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Hoff, M. D.

Paper Title Page
TUPAS045 Microwave Ion Source and Beam Injection for an Accelerator-driven Neutron Source 1745
  • J. H. Vainionpaa, R. Gough, M. D. Hoff, J. W. Kwan, B. A. Ludewigt, M. J. Regis, J. G. Wallig, R. P. Wells
    LBNL, Berkeley, California
  Funding: Supported by Office of Science, of the U. S. Department of Energy under Contract No. DE-AC02-05CH11231 and by the U. S. Department of Homeland Security under contract No. HSHQBP-05-X-00033.

An over-dense microwave driven ion source capable of producing deuterium (or hydrogen) beams at 100-200 mA/cm2 with an atomic fraction > 90% was designed as a part of an Accelerator Driven Neutron Source (ADNS). The ion source was tested with an electrostatic low energy beam transport section (LEBT) and measured emittance data was compared to PBGUNS simulations. In our design a 40 mA D+ beam is produced from a 6 mm diameter aperture using a 60 kV extraction voltage. The LEBT section consists of 5 electrodes arranged to form 2 Einzel lenses that focus the beam into the RFQ entrance. To create the ECR condition, 2 induction coils are used to generate a ~875 Gauss magnetic field on axis inside the source chamber. To prevent HV breakdown in the LEBT, a magnetic field clamp is necessary to minimize the field in this region. The microwave power is matched to the plasma by an autotuner. A significant improvement in the atomic fracion of the beam was achieved by installing a boron nitride liner inside the ion source

WEPMN118 Mechanical Design and Analysis of a 200 MHz, Bolt-together RFQ for the Accelerator Driven Neutron Source 2313
  • S. P. Virostek, M. D. Hoff, D. Li, J. W. Staples, R. P. Wells
    LBNL, Berkeley, California
  Funding: This work was supported by the U. S. Dept. of Energy under Contract No. DE-AC02-05CH11231 and by the Dept. of Homeland Security's Domestic Nuclear Detection Office under Award No. HSHQPB-05-X-00033.

A high-yield neutron source to screen sea-land cargo containers for shielded Special Nuclear Materials (SNM) has been designed at LBNL. The Accelerator-Driven Neutron Source (ADNS) utilizes the D(d,n)3He reaction to produce a forward directed neutron beam. Key components are a high-current radio-frequency quadrupole (RFQ) accelerator and a high-power neutron production target capable of delivering a neutron flux of >107 n/(cm2 s) at a distance of 2.5 m. The mechanical design and analysis of the four-module, bolt-together RFQ will be presented here. Operating at 200 MHz, the 5.1 m long RFQ will accelerate a 40 mA deuteron beam to 6 MeV. At a 5% duty factor, the time-average d+ beam current on target is 1.5 mA. Each of the 1.27 m long RFQ modules will consist of four solid OFHC copper vanes. A specially designed 3-D O-ring will be used to provide vacuum sealing between both the vanes and the modules. RF connections are made by means of canted coil spring contacts. Quadrupole mode stabilization is obtained with a series of 60 water-cooled pi-mode rods. A set of 80 evenly spaced fixed slug tuners is used for final frequency adjustment and local field perturbation correction.