69 Matching Results

Search Results

Advanced search parameters have been applied.

Applications of decelerated ions

Description: Many facilities whose sole purpose had been to accelerate ion beams are now becoming decelerators as well. The development and current status of accel-decel operations is reviewed here. Applications of decelerated ions in atomic physics experiments are discussed.
Date: March 1, 1985
Creator: Johnson, B.M.
Partner: UNT Libraries Government Documents Department

Two accel/decel experiments: electron capture for 6 to 20 MeV S/sup 10/-/sup 16 +/ on He and Ar and interference effects in MO K x-ray spectra for 5, 10, and 20 MeV Cl/sup 16 +/ on Ar

Description: The recent development of four-stage accel-decel operation of the dual MP tandem accelerators at Brookhaven National Laboratory has made it possible to extend atomic collision experiments over an unprecedented range of high charge states and low velocities. Briefly, this mode of operation uses the first MP tandem conventionally for two stages of acceleration, then with a negative terminal voltage the second MP tandem provides a third stage of acceleration to high velocity, stripping to high charge state and a final stage of deceleration to low velocity. Details of operation and recent upgrades of the facility were reviewed earlier. An overview of present capabilities and the results of two experimental studies using accel-decel beams are presented here.
Date: January 1, 1983
Creator: Johnson, B.M.
Partner: UNT Libraries Government Documents Department

Advanced dry and dry--wet cooling towers

Description: Although progressive restrictions on the use of fresh water for power plant cooling and the growing use of dry cooling is anticipated in many regions of the country, the transition to this form of cooling will occur slowly unless improved technology leads to lower cost systems. The need for supplemental power during periods of warm weather contribute to the high cost of dry cooling and have led to greater emphasis on combined dry and wet cooling. Experimental and demonstration programs are underway at several locations in the U.S. to develop new systems which will hopefully reduce the cost of dry and wet/dry systems and/or the need for supplemental power. If any of the projected improvements of these advanced systems can be developed to the point of commercial availability, the use of dry cooling would be greatly increased and many of the secondary benefits will be realized. These include greater freedom to take advantage of existing transmission corridors, multiple plants on presently water-limited sites and mine mount sites in water-limited regions. The more promising advanced concepts under study are reviewed and appraised as to their likelihood of having a significant impact on the future use of dry (including dry/wet) cooling.
Date: September 1, 1977
Creator: Johnson, B. M.
Partner: UNT Libraries Government Documents Department

Atomic physics research with second and third generation synchrotron light sources

Description: This contribution to these proceedings is intended to provide an introduction and overview for other contributions on atomic (and related) physics research at existing and planned synchrotron light sources. The emphasis will be on research accomplishments and future opportunities, but a comparison will be given of operating characteristics for first, second, and third generation machines. First generation light sources were built to do research with the primary electron and positron beams, rather than with the synchrotron radiation itself. Second generation machines were specifically designed to be dedicated synchrotron-radiation facilities, with an emphasis on the use of bending-magnet radiation. The new third generation light sources are being designed to optimize radiation from insertion devices, such as undulators and wigglers. Each generation of synchrotron light source offers useful capabilities for forefront research in atomic physics and many other disciplines. 27 refs., 1 fig., 3 tabs.
Date: October 1, 1990
Creator: Johnson, B.M.
Partner: UNT Libraries Government Documents Department

Beam-line considerations for experiments with highly-charged ions

Description: The APS offers exciting possibilities for a bright future in x-ray research. For example, measurements on the inner-shell photoionization of ions will be feasible using stored ions in ions traps or ion beams from an electron-cyclotron-resonance ion source, or perhaps even a heavy-ion storage ring. Such experiments with ionic targets are the focus for the discussion given here on the optimization of photon flux on a generic beamline at the APS. The performance of beam lines X26C, X26A, and X17 on the x-ray ring of the National Synchrotron Light Source will be discussed as specific examples of beam-line design considerations.
Date: January 1, 1990
Creator: Johnson, B.M.
Partner: UNT Libraries Government Documents Department

