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Brightness limitations in multi-kiloampere electron beam sources

Description: Heuristic relationships such as the Lawson-Penner criterion, used to scale Free Electron Laser (FEL) amplifier gain and efficiency over orders of magnitude in beam current and brightness, have no fundamental basis. The brightness of a given source is set by practical design choices such as peak voltage, cathode type, gun electrode geometry, and focusing field topology. The design of low emittance, high current electron guns has received considerable attention at Livermore over the past few years. The measured brightnesses of the Experimental Test Accelerator (ETA) and Advanced Test Accelerator (ATA) guns are less than predicted with the EBQ gun design code; this discrepancy is due to plasma effects from the present cold, plasma cathode in the code. The EBQ code is well suited to exploring the current limits of gridless relativistic Pierce columns with moderate current density (<50 A/cm/sup 2/) at the cathode. As EBQ uses a steady-state calculation it is not amenable for study of transient phenomena at the beam head. For this purpose, a Darwin approximation code, DPC, has been written. The main component in our experimental cathode development effort is a readily modified electron gun that will allow us to test many candidate cathode materials, types and electrode geometries at field stresses up to 1 MV/cm. 6 references, 6 figures.
Date: August 24, 1984
Creator: Barletta, W.A.; Boyd, J.K.; Paul, A.C. & Prono, D.S.
Partner: UNT Libraries Government Documents Department

GPHS (General Purpose Heat Source) uranium oxide encapsulations supporting satellite safety tests

Description: General Purpose Heat Source (GPHS) simulant-fueled capsules were assembled, welded, nondestructively examined, and shipped to Los Alamos National Laboratory (LANL) for satellite safety tests. Simulant-fueled iridium capsules contain depleted uranium oxide pellets that serve as a stand-in for plutonium-238 oxide pellets. Information on forty seven capsules prepared during 1987 and 1988 is recorded in this memorandum along with a description of the processes used for encapsulation and evaluation. LANL expects to use all capsules for destructive safety tests, which are under way. Test results so far have demonstrated excellent integrity of the Savannah River capsule welds. 10 refs., 5 figs., 3 tabs.
Date: April 24, 1989
Creator: Kanne, W. R.
Partner: UNT Libraries Government Documents Department

Resonances in near-threshold x-ray photoabsorption of inner shells

Description: Synchrotron radiation measurements of near-threshold and broad-range (20 eV - 3 keV) absolute photoabsorption cross sections were made at the Brookhaven National Laboratory (NSLS) and at Stanford (SSRL). Transmission data for well-characterized multilayer foils provided absolute cross sections with 10% overall uncertainties and better than 0.2% energy resolution. Several examples of our results are presented.
Date: August 24, 1987
Creator: Del Grande, N.K.; Tirsell, K.G.; Schneider, M.B.; Garrett, R.F.; Kneedler, E.M. & Manson, S.T.
Partner: UNT Libraries Government Documents Department