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Use of molybdenum ion source electrodes at RTNS-II
Reports are reported for an ongoing effort to optimize D+ beam production by the MATS-III ion source used at RTNS-II. The three seven-aperture electrodes, originally consisting of water-cooled copper, have now been tested using uncooled molybdenum and with water cooling on the second (decel) electrode only. Details of the change, the results of the testing, and the benefits in operation, performance and cost are given.
Date:
September 29, 1986
Creator:
Massoletti, D.J.; Harter, G.A. & Heikkinen, D.W.
System:
The UNT Digital Library
Structure functions: Their status and implications
I discuss the current status of structure functions. Attention is given to the uncertainties in them and the implications of these uncertainties for experimental predictions. I indicate which experiments are capable of removing these uncertainties. 17 refs., 17 figs., 1 tab.
Date:
September 29, 1988
Creator:
Hinchliffe, I.
System:
The UNT Digital Library
Top quark and light Higgs scalar mass bounds in no-scale supergravity
No-scale supergravity theories with the minimal low-energy particle content are shown to become untenable for a top quark mass m/sub T/ much less than 40 GeV. For m/sub T/ < 55 GeV, a stringent upper bound operates on the mass of the lowest-lying Higgs scalar. Further, the Higgs pseudoscalar is constrained to be nearly a quarter as massive as the gluino.
Date:
August 29, 1986
Creator:
Roy, P.
System:
The UNT Digital Library
Oxide cathode lifetime improvements at RTNS-II
Results are reported for an ongoing effort to optimize D/sup +/ beam production by the MATS-III ion source used at the RTNS-II. The oxide cathode assembly originally designed for lower power operation has been modified and redesigned for higher electron current yield, longer life and serviceability. A factor of 2.5 has been gained in cathode lifetime due to these changes. The details of the changes and results and benefits in operation and performance are given. In addition, the technique used for manufacture of the filament is described.
Date:
September 29, 1986
Creator:
Massoletti, D.J.
System:
The UNT Digital Library
Overview of radioactive waste management
The question of what to do with radioactive wastes is discussed. The need to resolve this issue promptly is pointed out. Two significant events which have occurred during the Carter administration are discussed. An Interagency Review Group (IRG) on waste management was formed to formulate recommendations leading to the establishment of a National policy for managing radioactive wastes. The technical findings in the IRG report are listed. The author points out some issues not addressed by the report. President Carter issued a national policy statement on Radioactive Waste Management in February 1980. The most significant elements of this statement are summarized. The cancellation of the Waste Isolation Pilot Plant is currently meeting opposition in Congress. This and other items in the National Policy Statement are discussed.
Date:
May 29, 1980
Creator:
Ritter, G.L.
System:
The UNT Digital Library
Applications of small computers for systems control on the Tandem Mirror Experiment-Upgrade
Desktop computers operating into a CAMAC-based interface are used to control and monitor the operation of the various subsystems on the Tandem Mirror Experiment-Upgrade (TMX-U) at Lawrence Livermore National Laboratory (LLNL). These systems include: shot sequencer/master timing, neutral beam control (four consoles), magnet power system control, ion-cyclotron resonant heating (ICRH) control, thermocouple monitoring, getter system control, gas fueling system control, and electron-cyclotron resonant heating (ECRH) monitoring. Two additional computers are used to control the TMX-U neutral beam test stand and provide computer-aided repair/test and development of CAMAC modules. These machines are usually programmed in BASIC, but some codes have been interpreted into assembly language to increase speed. Details of the computer interfaces and system complexity are described as well as the evolution of the systems to their present states.
Date:
November 29, 1983
Creator:
Bork, R. G.; Kane, R. J. & Moore, T. L.
System:
The UNT Digital Library
Control of beam dynamics in high energy induction linacs
The Advent of laser-ion-guiding in the Advanced test Accelerator along with the development of accelerator cavities optimized with respect to beam breakup coupling impedence now make it possible to consider a new class of high current, high emergy linear induction accelerators. The control of the beam breakup and other instabilities by laser guiding and by various magnetic focusing schemes will be discussed along with the scaling laws for the design of such machines to minimize the growth of the beam breakup instability. Many linacs, particularly induction linacs are limited in performance by the beam breakup (BBU) instability. The instability is found in two forms. In the first form the accelerating cavities communicate with one another through interaction with the beam and through propagation of cavity fields through the accelerator structure. In the second form which is the more virulent of the two, the cavities couple to each other only through their interactions with the beam. It is this second form of PPU that will be discussed in this paper.
