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Liquid nitrogen cooled liners for 2XIIB

Description: Liquid-nitrogen-cooled liners have been installed in the neutral-beam source tanks of 2XIIB. The installation has resulted in improvements in vacuum pumping, although testing is not complete. The liners are stainless-steel-flooded-type liners, using spot-welded-and-inflation construction. The natural-convection flow system must keep the liners cold during the high heat loads imposed during Ti gettering.
Date: October 17, 1977
Creator: Atkinson, D.P. & Calderon, M.O.
Partner: UNT Libraries Government Documents Department

Vacuum system for the Tandem Mirror Experiment

Description: The Tandem Mirror Experiment (TMX) under construction at LLL is a Q-enhancement experiment using two mirror fields to ''plug'' a central solenoid field. Neutral beam injection supplies the energetic neutrals to the plug regions with attendant quantities of cold gas. The vacuum vessel consists of two large stainless steel tanks, which house the plug coils, joined by an aluminum central cell tank, which fits inside the existing solenoid coils from the 2XIIB experiment. The plug tanks are subdivided into regions for differential pumping of the source gas by liquid-nitrogen- or water-cooled liners. The liners are gettered by Ti--Ta wire sublimators of the 2XIIB type, using 2XIIB power supplies, to supply the necessary high-speed surface pumping. The roughing vacuum system consists of mercury vapor diffusion pumps backed by Roots-type blowers.
Date: October 4, 1977
Creator: Atkinson, D.P.; Calderon, M.O. & Nagel, R.J.
Partner: UNT Libraries Government Documents Department

Vacuum system for the Tandem Mirror Experiment

Description: This paper is a sequel to the one prepared by Atkinson, et al., in which the authors described the vacuum system of Lawrence Livermore Laboratory's Tandem Mirror Experiment (TMX). We discuss here the final configuration, liquid nitrogen (LN/sub 2/) supply, and operation of the complete TMX vacuum system. The assembled vacuum system consists of two plug tanks with a volume of approximately 60 m/sup 3/ each and a center cell tank with a volume of approximately 10 m/sup 3/. In each plug tank there are 145 m/sup 2/ of titanium-gettered, LN/sub 2/-filled panels, which allow a pumping speed calculated to be 5 x 10/sup 7/ l/s for a period of 50 ms. The system maintains an operating pressure in the plasma chamber on the order of 10/sup -6/ Torr while 24 neutral-beam injectors are introducing 700 Torr l/s of hydrogen into the vacuum chamber.
Date: November 9, 1979
Creator: Richardson, M.J.; Atkinson, D.P. & Calderon, M.O.
Partner: UNT Libraries Government Documents Department

Geology and surface geochemistry of the Roosevelt Springs Known Geothermal Resource Area, Utah

Description: Available data on the Roosevelt area were synthesized to determine the spatial arrangement of the rocks, and the patterns of mass and energy flow within them. The resulting model lead to a new interpretation of the geothermal system, and provided ground truth for evaluating the application of soil geochemistry to exploration for concealed geothermal fields. Preliminary geochemical studies comparing the surface microlayer to conventional soil sampling methods indicated both practical and chemical advantages for the surface microlayer technique, which was particularly evident in the case of As, Sb and Cs. Subsequent multi-element analyses of surface microlayer samples collected over an area of 100 square miles were processed to produce single element contour maps for 41 chemical parameters. Computer manipulation of the multi-element data using R-mode factor analysis provided the optimum method of interpretation of the surface microlayer data. A trace element association of As, Sb and Cs in the surface microlayer provided the best indication of the leakage of geothermal solutions to the surface, while regional mercury trends may reflect the presence of a mercury vapour anomaly above a concealed heat source.
Date: January 1, 1980
Creator: Lovell, J.S.; Meyer, W.T. & Atkinson, D.J.
Partner: UNT Libraries Government Documents Department

Field screening of soils contaminated with explosives using ion mobility spectrometry

