Preliminary design for the SLAC Next Linear Collider Test Accelerator (NLCTA) requires a pulse power source to produce a 600 kV, 600 A, 1.4 {mu}s, 0.1% flat top pulse with rise and fall times of approximately 100 ns to power an X-Band klystron with a microperveance of 1.25 at {approx} 100 MW peak RF power. The design goals for the modulator, including those previously listed, are peak modulator pulse power of 340 MW operating at 120 Hz. A three-stage darlington pulse-forming network, which produces a >100 kV, 1.4 {mu}s pulse, is coupled to the klystron load through a 6:1 pulse transformer. Careful consideration of the transformer leakage inductance, klystron capacitance, system layout, and component choice is necessary to produce the very fast rise and fall times at 600 kV operating continuously at 120 Hz.

Preliminary design for the SLAC Next Linear Collider Test Accelerator (NLCTA) requires a pulse power source to produce a 600 kV, 600 A, 1.4 {mu}s, 0.1% flat top pulse with rise and fall times of approximately 100 ns to power an X-Band klystron with a microperveance of 1.25 at {approx} 100 MW peak RF power. The design goals for the modulator, including those previously listed, are peak modulator pulse power of 340 MW operating at 120 Hz. A three-stage darlington pulse-forming network, which produces a >100 kV, 1.4 {mu}s pulse, is coupled to the klystron load through a 6:1 pulse transformer. Careful consideration of the transformer leakage inductance, klystron capacitance, system layout, and component choice is necessary to produce the very fast rise and fall times at 600 kV operating continuously at 120 Hz.

This document serves as the proceedings for the annual project review meeting held by Sandia National Laboratories` Photovoltaic Technology and Photovoltaic Evaluation Departments. It contains information supplied by organizations making presentations at the meeting, which was held July 14--15, 1992 at the Sheraton Old Town Hotel in Albuquerque, New Mexico. Overview sessions covered the Department of Energy (DOE) program, including those at Sandia and the National Renewable Energy Laboratory (NREL), and non-DOE programs, including the EPRI concentrator collector program, The Japanese crystalline silicon program, and some concentrating photovoltaic activities in Europe. Additional sessions included papers on Sandia`s Photovoltaic Device Fabrication Laboratory`s collaborative research, cell processing research, the activities of the participants in the Concentrator Initiative Program, and photovoltaic technology evaluation at Sandia and NREL.

This report describes the 1992 yearly calibration of a gross gamma-ray geophysical pulse logging system owned by the US Department of Energy (DOE) and operated by Pacific Northwest Laboratory. The calibration was conducted to permit the continued use of this system for geologic and hydrologic studies associated with remedial investigation at the Hanford Site. The calibration is limited to the probe identified as CG27A-97. Primary calibrations to equivalent-uranium units were conducted in DOE borehole model standards that reside on the Hanford Site. The calibrations were performed in borehole models SBL/SBH and SBA/SBB, which contain low equivalent-uranium concentrations. A previous correlation for relating observed count rate in before- and after-logging field calibrations to equivalent-uranium concentrations was confirmed for field source Ra-20S-82. A computer-based digital collection/recording system was used simultaneously on many of the procedures with the original analog system so that the performance of the two collection systems could be correlated and compared at some future date.

An over-view of existing and planned radioactive nuclear beam facilities world-wide. Two types of production methods are distinguished: projectile fragmentation and the on-line isotope separator (ISOL) method. While most of the projectile fragmentation facilities are already in operation, almost all the ISOL-based facilities are in still the planning stage.

We present data from our study of a device known as the inverse free electron laser. First, numerical simulations were performed to optimize the design parameters for an experiment that accelerates electrons in the presence of an undulator by stimulated absorption of radiation. The Columbia free electron laser (FEL) was configured as an auto-accelerator (IFELA) system; high power (MW's) FEL radiation at {approximately}1.65 mm is developed along the first section of an undulator inside a quasi-optical resonator. The electron beam then traverses a second section of undulator where a fraction of the electrons is accelerated by stimulated absorption of the 1.65 mm wavelength power developed in the first undulator section. The second undulator section has very low gain and does not generate power on its own. We have found that as much as 60% of the power generated in the first section can be absorbed in the second section, providing that the initial electron energy is chosen correctly with respect to the parameters chosen for the first and second undulators. An electron momentum spectrometer is used to monitor the distribution of electron energies as the electrons exit the IFELA. We have found; using our experimental parameters, that roughly 10% of …