Date:
July 29, 1986
Creator:
Caporaso, G.J.
System:
The UNT Digital Library
Does the photino decay
The stability of the lightest superpartner is a crucial aspect of many experimental searches for supersymmetry and of supersymmetric dark matter candidates. It is shown that R parity may occur in operators of dimension four or less as an accidental consequence of an exact Z/sub N/ symmetry. In this case the lightest superpartner can decay via higher dimension operators. The lifetime depends on the scale of the new physics responsible for the non-renormalizable operators; it could be anywhere in the region 10/sup -20/ seconds to 10/sup +20/ seconds. Explicit examples are given. 12 refs.
Date:
August 29, 1986
Creator:
Hall, L.J.
System:
The UNT Digital Library
High energy negative deuterium beams using double charge-exchange or surface production
Experimental and theoretical research on production of negative ion beams is described. Results from a double charge-exchange experiment include 10 ms pulses of 100 ma of D/sup -/ accelerated to 60 kV. Equilibrium fractions of D/sup -/ in several metal vapors are presented. Mechanisms and measurements of D/sup -/ on surfaces are described, and a scheme is shown for producing high current, high energy beams originating on surfaces.
Date:
November 29, 1977
Creator:
Hooper, E. B. Jr.; Anderson, O. A.; Orzechowski, T. & Poulsen, P.
System:
The UNT Digital Library
Coil winder for the magnet of the mirror fusion test facility
A coil winder was designed for the purpose of fabricating the superconducting magnets of the Mirror Fusion Test Facility. The superconducting magnets are a displaced ying-yang pair, each having major and minor radii of 2.5 and 0.75 m, respectively, and cross section of 0.42 m by about 1.03 m. The superconductor cross section is a square, 13 mm on a side, and consists of a core of niobium-titanium embedded copper and a solid copper stabilizer. Conceptual studies made at Lawrence Livermore Laboratory of the coil winder resulted in concept drawings and a procurement specification. Final design was made by the contractor, and the coil winder is now in fabrication. This paper describes the performance requirements of the winder, and the evolution of its design from conceptual stage to completion.
Date:
August 29, 1977
Creator:
Ling, R.C.
System:
The UNT Digital Library
Localized corrosion of steels in geothermal steam/brine mixtures
Coupons of eight different carbon and chrome-moly alloy steels were exposed to high temperature, high salinity wellhead brine flow at a geothermal well in the Salton Sea Geothermal Field for periods of up to six months. The corrosion rate and corrosion attack morphology of each coupon was determined. Exposure time was a test variable and ranged from one month to six months. Test results indicate that carbon steels generally suffer high corrosion rates and are susceptible to severe localized attack which shows a mesa-canyon pattern. Chrome-moly alloy steels corrode at much lower rates and show an attack pattern of small shallow pits. With time, these pits grow mostly in the lateral direction. These results suggest that chrome-moly alloy steels offer significant improvement over carbon steels and that the disk-shaped pits are not likely to lead to rapid perforation.
Date:
May 29, 1980
Creator:
McCright, R. D.; Frey, W. F. & Tardiff, G. E.
System:
The UNT Digital Library
Samanid ceramics and neutron activation analysis
Glazed pottery known as ''Afrasiyab'' and ''Nishapur'' wares (early Islamic ceramics) are generally attributed to the Samanid dynasty (819-1005). The clay composition of Samanid wares and discarded kiln items found in situ were analyzed by NAA and the elemental composition compared with that of other sherds. 7 figures, 1 table. (DLC)
Date:
August 29, 1977
Creator:
Azarpay, G.; Frierman, J.D. & Asaro, F.
