Thoma, C. H.

Paper	Title	Page
THOBAB02	Commissioning the DARHT-II Scaled Accelerator Downstream Transport	2627
	M. E. Schulze SAIC, Los Alamos, New Mexico E. O. Abeyta, P. Aragon, R. Archuleta, J. Barraza, D. Dalmas, C. Ekdahl, K. Esquibel, S. Eversole, R. J. Gallegos, J. F. Harrison, E. Jacquez, J. Johnson, P. S. Marroquin, B. T. McCuistian, N. Montoya, S. Nath, L. J. Rowton, R. D. Scarpetti, M. Schauer LANL, Los Alamos, New Mexico R. Anaya, G. J. Caporaso, F. W. Chambers, Y.-J. Chen, S. Falabella, G. Guethlein, J. F. McCarrick, 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, A. Tipton, C.-Y. Tom NSTec, Los Alamos, New Mexico T. C. Genoni, T. P. Hughes, C. H. Thoma Voss Scientific, Albuquerque, New Mexico
	The DARHT-II accelerator will produce a 2-kA, 17-MeV beam in a 1600-ns pulse when completed this summer. After exiting the accelerator, the long pulse is sliced into four short pulses by a kicker and quadrupole septum and then transported for several meters to a tantalum target for conversion to bremsstrahlung for radiography. We describe tests of the kicker, septum, transport, and multi-pulse converter target using a short accelerator assembled from the first available refurbished cells, which are now capable of operating of operating at over 200 kV. This scaled accelerator was operated at ~ 8 Mev and ~1 kA, which provides a beam with approximately the same nu/gamma as the final 17-MeV, 2-kA beam, and therefore the same beam dynamics in the downstream transport. The results of beam measurements made during the commissioning of this scaled accelerator downstream transport are described.
	Slides
THPAN083	A Beam-Slice Algorithm for Transport Simulations of the DARHT-2 Accelerator	3411
	C. H. Thoma ATK-MR, Albuquerque, New Mexico T. P. Hughes Voss Scientific, Albuquerque, New Mexico
	A beam-slice algorithm has been implemented into the Lsp particle-in-cell (PIC) code to allow for efficient simulation of beam electron transport through a long accelerator. The slice algorithm pushes beam particles along a virtual axial dimension and performs a field solve on a transverse grid which moves with the particle slice. Any external electric and magnetic fields are also applied to the slice at each time step. For an axisymmetric beam problem the slice algorithm is very fast compared to full 2-D r-z PIC simulations. The algorithm also calculates beam emittance growth due to mismatch oscillations, in contrast to standard envelope codes which assume constant emittance. Using the slice algorithm we are able to simulate beam transport in the DARHT-2 accelerator at LANL from the region just downstream of the diode to the end of the accelerator, a distance of about 50 meters. Results from the slice simulation are compared to both 2-D PIC simulations and the beam envelope code Lamda. The sensitivity of the final emittance to imperfect tuning of the transport solenoids is calculated.