We present data from our study of a device known as the inverse free electron laser. First, numerical simulations were performed to optimize the design parameters for an experiment that accelerates electrons in the presence of an undulator by stimulated absorption of radiation. The Columbia free electron laser (FEL) was configured as an auto-accelerator (IFELA) system; high power (MW`s) FEL radiation at {approximately}1.65 mm is developed along the first section of an undulator inside a quasi-optical resonator. The electron beam then traverses a second section of undulator where a fraction of the electrons is accelerated by stimulated absorption of the 1.65 mm wavelength power developed in the first undulator section. The second undulator section has very low gain and does not generate power on its own. We have found that as much as 60% of the power generated in the first section can be absorbed in the second section, providing that the initial electron energy is chosen correctly with respect to the parameters chosen for the first and second undulators. An electron momentum spectrometer is used to monitor the distribution of electron energies as the electrons exit the IFELA. We have found; using our experimental parameters, that roughly 10% of …

The NLC design achieves high luminosity with multiple bunches in each RF pulse. Acceleration of a train of bunches without emittance growth requires control of long range dipole wakefields. SLAC is pursuing a structure design which suppresses the effect of wakefields by varying the physical dimensions of successive cells of the disk-loaded traveling wave structure in a manner which spreads the frequencies of the higher mode while retaining the synchronism between the electrons and the accelerating mode. The wakefields of structures incorporating higher mode detuning have been measured at the Accelerator Test Facility at Argonne. Mechanical design and brazing techniques which avoid getting brazing alloy into the interior of the accelerator are being studied. A test facility for high-power testing of these structures is complete and high power testing has begun.

The NLC design achieves high luminosity with multiple bunches in each RF pulse. Acceleration of a train of bunches without emittance growth requires control of long range dipole wakefields. SLAC is pursuing a structure design which suppresses the effect of wakefields by varying the physical dimensions of successive cells of the disk-loaded traveling wave structure in a manner which spreads the frequencies of the higher mode while retaining the synchronism between the electrons and the accelerating mode. The wakefields of structures incorporating higher mode detuning have been measured at the Accelerator Test Facility at Argonne. Mechanical design and brazing techniques which avoid getting brazing alloy into the interior of the accelerator are being studied. A test facility for high-power testing of these structures is complete and high power testing has begun.

Transport of alkali metal atoms through porous cathodes of alkali metal thermal-to-electric converter (AMTEC) cells is responsible for significant, reducible losses in the electrical performance of these cells. Experimental evidence for activated transport of metal atoms at grain surfaces and boundaries within some AMTEC electrodes has been derived from temperature dependent studies as well as from analysis of the detailed frequency dependence of ac impedance results for other electrodes, including thin, mature molybdenum electrodes which exhibit transport dominated by free molecular flow of sodium gas at low frequencies or dc conditions. Activated surface transport will almost always exist in parallel with free molecular flow transport, and the process of alkali atom adsorption/desorption from the electrode surface will invariably be part of the transport process, and possibly a dominant part in some cases. Little can be learned about the detailed mass transport process from the ac impedance or current voltage curves of an electrode at one set of operating parameters, because the transport process includes a number of important physical parameters that are not all uniquely determined by one experiment. The temperature dependence of diffusion coefficient of the alkali metal through the electrode in several cases provides an activation energy and …

Flux creep in a Bi-Sr-Ca-Cu-0 system has been investigated in wide temperature and field regimes. Previously reported studies of the flux-creep activation energy U have been controversial in terms of the temperature and field dependence, and the U values have not been consistent with the macroscopically measured critical current density, J{sub c} We have developed a new approach to obtain the activation energy by considering the nonlinearity between U and J. We find that the activation energy is considerably increased in liquid-quenched Bi-Sr-Ca-Cu-0, as a result of enhanced pinning by finely dispersed precipitates. Our results are consistent with the increased macroscopic parameter J{sub c}.

