Refine your search:     
Report No.
 - 
Search Results: Records 1-8 displayed on this page of 8
  • 1

Presentation/Publication Type

Initialising ...

Refine

Journal/Book Title

Initialising ...

Meeting title

Initialising ...

First Author

Initialising ...

Keyword

Initialising ...

Language

Initialising ...

Publication Year

Initialising ...

Held year of conference

Initialising ...

Save select records

Journal Articles

Small gas bubble experiment for mitigation of cavitation damage and pressure waves in short-pulse mercury spallation targets

Riemer, B. W.*; Wendel, M. W.*; Felde, D. K.*; Sangrey, R. L.*; Abdou, A.*; West, D. L.*; Shea, T. J.*; Hasegawa, Shoichi; Kogawa, Hiroyuki; Naoe, Takashi; et al.

Journal of Nuclear Materials, 450(1-3), p.192 - 203, 2014/07

 Times Cited Count:14 Percentile:72.72(Materials Science, Multidisciplinary)

Populations of small helium gas bubbles were introduced into a flowing mercury experiment test loop to evaluate mitigation of beam-pulse induced cavitation damage and pressure waves. The test loop was developed and thoroughly tested at the Spallation Neutron Source (SNS) prior to irradiations at the Los Alamos Neutron Science Center - Weapons Neutron Research Center (LANSCE-WNR) facility. Twelve candidate bubblers were evaluated over a range of mercury flow and gas injection rates by use of a novel optical measurement technique that accurately assessed the generated bubble size distributions. Final selection for irradiation testing included two variations of a swirl bubbler provided by Japan Proton Accelerator Research Complex (J-PARC) collaborators and one orifice bubbler developed at SNS. Bubble populations of interest consisted of sizes up to 150 $$mu$$m in radius with achieved gas void fractions in the 10$$^{-5}$$ to 10$$^{-4}$$ range. The nominal WNR beam pulse used for the experiment created energy deposition in the mercury comparable to SNS pulses operating at 2.5 MW. Nineteen test conditions were completed each with 100 pulses, including variations on mercury flow, gas injection and protons per pulse. The principal measure of cavitation damage mitigation was surface damage assessment on test specimens that were manually replaced for each test condition. Damage assessment was done after radiation decay and decontamination by optical and laser profiling microscopy with damaged area fraction and maximum pit depth being the more valued results. Damage was reduced by flow alone; the best mitigation from bubble injection was between half and a quarter that of flow alone. Other data collected included surface motion tracking by three laser Doppler vibrometers (LDV), loop wall dynamic strain, beam diagnostics for charge and beam profile assessment, embedded hydrophones and pressure sensors, and sound measurement by a suite of conventional and contact microphones.

Journal Articles

Validation of on- and off-axis neutral beam current drive against experiment in DIII-D

Park, J. M.*; Murakami, Masanori*; Petty, C. C.*; Heidbrink, W. W.*; Osborne, T. H.*; Holcomb, C. T.*; Van Zeeland, M. A.*; Prater, R.*; Luce, T. C.*; Wade, M. R.*; et al.

Physics of Plasmas, 16(9), p.092508_1 - 092508_10, 2009/09

 Times Cited Count:23 Percentile:64.7(Physics, Fluids & Plasmas)

Neutral beam current drive (NBCD) experiments in DIII-D using vertically shifted plasmas to move the current drive away from the axis have clearly demonstrated robust off-axis NBCD. Time-dependent measurements of magnetic pitch angles by the motional Stark effect diagnostic are used to obtain the evolution of the poloidal magnetic flux, which indicates a broad off-axis NBCD profile with a peak at about half the plasma radius. In most cases, the measured off-axis NBCD profile is consistent with calculations using an orbit-following Monte-Carlo code for the beam ion slowing down including finite-orbit effects, provided there is no large-scale MHD activity such as Alfv$'e$n eigenmodes modes or sawteeth. Good agreement is found between the measured pitch angles and those from simulations using transport-equilibrium codes. Two-dimensional image of Doppler-shifted fast ion D$$alpha$$ light emitted by neutralized energetic ions shows clear evidence for a hollow profile of beam ion density, consistent with classical beam ion slowing down. The magnitude of off-axis NBCD is sensitive to the alignment of the beam injection relative to the helical pitch of the magnetic field lines. If the signs of B and I yield the proper helicity, both measurement and calculation indicate that the efficiency is as good as on-axis NBCD because the increased fraction of trapped electrons reduces the electron shielding of the injected ion current, in contrast with electron current drive schemes where the trapping of electrons degrades the efficiency. The measured off-axis NBCD increases approximately linearly with the injection power, although a modest amount of fast ion diffusion is needed to explain an observed difference in the NBCD profile between the measurement and the calculation at high injection power.

Journal Articles

Off-axis neutral beam current drive for advanced scenario development in DIII-D

Murakami, Masanori*; Park, J. M.*; Petty, C. C.*; Luce, T. C.*; Heidbrink, W. W.*; Osborne, T. H.*; Prater, R.*; Wade, M. R.*; Anderson, P. M.*; Austin, M. E.*; et al.

