|TUPAL062||Recent Developments for Cyclotron Extraction Foils at TRIUMF||1159|
Funding: Funded under a contribution agreement with NRC (National Research Council Canada).
The TRIUMF 500 MeV H− cyclotron employs stripping foils to extract multiple beams for different experimental programs. The upgrades in foil material and foil holders lead to significant improvements in beam quality and foil life time, as well as reduction of Be-7 contamination originated in the foils. Thus, an accumulated beam charge extracted with a single foil increased from ~60 mA·hours to more than 500 mA·hours. A key role that lead to these advances was an understanding of the foil heating mechanism, major contribution to which is paid by the power deposition from electrons stripped by the foil. To further diminish this effect, we recently introduced a foil tilt from the vertical orientation that allows stripped electrons fast escape from the foil, well before losing their original momentum through the heat deposition. Other improvements were related to operational issues. Introduction of a "combo" foil consisting of wide portion and thin wire allowed both high and low intensity beam extraction without foils sacrifice. Deploying a wedge foil for extraction at 100 MeV helped reduction of beam intensity instabilities caused by beam vertical size and position fluctuations.
|DOI •||reference for this paper ※ https://doi.org/10.18429/JACoW-IPAC2018-TUPAL062|
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