Flux creep in a Bi-Sr-Ca-Cu-0 system has been investigated in wide temperature and field regimes. Previously reported studies of the flux-creep activation energy U have been controversial in terms of the temperature and field dependence, and the U values have not been consistent with the macroscopically measured critical current density, J{sub c} We have developed a new approach to obtain the activation energy by considering the nonlinearity between U and J. We find that the activation energy is considerably increased in liquid-quenched Bi-Sr-Ca-Cu-0, as a result of enhanced pinning by finely dispersed precipitates. Our results are consistent with the increased macroscopic parameter J{sub c}.

Superplastic forming has emerged as an important manufacturing process for producing near-net-shape parts. The design of a superplastic forming process is more difficult than conventional manufacturing operations, and is less amenable to trial and error approaches. This paper describes a superplastic forming process design capability incorporating nonlinear finite element analysis. The material constraints to allow superplastic behavior are integrated into an external constraint equation which is solved concurrently with the nonlinear finite element equations. The implementation of this approach using the ISLAND solution control language with the nonlinear finite element code NIKE2D is discussed in detail. Superplastic forming process design problems with one and two control parameters are presented as examples.

The numerical methods employed in the solution of many scientific computing problems require the computation of derivatives of a function f: R{sup n} {yields} R{sup m}. ADIFOR (Automatic Differentiation in FORtran) is a source transformation tool that accepts Fortran 77 code for the computation of a function and writes portable Fortran 77 code for the computation of the derivatives. In contrast to previous approaches, ADIFOR views automatic differentiation as a source transformation problem and employs the data analysis capabilities of the ParaScope Fortran programming environment. Experimental results show that ADIFOR can handle real- life codes and that ADIFOR-generated codes are competitive with divided-difference approximations of derivatives. In addition, studies suggest that the source-transformation approach to automatic differentation may improve the time required to compute derivatives by orders of magnitude.

The numerical methods employed in the solution of many scientific computing problems require the computation of derivatives of a function f: R{sup n} {yields} R{sup m}. Both the accuracy and the computational requirements of the derivative computation are usually of critical importance for the robustness and speed of the numerical method. ADIFOR (Automatic Differentiation In FORtran) is a source translation tool implemented using the data abstractions and program analysis capabilities of the ParaScope Parallel Programming Environment. ADIFOR accepts arbitrary Fortran-77 code defining the computation of a function and writes portable Fortran-77 code for the computation of its derivatives. In contrast to previous approaches, ADIFOR views automatic differentiation as a process of source translation that exploits computational context to reduce the cost of derivative computations. Experimental results show that ADIFOR can handle real-life codes, providing exact derivatives with a running time that is competitive with the standard divided-difference approximations of derivatives and which may perform orders of magnitude faster than divided-differences in cases. The computational scientist using ADIFOR is freed from worrying about the accurate and efficient computation of derivatives, even for complicated ``functions,`` and hence, is able to concentrate on the more important issues of algorithm design or system modeling. …

Advanced Cooling Technology (ACT), Inc., will perform the following tasks in order to develop an improved, more reliable and more marketable version of their ACT Evaporative Subcooling System: (1) Develop a more stable pump by reducing vibration levels; (2) Design and develop a drainage mechanism that will protect the coil; (3) Apply for Underwriters laboratories approval and perform follow-up and coordination work to complete task to insure product is safe, within its intended applications; (4) Test invention`s performance to demonstrate energy savings and long term resistance to scale and corrosion; (5) Contract with the American Refrigeration Institute to perform engineering tests under controlled laboratory conditions; (6) Organize data, and develop technical manual for helping purchasers determining energy savings and inventions merits, and (7) Perform a field test in a cooperative supermarket, where utility usage can be measured on a before and after basis. Tasks 1,2 are completed; task 3 was abandoned for reasons explained in the last quarterly progress report. Progress on tasks 4 and 5 is reported in this paper. (GHH)