Cost analysis of an ammonia dry cooling system with a Chicago Bridge and Iron peak shaving system

Description: A study was performed to determine the potential for reducing the cost associated with dry cooling by using an ammonia dry cooling system augmented with the Chicago Bridge and Iron (CP and I) peak shaving system. The cost analysis of an all-dry ammonia cooling system operating in conjunction with a peak shaving system is documented. The peak shaving system utilizes the excess cooling capability available at night to cool water to be used for supplemental cooling during the following day. The analysis consisted of determining the incremental cost of cooling for the CB and I system and comparing this cost to the incremental cost of cooling for both dry and wet/dry systems for a consistent set of design conditions and assumptions. The wet/dry systems were analyzed over a range of water usages. The basis of the comparisons was a cooling system designed for installations with a 650 mWe (gross) coal-fired power plant. From results of the study it was concluded that: the CB and I system shows a substantial economic advantage when compared with an all-dry cooling system; the CB and I system appears to be competitive with wet/dry cooling systems using about 2 to 3% water; and the CB and I system demonstrates a clear economic advantage when compared to both dry and wet/dry concepts for a winter peaking utility where the excess generation is assumed to displace both base-loaded coal-fired power generation and oil-fired gas turbine peaking units.
Date: December 1, 1980
Creator: Drost, M.K. & Johnson, B.M.
Partner: UNT Libraries Government Documents Department

Use of spectra from foil-excited heavy-ion beams to interpret radiation from plasmas

Description: Spectra from foil-excited heavy ion beams can be used to investigate the relative abundance and charge state composition of heavy metal contaminants which cause severe radiative energy losses in tokamak-produced plasmas. The degree of ionization of these metals in the tokamak plasma is not well known because of uncertainties in ionization and recombination rates and particle confinement times. Only a few stages of ionization are typically prominent in foil-excited spectra, however, and both the most probable charge state and distribution width are well known. Highly ionized heavy ions (e.g., Ti, Mo, W and Au) which span the range of charge states found in present tokamaks were produced by passing beams from the Brookhaven MP tandem Van de Graaff accelerator facility through 20 ..mu..g/cm/sup 2/ carbon stripping foils. EUV radiation was recorded with a grazing incidence spectrometer. Comparisons of the beam-foil spectra with radiation from plasmas, and recent direct determinations of atomic oscillator strengths for principal resonance lines of such highly ionized species as Li-like iron (Fe/sup 23 +/), Na-like bromine (Br/sup 24 +/), and Cu-like iodine (I/sup 24 +/) are discussed.
Date: January 1, 1978
Creator: Johnson, B M
Partner: UNT Libraries Government Documents Department

Dry cooling for power plants: incentives, problems, and R and D activities

Description: Projecting the use of dry cooling at steam-electric plants within the next twenty years is fraught with more than the usual amount of uncertainty associated with long-range predictions. Eventually the industry's cooling requirements may exceed the availability of cooling water and require the direct rejection of heat to the atmosphere. However, projecting the physical availability of water and the growth of power generating capacity in various regions is not sufficient to determine the use of dry cooling within a twenty-year time frame. The use will be largely determined by legislative decisions on the use of limited inland water resources and the accessibility of seawater for cooling in coastal areas. These legislative decisions, in turn, will be influenced by the perceived impact of dry cooling upon the cost and conservation of energy. Research and development in progress is focused on reducing the total evaluated cost of dry cooling through reducing the capital cost and/or reducing the cost of providing replacement energy and generating capability. The incentives, problems and research/development activities are reviewed to provide an overview of potential improvements in dry cooling and the impact they may have on future power plant construction.
Date: April 1, 1977
Creator: Johnson, B. M. & Maulbetsch, J. S.
Partner: UNT Libraries Government Documents Department