Description: Soils contaminated with explosives constitute a problem at DOE facilities and Army installations. Because explosives in soil are often heterogeneously distributed and require high density sampling, field screening is essential to characterize sites more quickly, economically and accurately. Current immunoassay and colorimetric field screening procedures have proven useful, but have significant per sample costs and limited throughput. At present, several field screening are available for TNT in soil, three procedures for RDX, and one procedure for 2,4-DNTand ammonium picrate/picric acid (AP/PA). Ion mobility spectrometry (IMS) has been used to detect explosives in air at ppt levels, but limited work has been done to apply the technique to quantify explosives in soils. The objective of this study has been to evaluate the utility of IMS as a screening technique for quantifying explosive residues in soils.
Date: September 1, 1996
Creator: Crockett, A.B.; Atkinson, D.A. & Jenkins, T.F.
Partner: UNT Libraries Government Documents Department

Field screening of soils contaminated with explosives using ion mobility spectrometry

Description: This study involved the comparison of IMS screening with EPA`s standard method for explosives, Method 8330. The US Army Corps of Engineers provided a large number of soil samples that had been collected from three locations at each of three explosive contaminated installations. The samples had been dried, ground, homogenized and analyzed in duplicate by Method 8330. Duplicate two gram aliquots of these samples were extracted with 10 mL of acetone by shaking for three minutes, allowed to settle, then analyzed by IMS for Method 8330 compounds. Half of the extracts from one location have also been analyzed in duplicate by IMS for TNT. Results from TNT contaminated soils look extremely promising. Correlation between IMS and EPA Method 8330 results was very high (r = 0.99). Based on these results, the intention is to further develop and evaluate IMS for simultaneously quantifying multiple analytes. IMS throughput and cost per sample makes it an attractive technique. The ultimate objective is to provide adequate validation data to EPA for inclusion of the method as a screening procedure in SW-846.
Date: May 1, 1997
Creator: Atkinson, D.A.; Crockett, A.B. & Jenkins, T.F.
Partner: UNT Libraries Government Documents Department

Fielding the NIF Cryogenic Ignition Target

Description: The United States Department of Energy has embarked on a campaign to conduct credible fusion ignition experiments on the National Ignition Facility (NIF) at the Lawrence Livermore National Laboratory in 2010. The target assembly specified for this campaign requires the formation of a deuterium/tritium (DT) fuel ice layer on the inside of a 2 millimeter diameter capsule positioned at the center of a 9 millimeter long by 5 millimeter diameter cylinder, called a hohlraum. The ice layer requires micrometer level accuracy and must be formed and maintained at temperatures below 19 K. At NIF shot time, the target must be positioned at the center of the NIF 10 meter diameter target chamber, aligned to the laser beam lines and held stable to less than 7 micrometers rms. We have completed the final design and are integrating the systems necessary to create, characterize and field the cryogenic target for ignition experiments. These designs, with emphasis on the challenges of fielding a precision cryogenic positioning system will be presented.
Date: February 28, 2008
Creator: Malsbury, T; Haid, B; Gibson, C; Atkinson, D; Skulina, K; Klingmann, J et al.
Partner: UNT Libraries Government Documents Department

RF cavity R&D at LBNL for the NLC Damping Rings,FY2000/2001

Description: This report contains a summary of the R&D activities at LBNL on RF cavities for the NLC damping rings during fiscal years 2000/2001. This work is a continuation of the NLC RF system R&D of the previous year [1]. These activities include the further optimization and fine tuning of the RF cavity design for both efficiency and damping of higher-order modes (HOMs). The cavity wall surface heating and stresses were reduced at the same time as the HOM damping was improved over previous designs. Final frequency tuning was performed using the high frequency electromagnetic analysis capability in ANSYS. The mechanical design and fabrication methods have been developed with the goals of lower stresses, fewer parts and simpler assembly compared to previous designs. This should result in substantial cost savings. The cavity ancillary components including the RF window, coupling box, HOM loads, and tuners have been studied in more detail. Other cavity options are discussed which might be desirable to either further lower the HOM impedance or increase the stored energy for reduced transient response. Superconducting designs and the use of external ''energy storage'' cavities are discussed. A section is included in which the calculation method is summarized and its accuracy assessed by comparisons with the laboratory measurements of the PEP-II cavity, including errors, and with the beam-sampled spectrum.
Date: June 1, 2001
Creator: Rimmer, R.A.; Atkinson, D.; Corlett, J.N.; Koehler, G.; Li, D.; Hartman, N. et al.
Partner: UNT Libraries Government Documents Department