System:
The UNT Digital Library
Compact 80-keV neutral-beam module
A compact and maintainable source of 80-keV neutral beams that focus to a high power density is required for the Mirror Fusion Test Facility (MFTF). In the new source being designed and built to meet these requirements, the cross-sectional area is reduced in two ways: by immersing the source in a vacuum where high voltage can be held over smaller distances and by redesigning grid supporting structures. Reliability is increased by reducing the electric fields everywhere else below those present between grids and by design innovations. The latter include techniques to reduce stray magnetic field and disperse gas uniformly, all metal-ceramic construction, and a 60-kV shield enclosing all 80-kV electrodes. Wherever possible, we have attempted to simplify the construction. We expect to solve problems that arise during testing either with add-on fixes or with the techniques already tested successfully on the Lawrence Berkeley Laboratory (LBL) 120-keV source. Easy maintenance is obtained by a compact isolation valve and by modular construction. Curving both the grid wires and their holders provides focusing in two planes.
Date:
September 29, 1977
Creator:
Molvik, A. W.; Baird, E. D.; Berkner, K. H.; Cooper, W. S.; Duffy, T. J.; Ehlers, K. W. et al.
System:
The UNT Digital Library
TMX tandem-mirror experiments and thermal-barrier theoretical studies
This paper describes recent analysis of energy confinement in the Tandem Mirror Experiment (TMX). TMX data also indicates that warm plasma limits the amplitude of the anisotropy driven Alfven ion cyclotron (AIC) mode. Theoretical calculations show strong AIC stabilization with off-normal beam injection as planned in TMX-U and MFTF-B. This paper reports results of theoretical analysis of hot electrons in thermal barriers including electron heating calculations by Monte Carlo and Fokker-Planck codes and analysis of hot electron MHD and microinstability. Initial results from the TMX-U experiment are presented which show the presence of sloshing ions.
Date:
July 29, 1982
Creator:
Simonen, T. C.; Baldwin, D. E. & Allen, S. L.
System:
The UNT Digital Library
Application of heavy-light methods to B meson physics
The heavy-light method is applied to the study of the B meson spectrum, the pseudoscalar decay constant f{sub B}, the mixing (B) parameter, and exclusive semileptonic B meson decays. Preliminary results are discussed for f{sub B} and the B parameter at {beta} = 5.7 and {kappa} = 0.165 on a 12{sup 3} {times} 24 lattice and at {beta} = 5.9 and {kappa} = 0.158 on a 16{sup 3} {times} 32 lattice. 9 refs., 2 figs., 2 tabs.
Date:
December 29, 1989
Creator:
Eichten, E.; Hockney, G. & Thacker, H.B.
System:
The UNT Digital Library
TMX tandem-mirror experiments and thermal-barrier theoretical studies
This paper describes recent analysis of energy confinement in the Tandem Mirror Experiment (TMX). TMX data also indicates that warm plasma limits the amplitude of the anisotropy driven Alfven ion cyclotron (AIC) mode. Theoretical calculations show strong AIC stabilization with off-normal beam injection as planned in TMX-U and MFTF-B. This paper reports results of theoretical analysis of hot electrons in thermal barriers including electron heating calculations by Monte Carlo and Fokker-Planck codes and analysis of hot electron MHD and microinstability. Initial results from the TMX-U experiment are presented which show the presence of sloshing ions.
Date:
July 29, 1982
Creator:
Simonen, T. C.; Baldwin, D. E. & Allen, S. L.
System:
The UNT Digital Library
Structural and electronic properties of carbon nanotube tapers
Article on structural and electronic properties of carbon nanotube tapers, a set of nanostructures comprised of straight tubular sections with decreasing diameters, joined to each other via conical funnels and terminated with a hemispherical cap.
Date:
October 29, 2001
Creator:
Meunier, Vincent; Buongiorno Nardelli, Marco; Roland, Christopher & Bernholc, Jerry
System:
The UNT Digital Library
4. pi. interferometric measurements of laser fusion targets
Apparatus is described for rapidly manipulating a hollow glass microsphere laser fusion target and scanning the entire wall with a double pass interference microscope.
Date:
September 29, 1977
Creator:
Weinstein, B.W.; Willenborg, D.L.; Weir, J.T. & Hendricks, C.D.