Advanced Cooling Technology (ACT), Inc., will perform the following tasks in order to develop an improved, more reliable and more marketable version of their ACT Evaporative Subcooling System: (1) Develop a more stable pump by reducing vibration levels; (2) Design and develop a drainage mechanism that will protect the coil; (3) Apply for Underwriters laboratories approval and perform follow-up and coordination work to complete task to insure product is safe, within its intended applications; (4) Test invention's performance to demonstrate energy savings and long term resistance to scale and corrosion; (5) Contract with the American Refrigeration Institute to perform engineering tests under controlled laboratory conditions; (6) Organize data, and develop technical manual for helping purchasers determining energy savings and inventions merits, and (7) Perform a field test in a cooperative supermarket, where utility usage can be measured on a before and after basis. Tasks 1,2 are completed; task 3 was abandoned for reasons explained in the last quarterly progress report. Progress on tasks 4 and 5 is reported in this paper. (GHH)

The mission of the ASCENT (Advanced Scientific Computing EnvironmenT) Team is continually keep pace with, evaluate, and select emerging computing technologies to define and implement prototypic scientific computing environments that maximize the ability of scientists and engineers to manage scientific data. These environments are to be implemented in a manner consistent with the site computing architecture and standards and strategic plans for scientific computing. A broad, long term, goal of the ASCENT Team is to provide a computing environment that will let scientists and engineers function at the higher level of abstraction that is their actual area of technical expertise. The scientist/engineer should be able to solve problems by interacting with conceptual representations drawn directly from the scientific and engineering domains. In this environment the scientist/engineer (i.e., the ``problem solver``) builds the problem model with reusable virtual objects having associated attributes and behaviors, including any real or artificial constraints. The problem solver could then test the model by perturbing it interactively and observing quantitative (archived experimental measurements; simulated or computed data) and/or qualitative (trends, approximations) responses. Such an environment would greatly aid the solution and understanding of scientific and engineering problems. This report discusses the proposed system, program, graphic tools …

The objective of this work is to develop a novel system for regenerable SO{sub 2} and NO{sub x} scrubbing of flue gas that focuses on (a) a novel method for regeneration of spent SO{sub 2} scrubbing liquor and (b) novel chemistry for reversible absorption of NO{sub x}. In addition, high efficiency hollow fiber contactors (HFC) are proposed as the devices for scrubbing the SO{sub 2} and NO{sub x} from the flue gas. The major cost item in existing technology is capital investment. Therefore, our approach is to reduce the capital cost by using high efficiency hollow fiber devices for absorbing and desorbing the SO{sub 2} and NO{sub x}. Our novel chemistry for scrubbing NO{sub x} win consist of water soluble phthalocyanine compounds invented by SRI and also of polymeric forms of Fe{sup ++} complexes similar to traditional NO{sub x} scrubbing media described in the open literature. Our past work with the phthalocyanine compounds, used as sensors for NO and NO{sub 2} in flue gases, shows that these compounds bind NO and NO{sub 2} reversibly and with no interference from O{sub 2}, CO{sub 2}, SO{sub 2}, or other components of flue gas. The final novelty of our approach is the arrangement …

The objective of this work is to develop a novel system for regenerable SO{sub 2} and NO{sub x} scrubbing of flue gas that focuses on (a) a novel method for regeneration of spent SO{sub 2} scrubbing liquor and (b) novel chemistry for reversible absorption of NO{sub x}. In addition, high efficiency hollow fiber contactors (HFC) are proposed as the devices for scrubbing the SO{sub 2} and NO{sub x} from the flue gas. The major cost item in existing technology is capital investment. Therefore, our approach is to reduce the capital cost by using high efficiency hollow fiber devices for absorbing and desorbing the SO{sub 2} and NO{sub x}. Our novel chemistry for scrubbing NO{sub x} win consist of water soluble phthalocyanine compounds invented by SRI and also of polymeric forms of Fe{sup ++} complexes similar to traditional NO{sub x} scrubbing media described in the open literature. Our past work with the phthalocyanine compounds, used as sensors for NO and NO{sub 2} in flue gases, shows that these compounds bind NO and NO{sub 2} reversibly and with no interference from O{sub 2}, CO{sub 2}, SO{sub 2}, or other components of flue gas. The final novelty of our approach is the arrangement …

