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in creator/contributor: "Leung, K.N."

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Operation of a DC large aperture volume-production H sup minus source

In testing a multicusp volume-production H{sup {minus}} ion source (20 cm diameter, 23 cm long), we optimized the gas pressure, the plasma electrode bias potential and the magnetic filter. At the optimum pressure of 9 mT, the H{sup {minus}} beam output increased linearly with discharge power. The maximum H{sup {minus}} beam, measured with a current transformer downstream of the accelerator, was 100 mA while using a 6.67 cm{sup 2} aperture. Presently we are limited by overheating of the cathodes… more

Date: April 1, 1989

Creator: Kwan, J. W.; Ackerman, G. D.; Anderson, O. A.; Chan, C. F.; Cooper, W. S.; deVries, G. J. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

A tandem-based compact dual-energy gamma generator

A dual-energy tandem-type gamma generator has been developed at E.O. Lawrence Berkeley National Laboratory and Sandia National Laboratories. The tandem accelerator geometry allows higher energy nuclear reactions to be reached, thereby allowing more flexible generation of MeV-energy gammas for active interrogation applications.

Date: November 11, 2009

Creator: Persaud, A.; Kwan, J. W.; Leitner, M.; Leung, K. N.; Ludewigt, B.; Tanaka, N. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Quantum yield measurements of photocathodes illuminated by pulsed ultraviolet laser radiation

The electron quantum yields from polycrystalline lanthanum hexaboride and barium irradiated by near ultraviolet laser excitation have been determined. These measurements show that the quantum yields from these materials are dependent on the processing and previous history of the photocathode material. For lanthanum hexaboride, a yield of 7 {times} 10{sup {minus}6} with 337 nm irradiation has been achieved. For barium, a yield of 1 {times} 10{sup {minus}6} has been measured with excitation at 30… more

Date: May 1, 1991

Creator: Young, A. T.; Chen, P.; Kunkel, W. B.; Leung, K. N.; Li, C. Y. (Lawrence Berkeley Lab., CA (United States)) & Watson, J. M. (Superconducting Super Collider Lab., Dallas, TX (United States))

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Development of a dc low pressure D sup minus surface-conversion source using a 10-cm-diameter solid barium converter

A D{sup {minus}} surface-conversion source using a solid barium converter is designed for steady-state operation to produce 200 mA of D{sup {minus}}. A similar ion source of twice the size as the one discussed here will meet the requirements set by the present US-ITER neutral beam injector design. Among the possible types of ion sources being considered for the US-ITER neutral beam design, the barium converter surface-conversion source is the only kind that does not use cesium in the discharge.… more

Date: September 1, 1991

Creator: Kwan, J. W.; Anderson, O. A.; Chan, C. F.; Cooper, W. S.; deVries, G. J.; Kunkel, W. B. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

First PGAA and NAA experimental results from a compact high intensity D-D neutron generator

Various types of neutron generator systems have been designed and tested at the Plasma and Ion Source Technology Group at Lawrence Berkeley National Laboratory. These generators are based on a D-D fusion reaction. These high power D-D neutron generators can provide neutron fluxes in excess of the current state of the art D-T neutron generators, without the use of pre-loaded targets or radioactive tritium gas. Safe and reliable long-life operations are the typical features of these D-D generator… more

Date: May 13, 2003

Creator: Reijonen, J.; Leung, K. N.; Firestone, R. B.; English, J. A.; Perry, D. L.; Smith, A. et al.

Item Type: Report

Partner: UNT Libraries Government Documents Department

open access

Development of a dc low pressure D{sup {minus}} surface-conversion source using a 10-cm-diameter solid barium converter

Date: September 1, 1991

Creator: Kwan, J. W.; Anderson, O. A.; Chan, C. F.; Cooper, W. S.; deVries, G. J.; Kunkel, W. B. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Ion-source and LEBT issues with the front-end systems for the Spallation Neutron Source

The Front-End Systems (FES) of the Spallation Neutron Source (SNS) project are being built by Berkeley Lab and will deliver a pulsed 40-mA H{sup -} ion beam at 2.5 MeV energy to the subsequent Drift-Tube Linac. The FES accelerator components comprise an rf driven, volume-production, cesium-enhanced, multi-cusp Ion Source; an electrostatic Low-Energy Beam Transport (LEBT) that includes provisions for transverse focusing, steering, and beam chopping; an RFQ accelerator; and a Medium-Energy Beam T… more

Date: September 1, 2001

Creator: Keller, R.; Cheng, D.; DiGennaro, R.; Gough, R. A.; Greer, J.; Leung, K. N. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

High Intensity, Pulsed, D-D Neutron Generator

Single ion-beam RF-plasma neutron generators are presented as a laboratory source of intense neutrons. The continuous and pulsed operations of such a neutron generator using the deuterium-deuterium fusion reaction are reported. The neutron beam can be pulsed by switching the RF plasma and/or a gate electrode. These generators are actively vacuum pumped so that a continuous supply of deuterium gas is present for the production of ions and neutrons. This contributes to the generator's long life. … more

Date: August 1, 2008

Creator: Williams, D. L.; Vainionpaa, J. H.; Jones, G.; Piestrup, M. A.; Gary, C. K.; Harris, J. L. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Analyses of Oxyanion Materials by Prompt Gamma Activation Analysis

Prompt gamma activation analysis (PGAA) has been used to analyze metal ion oxyanion materials that have multiple applications, including medicine, materials, catalysts, and electronics. The significance for the need for accurate, highly sensitive analyses for the materials is discussed in the context of quality control of end products containing the parent element in each material. Applications of the analytical data for input to models and theoretical calculations related to the electronic and… more

Date: March 24, 2008

Creator: Firestone, Richard B.; Perry, D. L.; English, G. A.; Firestone, R. B.; Leung, K. N.; Garabedian, G. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department

open access

Progress with the SNS front-end systems

The Front-End Systems (FES) of the Spallation Neutron Source (SNS) project have been described in detail elsewhere [1]. They comprise an rf-driven H{sup {minus}} ion source, electrostatic LEBT, four-vane RFQ, and an elaborate MEBT. These systems are planned to be delivered to the SNS facility in Oak Ridge in June 2002. This paper discusses the latest design features, the status of development work, component fabrication and procurements, and experimental results with the first commissioned beam… more

Date: May 1, 2001

Creator: Keller, R.; Abraham, W.; Ayers, J. J.; Cheng, D. W.; Cull, P.; DiGennaro, R. et al.

Item Type: Article

Partner: UNT Libraries Government Documents Department