System:
The UNT Digital Library
Reservoir response to tidal and barometric effects
Solid earth tidal strain and surface loading due to fluctuations in barometric pressure have the effect, although extremely minute, of dilating or contracting the effective pore volume in a porous reservoir. If a well intersects the formation, the change in pore pressure can be measured with sensitive quartz pressure gauges. Mathematical models of the relevant fluid dynamics of the well-reservoir system have been generated and tested against conventional well pumping results or core data at the Salton Sea Geothermal Field (SSGF), California and at the Raft River, Geothermal Field (RRGF), Idaho. Porosity-total compressibility product evaluation based on tidal strain response compares favorably with results based on conventional pumping techniques. Analysis of reservoir response to barometric loading using Auto Regressive Integrated Moving Average (ARIMA) stochastic modeling appears also to have potential use for the evaluation of reservoir parameters.
Date:
May 29, 1980
Creator:
Hanson, J.M.
System:
The UNT Digital Library
Regulated 15-V, 7500-A, neutral-beam filament supply
Lawrence Livermore Laboratory (LLL) designed a cost-effective, regulated 15-V, 7500-A filament supply for use with the High-Voltage Test Stand , a major ERDA developmental neutral-beam test facility. The filament supply can float to 200 kV and can provide pulse widths up to 30 s. Powered by a 24-V, 0.5-TJ battery bank, it avoids the use of expensive isolation transformers and induction voltage regulators (IVR's). Battery output is regulated by a water-cooled resistor-contactor combination in which contactors are closed in sequential format to create a staircase current waveform. A fine-tuning network tunes in-between the ''steps'' for regulation to less than 0.5 percent. The regulator is digitally controlled except for the sense amplifiers, which are optically coupled to the digital controller. All ground telemetry uses optical links to minimize effects of rfi and emi noise in the data channels.
Date:
September 29, 1977
Creator:
Reass, W.
System:
The UNT Digital Library
Tradeoffs in capacitor bank design
When designing a capacitor bank for energy storage, the engineer should not use more capacitors, voltage, or energy than necessary to supply the load and to overcome losses. Universal curves presented here aid the designer in making intelligent choices. For example, there is a minimum stored energy to be achieved, but no minimum voltage at which to store it. Included in the curves are the effects of series losses such as voltage drops in regulator tubes or in current-limiting resistors. Capacitor bank designs for the neutral-beam power supplies on 2XIIB and TMX are compared using the developed criteria.
Date:
September 29, 1977
Creator:
Leavitt, G.A.
System:
The UNT Digital Library
Ion microstability in tandem mirrors
The formalism describing ion-cyclotron modes in mirror traps will be developed. Emphasis will be placed on the effects of finite axial boundaries on the normal modes of the system. Wave properties are a composite picture of: positive energy waves (plasma oscillation, shear Alfven and drift waves), negative energy waves (ion Bernstein waves in a loss-cone media), positive dissipation (electron Landau damping, outgoing waves), and negative dissipation (ion cyclotron damping in a loss-cone and anisotropic temperature medium). Stability boundaries in this bounded media is affected by scale lengths along the magnetic field; first, because they determine the widths of the resonances, and second, because they restrict the parallel structure of the modes.
Date:
August 29, 1983
Creator:
Pearlstein, L.D.
System:
The UNT Digital Library
Mirror research: status and prospects
The tandem mirror program has evolved considerably in the last decade. Of significance is the viable reactor concept embodied in the MARS design. An aggressive experimental program culminating in the operation of MFTF-B in late 1986, will provide a firm basis for refining the MARS design as necessary for constructing a reactor prototype in the 1990s.
Date:
November 29, 1983
Creator:
Baldwin, D.E.
System:
The UNT Digital Library
LMFBR fuel component costs
A significant portion of the cost of fabricating LMFBR fuels is in the non-fuel components such as fuel pin cladding, fuel assembly ducts and end fittings. The contribution of these to fuel fabrication costs, based on FFTF experience and extrapolated to large LMFBR fuel loadings, is discussed. The extrapolation considers the expected effects of LMFBR development programs in progress on non-fuel component costs.
Date:
October 29, 1981
Creator:
Epperson, E.M.; Borisch, R.R. & Rice, L.H.
System:
The UNT Digital Library