Impurities Reduction Conditionings to Recover Best Beam Quality of J-PARC Cesiated RF-Driven H- Ion Source with New Parts Exposed to Plasma

Abstract For the J-PARC operations, only three plasma chambers (PCHs) of #7, #8 and #9PCHs among ten PCHs have been used since the transverse emittances of the beam produced with them are more superior than those with others for unknown reasons. However, the #7PCH beam emittances were enlarged by 16...

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Published inJournal of physics. Conference series Vol. 2244; no. 1; pp. 12029 - 12033
Main Authors Ueno, Akira, Ohkoshi, Kiyonori, Ikegami, Kiyoshi, Oguri, Hidetomo
Format Journal Article
LanguageEnglish
Published Bristol IOP Publishing 01.04.2022
Subjects
Impurities
Ion sources
Physics
Plasma
Proton accelerators
Temperature control
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Summary:Abstract For the J-PARC operations, only three plasma chambers (PCHs) of #7, #8 and #9PCHs among ten PCHs have been used since the transverse emittances of the beam produced with them are more superior than those with others for unknown reasons. However, the #7PCH beam emittances were enlarged by 16 % with a brand-new plasma electrode temperature control plate (PETCP) to solve the air leak at the VCR vacuum fitting. The impurities from the new parts exposed to the plasma seemed to cause the degradation. The beam with almost the best emittances was reproduced by #4PCH with a new PETCP after a new impurities reduction conditionings for 48 hours, in which the impurities produced by the plasma were reduced as small as possible by scanning both of 2-MHz-RF power and axial magnetic field in #4PCH.
ISSN:1742-6588
1742-6596
DOI:10.1088/1742-6596/2244/1/012029