Nuclear Fusion, 49(6), p.065031_1 - 065031_8, 2009/06

 Times Cited Count:43 Percentile:82.92(Physics, Fluids & Plasmas)

Modification of the two existing DIII-D neutral beam lines is planned to allow vertical steering to provide off-axis neutral beam current drive (NBCD) peaked as far off-axis as half the plasma minor radius. New calculations for a downward-steered beam indicate strong current drive with good localization off-axis so long as the toroidal magnetic field, BT, and the plasma current, Ip, point in the same direction. This is due to good alignment of neutral beam injection (NBI) with the local pitch of the magnetic field lines. This model has been tested experimentally on DIII-D by an injecting equatorially-mounted NBs into reduced size plasmas that are vertically displaced with respect to the vessel midplane. The existence of off-axis NBCD is evident in the changes seen in sawtooth behavior in the internal inductance. By shifting the plasma upward or downward, or by changing the sign of the toroidal field, measured off-axis NBCD profiles measured with motional Stark effect data and internal loop voltage show a difference in amplitude (40%-45%) consistent with predicted differences predicted by the changed NBI alignment with respect to the helicity of the magnetic field lines. The effects of NB injection direction relative to field line helicity can be large even in ITER: off-axis NBCD can be increased by more than 20% if the BT direction is reversed. Modification of the DIII-D NB system will strongly support scenario development for ITER and future tokamaks as well as providing flexible scientific tools for understanding transport, energetic particles and heating and current drive.

Journal Articles

Laboratory Examination of Microbial Perturbations in a Granitic Environment

West, J. M.*; Hama, Katsuhiro; Bateman, K.*; Coombs, P.*; Hards, V.*; Milodowski, A. E.*; Wetton, P. D.*; Yoshida, Hidekazu

Materials Research Society Symposium Proceedings, Vol.663, p.657 - 664, 2002/00

None

Journal Articles

Influence of bacteria on rock-water interaction, and clay mineral formation in subsurface granitic environments; Bacteria and Clay mineral formation

Hama, Katsuhiro; Hards, V. L.*; Milodo, A. E.*; West, J. M.*; Bateman, K.*; Coombs, P.*; Milodowski, A. E.*; Wetton, P. D.*; Yoshida, Hidekazu; Aoki, Kazuhiro

Clay Minerals, 36(4), p.599 - 613, 2001/00

 Times Cited Count:25 Percentile:57.19(Chemistry, Physical)

None

JAEA Reports

Laboratory work to examine microbial effects on redox and quantification of the effects of microbiological perturbations on the geological disposal of HLW (TRU)

Yoshida, Hidekazu; Hama, Katsuhiro; West, J. M.*; Bateman, K.*; Milodowski, A. E.*; Baker, S. J.*; Coombs, P.*; Hards, V. L.*; Spiro, B.*; Wetton, P. D.*

JNC TJ7400 99-013, 68 Pages, 1999/07

JNC-TJ7400-99-013.pdf:3.15MB

In April 1997 the Japan Nuclear Cycle Development Institute (JNC)commissioned a Three-Task project from the Bretish Geological Survey (BGS). Task 1 was a continuation of work started in 1996 to examine microbial effects on redox and to quantify the effects of microbiological perturbations on the geological disposal of HLW(TRU). Task 2 was commissioned to provide information on theTsukiyoshi Fault for use in ongoing work at the Tono Geoscience Centre. Task 3 was to draft a Technical programme for use in ongoing work at the Tono Geoscience Centre.Task 3 was to draft a Technical programme for a geochemical study of the Tono site. This report details the results of Task 1, undertaken in 1998/99.

JAEA Reports

A Three Task Project -Fluid Processes Group Series Technical Report

West, J. M.*

JNC TJ7400 99-006, 228 Pages, 1998/05

JNC-TJ7400-99-006.pdf:11.74MB

In April 1997 the Power Reactor and Nuclear Fuel Development Corporation (PNC) of Japan commissioned a Three Task projet from the British Geological Survey (BGS). Task 1 was a coutinuation of work started in 1996 to examine microbial effects on redox and to quantify the effects of microbiological perturbations on the geological disposal of HLW (TRU ). Task 2 was commissioned to provide information on the Tsukiyoshi Fault for use in ongoing work at the Tono Geoscience Centre. Task 3 was to publish the results of work undertaken in 1996/97 by attending two conferences. This report details the results of all the Tasks undertaken in 1997/98.

JAEA Reports

Complementary Laboratory Work to Examine Microbial Effects on Redox and Quantification of the Effects of Microbiological Perturbations on the Geological Disposal of HLW (TRU)

West, J. M.*; Aoki, Kazuhiro; Baker, S. J.*; Bateman, K.*; Coombs, P.*; Gillespie, M. R.*; Henney, P. J.*; Reeder, S.*; Milodowski, A. E.*; Yoshida, Hidekazu

JNC TJ7400 99-002, 117 Pages, 1997/01

JNC-TJ7400-99-002.pdf:7.79MB

In February 1996 the Power Reactor and Nuclear Fuel Development Corportation(PNC)of Japan commissioned a one year study from the British Geological Survey(BGS)to examine microbial effects on redox and to quantify the effects of microbiological perturbations on the geological disposal of HLW(TRU). The work was splitinto two tasks: Tas k 1:SKB REX Cooperation 'To perform laboratory experiments on bacterial processes to assess their influences on redox'.or Task 2:Microbiol ogical modelling the BGS developed code MGSE. This report details the results of Task 1.

8 (Records 1-8 displayed on this page)
  • 1