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Experimental evaluation of a negative ion source for a heavy ionfusion negative ion driver [electronic resource].

Published
Princeton, N.J. : Princeton University. Plasma Physics Laboratory, 2005.
Oak Ridge, Tenn. : Distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy.
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Princeton University. Plasma Physics Laboratory and United States. Department of Energy. Office of Scientific and Technical Information
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Summary
Negative halogen ions have recently been proposed as a possible alternative to positive ions for heavy ion fusion drivers because electron accumulation would not be a problem in the accelerator, and if desired, the beams could be photodetached to neutrals [1,2,3]. To test the ability to make suitable quality beams, an experiment was conducted at Lawrence Berkeley National Laboratory using chlorine in an RF-driven ion source. Without introducing any cesium (which is required to enhance negative ion production in hydrogen ion sources) a negative chlorine current density of 45 mA/cm² was obtained under the same conditions that gave 57 mA/cm² of positive chlorine, suggesting the presence of nearly as many negative ions as positive ions in the plasma near the extraction plane. The negative ion spectrum was 99.5% atomic chlorine ions, with only 0.5% molecular chlorine, and essentially no impurities. Although this experiment did not incorporate the type of electron suppression technology that is used in negative hydrogen beam extraction, the ratio of co-extracted electrons to Cl⁻ was as low as 7 to 1, many times lower than the ratio of their mobilities, suggesting that few electrons are present in the near-extractor plasma. This, along with the near-equivalence of the positive and negative ion currents, suggests that the plasma in this region was mostly an ion-ion plasma. The negative chlorine current density was relatively insensitive to pressure, and scaled linearly with RF power. If this linear scaling continues to hold at higher RF powers, it should permit current densities of 100 mA/cm², sufficient for present heavy ion fusion injector concepts. The effective ion temperatures of the positive and negative ions appeared to be similar and relatively low for a plasma source.
Report Numbers
E 1.99:lbnl--56914
E 1.99: hifan 1387
hifan 1387
lbnl--56914
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Note
Published through SciTech Connect.
01/18/2005.
"lbnl--56914"
" hifan 1387"
": AT5015031"
15th International Symposiuson Heavy Ion Fusion,Princeton, NJ, 06/7-11/ 2004.
Leung, K.N.; Kwan, J.W.; Grisham, L.R.; Hahto, S.K.
Ernest Orlando Lawrence Berkeley NationalLaboratory, Berkeley, CA (US)
Funding Information
DE-AC02-05CH11231
Z41003
View MARC record | catkey: 14073979