IPAC2015 - List of Authors (Lewellen, J.W.)

Paper	Title	Page
TUPMA018	An Improved Analytic Model of Electron Back-Bombardment in Thermionic Cathode RF Guns	1872
	J.P. Edelen, S. Biedron, J.R. Harris, S.V. Milton CSU, Fort Collins, Colorado, USA J.W. Lewellen LANL, Los Alamos, New Mexico, USA
	This paper describes work done at Colorado State University to improve upon the recent theory developed to predict the back-bombardment power in single-cell thermionic-cathode electron guns. The previous theory used a square-wave approximation of the time varying field to solve for the total kinetic energy deposited on the cathode due to the back-bombarded electrons. In addition the transit time factor was added as a correction to compensate for the non-sinusoidal field. By solving for the back-bombardment power using a sinusoidal field, the transit time factor can be removed and therefore a better overall model is produced. These alterations continue to accurately predict how back-bombardment varies as a function of the gun parameters and provides improvement when compared to the existing theory.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPMA018
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TUPMA026	Status of the MaRIE X-FEL Accelerator Design	1894
	J.W. Lewellen, K. Bishofberger, B.E. Carlsten, L.D. Duffy, F.L. Krawczyk, Q.R. Marksteiner, D.C. Nguyen, S.J. Russell, R.L. Sheffield, N.A. Yampolsky LANL, Los Alamos, New Mexico, USA
	Funding: Work supported by the MaRIE program at Los Alamos National Laboratory, under contract DE-AC52-06NA25396 The Matter-Radiation Interactions in Extremes (MaRIE) facility is intended to probe and control the time-dependent properties of materials under extreme conditions. At its core, the “MaRIE 1.0” X-FEL is being designed to deliver pulse trains of ~10¹⁰ 42 keV photons, with a minimum bunch spacing of 2.4 ns, enabling time-dependent studies particularly of mesoscale phenomena. The X-FEL accelerator is also intended to deliver a series of 2 nC electron bunches to enable electron radiography concurrently with the X-ray pulse train, so as to provide multi-probe capability to MaRIE. In 2014, the reference design for the MaRIE X-FEL 12 GeV driver linac was changed from an S-band normal-conducting to an L-band superconducting linac to accommodate pulse trains up to 100 μs in duration. This paper does not present a complete solution for the MaRIE linac design; rather it describes our current reference design, achieved parameters, areas of concern and paths towards mitigation of identified issues.
DOI •	reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPMA026
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Paper

Title

Page

An Improved Analytic Model of Electron Back-Bombardment in Thermionic Cathode RF Guns

1872

J.P. Edelen, S. Biedron, J.R. Harris, S.V. Milton
CSU, Fort Collins, Colorado, USA
J.W. Lewellen
LANL, Los Alamos, New Mexico, USA

This paper describes work done at Colorado State University to improve upon the recent theory developed to predict the back-bombardment power in single-cell thermionic-cathode electron guns. The previous theory used a square-wave approximation of the time varying field to solve for the total kinetic energy deposited on the cathode due to the back-bombarded electrons. In addition the transit time factor was added as a correction to compensate for the non-sinusoidal field. By solving for the back-bombardment power using a sinusoidal field, the transit time factor can be removed and therefore a better overall model is produced. These alterations continue to accurately predict how back-bombardment varies as a function of the gun parameters and provides improvement when compared to the existing theory.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPMA018

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)

TUPMA026

Status of the MaRIE X-FEL Accelerator Design

1894

J.W. Lewellen, K. Bishofberger, B.E. Carlsten, L.D. Duffy, F.L. Krawczyk, Q.R. Marksteiner, D.C. Nguyen, S.J. Russell, R.L. Sheffield, N.A. Yampolsky
LANL, Los Alamos, New Mexico, USA

Funding: Work supported by the MaRIE program at Los Alamos National Laboratory, under contract DE-AC52-06NA25396
The Matter-Radiation Interactions in Extremes (MaRIE) facility is intended to probe and control the time-dependent properties of materials under extreme conditions. At its core, the “MaRIE 1.0” X-FEL is being designed to deliver pulse trains of ~10¹⁰ 42 keV photons, with a minimum bunch spacing of 2.4 ns, enabling time-dependent studies particularly of mesoscale phenomena. The X-FEL accelerator is also intended to deliver a series of 2 nC electron bunches to enable electron radiography concurrently with the X-ray pulse train, so as to provide multi-probe capability to MaRIE. In 2014, the reference design for the MaRIE X-FEL 12 GeV driver linac was changed from an S-band normal-conducting to an L-band superconducting linac to accommodate pulse trains up to 100 μs in duration. This paper does not present a complete solution for the MaRIE linac design; rather it describes our current reference design, achieved parameters, areas of concern and paths towards mitigation of identified issues.

DOI •

reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2015-TUPMA026

Export •

reference for this paper using ※ BibTeX, ※ LaTeX, ※ Text/Word, ※ RIS, ※ EndNote (xml)