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2. Homeless Veterans and the Impacts of a Dedicated Discipleship Program

Author

Poole, B. Keith, Jr. and Poole, B. Keith, Jr.

Abstract

Homelessness represents an incredibly damaging and challenging reality across the United States; of the 588,000 homeless in this country, 33,000 are military Veterans. Homelessness among Veterans is intensified by afflictions of Post-Traumatic Stress Disorder (PTSD), Traumatic Brain Injury (TBI), Suicide Ideations, Moral Injuries, and Substance Abuse. The purpose of this DMIN action project was to establish a discipleship program to develop disciples among homeless Veterans to reduce their homeless rates. The objectives of this project were to bring homeless Veterans to Jesus, decrease Veteran homelessness, establish ongoing relationships with homeless Veterans, assist homeless Veterans in overcoming specific factors impacting their continued homelessness, instill an atmosphere of inclusion and care among homeless Veterans, and provide biblically-based mentorship and guidance to homeless Veterans through discipleship. Homeless Veterans and support staff from outreach organizations that met specific criteria participated in the project. Surveys provided to homeless Veterans focused on the occurrence rate and impacts of PTSD, TBI, Moral Injuries, and Substance Abuse. Questionnaires given to homeless Veterans and support staff participants centered on the “why” of the question of homelessness. Roundtable discussions with homeless Veterans concentrated on Spiritual Warfare, Suicide Ideations, and the previous subjects of PTSD, TBI, Moral Injuries, and Substance Abuse. Substance Abuse was shown to be the most widespread of the ailments afflicting homeless Veterans. The encouraging results of this project indicate that a Jesus-centric ministry approach to engaging homeless Veterans through a dedicated discipleship program can produce positive, realistic outcomes for Veterans suffering from chronic homelessness.

Published
2024

3. Dipole Septum Magnet in the Fast Kicker System for Multi-Axis Advanced Radiography

Author

Wang, L., Lund, S. M., and Poole, B. R.

Subjects
Physics - Accelerator Physics
Abstract

Here we present designs for a static septum magnet with two adjacent apertures where ideally one aperture has a uniform dipole field and the other zero field. Two designs are considered. One is a true septum magnet with a thin layer of coils and materials separating the dipole field region from the null field region. During the beam switching process, the intense electron beam will spray across this material septum leading to concerns on beam control, vacuum quality, radiation damage, etc. due to the lost particles. Therefore, another configuration without a material septum is also considered. With this configuration it is more difficult to achieve high field quality near the transition region. Shaped shims are designed to limit the degradation of beam quality (emittance growth). This approach is closely related to a previous septum magnet design with two oppositely oriented dipole field regions presented by the authors [1]. Simulations are performed to obtain the magnetic field profile in both designs. A PIC simulation is used to transport a beam slice consisting of several thousand particles through the magnet to estimate emittance growth in the magnet due to field non-uniformity., Comment: 3 pages, 8 figures, LINAC 2000, TUC08

Published
2000

9. Novel Hendra Virus Variant Detected by Sentinel Surveillance of Horses in Australia

Author

Annand, E. J., Horsburgh, B. A., Xu, K., Reid, P. A., Poole, B., de Kantzow, M. C., Brown, N., Tweedie, A., Michie, M., Grewar, J. D., Jackson, A. E., Singanallur, N. B., Plain, K. M., Kim, K., Tachedjian, M., van der Heide, B., Crameri, S., Williams, D. T., Secombe, C., Laing, E. D., Sterling, S., Yan, L., Jackson, Louise A., Jones, C., Plowright, R. K., Peel, A. J., Breed, A. C., Diallo, I., Dhand, N. K., Britton, P. N., Broder, C. C., Smith, I., Eden, J. S., Annand, E. J., Horsburgh, B. A., Xu, K., Reid, P. A., Poole, B., de Kantzow, M. C., Brown, N., Tweedie, A., Michie, M., Grewar, J. D., Jackson, A. E., Singanallur, N. B., Plain, K. M., Kim, K., Tachedjian, M., van der Heide, B., Crameri, S., Williams, D. T., Secombe, C., Laing, E. D., Sterling, S., Yan, L., Jackson, Louise A., Jones, C., Plowright, R. K., Peel, A. J., Breed, A. C., Diallo, I., Dhand, N. K., Britton, P. N., Broder, C. C., Smith, I., and Eden, J. S.