Numerical Tests and Properties of Waves in Radiating Fluids

Description: We discuss the properties of an analytical solution for waves in radiating fluids, with a view towards its implementation as a quantitative test of radiation hydrodynamics codes. A homogeneous radiating fluid in local thermodynamic equilibrium is periodically driven at the boundary of a one-dimensional domain, and the solution describes the propagation of the waves thus excited. Two modes are excited for a given driving frequency, generally referred to as a radiative acoustic wave and a radiative diffusion wave. While the analytical solution is well known, several features are highlighted here that require care during its numerical implementation. We compare the solution in a wide range of parameter space to a numerical integration with a Lagrangian radiation hydrodynamics code. Our most significant observation is that flux-limited diffusion does not preserve causality for waves on a homogeneous background.
Date: September 3, 2009
Creator: Johnson, B M & Klein, R I
Partner: UNT Libraries Government Documents Department

Synchrotron radiation production and trapping of highly charged ions

Description: Wiggler-enhanced synchrotron radiation will soon be available at dedicated facilities such as the National Synchrotron Light Source (NSLS) at Brookhaven National Laboratory. Two recent proposals to study highly-charged ions produced by successive photoionization with broad-band synchrotron radiation are based on the design parameters of the NSLS x-ray ring. Previous calculations indicated that in a suitable Kingdon trap, concentrations of 5 x 10/sup 7/ Ar/sup 18 +/ ions per cm can be attained in a few seconds trapping time and that in a Penning trap 5 x 10/sup 3/ Ar/sup 17 +/ ions could be stored at near thermal energies (300/sup 0/K) to study, for example, charge transfer collision processes for cold, highly-charged ions. Here the previous work is reviewed and the earlier calculations are extended. The addition of an axial magnetic field to a Kingdon trap is shown to improve expected PHOBIS performance.
Date: September 1, 1984
Creator: Johnson, B.M.; Jones, K.W. & Meron, M.
Partner: UNT Libraries Government Documents Department

Informal proposal for an Atomic Physics Facility at the National Synchrotron Light Source

Description: An Atomic Physics Facility (APF) for experiments that will use radiation from a superconducting wiggler on the NSLS X-13 port is described. The scientific justification for the APF is given and the elements of the facility are discussed. It is shown that it will be possible to conduct a uniquely varied set of experiments that can probe most aspects of atomic physics. A major component of the proposal is a heavy-ion storage ring capable of containing ions with energies of about 10 MeV/nucleon. The ring can be filled with heavy ions produced at the BNL MP Tandem Laboratory or from independent ion-source systems. A preliminary cost estimate for the facility is presented.
Date: January 1, 1986
Creator: Jones, K.W.; Johnson, B.M. & Meron, M.
Partner: UNT Libraries Government Documents Department

Technical and economic assessment of the use of ammonia expanders for energy recovery in air-cooled power plants

Description: Binary cycle power plants have been the subject of much discussion among engineers and scientists for nearly 100 years. Current economic and environmental concerns have stimulated new interest and research. Ammonia has been recommended by other studies as the leading contender for use as simply the heat rejection medium in an air-cooled power plant. This study investigates the technical feasibility and economic potential of including an expander in the heat rejection system of an air-cooled power plant. The expander would be used during certain parts of the year to increase the total output of the power plant. Five different plant locations (Miami, San Francisco, Bakersfield, Chicago, Anchorage) were investigated to show the effect which climate has on the economic potential of this ammonia bottoming cycle. The study shows that the expected energy costs for the bottoming cycle only will be less than 50 mills/kWh for any of the five plant locations. This cost assumes that an ammonia phase-change heat rejection system is already a part of the existing plant. The colder climates of Chicago and Anchorage demonstrate an even smaller energy cost of less than 15 mills/kWh. Further investigation of the concept is merited to substantiate these costs and determine the needed technology.
Date: July 1, 1982
Creator: Hauser, S.G.; Hane, G.J. & Johnson, B.M.
Partner: UNT Libraries Government Documents Department

