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Vacuum status at KEKB. Junji Haba. KEKB Vacuum system. Vacuum monitoring. HER vacuum characteristics. Dependence on HER current is clear. <p> ~ 0.3 (0A) 1.2 (1.3A) x10 -7 Pa 1nTorr (PEPII) =1.3 x 10 -7 Pa (KEKB) Far from “base pressure dominance” Not always simple linear relation
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Vacuum status at KEKB Junji Haba
HER vacuum characteristics • Dependence on HER current is clear. • <p> ~ 0.3 (0A) 1.2 (1.3A) x10-7Pa 1nTorr (PEPII) =1.3 x 10-7 Pa (KEKB) • Far from “base pressure dominance” • Not always simple linear relation • Some show a clear thermal behavior • Beam life time is a function not only of pressure but also luminosity or beam-beam effect.
Heat up at the feed back kicker structure Discharge starts around 0.9A at septum?
Beam-beam also affects the lifetime LER current HER beam size vs LER current HER life and beam size
LER vacuum characteristics • Current dependence is clear • <p>~ 0.2 (0A) 0.8 (1.6A) x10-7Pa • Thermal behavior everywhere we have the parts with a special internal shape like GV, crotches, injection chamber etc.