• C. Ekdahl, E.O. Abeyta, P. Aragon, R.D. Archuleta, G.V. Cook, D. Dalmas, K. Esquibel, R.J. Gallegos, R.W. Garnett, J.F. Harrison, E.B. Jacquez, J.B. Johnson, B.T. McCuistian, N. Montoya, S. Nath, K. Nielsen, D. Oro, L.J. Rowton, M. Sanchez, R.D. Scarpetti, M. Schauer, G.J. Seitz, H.V. Smith, R. Temple
  LANL, Los Alamos, New Mexico
• R. Anaya, G.J. Caporaso, F.W. Chambers, Y.-J. Chen, S. Falabella, G. Guethlein, B.A. Raymond, R.A. Richardson, J.A. Watson, J.T. Weir
  LLNL, Livermore, California
• H. Bender, W. Broste, C. Carlson, D. Frayer, D. Johnson, C.-Y. Tom, C.P. Trainham, J.T. Williams
  NSTec, Los Alamos, New Mexico
• T.C. Genoni, T.P. Hughes, C.H. Thoma
  Voss Scientific, Albuquerque, New Mexico
• B.A. Prichard, M.E. Schulze
  SAIC, Los Alamos, New Mexico

Funding: This work was supported by the US National Nuclear Security Agency and the US Department of Energy under contract W-7405-ENG-36.

The DARHT-II linear induction accelerator (LIA) now accelerates 2-kA electron beams to more than 17 MeV. This LIA is unique in that the accelerated current pulse width is greater than 2 microseconds. This pulse has a flat-top region where the final electron kinetic energy varies by less than 1% for more than 1.5 microseconds. The long risetime of the 6-cell injector current pulse is 0.5 microsecond, which can be scraped off in a beam-head cleanup zone (BCUZ) before entering the 68-cell main accelerator. We discuss our experience with tuning this novel accelerator; and we will present data for the resulting beam transport and dynamics. We will also present beam stability data, and relate these to previous stability experiments at lower current and energy*.

* “Long-pulse beam stability experiments on the DARHT-II linear induction accelerator,” Carl Ekdahl, et al., IEEE Trans. Plasma. Sci. Vol. 34, 2006, pp. 460-466

Slides

• J.B. Johnson, C. Ekdahl
  LANL, Los Alamos, New Mexico
• W. Broste
  NSTec, Los Alamos, New Mexico

Funding: Work supported by the United States Department of Energy, DOE contract Number: W-7405-ENG-36

Accurate and reliable beam position measurements are required to commission and operate the DARHT II Accelerator. The Beam Position Monitor (BPM) system developed for use on the DARHT II accelerator consists of 31 electro-magnetic detector assemblies, a computer network based data acquisition system, and custom analysis software. During an accelerator “shot”, each BPM uses arrays of b-dot detectors to intercept the electron beam’s changing magnetic field. Post shot analysis of the BPM data provides the beam current and position information used for steering and tuning subsequent shots. This paper will analyze the performance of the BPM system, now that several thousand beam shots have been achieved.