Penning discharge ion source with self-cleaning aperture
An ion source of the Penning discharge type having a self-cleaning aperture is provided by a second dynode with an exit aperture in a position opposite a first dynode, from which the ions are sputtered, two opposing cathodes, each with an anode for accelerating electrons emitted from the cathodes into a cylindrical space defined by the first and second dynode. A support gas maintained in this space is ionized by the electrons. While the cathodes are supplied with a negative pulse to emit electrons, the first dynode is supplied with a negative pulse (e.g., -300 V) to attract atoms of the ionized gas (plasma). At the same time, the second dynode may also be supplied with a small voltage that is negative with respect to the plasma (e.g., -5 V) for tuning the position of the plasma miniscus for optimum extraction geometry. When the negative pulse to the first dynode is terminated, the second dynode is driven strongly negative (e.g., -600 V) thereby allowing heavy sputtering to take place for a short period to remove virtually all of the atoms deposited on the second dynode from material sputtered off the first dynode. An extractor immediately outside the exit aperture of the second dynode is maintained at ground potential while the anode, dynode, and cathode reference voltage is driven strongly positive (about +20 kV to +30 kV) so that ions accelerated through the aperture will be at ground potential. Material from the first dynode deposited on the second dynode will be sputtered, in time, to add to the ion beam.
- DOE Contract Number:
- W-7405-ENG-48
- Assignee:
- Dept. of Energy
- OSTI ID:
- 6224072
- Country of Publication:
- United States
- Language:
- English
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Penning discharge ion source with self-cleaning aperture
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GENERAL PHYSICS
43 PARTICLE ACCELERATORS
07 ISOTOPES AND RADIATION SOURCES
PENNING ION SOURCES
DESIGN
ANODES
APERTURES
CATHODES
CLEANING
ELECTRONS
SPUTTERING
ELECTRODES
ELEMENTARY PARTICLES
FERMIONS
ION SOURCES
LEPTONS
OPENINGS
640301* - Atomic
Molecular & Chemical Physics- Beams & their Reactions
430301 - Particle Accelerators- Ion Sources
070201 - Radiation Sources- Design
Fabrication & Operation