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Briggs, R. J.

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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 icon 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.