Toda lattice with transverse degree of freedom

A transverse degree of freedom is introduced in the Toda lattice. The corresponding continuum approximations are discussed. 9 refs

Complex dynamics of the integer quantum Hall effect

We investigate both classical and quantum potential scattering in two dimensions in a magnetic field, with applications to the integer quantum Hall effect. Classical scattering is complex, due in one case to the approach of scattering states to an infinite number of bound states. We show that bound states are generic, and occur for all but extremely smooth scattering potentials ({vert bar}{rvec {gradient}}{vert bar} {yields} 0). Quantum scattering follows the classical behavior rather closely, exhibiting sharp resonances rather than classical bound states. Extended scatterers provide an explanation for the breakdown of the QHE at a comparatively small Hall voltage. 16 refs., 14 figs

Detoxification of hazardous waste streams using microwave-assisted fluid-bed oxidation

Microwave-assisted oxidation of trichloroethane (TCE) performed at 500-580{degree}C has been found to be significantly more efficient than conventional oxidation methods. Experiments were conducted using a 6 kilowatt, 2.45 gigohertz power supply and a 6 inch bed of silicon carbide granules in a 1 inch diameter quartz reactor tube which in turn was placed in a microwave cavity. After heating the reactor to a given temperature a TCE-air stream was passed through the silicon carbide bed. TCE was almost completely detoxified (98--99%) in a single pass through the silicon carbide bed at 500--580{degree}C. The oxidation products are HCl, CO{sub 2} and CO. By comparison the corresponding single-pass detoxification using conventional thermal methods results in only partial conversion. The principal products being dichloroethylene (C{sub 2}H{sub 2}Cl{sub 2}) and HCl. 5 refs., 1 tab

Robust rf control of accelerators

The problem of controlling the variations in the rf power systems can be effectively cast as an application of modern control theory. Two components of this theory are obtaining a model and a feedback structure. The model inaccuracies influence the choice of a particular controller structure. One can design wither a variable, adaptive controller or a fixed, robust controller to achieve the desired objective. The adaptive control scheme usually results in very complex hardware; and therefore, shall not be pursued. In contrast, the robust control method leads to simplified hardware. However, robust control requires a more accurate mathematical model of the physical process than is required by adaptive control. Our research at the Los Alamos National Laboratory (LANL) and the University of New Mexico has led to the development and implementation of a new rf power feedback system. In this paper, we report on our research progress. In section one, the robust control problem for the rf power system and the philosophy adopted for the beginning phase of our research is presented. In section two, results of our proof-of-principle experiments are presented. In section three, we describe the actual controller configuration that is used in LANL FEL physics experiments. The novelty of our approach is that the control hardware is implemented directly in rf without demodulating, compensating, and then remodulating

ENDF/B-VI six-group delayed neutron data

This paper evaluates ENDF/B-VI delayed neutron data for {sup 235}U, {sup 238}U, and {sup 239}Pu. (LSP

Possible design modifications of ITER fuel cycle

During the ITER design phase, the conceptual design of the fuel processing cycle has been established. The fuel processing cycle is designed to be able to handle all the tritium containing streams of the ITER. These streams include plasma exhaust, blanket tritium recovery, pellet propellant, neutron beam exhaust, water coolant detritiation, waste water from the room air detritiation system. The design is very conservative, i.e., the flow rate of each stream is high and the detritiation factor required is very high. A preliminary optimization study has been carried out to simplify the ITER fuel cycle design. We investigated: The throughput and composition of the input tritium containing streams from various components to the fuel processing cycle. The fraction of those streams needed to be detritiated. The required detritiation factors required for each of the streams. The results of the investigation determined that the major input tritium containing steams can be reduced by at least a factor of 10. The required detritiation factor can be reduced from a factor of 100 to 10{sup 6}. The size of the fuel processing cycle, the tritium inventory and the complexity of this system can, therefore, also be reduced

Observations of tornadoes and wall clouds with a portable FM-CW Doppler radar: 1989--1990 results

The purpose of this paper is to report on our progress using a portable, 1 W,FM (frequency modulated)-CW (continuous wave) Doppler radar developed at the Los Alamos National Laboratory (LANL), to make measurements of the wind field in tornadoes and wall clouds along with simultaneous visual documentation. Results using a CW version of the radar in 1987--1988 are given in Bluestein and Unruh (1989). 18 refs., 2 figs., 1 tab

Invariant metrics for Hamiltonian systems

In this paper, invariant metrics are constructed for Hamiltonian systems. These metrics give rise to norms on the space of homeogeneous polynomials of phase-space variables. For an accelerator lattice described by a Hamiltonian, these norms characterize the nonlinear content of the lattice. Therefore, the performance of the lattice can be improved by minimizing the norm as a function of parameters describing the beam-line elements in the lattice. A four-fold increase in the dynamic aperture of a model FODO cell is obtained using this procedure. 7 refs

QCD with dynamical Wilson fermions

Results for the spectrum and the F and D parameters are obtained with precision similar to that in the quenched approximation. Present data for m{sub q} {ge} m{sub s} show measurable effects due to vacuum polarization only in the pion-Nucleon {Sigma} term suggesting that {Sigma}{sup sea} {approximately} {Sigma}{sup val}. The lattice update is being done on the Connection Machine which is very well suited to simulate QCD with 2 flavors of Wilson fermions (with mass close to the strange quark) using HMCA on 16{sup 3} {times} 32 lattices. 7 refs., 3 figs., 5 tabs

Monte Carlo photon benchmark problems

Photon benchmark calculations have been performed to validate the MCNP Monte Carlo computer code. These are compared to both the COG Monte Carlo computer code and either experimental or analytic results. The calculated solutions indicate that the Monte Carlo method, and MCNP and COG in particular, can accurately model a wide range of physical problems. 8 refs., 5 figs