Abstract

We identified and isolated a novel Hendra virus (HeV) variant not detected by routine testing from a horse in Queensland, Australia, that died from acute illness with signs consistent with HeV infection. Using whole-genome sequencing and phylogenetic analysis, we determined the variant had ≈83% nt identity with prototypic HeV. In silico and in vitro comparisons of the receptor-binding protein with prototypic HeV support that the human monoclonal antibody m102.4 used for postexposure prophylaxis and current equine vaccine will be effective against this variant. An updated quantitative PCR developed for routine surveillance resulted in subsequent case detection. Genetic sequence consistency with virus detected in grey-headed flying foxes suggests the variant circulates at least among this species. Studies are needed to determine infection kinetics, pathogenicity, reservoir-species associations, viral-host coevolution, and spillover dynamics for this virus. Surveillance and biosecurity practices should be updated to acknowledge HeV spillover risk across all regions frequented by flying foxes. © 2022 Centers for Disease Control and Prevention (CDC). All rights reserved.

Published
2022

10. Novel Hendra Virus Variant Detected by Sentinel Surveillance of Horses in Australia

Author

Annand, E.J., Horsburgh, B.A., Xu, K., Reid, P.A., Poole, B., de Kantzow, M.C., Brown, N., Tweedie, A., Michie, M., Grewar, J.D., Jackson, A.E., Singanallur, N.B., Plain, K.M., Kim, K., Tachedjian, M., van der Heide, B., Crameri, S., Williams, D.T., Secombe, C., Laing, E.D., Sterling, S., Yan, L., Jackson, L., Jones, C., Plowright, R.K., Peel, A.J., Breed, A.C., Diallo, I., Dhand, N.K., Britton, P.N., Broder, C.C., Smith, I., Eden, J-S, Annand, E.J., Horsburgh, B.A., Xu, K., Reid, P.A., Poole, B., de Kantzow, M.C., Brown, N., Tweedie, A., Michie, M., Grewar, J.D., Jackson, A.E., Singanallur, N.B., Plain, K.M., Kim, K., Tachedjian, M., van der Heide, B., Crameri, S., Williams, D.T., Secombe, C., Laing, E.D., Sterling, S., Yan, L., Jackson, L., Jones, C., Plowright, R.K., Peel, A.J., Breed, A.C., Diallo, I., Dhand, N.K., Britton, P.N., Broder, C.C., Smith, I., and Eden, J-S

Abstract

We identified and isolated a novel Hendra virus (HeV) variant not detected by routine testing from a horse in Queensland, Australia, that died from acute illness with signs consistent with HeV infection. Using whole-genome sequencing and phylogenetic analysis, we determined the variant had ≈83% nt identity with prototypic HeV. In silico and in vitro comparisons of the receptor-binding protein with prototypic HeV support that the human monoclonal antibody m102.4 used for postexposure prophylaxis and current equine vaccine will be effective against this variant. An updated quantitative PCR developed for routine surveillance resulted in subsequent case detection. Genetic sequence consistency with virus detected in grey-headed flying foxes suggests the variant circulates at least among this species. Studies are needed to determine infection kinetics, pathogenicity, reservoir-species associations, viral-host coevolution, and spillover dynamics for this virus. Surveillance and biosecurity practices should be updated to acknowledge HeV spillover risk across all regions frequented by flying foxes.

Published
2022

11. Novel Hendra Virus Variant Detected by Sentinel Surveillance of Horses in Australia.

Author

Annand, EJ, Horsburgh, BA, Xu, K, Reid, PA, Poole, B, de Kantzow, MC, Brown, N, Tweedie, A, Michie, M, Grewar, JD, Jackson, AE, Singanallur, NB, Plain, KM, Kim, K, Tachedjian, M, van der Heide, B, Crameri, S, Williams, DT, Secombe, C, Laing, ED, Sterling, S, Yan, L, Jackson, L, Jones, C, Plowright, RK, Peel, AJ, Breed, AC, Diallo, I, Dhand, NK, Britton, PN, Broder, CC, Smith, I, Eden, J-S, Annand, EJ, Horsburgh, BA, Xu, K, Reid, PA, Poole, B, de Kantzow, MC, Brown, N, Tweedie, A, Michie, M, Grewar, JD, Jackson, AE, Singanallur, NB, Plain, KM, Kim, K, Tachedjian, M, van der Heide, B, Crameri, S, Williams, DT, Secombe, C, Laing, ED, Sterling, S, Yan, L, Jackson, L, Jones, C, Plowright, RK, Peel, AJ, Breed, AC, Diallo, I, Dhand, NK, Britton, PN, Broder, CC, Smith, I, and Eden, J-S

