Design aspects of a compact, single-frequency, permanent magnet ECR ion source with a large uniformly distributed resonant plasma volume
A compact, all-permanent-magnet single-frequency 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 (ORNL). 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 volume. The magnetic field design strongly contrasts with those used in conventional ECR ion sources where the central field regions are approximately parabolic and the consequent ECR zones are surfaces. The plasma confinement magnetic field mirror has a mirror ratio B{sub max}/B{sub ECR} of slightly greater than two. 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 to 6.8 GHz. The RF injection system is broadband to ensure excitation of transverse electric (TE) 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 hot electron population within the plasma volume of the source. The creation of an ECR volume rather than a surface is commensurate with higher charge states and higher beam intensities within a particular charge state.
- Research Organization:
- Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
- Sponsoring Organization:
- USDOE Office of Energy Research, Washington, DC (United States)
- DOE Contract Number:
- FG05-87ER40361; AC05-96OR22464
- OSTI ID:
- 634054
- Report Number(s):
- ORNL/CP-94794; CONF-970958-; ON: DE98000591; TRN: 98:009795
- Resource Relation:
- Conference: 7. international conference on ion sources, Taormina (Italy), 7-13 Sep 1997; Other Information: PBD: Sep 1997
- Country of Publication:
- United States
- Language:
- English
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