CAPRICE ECR Ion Source

CHRONOLOGY

Oringinal ORNL ECR Source in operation since 1984; fabricated with AT funds; was first ECR source worldwide to be exclusively dedicated to study of atomic collisions of multicharged ions

BES funded source upgrade approved in FY 1991.

  • state-of-the-art CAPRICE ECR source installed
  • number of beam lines expanded
  • improved data acquisition and source control
  • improved the quality of charge state performance

    • Mini-oven for metallic species installed and tested Dec. 1993

  • can produce multicharged ion beams of virtually any element of Periodic Table

    • 1 Tesla hexapole installed Nov., 1995

  • provides better electron confinement than original 8.5 kG hexople

    • RECENT PROGRESS

    In-Situ Plasma potential measurements using Langmuir & Emissive probe method done in May 2005

  • Found that, for normal ECR ion source operating conditions, the large population of hot electrons may make the emissive floating point method fail, and may cause the values deduced using the LP method to be in error by more than 10%.
  • Found significant decrease of the plasma potential during gas mixing; the corresponding increase in ion confinement time may be the dominant mechanism responsible for the gas mixing effect.
  • Plasma potential values extreamely sensitive to the surface condition of source chamber walls. Contaminated surface gave plasma potential values larger by 10-15 V.

    • Floating Beamline Upgrade Project

    As a second phase of the MIRF upgrade project, the CAPRICE ECR ion source is being relocated within MIRF. The beamline into which beams will be extracted/accelerated will be able to be biased to voltages up to -20kV. In this way the ECR ion source can be held at ground potential, to permit production of very low energy ion beams in grounded experimental chambers.

    Implementation of floating beamline (1 - 20,000 eV/q):

  • permits attainment of eV/q energies without use of floating scattering chamber (Low energy ion surface interactions)
  • permits more efficient transport of keV/q energy beams (Electron- Ion Crossed-Beams, Low energy I ion surface interactions )
  • increases beam access
  • permits access to new low energy user beamline

    • TIMELINE

    Floating Beamline

  • Relocation of CAPRICE together with floating beamline -- fall 2005
  • Installation of decelerated beams surface sattering chamber -- fall 2005
  • Relocation of electron-ion crossed beams apparatus installation -- fall 2005

    • CAPRICE ECR ion source


    CAPRICE ECR Ion Source and Performance

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    Charge State Performance

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    Improvement on Metal Multicharged Ions

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    Rev: 17-Sep-2005 12:13:05 EDT by H.J. You