Abstract

We identified and isolated a novel Hendra virus (HeV) variant not detected by routine testing from a horse in Queensland, Australia, that died from acute illness with signs consistent with HeV infection. Using whole-genome sequencing and phylogenetic analysis, we determined the variant had ≈83% nt identity with prototypic HeV. In silico and in vitro comparisons of the receptor-binding protein with prototypic HeV support that the human monoclonal antibody m102.4 used for postexposure prophylaxis and current equine vaccine will be effective against this variant. An updated quantitative PCR developed for routine surveillance resulted in subsequent case detection. Genetic sequence consistency with virus detected in grey-headed flying foxes suggests the variant circulates at least among this species. Studies are needed to determine infection kinetics, pathogenicity, reservoir-species associations, viral-host coevolution, and spillover dynamics for this virus. Surveillance and biosecurity practices should be updated to acknowledge HeV spillover risk across all regions frequented by flying foxes.

Published
2022

17. Archaeological excavation Report: City Place, Chester

Author

Eloy, P. and Poole, B.

Subjects
Archaeology, Grey Literature
Abstract

Strip and map of two 19th century structures associated with Chester railway. Planning permission has been granted for the erection of a hotel with ground floor restaurant/retail uses and associated infrastructure and landscaping. As a condition of development a strip and map excavation was carried out on a discrete area of the site by L - P : Archaeology on behalf of Orion Heritage. The site is located on land off Queens Road within a car park to the south of the railway, at City Place, Chester, The fieldwork was carried out between the 15th and 23rd February 2020 in accordance with a written scheme of investigation. The excavation area was located at the northwestern corner of the site and measured 16m by 7.9m in plan. The series of structural remains uncovered during the excavation appear to represent three phases of activity on the site. These three phases all appear to have occurred within a short timeframe, with the earliest phase being a series of culverts, likely managing the low lying land between the canal and brook. A small brick structure was constructed prior to 1843, as the 2nd phase of development, which respected the alignment of one of the culverts, and can be seen to be trapezoidal in plan on the 1843 map. This structure was demolished by 1853. A larger brick structure was revealed, representing the 3rd phase of development. This ties in with a structure seen on the 1873 OS map, demolished by the 1899 OS map. It is possible that all three of these elements relate to the railway development of the area from 1840. The interpretation of the site suggests the culverts were put in place to raise the level of low lying areas between the canal and brook. A small temporary store or warehouse was then erected by 1843, with the eastern wall respecting the alignment of the culvert. This building was demolished by 1853, and replaced by 1873 by a workshop, which was removed by 1899.

Published
2021
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19. Weakly-Supervised Disentanglement Without Compromises

Author

Locatello, F., Poole, B., Rätsch, G., Schölkopf, B., Bachem, O., and Tschannen, M.

Subjects
FOS: Computer and information sciences, Computer Science - Machine Learning, Statistics - Machine Learning, Machine Learning (stat.ML), Machine Learning (cs.LG)
Abstract

Intelligent agents should be able to learn useful representations by observing changes in their environment. We model such observations as pairs of non-i.i.d. images sharing at least one of the underlying factors of variation. First, we theoretically show that only knowing how many factors have changed, but not which ones, is sufficient to learn disentangled representations. Second, we provide practical algorithms that learn disentangled representations from pairs of images without requiring annotation of groups, individual factors, or the number of factors that have changed. Third, we perform a large-scale empirical study and show that such pairs of observations are sufficient to reliably learn disentangled representations on several benchmark data sets. Finally, we evaluate our learned representations and find that they are simultaneously useful on a diverse suite of tasks, including generalization under covariate shifts, fairness, and abstract reasoning. Overall, our results demonstrate that weak supervision enables learning of useful disentangled representations in realistic scenarios., We updated the description of the generation of the dataset compared to the ICML version

Published
2020

21. Historic Building Recording at MERSEYSIDE FORCE HQ, JUVENAL STREET, LIVERPOOL

Author

Poole, B.

