• R.F. Welton, J.R. Carmichael, D.W. Crisp, S.N. Murray, T.R. Pennisi, M. Santana, M.P. Stockli
  ORNL, Oak Ridge, Tennessee
• B. Han
  ORNL RAD, Oak Ridge, Tennessee

Funding: The work at Oak Ridge National Laboratory, which is managed by UT-Battelle, LLC, was performed under contract DE-AC05-00OR2275 for the US Department of Energy.

The U.S. Spallation Neutron Source (SNS) is an accelerator-based, pulsed neutron-scattering facility, currently in the process of ramping up neutron production. In order to insure that we will meet our operational commitments as well as provide for future facility upgrades with high reliability, we have developed an RF-driven, H^- ion source based on a ceramic aluminum nitride (AlN) plasma chamber*. This source is expected to enter service as the SNS neutron production source starting in 2009. This report details the design of the production source which features an AlN plasma chamber, 2-layer external antenna, cooled-multicusp magnet array, Cs2CrO4 cesium system and a Molybdenum plasma ignition gun. Performance of the production source both on the SNS accelerator and SNS test stand is reported. The source has also been designed to accommodate an elemental Cs system with an external reservoir which has demonstrated unanalyzed beam currents up to ~100mA (60Hz, 1ms) on the SNS ion source test stand.

*R.F. Welton, et al., “Next Generation Ion Sources for the SNS”, Proceedings of the 1st Conference on Negative Ion Beams and Sources, Aix-en-Provence, France, 2008

• R.F. Welton, J.R. Carmichael, D.W. Crisp, S.C. Forrester, R.H. Goulding, S.N. Murray, D.O. Sparks, M.P. Stockli
  ORNL, Oak Ridge, Tennessee
• O.A. Tarvainen
  LANL, Los Alamos, New Mexico

Funding: Research sponsored by the Laboratory Directed Research and Development Program of Oak Ridge National Laboratory (ORNL), managed by UT-Battelle, LLC for the U. S. Department of Energy

Plasmas produced by helicon wave excitation typically develop higher densities, particularly near the radial plasma core, at lower operating pressures and RF powers than plasmas produced using traditional inductive RF coupling methods. Approximately two years ago we received funding to develop an H^- ion source based on helicon wave coupling. Our approach was to combine an existing high-density, hydrogen helicon plasma generator developed at ORNL for the Variable Specific Impulse Magnetoplasma Rocket (VASIMR) project with the SNS external antenna H^- source. To date we have achieved plasma densities >10¹³ e/cm³ inside the ion source using <10kW of RF power and <5 SCCM of H2 gas flow. This report discusses the first cesiated H^- beam current extraction measurements from the source.