The objective of this task is to perform a technical assessment of turbine blading for advanced second generation PFBC conditions, identify specific problems/issues, and recommend an approach for solving any problems identified. A literature search was conducted, problems associated with hot corrosion defined and limited experiments performed. Sulfidation corrosion occurs in industrial, marine and aircraft gas turbine engines and is due to the presence of condensed alkali (sodium) sulfates. The principle source of the alkali in industrial, marine and aircraft gas turbine engines is sea salt crystals. The principle source of the sulfur is not the liquid fuels, but the same ocean born crystals. Moreover deposition of the corrosive salt occurs primarily by a non-equilibrium process. Sodium will be present in the cleaned combusted gases that enter the PFBC turbine. Although equilibrium condensation is not favored, deposition via impaction is probable. Marine gas turbines operate in sodium chloride rich environments without experiencing the accelerated attack noted in coal fired boilers where condensed chlorides contact metallic surfaces. The sulfates of calcium and magnesium are the products of the reactions used to control sulfur. Based upon industrial gas turbine experience and laboratory tests, calcium and magnesium sulfates are, at temperatures up to …

The objective of this task is to perform a technical assessment of turbine blading for advanced second generation PFBC conditions, identify specific problems/issues, and recommend an approach for solving any problems identified. A literature search was conducted, problems associated with hot corrosion defined and limited experiments performed. Sulfidation corrosion occurs in industrial, marine and aircraft gas turbine engines and is due to the presence of condensed alkali (sodium) sulfates. The principle source of the alkali in industrial, marine and aircraft gas turbine engines is sea salt crystals. The principle source of the sulfur is not the liquid fuels, but the same ocean born crystals. Moreover deposition of the corrosive salt occurs primarily by a non-equilibrium process. Sodium will be present in the cleaned combusted gases that enter the PFBC turbine. Although equilibrium condensation is not favored, deposition via impaction is probable. Marine gas turbines operate in sodium chloride rich environments without experiencing the accelerated attack noted in coal fired boilers where condensed chlorides contact metallic surfaces. The sulfates of calcium and magnesium are the products of the reactions used to control sulfur. Based upon industrial gas turbine experience and laboratory tests, calcium and magnesium sulfates are, at temperatures up to …

The Advanced Water Cooled Phosphoric Acid Fuel Cell Development program is being conducted by International Fuel Cells Corporation (IFC) to improve the performance and minimize the cost of water-cooled, electric utility phosphoric acid fuel cell stacks. The program adapts the existing on-site Configuration B cell design to electric utility operating conditions and introduces additional new design features. Task 1 consists of the conceptual design of a full-scale electric utility cell stack that meets program objectives. Tasks 2 and 3 develop the materials and processes required to fabricate the components that meet the program objective. The design of the small area and two 10-ft[sup 2] short stacks is conducted in Task 4. The conceptual design also is updated to incorporate the results of material and process developments, as well as results of stack tests conducted in Task 6. Fabrication and assembly of the short stacks are conducted in Task 5 and subsequent tests are conducted in Task 6. The Contractor expects to enter into a contract with the Electric Power Research Institute (EPRI) to assemble and endurance test the second 10-ft[sup 2] short stack. The management and reporting functions of Task 7 provide DOE/METC with program visibility through required documentation and …

The Advanced Water Cooled Phosphoric Acid Fuel Cell Development program is being conducted by International Fuel Cells Corporation (IFC) to improve the performance and minimize the cost of water-cooled, electric utility phosphoric acid fuel cell stacks. The program adapts the existing on-site Configuration B cell design to electric utility operating conditions and introduces additional new design features. Task 1 consists of the conceptual design of a full-scale electric utility cell stack that meets program objectives. Tasks 2 and 3 develop the materials and processes required to fabricate the components that meet the program objective. The design of the small area and two 10-ft{sup 2} short stacks is conducted in Task 4. The conceptual design also is updated to incorporate the results of material and process developments, as well as results of stack tests conducted in Task 6. Fabrication and assembly of the short stacks are conducted in Task 5 and subsequent tests are conducted in Task 6. The Contractor expects to enter into a contract with the Electric Power Research Institute (EPRI) to assemble and endurance test the second 10-ft{sup 2} short stack. The management and reporting functions of Task 7 provide DOE/METC with program visibility through required documentation and …