Alpha particle diagnostic beam line system to generate an intense Li/sup 0/ beam with an ORNL SITEX source
The Oak Ridge National Laboratory (ORNL) SITEX (Surface Ionization with Transverse Extraction) negative ion source utilizes a 100-V/20-A reflex arc discharge in a 1300-gauss magnetic field to generate Cs+ ions and H+ or D+ ions, depending on the beam required. A shaped molybdenum plate is placed directly behind the arc column. Cesium coverage on this plate is used to minimize the surface work function, which requires two-thirds of a monolayer coverage. Cesium coverage ia adjusted both by cesium flow control into the arc discharge chamber and by temperature control of the converter using gaseous-helium cooling channels in the converter plate. Normal converter operational temperatures are 300/sup 0/ to 500/sup 0/C H/sup -//D/sup -/ beams are generated at the biased converter surface (-150 V with respect to the anode) by Cs/sup +/ sputtering of absorbed hydrogen or deuterium and by the reflection-conversion mechanism of H/sup +//D/sup +/ ions which strike the converter surface at 150 eV. The negative ions are accelerated through the 150-V plasma sheath at the converter surface and are focused by the converter geometry and magnetic field so as to pass through the exit aperture with minimum angular divergence. The ion optics of the SITEX accelerator has been calculated using the ORNL 3-D optics code and results in a divergence perpendicular to the slot of theta/sub perpendicular rms/ = 0.35/sup 0/ and parallel to the slot of theta/sub parallel rms/ = 0.18/sup 0/. This beam divergence should be adequate for injection into a radio frequency quadrupole (RFQ) for further acceleration.
- Research Organization:
- Oak Ridge National Lab., TN (USA)
- DOE Contract Number:
- AC05-84OR21400
- OSTI ID:
- 5689967
- Report Number(s):
- CONF-850310-83; ON: DE85010564; TRN: 85-012550
- Resource Relation:
- Conference: 6. topical meeting on the technology of fusion energy, San Francisco, CA, USA, 3 Mar 1985; Other Information: Portions of this document are illegible in microfiche products
- Country of Publication:
- United States
- Language:
- English
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