Subjects
Archaeology, Grey Literature
Abstract

Level II to III photographic historic building recording of four structures : 15 Cazneau Street, The Presbytery, Victoria Building and the Hopscotch Nursery, between Juveanl Street, Cazneau Street and Grosvenor Street. A site off Juvenal Street, Liverpool, L3 3AN is proposed for redevelopment into the new Merseyside Police Force HQ. As a condition of the development a photographic level II/III historic building recording was required for the surviving structures on the site. The fieldwork and reporting was undertaken by L - P : Archaeology on behalf of Willmott Dixon Construction Ltd. The historic research suggests limited phases of development for the standing buildings. 15 Cazneau Street is thought to have been built between 1864 and 1891. The Bishop Goss School (Victoria Building), was built around 1877, with a southeastern extension built between 1908 and 1927. The Presbytery building was built around 1878, with phase two represented by the added northwestern porch between 1976 and 1983, and the final modification creating the solid southern facade in the late 20th century. The southern school building (Hopscotch Nursery) was built around 1911, with a southeastern wing forming phase two, added between 1954 and 1958, and a final block added to the southwestern corner of the extension between 1983 and 1993. All of the buildings surveyed showed extensive internal remodelling dating from the later 20th century and early 21st century. However, the Victoria Building and Hopscotch Nursery building had both been schools, with large classrooms, which allowed the intended design layout to be identified and understood. Both of these buildings also maintained some historic fabric, such as internal arched window lights, vents and fireplaces.

Published
2020
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22. Compact accelerator concept for proton therapy

Author

Caporaso, G.J., Sampayan, S., Chen, Y.-J., Harris, J., Hawkins, S., Holmes, C., Krogh, M., Nelson, S., Nunnally, W., Paul, A., Poole, B., Rhodes, M., Sanders, D., Selenes, K., Sullivan, J., Wang, L., and Watson, J.

Published
2007
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24. Solenoid transport of beams with current-dependent initial conditions.

Author

Harris, J. R., Poole, B. R., and Lewellen, J. W.

Subjects
*PARTICLE beams, *SPACE charge, *ELECTRON gun, *DIRECT currents, *SOLENOIDS
Abstract

Intense charged particle beams will generally be formed with an initial correlation between their longitudinal properties, including longitudinal variations in current, and their transverse properties, including their radius and divergence. This is due to the competition between the transverse focusing fields in the beam source and the time-varying space charge forces in the beam. In DC electron guns where the current modulation is slow compared to the electron transit time, the nature of these correlations was previously shown to depend on the gun geometry, exhibiting a linear dependence of the beam radius and divergence on the beam current at the gun exit. Here, we extend the previous work to study the transport of beams with such correlation in uniform and periodic solenoid channels. For each transport channel configuration studied, the transverse envelope equation is used to calculate the envelope of 101 beam slices differing in their slice currents, as well as initial radius and divergence (due to their dependence on slice current). For each channel configuration, these calculations are performed 546 times, with each of these iterations considering a different degree of correlation between the radius and divergence, and the slice current. It is found that some degree of correlation between the initial radius and slice current actually aids in beam transport, and the required strength of correlation can be estimated with simple models. Increasing the degree of correlation between the initial divergence and slice current is generally counterproductive, and the degree of sensitivity to such correlations depends on the design of the transport channel. [ABSTRACT FROM AUTHOR]

Published
2017
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27. 80 Years Ago in Mekeel's: Seebeck Stamps.

Author

Poole, B. W. H.

Subjects
POSTAL service, WORLD War II, POSTAGE stamps, CREDIT cards
Abstract

This article provides a historical account of "Seebeck" stamps, which were postage stamps produced by Nicholas F. Seebeck and his company, the Hamilton Bank Note Co., in the late 19th century. Seebeck made agreements with the governments of Salvador, Honduras, Nicaragua, and Ecuador to supply postage stamps and postal stationery for a period of ten years in exchange for certain benefits. However, these stamps became highly unpopular among stamp collectors due to the ability to reprint them indefinitely, leading to a decline in their value. The contracts eventually ended, and today, these stamps are considered an interesting study and can be difficult to obtain in good condition. The given text appears to be a list of various stamps and their prices. It includes different sets such as Set 69.00, 3139-40 Pacific 97, 3209-10 Trans-Mississippi, and others. The prices range from $3.50 to $24.95. The text also mentions a minimum order of $10 and additional charges for postage and insurance. The contact information for placing an order is provided at the end. [Extracted from the article]

Published
2024

28. Archaeological Strip and Map Report for Brook Farm, Dowbridge

Author

Poole, B., Matthews, R., and Eloy, P.