Measurement of Ultra Low Outgassing Rates for NLC UHV Vacuum Chambers

Description: Ultra low outgassing rates would be highly advantageous in accelerators and storage rings, such as the Next Linear Collider (NLC), where an outgassing rate of <10{sup -12} Torr liter/sec/cm{sup 2} could eliminate the need for costly distributed pumping. Measuring such low outgassing rates at room temperature has many difficulties. However, by inspection of Fick's law, it can be seen that thermal desorption is proportional to outgassing rate. It is commonly observed that the outgas rate doubles approximately every 15 C for temperatures under 100 C. By measuring outgassing rate versus temperature and time and extrapolating back to room temperature we can measure outgassing rates that would otherwise be difficult to make. To produce a reliable measurement also requires the total surface area under study to be approximately an order of magnitude greater than the area of the measurement chamber walls. To accomplish this, 27 plates of 5083 aluminum were placed in the measurement chamber. This technique will be the basis for future investigation of outgassing rates of other sample plates fabricated with different machining and cleaning techniques.
Date: June 12, 2001
Creator: Kishiyama, K; Shen, S; Behne, D; Corlett, J N; Atkinson, D; Kennedy, K et al.
Partner: UNT Libraries Government Documents Department

High-Power Multimode X-Band RF Pulse Compression System for Future Linear Colliders

Description: We present a multimode X-band rf pulse compression system suitable for a TeV-scale electron-positron linear collider such as the Next Linear Collider (NLC). The NLC main linac operating frequency is 11.424 GHz. A single NLC rf unit is required to produce 400 ns pulses with 475 MW of peak power. Each rf unit should power approximately 5 m of accelerator structures. The rf unit design consists of two 75 MW klystrons and a dual-moded resonant-delay-line pulse compression system that produces a flat output pulse. The pulse compression system components are all overmoded, and most components are designed to operate with two modes. This approach allows high-power-handling capability while maintaining a compact, inexpensive system. We detail the design of this system and present experimental cold test results. We describe the design and performance of various components. The high-power testing of the system is verified using four 50 MW solenoid-focused klystrons run off a common 400 kV solid-state modulator. The system has produced 400 ns rf pulses of greater than 500 MW. We present the layout of our system, which includes a dual-moded transmission waveguide system and a dual-moded resonant line (SLED-II) pulse compression system. We also present data on the processing and operation of this system, which has set high-power records in coherent and phase controlled pulsed rf.
Date: August 10, 2005
Creator: Tantawi, S.G.; Nantista, C.D.; Dolgashev, V.A.; Pearson, C.; Nelson, J.; Jobe, K. et al.
Partner: UNT Libraries Government Documents Department

High-average-power millimeter-wave FEL (free-electron laser) for plasma heating using the ETA-II accelerator

Description: The Microwave Tokamak Experiment (MTX) is under construction at LLNL to investigate the feasibility of intense, pulsed microwave radiation for plasma heating on future ignition tokamaks. A high-average-power free-electron laser (FEL) will use the Experimental Test Accelerator (ETA-II), a linear induction accelerator, in combination with an advanced high-field wiggler, to produce 1-2 MW of power at 1-2-mm wavelengths for periods of up to 0.5s. The design of the FEL, termed the intense microwave prototype (IMP), is described, along with the status and major issues associated with the status and major issues associated with the experiment. 10 refs., 8 figs., 4 tabs.
Date: March 10, 1989
Creator: Throop, A.L.; Atkinson, D.P.; Clark, J.C.; Deis, G.A.; Jong, R.A.; Nexsen, W.E. et al.
Partner: UNT Libraries Government Documents Department

