• V.G. Dudnikov, R.P. Johnson
  Muons, Inc, Batavia
• G. Dudnikova
  UMD, College Park, Maryland
• M.P. Stockli, R.F. Welton
  ORNL, Oak Ridge, Tennessee

Funding: Supported in part by the US DOE Contract DE-AC05-00OR22725

Spallation neutron source user facilities require reliable, intense beams of protons. The technique of H^- charge exchange injection into a storage ring or synchrotron can provide the needed beam currents, but may be limited by the ion sources that have currents and reliability that do not meet future requirements and emittances that are too large for efficient acceleration. In this project we are developing an H^- source which will synthesize the most important developments in the field of negative ion sources to provide high current, small emittance, good lifetime, high reliability, and power efficiency. We describe planned modifications to the present external antenna source at SNS that involve: 1) replacing the present 2 MHz plasma-forming solenoid antenna with a 60 MHz saddle-type antenna and 2) replacing the permanent multicusp magnet with a weaker electro-magnet, in order to increase the plasma density near the outlet aperture. The SNS test stand will then be used to verify simulations of this approach that indicate significant improvements in H^- output current and efficiency, where lower RF power will allow higher duty factor, longer source lifetime, and/or better reliability.

• V.V. Danilov, Y. Liu
  ORNL, Oak Ridge, Tennessee
• K.B. Beard, V.G. Dudnikov, R.P. Johnson
  Muons, Inc, Batavia
• M.D. Shinn
  JLAB, Newport News, Virginia

Funding: Supported in part by USDOE Contract No. DE-AC05-84-ER-40150. Supported in part by USDOE Contract DE-AC05-00OR22725

The ORNL spallation neutron source (SNS) user facility requires a reliable, intense beams of protons. The technique of H^- charge exchange injection into a storage ring or synchrotron has the potential to provide the needed beam currents, but it will be limited by intrinsic limitations of carbon and diamond stripping foils. A laser in combination with magnetic stripping has been used to demonstrate a new technique for high intensity proton injection, but several problems need to be solved before a practical system can be realized. Technology developed for use in Free Electron Lasers is being used to address the remaining challenges to practical implementation of laser controlled H^- charge exchange injection for the SNS. These technical challenges include (1) operation in vacuum, (2) the control of the UV laser beam to synchronize with the H^- beam and to shape the proton beam, (3) the control and stabilization of the Fabry-Perot resonator, and (4) protection of the mirrors from radiation.