Subjects
Archaeology, Grey Literature
Abstract

Archaeological strip and map at a site in Dowbridge, Kirkham. Uncovered Prehistoric flint and cup marked stone. Roman activity between the 1st and 3rd century. Early Medieval activity and Post Medieval activity. The results of the Strip and Map revealed scatters of Prehistoric worked flints dating from between the Mesolithic and Early Bronze Age, as well as cup marked stone also thought to date from the Bronze Age. Evidence of Romano British activity was identified in the south including an oval building with associated post holes and hearth, with possible oven bases to the southwest; to the north was a fire pit and multiple extraction pits. An Early Medieval wooden feature, thought to be a fish trap, was identified at the southwestern end of the site. Multiple linear features were located across the site, most were undateable but thought to be a mix of remnant Medieval ridge and furrow, as well as Post Medieval agricultural and drainage ditches. Palaeoenvironmental evidence from the site suggests that the area was used for grain storage as part of bread production during the later Roman period. Scatters of slag identified across the site also suggest industrial activity from this period may have been undertaken in the wider area.

Published
2019
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29. Associations between clinical indicators of quality and aged-care residents' needs and consumer and staff satisfaction: the first Australian study

Author

Jeon, YH, Casey, AN, Vo, K, Rogers, K, Poole, B, Fethney, J, Jeon, YH, Casey, AN, Vo, K, Rogers, K, Poole, B, and Fethney, J

Abstract

© 2019 AHHA. Objectives: To ascertain Australian multistate prevalence and incidence of five commonly collected clinical indicators of aged-care home quality and to measure associations between these clinical indicators and levels of care needs and consumer and staff satisfaction. Methods: A retrospective analysis of national audit data collected from 426 facilities between 2015 and 2016 was performed. Regression models were used to examine associations between five clinical indicators (falls, pressure injury, physical restraint, unplanned weight loss and polypharmacy) and level of care needs measured by the Aged Care Funding Instrument (ACFI) and consumer and care staff survey responses. Results: With the exception of polypharmacy, commonly collected negative clinical outcomes were rare events. Compared with care homes with <25% of residents having high-level care needs (high ACFI), homes with 25<75% high-ACFI residents had more occurrences of all negative clinical outcomes except pressure injury. Homes with ≥75% high-ACFI residents reported the highest rates of polypharmacy (odds ratio 1.48, 95% confidence interval 1.39-1.57). Falls, unplanned weight loss and pressure injury were inversely associated with satisfaction scores adjusted for residents' level of care needs. Conclusions: This first Australian study of multistate clinical indicator data suggests interpretation of clinical indicators of aged-care home quality requires consideration of the level of residents' care needs. What is known about the topic?: Many Australian aged-care providers use quality indicators (QI) through benchmarking companies or in-house programs. The five most widely used aged-care clinical QIs in Australia are falls, pressure injury, physical restraint, unplanned weight loss and polypharmacy. Prevalence and incidence of these QIs are highly variable among Australian studies. A consistent message in the international literature is that residents' clinical characteristics influence QI o

Published
2019

31. IV: The River Dee, Roodee Cop and the workhouse: recent excavations

Author

Poole, B S

Abstract

Journal of the Chester Archaeological Society, 82, 85-107, Between 2001 and 2005, investigations were undertaken at a series of sites in the old port and Roodee areas of Chester, extending from the Grosvenor Bridge in the south to the Cop Recreational Ground at Sealand Road in the north. These investigations have contributed significant information about the changing course of the river Dee, the city's attempts to control the flooding at the port and Roodee areas and the construction of port installations. In addition, considerable light has been shed on the structural remains of Chester's first workhouse, which lay adjacent to the port.

Published
2018
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36. Letters to the Editors

Author

Poole, B. A., Beaumier, Robert G., Poole, B. A, Jensen, Emil C., McGowan, T. F., Miller, Floyd M., and Steele, Chas.

Published
1955

37. Generation and focusing of electron beams with initial transverse-longitudinal correlation.

Author

Harris, J. R., Lewellen, J. W., and Poole, B. R.

Subjects
ELECTRON beams, CATHODE rays, ELECTRIC discharges, CLASS B metals, ANALYTICAL mechanics
Abstract

In charged particle beams, one of the roles played by space charge is to couple the transverse and longitudinal dynamics of the beam. This can lead to very complex phenomena which are generally studied using computer simulations. However, in some cases models based on phenomenological or analytic approximations can provide valuable insight into the system behavior. In this paper, we employ such approximations to investigate the conditions under which all the slices of a space charge dominated electron beam with slowly varying current could be focused to a waist with the same radius and at the same location, independent of slice current, and show that this can be accomplished approximately if the initial transverse-longitudinal correlation introduced onto the beam by the electron gun is chosen to compensate for the transverse-longitudinal correlation introduced onto the beam in the drift section. The validity of our approximations is assessed by use of progressively more realistic calculations. We also consider several design elements of electron guns that affect the initial correlations in the beams they generate. [ABSTRACT FROM AUTHOR]

Published
2014
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40. Transport of electron beams with initial transverse-longitudinal correlation.

