and Electrical Engineering and 36 Lasers and Masers. N89-27543# Los Alamos National Lab., NM. Materials Science and Technology Div. WEAR AND FRICTION OF THIN FILM HIGH TEMPERATURE OXIDE SUPERCONDUCTORS 14 P Michael Nastasi, Juha-Pekka Hirvonen, and Risto O. Toivanen (Helsinki Univ. of Technology, Espoo, Finland) Presented at the 16th International Conference on Metallurgical Coatings and Equipment Exhibit, San Diego, CA, 17-21 Apr. 1989 (Contract W-7405-eng-36) 1989 (DE89-009397; LA-UR-89-825; CONF-890468-1) Avail: NTIS HC A03/MF A01 The sliding properties of a Nd-Fe-B magnet were examined against a thin film YBa2Cu307 superconductor. Pin-on-disk experiments were performed at room temperature and in normal air using a 10 mm magnetic Nd-Fe-B ball loaded to 31.22 g and a sliding speed of approximately 0.57 cm/sec. Such condition produced a steady state friction coefficient of 1.1 + or - 0.3. Wear rate measurements indicated that Nd-Fe-B will wear YBa2Cu307 at a rate 1.3 x 10(-14) cu m/m and that the Nd-Fe-B/YBa2Cu307 sliding system possess a wear coefficient of 4.2 x 10(-14) cu m/Nm. These unusually high values appear to be the result of both abrasive and adhesive wear. Adhesion between the sliding surfaces is most probably enhanced by the oxygen reactivity of the pin material and the high oxygen content in the superconductor. DOE N89-27544# International Centre for Theoretical Physics, Trieste (Italy). MODEL FOR HOT ELECTRON PHENOMENA: THEORY AND J. L. Carrillo and M. A. Rodriquez (Universidad Autonoma de Puebla, We propose a model for the description of the hot electron phenomena in semiconductors. Based on this model we are able to reproduce accurately the main characteristics observed in experiments of electric field transport, optical absorption, steady state photoluminescence and relaxation process. Our theory does not contain free nor adjustable parameters, it is very fast computerwise, and incorporates the main collision mechanisms including screening and phonon heating effects. Our description is based on a set of nonlinear rate equations in which the interactions are represented by coupling coefficients or effective frequencies. We calculate three coefficients from the characteristic constants and the band structure of the material. DOE A process of fabricating a hybrid single crystal fiber having nonlinear optical properties such as frequency doubling is presented. Said process includes applying a force to a fiber core resting upon a bulk nonlinear crystal such as LilO3 in a saturated solution of LilO3 in water. After the core is embedded a sufficient distance into the crystal the force is removed. This invention relates generally to glass fiber optics, and particularly, relates to a process of fabricating fibers useful in nonlinear optics applications. The instant invention set forth a process of fabricating hybrid single crystal optical fibers having nonlinear optical properties therein and thereby overcome the problems set forth hereinabove. This process is distinct from the well known process of regelation. In the process of this invention, a fiber core is placed in direct contact with a bulk nonlinear crystal having an essentially flat surface thereon. The fiber core and bulk nonlinear crystal are immersed in a saturated solution where the equilibrium solid phase has the same composition as the bulk nonlinear crystal. GRA = The tracer diffusion of oxygen was measured in the high T(sub c) superconductors La(2-x)Sr(x)CuO4 (x 0.1, 0.15, 0.2) and in YBa2Cu30(7 - delta), using secondary ion mass spectrometry (SIMS) to obtain the depth profiles. The diffusion coefficients in La(2-x)Sr(x)CuO4 decrease with increasing x, a result that is explained on the basis of a simple defect model, which also provides an explanation for the peak in the plot of T(sub c) vs x. The depth profiles for YBa2Cu30(7 - delta) require two volume diffusion terms for a good fit, and this is explained in terms of the |