Atomic physics with high-brightness synchrotron x-ray sources

Description: A description of atomic physics experiments that we intend to carry out at the National Synchrotron Light Source is given. Emphasis is given to work that investigates the properties of multiply charged ions. The use of a synchrotron storage ring for highly charged heavy ions is proposed as a way to produce high current beams which will make possible experiments to study the photoexcitation and ionization of multiply charged ions for the first time. Experiments along the same lines which are feasible at the proposed Advanced Light Source are considered briefly. 7 refs., 2 figs.
Date: November 1, 1985
Creator: Jones, K.W.; Johnson, B.M. & Meron, M.
Partner: UNT Libraries Government Documents Department

Atomic collision experiments utilizing low-velocity, highly-charged ion beams

Description: Intense beams of highly-stripped ions are now routinely produced at low velocities using the Brookhaven dual MP-tandens in a unique four-stage accel/decel mode. This mode of operation combines three stages of acceleration, stripping at high energy, and one stage of deceleration to near-zero velocity. To date, experiments have used 10-100 nA beams of bare and few-electron heavy ions at energies as low as 0.2 MeV/amu, and upgrades of the facility should push the lower limit below 0.1 MeV/amu. Recent experiments, such as measurements of charge transfer and x-ray production for S/sup 6-16+/ on He and Ar at 6 to 20 MeV and P(b) measurements for MO x-rays produced in Cl/sup 16 +/ + Ar collisions at 20, 10, and 5 MeV have demonstrated the usefulness of highly-stripped, low-velocity projectiles. These experiments and a few possibilities for future experiments are discussed.
Date: January 1, 1982
Creator: Johnson, B.M.; Jones, K.W. & Meron, M.
Partner: UNT Libraries Government Documents Department

Experiments with a synchrotron x-ray source and conventional, ECR, and storage-ring ion sources

Description: The present intensities of photon beams produced by synchrotron-radiation x-ray sources and of ion beams from conventional ion sources, electron-cyclotron resonance ion sources (ECRIS), and cooled heavy-ion storage rings (CHISR) make possible investigations of photoionization and photoexcitation processes that have not previously been feasible. An evaluation of the signal and background rates for experiments that employ the different types of ion sources is given here. 11 refs., 3 figs., 6 tabs.
Date: January 1, 1988
Creator: Jones, K.W.; Johnson, B.M. & Meron, M.
Partner: UNT Libraries Government Documents Department

Present and future directions of atomic physics research with multiply-charged ions at Brookhaven National Laboratory

Description: Atomic physics research with multiply-charged ions is now in progress using ion beams from the Brookhaven Double MP-Tandem van de Graaff facility. In the near future, experiments will start using ions produced by photons from the National Synchrotron Light Source (NSLS). Examples of typical experiments are discussed to illustrate the comprehensive nature of these facilities. Plans for future expansion by addition of a CRYEBIS type ion source coupled to a heavy-ion storage ring for use in crossed-beam experiments at the NSLS are discussed. 18 refs., 8 figs.
Date: March 1, 1985
Creator: Jones, K.W.; Johnson, B.M. & Meron, M.
Partner: UNT Libraries Government Documents Department

Science with multiply-charged ions at Brookhaven National Laboratory

Description: Methods for producing multiply-charged ions at different charge states and energies were discussed in the context of the facilities and capabilities that are part of the atomic physics program at Brookhaven. Examples were given of some of the experiments that have been accomplished. It was shown that ions with energies from a fraction of an MeV to ions with an energy of several hundred MeV are necessary to properly investigate the science of low-energy multiply-charged ions. Also discussed was the use of synchrotron photons as a fertile method for extending the field of ionic studies.
Date: January 1, 1987
Creator: Jones, K.W.; Johnson, B.M.; Meron, M. & Thieberger, P.
Partner: UNT Libraries Government Documents Department