Author

Harris, J. R., Lewellen, J. W., and Poole, B. R.

Subjects
ELECTRON beam research, SPACE charge, ELECTRON transport, STATISTICAL correlation, DIODES
Abstract

When an electron beam whose current varies in time is extracted from a DC gun, the competition between the time-dependent space charge force and the time-independent focusing force will cause a correlation between radius, divergence, current, and position along the beam. This correlation will determine the beam's configuration in trace space, and together with the design of the downstream transport system, will determine the quality of the transport solutions that can be obtained, including the amplitude of the mismatch oscillations occurring in each slice of the beam. Recent simulations of a simplified diode with Pierce-type focusing operating at nonrelativistic voltages indicated that the radius and divergence of beams extracted from such guns can be approximated to high accuracy as linear functions of current. Here, we consider the impact of this dependence on the beam configuration in trace space and investigate the implications for matching and transport of such correlated beams in uniform linear focusing channels. [ABSTRACT FROM AUTHOR]

Published
2013
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42. A synopsis of Langley Research Center's lidar effort for the 1986 FIRE IFO

Author

Alvarez, Jose M, Mccormick, M. P, Moore, J. D, Hunt, W. H, Rouse, B. R, Poole, L. R, and Poole, B. D

Subjects
Meteorology And Climatology
Abstract

The lidar data obtained by the Langley Aircraft Lidar in October 1986 in Wisconsin is being reduced in a transparent, simple fashion and will be published in its reduced form in a NASA Reference Publication (RP). This reduced data will also be submitted to the FIRE data archives. Some of this reduced data will be presented at the FIRE FSET Workshop to acquaint the science team with the data format to be used in the archive and the upcoming catalog contained in the RP. A new method was utilized in Wisconsin for obtain the depolarization ratio of aerosols. This method involves using a half-wave plate to calibrate the lidar under field conditions. The theory behind this technique will be presented at this workshop as well as some of the lidar calibration results. The lidar calibration will be utilized in interpreting some of the dual polarization lidar data obtained during the IFO in Wisconsin. Some of these data are also discussed. A continuous wave laser lab-type lidar simulator was constructed during the previous year. One of the primary reasons for the construction of the simulator was to attempt dual-polarization lidar-like calibrations under laboratory, rather than field conditions. The data collected by this system was used to experimentally check and thus, inspire confidence in the algorithms being used to interpret the lidar data obtained in the field. A computer program which simulates noisy lidar data was used as a part of this effort in order to obtain some feel for the noise in the inversion parameters as a function of noise in the actual measurements. The lidar simulation will be described in addition to presenting some of the lab-generated calibration data.

Published
1990

43. Vacuum insulator development for the dielectric wall accelerator.

Author

Harris, J. R., Blackfield, D., Caporaso, G. J., Chen, Y.-J., Hawkins, S., Kendig, M., Poole, B., Sanders, D. M., Krogh, M., and Managan, J. E.

Subjects
VACUUM, VACUUM technology, ELECTRIC discharges, COMPRESSIBILITY, DIELECTRIC amplifiers, DIELECTRICS, COLLIDERS (Nuclear physics), ELECTRON accelerators
Abstract

At Lawrence Livermore National Laboratory, we are developing a new type of accelerator, known as a dielectric wall accelerator, in which compact pulse-forming lines directly apply an accelerating field to the beam through an insulating vacuum boundary. The electrical strength of this insulator may define the maximum gradient achievable in these machines. To increase the system gradient, we use “high-gradient insulators” composed of alternating layers of dielectric and metal for the vacuum insulator. In this paper, we present our recent results from experiment and simulation, including successful testing of a high-gradient insulator in a functioning dielectric wall accelerator cell. Our results indicate that proper high-voltage conditioning of the insulators can delay the onset of flashover, that the observed conditioning consists of both a permanent and a temporary part, and that the insulators’ voltage-holding capability increases with increasing dielectric layer thickness. [ABSTRACT FROM AUTHOR]

Published
2008
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