Design aspects of a compact, single-frequency, permanent-magnet electron cyclotron resonance ion source with a large uniformly distributed resonant plasma volume
- Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831-6368 (United States)
A compact, all-permanent-magnet, single-frequency electron cyclotron resonance (ECR) ion source with a large uniformly distributed ECR plasma volume has been designed and is presently under construction at the Oak Ridge National Laboratory. The central region of the field is designed to achieve a flat field (constant mod-B) which extends over the length of the central field region along the axis of symmetry and radially outward to form a uniformly distributed ECR plasma {open_quotes}volume.{close_quotes} The magnetic field design strongly contrasts with those used in conventional ECR ion sources where the central field regions are approximately parabolic and the resulting ECR zones are {open_quotes}surfaces.{close_quotes} The plasma confinement magnetic field mirror has a mirror ratio B{sub max}/B{sub ECR} of slightly greater than 2. The source is designed to operate at a nominal rf frequency of 6 GHz. The central flat magnetic field region can be easily adjusted by mechanical means to tune the source to the resonant conditions within the limits of 5.5{endash}6.8 GHz. The rf injection system is broadband to ensure excitation of transverse electric modes so that the rf power is largely concentrated in the resonant plasma volume which lies along and surrounds the axis of symmetry of the source. Because of the much larger ECR zone, the probability for absorption of microwave power is dramatically increased, thereby increasing the probability for acceleration of electrons, the electron temperature of the plasma, and, consequently, the {open_quotes}hot{close_quotes} electron population within the plasma volume of the source. The creation of an ECR {open_quotes}volume{close_quotes} rather than a {open_quotes}surface{close_quotes} is commensurate with higher charge states and higher beam intensities within a particular charge state. The source has also been designed so that it can be easily converted into a conventional magnetic field geometry source so that comparisons of the performances of the {open_quotes}volume{close_quotes} and {open_quotes}surface{close_quotes} forms of the source can be easily made. The design features of the source and rf injection system will be described in detail in this article. {copyright} {ital 1998 American Institute of Physics.}
- OSTI ID:
- 591887
- Report Number(s):
- CONF-980145-; ISSN 0034-6748; TRN: 98:004852
- Journal Information:
- Review of Scientific Instruments, Vol. 69, Issue 2; Conference: 7. international conference on ion sources, Shirahama (Japan), 26-27 Jan 1998; Other Information: PBD: Feb 1998
- Country of Publication:
- United States
- Language:
- English
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