The next linear collider damping ring complex

Description: We report progress on the design of the Next Linear Collider (NLC) Damping Rings complexes. The purpose of the damping rings is to provide low emittance electron and positron bunch trains to the NLC linacs, at a rate of 120 Hz. As an option to operate at the higher rate of 180 Hz, two 1.98 GeV main damping rings per beam are proposed, and one positron pre-damping ring. The main damping rings store up to 0.8 amp in 3 trains of 190 bunches each and have normalized extracted beam emittances {gamma}{var_epsilon}x = 3 mm-mrad and {gamma}{var_epsilon}y = 0.02 mm-mrad. The optical designs, based on a theoretical minimum emittance lattice (TME), are described, with an analysis of dynamic aperture and non-linear effects. Key subsystems and components are described, including the wiggler, the vacuum systems and photon stop design, and the higher-order-mode damped RF cavities. Impedance and instabilities are discussed.
Date: June 12, 2001
Creator: Corlett,J.; Atkinson,D.; De Santis,S.; Hartman, N.; Kennedy, K.; Li, D. et al.
Partner: UNT Libraries Government Documents Department

Is there a P-wave bound state of W sub L W sub L On the dynamical generation of a. rho. meson in the. sigma. model

Description: We investigate the possibility that the Higgs lagrangian predicts the existence of a P-wave W{sub L}W{sub L} resonance. This problem is equivalent to studying the formation of the {rho} meson by the dynamics contained in the {sigma} model. Using the Pade approximation, Basdevant and Lee had claimed that {rho} is generated dynamically. We show that their result, while computationally correct, is not significant, because of the position of the Landau ghost. For the same reason, a W{sub L}W{sub L} P-wave resonance below 2 TeV is not expected, unless the standard model is violated. 10 refs., 8 figs.
Date: October 1, 1991
Creator: Atkinson, D. (Fermi National Accelerator Lab., Batavia, IL (United States) Institute for Theoretical Physics, Groningen, The Netherlands (NL)); Harada, M. (Nagoya Univ. (Japan). Dept. of Physics) & Sanda, A.I. (Superconducting Super Collider Lab., Dallas, TX (United States) Rockefeller Univ., New York, NY (United States). Dept. of Physics)
Partner: UNT Libraries Government Documents Department

The Neutron Imaging System Fielded at the National Ignition Facility

Description: We have fielded a neutron imaging system at the National Ignition Facility to collect images of fusion neutrons produced in the implosion of inertial confinement fusion experiments and scattered neutrons from (n, n') reactions of the source neutrons in the surrounding dense material. A description of the neutron imaging system will be presented, including the pinhole array aperture, the line-of-sight collimation, the scintillator-based detection system and the alignment systems and methods. Discussion of the alignment and resolution of the system will be presented. We will also discuss future improvements to the system hardware.
Date: October 24, 2011
Creator: Fittinghoff, D N; Atkinson, D P; Bower, D E; Drury, O B; Dzenitis, J M; Felker, B et al.
Partner: UNT Libraries Government Documents Department

Summary of the first neutron image data collected at the National Ignition Facility

Description: A summary of data and results from the first neutron images produced by the National Ignition Facility (NIF), Lawrence Livermore National Laboratory, Livermore, CA, USA are presented. An overview of the neutron imaging technique is presented, as well as a synopsis of the data collected and measurements made to date. Data form directly driven, DT filled microballoons, as well as, indirectly driven, cryogenically layered ignition experiments are presented. The data presented show that the primary cores from directly driven implosions are approximately twice as large, 64 {+-} 3 {mu}m, as indirect cores 25 {+-} 4 and 29 {+-} 4 {mu}m and more asymmetric, P2/P0 = 47% vs. -14% and 7%. Further, comparison with the size and shape of X-ray image data on the same implosions show good agreement, indicating X-ray emission is dominated by the hot regions of the implosion.
Date: November 1, 2011
Creator: Grim, G P; Archuleta, T N; Aragonez, R J; Atkinson, D P; Batha, S H; Barrios, M A et al.
Partner: UNT Libraries Government Documents Department