Atomic physics experiments with photon and ion beams

Description: The experiments investigated the feasibility of: (1) producing multiply-charged argon ions (up to 7+) at very low energies in quantities sufficient for experimental purposes, (2) using ion trap techniques for further study of the ions and repetitive photoionization to achieve higher charge states, and (3) using a VUV spectrometer to study fluorescent radiation emitted from the ions.
Date: March 1, 1987
Creator: Jones, K.W.; Johnson, B.M. & Meron, M.
Partner: UNT Libraries Government Documents Department

Interactions of multiply-charged ions with electrons and photons

Description: The current status of ion beam excitation and ionization by high energy electrons and photons is discussed. Recent advances in multiply-charged ion source development are mentioned, and plans for electron-ion and synchrotron-ion crossed beam experiments at Brookhaven National Laboratory are described.
Date: January 1, 1980
Creator: Gregory, D.C.; Johnson, B.M. & Jones, K.W.
Partner: UNT Libraries Government Documents Department

Atomic physics and synchrotron radiation: The production and accumulation of highly charged ions

Description: Synchrotron radiation can be used to produce highly-charged ions, and to study photoexcitation and photoionization for ions of virtually any element in the periodic table. To date, with few exceptions, atomic physics studies have been limited to rare gases and a few metal vapors, and to photoexcitation energies in the VUV region of the electromagnetic spectrum. These limitations can now be overcome using photons produced by high-brightness synchrotron storage rings, such as the x-ray ring at the National Synchrotron Light Source (NSLS) at Brookhaven. Furthermore, calculations indicate that irradiation of an ion trap with an intense energetic photon beam will result in a viable source of highly-charged ions that can be given the name PHOBIS: the PHOton Beam Ion Source. Promising results, which encourage the wider systematic use of synchrotron radiation in atomic physics research, have been obtained in recent experiments on VUV photoemission and the production and storage of multiply-charged ions. 26 refs., 4 figs., 1 tab.
Date: January 1, 1986
Creator: Johnson, B.M.; Meron, M.; Agagu, A. & Jones, K.W.
Partner: UNT Libraries Government Documents Department

Dry/wet performance of a plate-fin air-cooled heat exchanger with continuous corrugated fins

Description: The performance and operating characteristics of a plate-fin heat exchanger in dry/wet or deluge operations was experimentally determined. Development of the deluge heat/mass transfer model continued. The experiments were conducted in a specially-designed wind tunnel at the PNL. Air that was first heated and humidified to specified conditions was circulated at a controlled rate through a 2 ft x 6 ft heat exchanger module. The heat exchanger used in the tests was a wavy surface, plate fin on tube configuration. Hot water was circulated through the tubes at high flow rates to maintain an essentially isothermal condition on the tube side. Deionized water sprayed on the top of the vertically oriented plate fins was collected at the bottom of the core and recirculated. Instrumentation was provided for measurement of flow rates and thermodynamic conditions in the air, in the core circulation water, and in the deluge water. Measurements of the air side pressure drop and heat rejection rate were made as a function of air flow rate, air inlet temperature and humidity, deluge water flow rate, and the core inclination from the vertical. An overall heat transfer coefficient and an effective deluge film convective coefficient was determined. The deluge model, for predicting heat transfer from a wet finned heat exchanger was further developed and refined, and a major extension of the model was formulated that permits simultaneous calculation of both the heat transfer and evaporation rates from the wetted surface. The experiments showed an increase in the heat rejection rate due to wetting, accompanied by a proportional increase in the air side pressure drop. For operation at the same air side pressure drop, the enhancement ratio Q/sub w//Q/sub d/ varied between 2 and 5 for the conditions tested. Thus, the potential enhancement of heat transfer due to wetting can be ...
Date: January 1, 1981
Creator: Hauser, S.G.; Kreid, D.K. & Johnson, B.M.
Partner: UNT Libraries Government Documents Department