PAC07 - List of Authors (Henestroza, E.)

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Henestroza, E.

Paper	Title	Page
TUYC01	Studies of the Pulse Line Ion Accelerator	852
	W. L. Waldron, E. Henestroza, L. R. Reginato LBNL, Berkeley, California R. J. Briggs SAIC, Alamo, California A. Friedman LLNL, Livermore, California
	Funding: This work was supported by the Director, Office of Science, Office of Fusion Energy Sciences, of the U. S. Department of Energy under Contracts No. DE-AC02-05CH11231 and W-7405-Eng-48. The Pulse Line Ion Accelerator concept was motivated by the need for an inexpensive way to accelerate intense short pulse heavy ion beams to regimes of interest for studies of High Energy Density Physics and Warm Dense Matter. A pulse power driver applied to one end of a helical pulse line creates a traveling wave that accelerates and axially confines the heavy ion beam pulse. The concept has been demonstrated with ion beams at modest acceleration gradients. Acceleration scenarios with constant parameter helical lines are described which result in output energies of a single stage much larger than the several hundred kilovolt peak voltages on the line, with a goal of 3-5 MeV/m acceleration gradients. This method has the potential to reduce the length of an equivalent induction accelerator by a factor of 6-10 while simplifying the pulsed power systems. The performance of prototype hardware has been limited by high voltage flashover across the vacuum insulator. Bench tests and analysis have led to significantly improved flashover thresholds. Further studies using a variety of experimental configurations are planned.
	Slides
WEPMS016	Modeling the Pulse Line Ion Accelerator (PLIA): An Algorithm for Quasi-Static Field Solution	2364
	A. Friedman, D. P. Grote LLNL, Livermore, California R. J. Briggs SAIC, Alamo, California E. Henestroza, W. L. Waldron LBNL, Berkeley, California
	Funding: Work performed under auspices of U. S. DoE by the Univ. of CA, LLNL & LBNL under Contract Nos. W-7405-Eng-48 and DE-AC02-05CH11231 The Pulse-Line Ion Accelerator* (PLIA) is a helical distributed transmission line. A rising pulse applied to the upstream end appears as a moving spatial voltage ramp, on which an ion pulse can be accelerated. This is a promising approach to acceleration and longitudinal compression of an ion beam at high line charge density. In most of the studies carried out to date, using both a simple code for longitudinal beam dynamics and the Warp PIC code, a circuit model for the wave behavior was employed; in Warp, the helix I and V are source terms in elliptic equations for E and B. However, it appears possible to obtain improved fidelity using a "sheath helix" model in the quasi-static limit. Here we describe an algorithmic approach that may be used to effect such a solution. *R. J. Briggs, PRST-AB 9, 060401 (2006).
WEPMS024	Upgrades to the DAHRT Second Axix Induction Cells	2385
	K. Nielsen, J. Barraza, M. Kang LANL, Los Alamos, New Mexico F. M. Bieniosek, K. Chow, W. M. Fawley, E. Henestroza, L. R. Reginato, W. L. Waldron LBNL, Berkeley, California R. J. Briggs, B. A. Prichard SAIC, Los Alamos, New Mexico T. E. Genoni, T. P. Hughes Voss Scientific, Albuquerque, New Mexico
	The Dual-Axis Radiographic Hydrodynamics Test (DARHT) facility will employ two perpendicular electron Linear Induction Accelerators to produce intense, bremsstrahlung x-ray pulses for flash radiography. The second axis, DARHT II, features a 3-MeV injector and a 15-MeV, 2-kA, 1.6-microsecond accelerator consisting of 74 induction cells and drivers. Major induction cell components include high flux swing magnetic material (Metglas 2605SC) and a MycalexTM insulator. The cell drivers are pulse forming networks (PFNs). The DARHT II accelerator cells have undergone a series of test and modeling efforts to fully understand their operational parameters. Physical changes in the cell oil region, the cell vacuum region, and the cell drivers, together with different operational and maintenance procedures, have been implemented in the prototype. A series of prototype acceptance tests have demonstrated that the required cell lifetime is met at the increased performance levels. Shortcomings of the original design are summarized and improvements to the design, their resultant enhancement in performance, and various test results are discussed.
THPAN086	End-to-end Simulations of an Accelerator for Heavy Ion Beam Bunching	3420
	D. R. Welch, D. Rose Voss Scientific, Albuquerque, New Mexico J. E. Coleman, E. Henestroza, P. K. Roy, P. A. Seidl LBNL, Berkeley, California E. P. Gilson, A. B. Sefkow PPPL, Princeton, New Jersey
	Funding: This research was supported by the U. S. Department of Energy through Princeton Plasma Physics Laboratory and Lawrence Berkeley National Laboratory for the HIFS-VNL. Longitudinal bunching factors in excess of 70 of a 300-keV, 27-mA K+ ion beam have been demonstrated in the Neutralized Drift Compression Experiment in rough agreement with LSP particle-in-cell end-to-end simulations. These simulations include both the experimental diode voltage and induction bunching module voltage waveforms in order to specify the initial beam longitudinal phase space critical to longitudinal compression. To maximize simultaneous longitudinal and transverse compression, we designed a solenoidal focusing system that compensated for the impact of the applied velocity tilt on the transverse phase space of the beam. Here, pre-formed plasma provides beam neutralization in the last one meter drift region where the beam perveance becomes large. Integrated LSP simulations, that include detailed modeling of the diode, magnetic transport, induction bunching module, plasma neutralized transport, were critical to understanding the interplay between the various accelerator components. Here, we compare simulation results with the experiment and discuss the contributions to longitudinal and transverse emittance that limit compression.